CNS..pdf

Radiology Review Manual

6th Edition

2007 Lippincott Williams & Wilkins

Central Nervous System

Differential Diagnosis of Skull and Spine Disorders

Low back pain

Low Back Pain in Childhood

Spondylosis, spondylolisthesis

Osteomyelitis, diskitis

Leukemia

Histiocytosis X

Osteoid osteoma

Lumbosacral Postsurgical Syndrome

= Failed back surgery syndrome

= signs of dysfunction and disability + pain and paresthesia following surgery

Interpretation in immediate postoperative period difficult, stabilization of

findings occurs in 26 months

Frequency: failure of improvement in 515%

OSSEOUS CAUSES

Spondylolisthesis

Central stenosis

Foraminal stenosis

Pseudarthrosis

SOFT-TISSUE CAUSES

Perioperative intraspinal hemorrhage

(onset

post injection)

Fibrosing arachnoiditis = adhesive arachnoiditis

thickened irregular clumped nerve roots

adhesion of roots to wall of thecal sac

abnormal enhancement of thickened meninges + matted nerve roots

SURGICAL ERRORS

Wrong level / side of surgery

Direct nerve injury

Remote phenomena unrelated to spine

mnemonic: ABCDEF

Arachnoiditis

Bleeding

Contamination (infection)

Disk (residual / recurrent / new level)

Error (wrong disk excised)

Fibrosis (scar)

Cauda Equina Syndrome

= constellation of signs + symptoms resulting from compressive lesion in lower

lumbar spinal canal

Cause:

displaced disk fragment

intra- / extramedullary tumor

osseous: Paget disease, osteomyelitis, osteoarthrosis of facet joints,

complication of ankylosing spondylitis

diminished sensation in lower lumbar + sacral

dermatomes

wasting + weakness of muscles

decreased ankle reflexes

impotence

disturbed sphincter function + overflow incontinence

decreased sphincter tone

Skull

Sutural Abnormalities

Wide Sutures

= >10 mm at birth, >3 mm at 2 years, >2 mm at 3 years of age; (sutures are

splittable up to age 1215; complete closure by age 30)

NORMAL VARIANT

in neonate + prematurity; growth spurt occurs at 23 years and 57 years

Congenital underossification

osteogenesis imperfecta, hypophosphatasia, rickets, hypothyroidism,

pyknodysostosis, cleidocranial dysplasia

METABOLIC DISEASE

hypoparathyroidism; lead intoxication; hypo- / hypervitaminosis A

RAISED INTRACRANIAL PRESSURE

Cause:

intracerebral tumor

subdural hematoma

hydrocephalus

Age: seen only if sagittal > lambdoid > squamosal suture

INFILTRATION OF SUTURES

Cause: metastases to meninges from

neuroblastoma

leukemia

lymphoma

poorly defined margins

RECOVERY

from

deprivational dwarfism

chronic illness

prematurity

hypothyroidism

P.178

Craniosynostosis

= CRANIOSTENOSIS = premature closure of sutures (normally at about 30

years of age)

Age: often present at birth; M:F = 4:1

Etiology:

Primary craniosynostosis

Secondary craniosynostosis

hematologic: sickle cell anemia, thalassemia

metabolic: rickets, hypercalcemia, hyperthyroidism, hypervitaminosis D

bone dysplasia: hypophosphatasia, achondroplasia, metaphyseal dysplasia,

mongolism, Hurler disease, skull hyperostosis, Rubinstein-Taybi syndrome

syndromes: Crouzon, Apert, Carpenter, Treacher-Collins, cloverleaf skull,

craniotelen-cephalic dysplasia, arrhinencephaly

microcephaly: brain atrophy / dysgenesis

after shunting procedures

Types:

Sagittal suture most commonly affected followed by coronal suture

Scaphocephaly = Dolichocephaly (55%):

premature closure of sagittal suture (long skull)

Brachycephaly = Turricephaly (10%):

premature closure of coronal / lambdoid sutures (short tall skull)

Plagiocephaly (7%):

unilateral early fusion of coronal + lambdoidal suture (lopsided skull)

Trigonocephaly:

premature closure of metopic suture (forward pointing skull)

Oxycephaly:

premature closure of coronal, sagittal, lambdoid sutures

Cloverleaf skull = Kleeblattschdel:

intrauterine premature closure of sagittal, coronal, lambdoid sutures;

May be associated with: thanatophoric dysplasia

sharply defined thickened sclerotic suture margins

delayed growth of BPD in early pregnancy

Wormian Bones

= intrasutural ossicles in lambdoid, posterior sagittal, temporosquamosal

sutures; normal up to 6 months of age (most frequently)

mnemonic: PORK CHOPS I

Pyknodysostosis

Osteogenesis imperfecta

Rickets in healing phase

Kinky hair syndrome

Cleidocranial dysostosis

Hypothyroidism / Hypophosphatasia

Oto-palato-digital syndrome

Primary acroosteolysis (Hajdu-Cheney) / Pachydermoperiostosis / Progeria

Syndrome of Down

Idiopathic

Increased Skull Thickness

GENERALIZED

Chronic severe anemia (eg, thalassemia, sickle cell disease)

Cerebral atrophy following shunting of hydrocephalus

Engelmann disease: mainly skull base

Hyperparathyroidism

Acromegaly

Osteopetrosis

FOCAL

Meningioma

Fibrous dysplasia

Paget disease

Dyke-Davidoff-Mason syndrome

Hyperostosis frontalis interna = dense hyperostosis of inner table of frontal

bone; M < F

mnemonic: HIPFAM

Hyperostosis frontalis interna

Idiopathic

Paget disease

Fibrous dysplasia

Anemia (sickle cell, iron deficiency, thalassemia, spherocytosis)

Metastases

Hair-on-end Skull

mnemonic: HI NEST

Hereditary spherocytosis

Iron deficiency anemia

Neuroblastoma

Enzyme deficiency (glucose-6-phosphate dehydrogenase deficiency causes

hemolytic anemia)

Sickle cell disease

Thalassemia major

Leontiasis Ossea

= overgrowth of facial bones causing leonine (lionlike) facies

Fibrous dysplasia

Paget disease

Craniometaphyseal dysplasia

Hyperphosphatasia

Abnormally Thin Skull

GENERALIZED

Obstructive hydrocephalus

Cleidocranial dysostosis

Progeria

Rickets


Craniolacunia

FOCAL

Neurofibromatosis

Chronic subdural hematoma

Arachnoid cyst

Inadequate Calvarial Calcification

Achondroplasia


Hypophosphatasia

P.179

Osteolytic Lesion of Skull

NORMAL VARIANT

Emissary vein

connecting venous systems inside + outside skull

bony channel 18 months; usually adulthood

usually multiple punched-out lesions with irregular contour in

parasagittal location

Location: within 3 cm of superior sagittal sinus, anterior > posterior frontal

bone

Site: inner table > diploe > outer table

Parietal foramina

nonossification of embryonal rests in parietal fissure; bilateral at superior

posterior angles of parietal bone; hereditary transmission

TRAUMA

Surgical burr hole

Leptomeningeal cyst

INFECTION

Osteomyelitis

Hydatid disease

Syphilis

Tuberculosis

CONGENITAL

Epidermoid / dermoid

Neurofibromatosis (asterion defect)

Meningoencephalocele

Fibrous dysplasia

Osteoporosis circumscripta of Paget disease

BENIGN TUMOR

Hemangioma

Enchondroma

Brown tumor

Eosinophilic granuloma

MALIGNANT TUMOR

Solitary / multiple metastases

Multiple myeloma

Leukemia

Neuroblastoma

Solitary Lytic Lesion in Skull

mnemonic: HELP MFT HOLE

Hemangioma

Epidermoid / dermoid

Leptomeningeal cyst

Postop, Paget disease

Metastasis, Myeloma

Fibrous dysplasia

Tuberculosis

Hyperparathyroidism

Osteomyelitis

Lambdoid defect (neurofibromatosis)


Multiple Lytic Lesions in Skull

mnemonic: BAMMAH

Brown tumor

AVM

Myeloma

Metastases

Amyloidosis

Histiocytosis

Lytic Area in Bone Flap

mnemonic: RATI

Radiation necrosis

Avascular necrosis

Tumor

Infection

Button Sequestrum

mnemonic: TORE ME

Tuberculosis

Osteomyelitis

Radiation


Metastasis

Epidermoid

Absent Greater Sphenoid Wing

mnemonic: M FOR MARINE

Meningioma

Fibrous dysplasia

Optic glioma

Relapsing hematoma

Metastasis

Aneurysm

Retinoblastoma

Idiopathic

Neurofibromatosis


Absence of Innominate Line

= Oblique carotid line

= vertical line projecting into orbit (on PA skull film) produced by orbital

process of sphenoid

CONGENITAL

Fibrous dysplasia

Neurofibromatosis

INFECTION

TUMOR

Widened Superior Orbital Fissure

mnemonic: A FAN

Aneurysm (internal carotid artery)

Fistula (cavernous sinus)

Adenoma (pituitary)

Neurofibroma

Tumors of Central Skull Base

DEVELOPMENTAL

Encephalocele

INFECTION / INFLAMMATION

Extension from paranasal sinus / mastoid infection

Complication of trauma

P.180

Fungal disease: mucormycosis in diabetics, aspergillosis in immunosuppressed

patients

Sinus + nasopharyngeal sarcoidosis

Radiation necrosis

BENIGN

Juvenile angiofibroma

Meningioma

Chordoma

Pituitary tumor

Paget disease

Fibrous dysplasia

MALIGNANT

Metastasis: prostate, lung, breast

Chondrosarcoma

Nasopharyngeal carcinoma

Rhabdomyosarcoma

Perineural tumor spread: head + neck neoplasm

Craniofacial Syndromes

= developmental malformations of the face + skull associated with CNS

malformations

Midfacial clefts

Goldenhar syndrome

Apert syndrome

Crouzon syndrome

Treacher-Collins syndrome

Maxilla and mandible

Maxillary Hypoplasia

Down syndrome

Drugs (alcohol, dilantin, valproate)

Apert / Crouzon syndrome

Achondroplasia

Cleft lip / palate

Mandibular Hypoplasia = Micrognathia

WITH ABNORMAL EARS

Treacher-Collins syndrome

Goldenhar syndrome (hemifacial microsomia) = facio-auriculo-vertebral

spectrum (x-rays of vertebrae!)

Langer-Giedion syndrome (IUGR, protruding ears)

ABNORMALITIES OF EARS + OTHER ORGANS

Miller syndrome (severe postaxial hand anomalies)

Velo-cardio-facial syndrome (hand + cardiac lesions)

Oto-palato-digital syndrome - type II (hand abnormalities)

Stickler syndrome (ear anomalies not severe)

Pierre-Robin syndrome (large fleshy ears)

NO EAR ANOMALIES

Pyknodysostosis

OTHERS

Seckel syndrome (bird-headed dwarfism)

Multiple pterygium syndrome

Pena-Shokeir syndrome

Beckwith-Wiedemann syndrome

Arthrogryposis

Skeletal dysplasias

Trisomy 13, 18, 9 (abnormal karyotype in 25%)

Destruction of Temporomandibular Joint

mnemonic: HIRT

Hyperparathyroidism

Infection

Rheumatoid arthritis

Trauma

Radiolucent Lesion of Mandible

SHARPLY MARGINATED LESION

around apex of tooth

Radicular cyst

Cementoma

around unerupted tooth

Dentigerous cyst

Ameloblastoma

unrelated to tooth

Simple bone cyst

Fong disease

Basal cell nevus syndrome

POORLY MARGINATED LESIONS

floating teeth: suggestive of primary / secondary malignancy

resorption of tooth root: hallmark of benign process

infection

Osteomyelitis: actinomycosis

radiotherapy

Osteoradionecrosis

malignant neoplasm

Osteosarcoma (1/3 lytic, 1/3 sclerotic, 1/3 mixed)

Local invasion from gingival / buccal neoplasms (more common)

Metastasis from breast, lung, kidney in 1% (in 70% adenocarcinoma)

other

Eosinophilic granuloma: floating tooth

Fibrous dysplasia

Osteocementoma

Ossifying fibroma (very common)

Cystic Lesion of Jaw

ODONTOGENIC WITHOUT MINERALIZATION

= mostly benign lesion developing during / after formation of teeth

asymptomatic / pain swelling

paresthesia, tooth displacement / mobility

radiolucent

Ameloblastoma = adamantinoma of jaw

= benign locally aggressive epithelial neoplasm

Prevalence: 10% of odontogenic tumors

Origin: enamel-type epithelial tissue elements around tooth; 3050% arise

from epithelium of dentigerous cyst (= mural ameloblastoma)

Age: 3rd5th decade; M:F = 1:1

slow-growing painless mass

Location: ramus + posterior body of mandible (75%), maxilla (25%)

Site: in region of bicuspids + molars (angle of mandible commonly affected)

well-defined well-corticated unilocular lucent lesion (DDx: odontogenic

keratocyst, dentigerous cyst)

P.181

multilocular lesion with internal septations (honeycomb / soap bubble

appearance)

typically expansile with scalloped margin

may perforate the lingual cortex + infiltrate adjacent soft tissues

often associated with the crown of an impacted / unerupted tooth

resorption of the root of a tooth

Prognosis: frequently local recurrence even more aggressive after excision

Odontogenic keratocyst

Origin: dental lamina + other sources of odontogenic epithelium

Prevalence: 515% of all jaw cysts

Age: 2nd4th decade

Path: daughter cysts + nests of cystic epithelia in vicinity (high rate of

recurrence)

Histo: parakeratinized lining epithelium + cheesy material in lumen of

lesion

Location: body + ramus of mandible (most often); may be anywhere in

mandible / maxilla

unilocular lucent lesion with smooth corticated border

often associated with impacted tooth

undulating borders / multilocular appearance

cortical thinning, tooth displacement, root resorption

DDx: indistinguishable from dentigerous cyst / ameloblastoma

Dentigerous cyst = follicular cyst

Prevalence: most common type of noninflammatory odontogenic cyst

Path: epithelial-lined cyst from odontogenic epithelium developing around

unerupted tooth

Histo: forms within lining of dental follicle

Age: adolescent / young adult

typically painfree

Location: mandible, maxilla (may expand into maxillary sinus)

Site: around the crown of an unerupted tooth (usually 3rd molar)

cystic expansile pericoronal lesion containing impacted tooth

root of tooth often outside lesion

well-defined round / ovoid corticated lucent lesion mandibular expansion

Cx: may degenerate into mural ameloblastoma (rare)

DDx: unilocular odontogenic keratocyst

Radicular cyst = periapical cyst

Prevalence: most common cyst of the jaw

Cause: periapical inflammatory lesion secondary to pulpal necrosis in deep

carious lesion / deep filling / trauma

Age: 3050 years

Site: intimately associated with apex of nonvital tooth

round / pear-shaped unilocular periapical lucent lesion, usually

ODONTOGENIC WITH MINERALIZATION

= elaborate enamel, dentin, cementum

varying degrees of opacity

Odontoma

= odontogenic hamartomatous malformation

Prevalence: most common odontogenic mass (67%)

Age: 2nd decade

13 cm in diameter

may be surrounded by lucent follicle

Types:

compound odontoma (more common)

multiple teeth / tooth-like structures

complex odontoma

= multiple masses of dental tissue

well-defined lesion with amorphous calcifications

Cx: impaction, malpositioning, resorption of adjacent teeth

DDx: focal cemento-osseous dysplasia, ameloblastic fibro-odontoma,

adenomatoid odontogenic tumor

Odontogenic myxoma

Prevalence: 36% of odontogenic tumors

Origin: mesenchymal odontogenic tissue

Age: 1030 years; M < F

usually painless

Location: maxilla > mandible

well-demarcated / ill-defined lytic lesion of varying size

often multilocular with honeycomb-like internal structure

foci of irregular calcifications (frequent)

Cx: can be locally aggressive causing considerable destruction of adjacent bone

+ soft-tissue infiltration

DDx: malignancy, traumatic bone cyst, central giant cell granuloma, calcifying

epithelial odontogenic tumor

Nonodontogenic

Ossifying fibroma (conventional slow-growing ossifying fibroma, juvenile

active aggressive ossifying fibroma)

= encapsulated circumscribed benign neoplasm

Histo: highly cellular fibrous connective tissue containing varying amounts of

osteoid, bone, cementum, cementum-like calcified tissue

asymptomatic

facial asymmetry due to bone expansion

tooth displacement

initially lucent + later often opaque lesion (depending on degree of

calcification)

surrounded by thin line of lucency (= fibrous capsule) + in turn surrounded

by thin sclerotic rim of reactive bone

intense focal uptake on bone scan

P.182

DDx: odontoma, sequestrum, fibrous dysplasia, vascular lesion

Focal cemento-osseous dysplasia

= nonneoplastic benign fibro-osseous lesion

Age: adult life

asymptomatic

Location: mandible >> maxilla

one / more, closely apposed / confluent, round / ovoid lucent lesion with

varying amounts of opacity

initially cystic lucency + later progressively more opaque internally

no extension into adjacent bone

no cortical expansion

DDx: periapical periodontitis, ossifying fibroma

Periapical cemento-osseous dysplasia

(= cementoma) = fibro-osteoma

Age: 3040 years of age; most common in women

asymptomatic

Location: in anterior portion of mandible

Site: at apex of vital tooth

often multicentric

mixed lucent + sclerotic lesion with little expansion, calcifies with time

DDx: ossifying fibroma, fibrous dysplasia, Paget disease

Florid osseous dysplasia

Age: adult life

asymptomatic

diffuse multiquadrant distribution of mixed lucent-opaque osseous changes

Traumatic bone cyst

= not a true cyst for lack of epithelial lining

Cause: ? response to trauma

Age: 2nd decade

asymptomatic

Location: mandible

unilocular sharply marginated lucent defect

scalloped superior margin with fingerlike projections extending between

roots of teeth

thinning of mandibular cortex osseous expansion

DDx: vascular lesion, central giant cell granuloma, ossifying fibroma

Lingual salivary gland inclusion defect

= well-defined depression in lingual surface of mandible (= Stafne cyst)

Path: aberrant lobe of submandibular gland / fat

asymptomatic

Location: usually near mandibular angle

Site: just above inferior border of mandible, anterior to angle of jaw, inferior to

mandibular canal, posterior to 3rd molar

oval / rectangular well-defined area of lucency

border surrounded by an opaque line

may extend to buccal cortex

DDx: arteriovenous malformation

Central giant cell granuloma (common)

Age:

cystlike due to bone resorption calcifications

multilocular bone expansion

erosive margins

angiogram confirms diagnosis

DDx: traumatic bone cyst, central giant cell granuloma, ossifying fibroma

Mucoepidermoid carcinoma

Tooth Mass

CYSTIC LESION

Radicular cyst = periapical cyst

Ameloblastoma = adamantinoma of jaw

Giant cell reparative granuloma

Primordial cyst

arising from follicle of tooth that never developed

Traumatic bone cyst

Dentigerous cyst = follicular cyst

Odontogenic keratocyst

SCLEROTIC LESION

Cementoma

True cementoma = benign cementoblastoma

Gigantiform cementoma

Hypercementosis

= bulbous enlargement of a root

idiopathic

associated with Paget disease

Benign fibro-osseous lesions

ossifying fibroma: young adults; mandible > maxilla

monostotic fibrous dysplasia: M < F, younger patients

condensing osteitis = focal chronic sclerosing osteitis

near apex of nonvital tooth

Paget disease

involvement of jaw in 20%; maxilla > mandible

Location: bilateral, symmetric involvement

widened alveolar ridges

flat palate

P.183

loosening of teeth

hypercementosis

may cause destruction of lamina dura

Torus mandibularis = exostosis

Site: midline of hard palate; lingual surface of mandible in region of bicuspids

Craniovertebral junction

Craniovertebral Junction Anomaly

Basilar Invagination

= primary developmental anomaly with abnormally high position of vertebral

column prolapsing into skull base

Associated with: Chiari malformation, syringohydromyelia in 2535%

Cause:

Condylus tertius = ossicle at distal end of clivus

pseudojoint with odontoid process / anterior arch of C1

Condylar hypoplasia

lateral masses of atlas may be fused to condyles

violation of Chamberlain line

widening of atlanto-occipital joint axis angle

tip of odontoid >10 mm above bimastoid line

Basiocciput hypoplasia

shortening of clivus


clivus-canal angle typically decreased

Atlanto-occipital assimilation

= complete / partial failure of segmentation between skull + 1st cervical

vertebra


clivus-canal angle decreased

May be associated with: fusion of C2 + C3

Cx: atlantoaxial subluxation (50%); sudden death

limitation in range of motion of CVJ

abnormal craniometry

C-spine + foramen magnum bulge into cranial cavity

elevation of posterior arch of C1

Basilar Impression

= acquired form of basilar invagination with bulging of C-spine and foramen

magnum into cranial cavity

tip of odontoid process projects >5 mm above Chamberlain line (= line

between hard palate + opisthion)

Cause: Paget disease, osteomalacia, rickets, fibrous dysplasia,

hyperparathyroidism, Hurler syndrome, osteogenesis imperfecta, skull base

infection

mnemonic: PF ROACH

Paget disease

Fibrous dysplasia

Rickets

Osteogenesis imperfecta, Osteomalacia

Achondroplasia

Cleidocranial dysplasia

Hyperparathyroidism, Hurler syndrome

Platybasia

= anthropometric term referring to flattening of skull base

May be associated with: basilar invagination

cord symptoms

craniovertebral = clivus-canal angle becomes acute (140

bowstring deformity of cervicomedullary junction

Atlas and axis

Atlas Anomalies

POSTERIOR ARCH ANOMALIES

Posterior atlas arch rachischisis (4%)

Location: midline (97%), lateral through sulcus of vertebral artery (3%)

absence of arch-canal line (LAT view)

superimposed on odontoid process / axis body simulating a fracture (open-

mouth odontoid view)

Total aplasia of posterior atlas arch

Keller-type aplasia with persistence of posterior tubercle

Aplasia with uni- / bilateral remnant + midline rachischisis

Partial / total hemiaplasia of posterior arch

ANTERIOR ARCH ANOMALIES

Isolated anterior arch rachischisis (0.1%)

Split atlas = anterior + posterior arch rachischisis

plump rounded anterior arch overlapping the odontoid process making

identification of predental space impossible (LAT view)

duplicated anterior margins (LAT view)

Axis Anomalies

Persistent ossiculum terminale = Bergman ossicle

unfused odontoid process >12 years of age

DDx: type 1 odontoid fracture

Odontoid aplasia (extremely rare)

Os odontoideum

= independent os cephalad to axis body in location of odontoid process

absence of odontoid process

anterior arch of atlas hypertrophic + situated too far posterior in relation to

axis body

Cx: atlantoaxial instability

DDx: type 2 odontoid fracture (uncorticated margin)

Primary and Secondary Ossification Centers

P.184

Odontoid Erosion

mnemonic: P LARD

Psoriasis

Lupus erythematosus

Ankylosing spondylitis


Down syndrome

Atlantoaxial Subluxation

= displacement of atlas with respect to axis

Posterior atlantoaxial subluxation (rare)

Anterior atlantoaxial subluxation (common)

= distance between dens + anterior arch of C1 (measurement along midplane

of atlas on lateral view):

predental space: >2.5 mm; >4.5 mm (in children)

retrodental space:

Arthritis

due to laxity of transverse ligament or erosion of dens


Psoriatic arthritis

Reiter syndrome


SLE

rare: in gout + CPPD

Inflammatory process

pharyngeal infection in childhood, retropharyngeal abscess, coryza, otitis

media, mastoiditis, cervical adenitis, parotitis, alveolar abscess

dislocation 810 days after onset of symptoms

Trauma (very rare without odontoid fracture)

Marfan disease

mnemonic: JAP LARD

Juvenile rheumatoid arthritis


Psoriatic arthritis

Lupus erythematosus

Accident (trauma)

Retropharyngeal abscess, Rheumatoid arthritis

Down syndrome

Pseudosubluxation of Cervical Spine

= ligamentous laxity in infants allows for movement of the vertebral bodies on

each other, esp. C2 on C3

Spinal dysraphism

= abnormal / incomplete fusion of midline embryologic mesenchymal,

neurologic, bony structures

External signs (in 50%):

subcutaneous lipoma spastic gait disturbance

hypertrichosis foot deformities

pigmented nevi absent tendon reflexes

skin dimple sinus tract

bladder + bowel dysfunction

pathologic plantar response

Spina Bifida

= incomplete closure of bony elements of the spine (lamina + spinous

processes) posteriorly

Spina Bifida Occulta

= OCCULT SPINAL DYSRAPHISM

= cleft / tethered cord WITH skin cover

Frequency: 15% of spinal dysraphism

rarely leads to neurologic deficit in itself

Associated with:

vertebral defect (8590%)

lumbosacral dermal lesion (80%): hairy tuft (= hypertrichosis), dimple, sinus

tract, nevus, hyperpigmentation, hemangioma, subcutaneous mass

Diastematomyelia

Lipomeningocele

Tethered cord syndrome

Filum terminale lipoma

Intraspinal dermoid

Epidermoid cyst

Myelocystocele

Split notochord syndrome

Meningocele

Dorsal dermal sinus

Tight filum terminale syndrome

Spina Bifida Aperta

= SPINA BIFIDA CYSTICA

= posterior protrusion of all / parts of the contents of the spinal canal through

a bony spinal defect

Frequency: 85% of spinal dysraphism

Associated with: hydrocephalus, Arnold-Chiari II malformation

Most severe form of midline fusion defect

neural placode WITHOUT skin cover

associated with neurologic deficit in >90%

Simple meningocele

= herniation of CSF-filled sac without neural elements

Myelocele

= midline plaque of neural tissue lying exposed at the skin surface

Myelomeningocele

= a myelocele elevated above skin surface by expansion of subarachnoid space

ventral to neural plaque

Myeloschisis

= surface presentation of neural elements completely uncovered by meninges

Caudal Spinal Anomalies

= malformation of distal spine and cord in association with hindgut, renal, and

genitourinary anomalies

Terminal myelocystocele

Lateral meningocele

Caudal regression

P.185

Segmentation Anomalies of Vertebral Bodies

Clefts in Neural Arch

during 912th week of gestation two ossification centers form for the ventral +

dorsal half of vertebral body

Asomia = agenesis of vertebral body

complete absence of vertebral body

hypoplastic posterior elements may be present

Hemivertebra

Unilateral wedge vertebra

right / left hemivertebra

scoliosis at birth

Dorsal hemivertebra

rapidly progressive kyphoscoliosis

Ventral hemivertebra (extremely rare)

Coronal cleft

= failure of fusion of anterior + posterior ossification centers

May be associated with: premature male infant, Chondrodystrophia

calcificans congenita

Location: usually in lower thoracic + lumbar spine

vertical radiolucent band just behind midportion of vertebral body;

disappears mostly by 6 months of life

Butterfly vertebra

= failure of fusion of lateral halves secondary to persistence of notochordal

tissue

May be associated with: anterior spina bifida anterior meningocele

widened vertebral body with butterfly configuration (AP view)

adaptation of vertebral endplates of adjacent vertebral bodies

Block vertebra

= congenital vertebral fusion

Location: lumbar / cervical

height of fused vertebral bodies equals the sum of heights of involved bodies

+ intervertebral disk

waist at level of intervertebral disk space

Hypoplastic vertebra

Klippel-Feil syndrome

Vertebral body

Destruction of Vertebral Body

NEOPLASM

Metastasis

Primary neoplasm: lymphoma, multiple myeloma, chordoma

INFECTION

Pyogenic vertebral osteomyelitis

Tuberculous spondylitis

Brucellosis

Fungal disease

Echinococcosis

Sarcoidosis

Gas in Vertebral Body

Osteonecrosis = Kmmell disease: linear collection

Osteomyelitis: small gas bubbles extension into adjacent soft-tissues

Intraosseous displacement of cartilaginous / Schmorl node: branching gas

pattern

Malignancy

Small Vertebral Body

Radiation therapy

during early childhood in excess of 1,000 rads

Juvenile rheumatoid arthritis

Location: cervical spine

atlantoaxial subluxation may be present

vertebral fusion may occur


Location: lumbar / lower thoracic spine

compression deformity / vertebra plana

Gaucher disease

= deposits of glucocerebrosides within RES

compression deformity

Platyspondyly generalisata

= flattened vertebral bodies associated with many hereditary systemic disorders

(achondroplasia, spondyloepiphyseal dysplasia tarda, mucopolysaccharidosis,

osteopetrosis, neurofibromatosis, osteogenesis imperfecta, thanatophoric

dwarfism)

disk spaces of normal height

Vertebra Plana

mnemonic: FETISH

Fracture (trauma, osteogenesis imperfecta)


Tumor (metastasis, myeloma, leukemia)

Infection

Steroids (avascular necrosis)

Hemangioma

Signs of Acute Vertebral Collapse on MRI

OSTEOPOROSIS

retropulsion of posterior bone fragment

MALIGNANCY

epidural soft-tissue mass

no residual normal marrow signal intensity

abnormal enhancement

P.186

Enlarged Vertebral Body

Paget disease

picture framing; bone sclerosis

Gigantism

increase in height of body + disk

Myositis ossificans progressiva

bodies greater in height than width

osteoporosis

ossification of ligamentum nuchae

Enlarged Vertebral Foramen

Neurofibroma

Congenital absence / hypoplasia of pedicle

Dural ectasia (Marfan syndrome, Ehlers-Danlos syndrome)

Intraspinal neoplasm

Metastatic destruction of pedicle

Cervical Spine Fusion

mnemonic: SPAR BIT

Senile hypertrophic ankylosis (DISH)

Psoriasis, Progressive myositis ossificans


Reiter disease, Rheumatoid arthritis (juvenile)

Block vertebra (Klippel-Feil)

Infection (TB)

Trauma

Vertebral Border Abnormality

Straightening of Anterior Border


Paget disease

Psoriatic arthritis

Reiter disease


Normal variant

Anterior Scalloping of Vertebrae

Aortic aneurysm

Lymphadenopathy

Tuberculosis

Multiple myeloma (paravertebral soft-tissue mass)

Posterior Scalloping of Vertebrae

in conditions associated with dural ectasia

INCREASED INTRASPINAL PRESSURE

Communicating hydrocephalus

Ependymoma

MESENCHYMAL TISSUE LAXITY (dural ectasia)

Neurofibromatosis

Marfan syndrome

Ehlers-Danlos syndrome

Posterior meningocele

BONE SOFTENING

Mucopolysaccharidoses: Hurler, Morquio, Sanfilippo

Achondroplasia

Acromegaly (lumbar vertebrae)

Ankylosing spondylitis (lax dura acting on osteoporotic vertebrae)

mnemonic: DAMN MALE SHAME

Dermoid


Meningioma

Neurofibromatosis

Marfan syndrome

Acromegaly

Lipoma

Ependymoma

Syringohydromyelia

Hydrocephalus

Achondroplasia

Mucopolysaccharidoses

Ehlers-Danlos syndrome

Bony Outgrowths from Vertebra

CHILDHOOD

Hurler syndrome = gargoylism

rounded appearance of vertebral bodies

mild kyphotic curve with smaller vertebral body at apex of kyphosis

displaying tonguelike beak at anterior half (usually at T12 / L1)

step-off deformities along anterior margins

Hunter syndrome

less severe changes than in Hurler syndrome

Morquio disease

flattened + widened vertebral bodies

anterior tonguelike elongation of central portion of vertebral bodies

Hypothyroidism = cretinism

small flat vertebral bodies

anterior tonguelike deformity (in children only)

widened disk spaces + irregular endplates

ADULTS

Spondylosis deformans

osteophytosis along anterior + lateral aspects of endplates with horizontal +

vertical course as a result of shearing of the outer annular fibers (Sharpey

fibers connecting the annulus fibrosus to adjacent vertebral body)

Diffuse idiopathic skeletal hyperostosis (DISH)

flowing calcifications + ossifications along anterolateral aspect of >4

contiguous thoracic vertebral bodies osteophytosis


bilateral symmetric syndesmophytes (ossification of annulus fibrosus)

bamboo spine

Syndesmophytes

P.187

diskal ballooning = biconvex intervertebral disks secondary to

osteoporotic deformity of endplates

straightening of anterior margins of vertebral bodies (erosion)

ossification of paraspinal ligaments

Fluorosis

vertebral osteophytosis + hyperostosis

sclerotic vertebral bodies + kyphoscoliosis

calcification of paraspinal ligaments

Acromegaly

increase in anteroposterior diameter of vertebrae + concavity on posterior

portion

enlargement of intervertebral disk

Hypoparathyroidism

Neuropathic arthropathy

Sternoclavicular hyperostosis

Spine Ossification

Syndesmophyte = ossification of annulus fibrosus

thin slender vertical outgrowth extending from margin of one vertebral body to

next

Associated with: ankylosing spondylitis, ochronosis

Osteophyte

= ossification of anterior longitudinal ligament

initially triangular outgrowth several millimeters from edge of vertebral body

Associated with: osteoarthritis

Flowing anterior ossification

= ossification of disk, anterior longitudinal ligament, paravertebral soft tissues

Associated with: DISH

Paravertebral ossification

initially irregular / poorly defined paravertebral ossification eventually

merging with vertebral body

Associated with: psoriatic arthritis, Reiter syndrome

Vertebral Endplate Abnormality

Cupids bow vertebra

Cause: ? (normal variant)

Location: 35th lumbar vertebra

two parasagittal posterior concavities on inferior aspect of vertebral body

(viewed on AP)

Osteoporosis (senile / steroid-induced)

fish / fish-mouth vertebrae

Cause: osteomalacia, Paget disease, hyperparathyroidism, Gaucher disease

biconcave vertebrae

bone sclerosis along endplates

wedge-shaped vertebrae

anterior border height reduced by >4 mm compared to posterior border

height

pancake vertebrae

overall flattening of vertebra

H-vertebrae

= compression of central portions from subchondral infarcts

Cause: sickle cell + other anemias, Gaucher disease

Schmorl / cartilaginous node

= intraosseous herniation of nucleus pulposus at center of weakened endplate

Vertebral Endplate Abnormalities

Cause: Scheuermann disease, trauma, hyperparathyroidism, osteochondrosis

Butterfly vertebra

Cause: congenital defect

Ring epiphysis

Limbus vertebrae

= intraosseous herniation of disk material at junction of vertebral bony rim of

centra + endplate (anterosuperior corner)

Rugger-jersey spine

Cause: hyperparathyroidism, myelofibrosis

horizontal sclerosis subjacent to vertebral endplates with intervening normal

osseous density (resembling the stripes on rugby jerseys)

Sandwich / hamburger vertebrae

Cause: osteopetrosis, myelofibrosis

sclerotic endplates alternate with radiolucent midportions of vertebral

bodies

Ring Epiphysis

= normal aspect of developing vertebra (between 6 and 12 years of age)

small steplike recess at corner of anterior edge of vertebral body

Severe osteoporosis

Healing rickets

Scurvy

Bullet-shaped Vertebral Body

mnemonic: HAM

Hypothyroidism

Achondroplasia

Morquio syndrome

Bone-within-bone Vertebra

= ghost vertebra following stressful event during vertebral growth phase in

childhood

Stress line of unknown cause

Leukemia

Heavy metal poisoning

Thorotrast injection, TB

Rickets

Scurvy

Hypothyroidism

Hypoparathyroidism

P.188

Ivory Vertebra

mnemonic: LOST FROM CHOMP

Lymphoma

Osteopetrosis

Sickle cell disease

Trauma, Tuberculous spondylitis

Fluorosis

Renal osteodystrophy

Osteoblastic metastasis

Myelosclerosis

Chronic sclerosing osteomyelitis, Chordoma

Hemangioma

Osteosarcoma

Myeloma

Paget disease

Sclerotic Pedicle

Osteoid osteoma

Unilateral spondylolysis

Contralateral congenitally absent pedicle

Tumor of vertebra

Expansile Lesion of Vertebrae

INVOLVEMENT OF MULTIPLE VERTEBRAE

Metastases, multiple myeloma / plasmacytoma, lymphoma, hemangioma,

Paget disease, angiosarcoma, eosinophilic granuloma

INVOLVEMENT OF TWO / MORE CONTIGUOUS VERTEBRAE

Osteochondroma, chordoma, aneurysmal bone cyst, myeloma

BENIGN LESION

Osteochondroma (15% with solitary osteochondromas, 79% with hereditary

multiple exostoses) commonly cervical, esp. C2; commonly rising from

posterior elements

Osteoblastoma (3040% in spine)

M:F = 2:1; equal distribution in spine; posterior elements (lamina, pedicle),

may involve body if large; expansile lesion with sclerotic / shell-like rim, foci

of calcified tumor matrix in 50%

Giant cell tumor (57% in spine)

commonly sacrum, expansile lytic lesion of vertebral body with well-defined

borders; secondary invasion of posterior elements; malignant degeneration in

520% after radiation therapy

Osteoid osteoma (1025% in spine)

commonly lower thoracic / upper lumbar spine, posterior elements (pedicle,

lamina, spinous process), painful scoliosis with concavity toward lesion

Aneurysmal bone cyst (1230% in spine)

thoracic > lumbar > cervical spine, posterior elements with frequent extension

into vertebral bodies, well-defined margins, may arise from primary bone

lesion (giant cell tumor, fibrous dysplasia) in 50%, may involve two contiguous

vertebrae

Hemangioma (30% in spine)

10% incidence in general population; commonly lower thoracic / upper

lumbar spine, vertebral body, accordion / corduroy appearance

Hydatid cyst (1% in spine)

slow-growing destructive lesion, well-defined sclerotic borders, endemic areas

Paget disease

vertebral body posterior elements, enlargement of bone, picture framing;

bone sclerosis

Eosinophilic granuloma (6% in spine)

most often cervical / lumbar spine, vertebral body, vertebra plana; multiple

involvement common

Fibrous dysplasia (1% in spine)

vertebral body, nonhomogeneous trabecular ground-glass appearance

Enostosis (114% in spine)

Location: T1T7 > L2L3

MALIGNANT

Chordoma (15% in spine)

most common nonlymphoproliferative primary malignant tumor of the spine

in adults; particularly C2, within vertebral body; violates disk space

Metastasis (especially from lung, breast)

Age: >50 years of age;

Clue: pedicles often destroyed

Multiple myeloma / plasmacytoma

Clue: vertebral pedicles usually spared

Angiosarcoma

10% involve spine, most commonly lumbar

Chondrosarcoma (312% in spine)

2nd most common nonlymphoproliferative primary malignant tumor of the

spine in adults

Site: vertebral body (15%), posterior elements (40%), both (45%)

involvement of adjacent vertebra by extension through disk (35%)

Ewing sarcoma and PNET

most common nonlymphoproliferative primary malignant tumor of the spine

in children; metastases more common than primary

Site: vertebral body with extension to posterior elements

diffuse sclerosis + osteonecrosis (69%)

Osteosarcoma (0.63.2% in spine)

Average age: 4th decade

Location: lumbosacral segments

Site: vertebral body, posterior elements (1017%)

may present as ivory vertebra

Lymphoma

Blowout Lesion of Posterior Elements

mnemonic: GO APE

Giant cell tumor

Osteoblastoma

Aneurysmal bone cyst

Plasmacytoma


Bone Tumors Favoring Vertebral Bodies

mnemonic: CALL HOME

Chordoma


P.189

Leukemia

Lymphoma

Hemangioma

Osteoid osteoma, Osteoblastoma

Myeloma, Metastasis


Primary Vertebral Tumors in Children

[in order of frequency:]

Osteoid osteoma

Benign osteoblastoma


Ewing sarcoma

Primary Tumor of Posterior Elements

mnemonic: A HOG


Hydatid cyst, Hemangioma

Osteoblastoma, Osteoid osteoma

Giant cell tumor

Sacrum

Destructive Sacral Lesion

mnemonic: SPACEMON

Sarcoma

Plasmacytoma


Chordoma

Ependymoma

Metastasis

Osteomyelitis

Neuroblastoma

Sacral Tumor

Sacral Bone Tumor

BENIGN

Giant cell tumor (2nd most common primary)

Aneurysmal bone cyst (rare)

Cavernous hemangioma (very rare)

Osteoid osteoma / osteoblastoma (very rare)

MALIGNANT

Metastases (most common sacral neoplasm):

hematogenous: lung, breast, kidney, prostate

contiguous: rectum, uterus, bladder

Plasmacytoma, multiple myeloma

Lymphoma, leukemia

Chordoma (most common primary)

24% of malignant osseous neoplasms!

Sacrococcygeal teratoma

Ewing sarcoma (rare)

Sacral Canal Tumor (less common)

BENIGN

Neurofibroma: multiple suggestive of NF

Schwannoma (rare)

Meningioma (very rare)

MALIGNANT

Ependymoma

Drop metastases

Carcinoid tumor

Intervertebral disk

Loss of Disk Space

Degenerative disk disease

Neuropathic osteoarthropathy

Dialysis spondyloarthropathy with amyloidosis

Ochronosis

Ankylosing spondylitis with pseudarthrosis

Sarcoidosis

Spinal Vacuum Phenomena

nucleus pulposus Osteochondrosis

annulus fibrosus Spondylosis deformans

disk within vertebral body Cartilaginous node

disk within spinal canal Intraspinal disk herniation

apophyseal joint Osteoarthritis

vertebral body Ischemic necrosis

Vacuum Phenomenon in Intervertebral Disk Space

= liberation of nitrogen gas from surrounding tissues into clefts with an

abnormal nucleus or annulus attachment

Prevalence: in up to 20% of plain radiographs / in up to 50% of spinal CT in

patients > age 40

Cause:

Primary / secondary degeneration of nucleus pulposus

Intraosseous herniation of disk (= Schmorl node)

Spondylosis deformans (gas in annulus fibrosus)

Adjacent vertebral metastatic disease with vertebral collapse

Infection (extremely rare)

Intervertebral Disk Calcification

mnemonic: A DISC SO WHITE

Amyloidosis, Acromegaly

Degenerative

Infection

Spinal fusion

CPPD

Spondylitis ankylosing

Ochronosis

Wilson disease

Hemochromatosis, Homocystinuria, Hyperparathyroidism

Idiopathic skeletal hyperostosis

Traumatic

Etceteras: Gout and other causes of chondrocalcinosis

Intervertebral Disk Ossification

Associated with: fusion of vertebral bodies


Ochronosis

Sequelae of trauma

Sequelae of disk-space infection

Degenerative disease

Schmorl = Cartilaginous Node

= superior / inferior intravertebral herniation of disk material through

weakened area of vertebral endplate

Pathogenesis: disruption of cartilaginous plate of vertebral body left during

regression of chorda dorsalis, ossification gaps, previous vascular channels

P.190

Cause:

osseous: osteoporosis, osteomalacia, Paget disease, hyperparathyroidism,

infection, neoplasm

cartilaginous: intervertebral osteochondrosis, disk infection, juvenile kyphosis

concave defects at upper and lower vertebral endplates with sharp margins

MR:

node of similar signal intensity as disk

low signal intensity of rim

associated with narrowed disk space

Mneumonic of DDx: SHOOT

Scheuermann disease

Hyperparathyroidism

Osteoporosis

Osteomalacia

Trauma

Spinal cord

Most spinal cord neoplasms are malignant!

9095% are classified as gliomas

Intramedullary Lesion

Prevalence: 410% of all CNS tumors; 20% of all intraspinal tumors in adults

(35% in children)

TUMOR

expansion of cord

heterogeneous signal on T2WI

cysts + necrosis

variable enhancement (vast majority with some enhancement)

primary:

Ependymoma (60% of all spinal cord tumors)

The most common glial tumor in adults

Astrocytoma (25%)

The most common intramedullary tumor in children

Hemangioblastoma (5%)

Oligodendroglioma (3%)

Epidermoid, dermoid, teratoma (12%)

Ganglioglioma (1%)

Lipoma (1%)

Location:

cervical region: astrocytoma

thoracic region: teratoma-dermoid, astrocytoma

lumbar region: ependymoma, dermoid

metastatic: eg, malignant melanoma, breast, lung

CYSTIC LESION

fluid isointense to CSF

smooth well-defined internal margins

thinned adjacent parenchyma

cord atrophy

no contrast enhancement

peritumoral cyst = syringomyelia

polar / satellite cysts = rostral / caudal cysts representing reactive dilatation

of central canal

A higher location within spinal canal raises the likelihood of syrinx

development

Prevalence: in 60% of all intramedullary tumors

Syringomyelia

Hydromyelia

Reactive cyst

tumoral cyst

shows peripheral enhancement

Ganglioglioma (in 46%)

Astrocytoma (in 20%)

Ependymoma (in 3%)

Hemangioblastoma (24%)

VASCULAR

Cord concussion = reversible local edema

Hemorrhagic contusion

Cord transection

AVM

CHRONIC INFECTION

Sarcoid

Transverse myelitis

Multiple sclerosis

mnemonic: IM ASHAMED

Inflammation (multiple sclerosis, sarcoidosis, myelitis)

Medulloblastoma

Astrocytoma

Syringomyelia / hydromyelia

Hematoma, Hemangioblastoma

Arteriovenous malformation

Metastasis

Ependymoma

Dermoid

Intramedullary Neoplastic Lesion

GLIAL NEOPLASM (9095%)

Ependymoma (60%)

Astrocytoma (33%)

Ganglioglioma (1%)

NONGLIAL NEOPLASM

highly vascular lesions:

Hemangioblastoma

Paraganglioma

rare lesions:

Metastasis

Lymphoma

Primitive neuroectodermal tumor

USUALLY EXTRAMEDULLARY NEOPLASM

Intramedullary meningioma

Intramedullary schwannoma

Intramedullary Nonneoplastic Mass

Epidermoid

Congenital lipoma

Posttraumatic pseudocyst

Wegener granuloma

Cavernous malformation

Abscess

Intramedullary Nonneoplastic Lesion

Prevalence: 4%

no cord expansion

Demyelinating disease

Sarcoidosis

Amyloid angiopathy

Pseudotumor

P.191

Dural arteriovenous fistula

Cord infarction

Chronic arachnoiditis

Cystic myelomalacia

Cord Lesions

INFLAMMATION

Multiple sclerosis

Acute disseminated encephalomyelitis

Acute transverse myelitis

involves half the cross-sectional area of cord

Lyme disease

Devic syndrome

INFECTION

Cytomegalovirus

Progressive multifocal leukoencephalopathy

HIV

VASCULAR

Anterior spinal artery infarct

affects central gray matter first

extends to anterior two-thirds of cord

Venous infarct / ischemia

starts centrally progressing centripetally

NEOPLASM

Intradural Extramedullary Mass

Nerve sheath tumor (35%)

Meningioma (25%)

Lipoma

Dermoid

commonly conus / cauda equina; associated with spinal dysraphism (1/3)

Ependymoma

commonly filum terminale; NO spinal dysraphism

Metastasis

Drop metastases from CNS tumors

Metastases from outside CNS

Arachnoid cyst

Neurenteric cyst

Hemangioblastoma

Paraganglioma

mnemonic: MAMA N

Metastasis

Arachnoiditis

Meningioma

AVM, Arachnoid cyst

Neurofibroma

Epidural Extramedullary Lesion

= EXTRADURAL LESIONS OF SPINE

arise from bone, fat, vessels, lymph nodes, extramedullary neural elements

Prevalence: 30% of all spinal tumors

TUMOR

benign

Dermoid, epidermoid

Lipoma: over several segments

Fibroma

Neurinoma (with intradural component)

Meningioma (with intradural component)

Ganglioneuroblastoma, ganglioneuroma

malignant

Hodgkin disease

Lymphoma: most commonly in dorsal space

Metastasis: breast, lung most commonly from involved vertebrae without

extension through dura

Paravertebral neuroblastoma

DISK DISEASE

Bulging disk

Herniated nucleus pulposus

Sequestered nucleus pulposus

BONE

Tumor of vertebra

Spinal stenosis

Spondylosis

INFECTION: epidural abscess

BLOOD: hematoma

OTHERS: synovial cyst, arachnoid cyst, extradural lipomatosis,

extramedullary hematopoiesis

mnemonic: MANDELIN

Metastasis (drop mets from CNS tumor), Meningioma

Arachnoiditis, Arachnoid cyst

Neurofibroma

Dermoid / epidermoid

Ependymoma

Lipoma

Infection (TB, cysticercosis)

Normal but tortuous roots

Cord Atrophy

Multiple sclerosis

Amyotrophic lateral sclerosis

Cervical spondylosis

Sequelae of trauma

Ischemia

Radiation therapy

AVM of cord

Delayed Uptake of Water-Soluble Contrast in Cord Lesion

Syringohydromyelia

Cystic tumor of cord

Osteomalacia

exceedingly rare:

Demyelinating disease

Infection

Infarction

Extraarachnoid Myelography

SUBDURAL INJECTION

spinal cord, nerve roots, blood vessels not outlined

irregular filling defects

slow flow of contrast material

CSF pulsations diminished

contrast material pools at injection site within anterior / posterior

compartments

EPIDURAL INJECTION

contrast extravasation along nerve roots

contrast material lies near periphery of spinal canal

intraspinal structures are not well outlined

P.192

Musculoskeletal neurogenic tumors

BENIGN NEUROGENIC TUMOR

Traumatic neuroma

Morton neuroma

Neural fibrolipoma

Nerve sheath ganglion

Benign peripheral nerve sheath tumors (PNST)

Schwannoma = Neurilemmoma

Neurofibroma: localized, diffuse

Plexiform neurofibroma

MALIGNANT NEUROGENIC NEOPLASM

= malignant peripheral nerve sheath tumor (MPNST)

Spinal fixation devices

Function:

to restore anatomic alignment in fractures (fracture reduction)

to stabilize degenerative disease

to correct congenital deformities (scoliosis)

to replace diseased / abnormal vertebrae (infection, tumor)

Posterior Fixation Devices

using paired / unpaired rods attached with

Sublaminar wiring

= passing a wire around lamina + rod

Interspinous wiring

= passing a wire through a hole in the spinous process; a Drummond button

prevents the wire from pulling through the bone

Subpars wiring

= passing a wire around the pars interarticularis

Laminar / sublaminar hooks

used on rods for compression / distraction forces to be applied to pedicles /

laminae

upgoing hook curves under lamina

downgoing hook curves over lamina

Pedicle / transpedical screws

Rods

Luque rod = straight / L-shaped smooth rod 68 mm in diameter

O-ring fixator, rhomboid-shaped bar, Luque rectangle, segmental rectangle =

preshaped loop to form a flat rectangle

Harrington distraction rod

Harrington compression rod

Knodt rod = threaded distraction rod with a central fixed nut (turnbuckle) and

opposing thread pattern

Cotrel-Dubousset rods = a pair of rods with a serrated surface connected by a

cross-link with 4 laminar hooks / pedicle screws

Plates

Roy-Camille plates

= simple straight plates with round holes

Luque plates

= long oval holes with clips encircling the plate

Steffee plates = straight plates with long slots

Translaminar screw

= cancellous screws for single level fusion

Percutaneous pinning

= (hollow) interference screws placed across disk level

Anterior Fixation Devices

Dwyer device

= screws threaded into vertebral body over staples embedded into vertebral

body connected by braided titanium wire; placed on convex side of spine

Zielke device

= modified Dwyer system replacing cable with solid rod

Kaneda device

= 2 curved vertebral plates with staples attached to vertebral bodies with

screws, plates connected by 2 threaded rods attached to screw heads

Dunn device

(similar to Kaneda device, discontinued)

Spinal Fixation Devices

P.193

Cotrel-Dubousset Rods and Pedicle Screws

P.194

Anatomy of Skull and Spine

Foramina of base of skull

on inner aspect of middle cranial fossa 3 foramina are oriented along an

oblique line in the greater sphenoidal wing from anteromedial behind the

superior orbital fissure to posterolateral

mnemonic: rotos

foramen rotundum

foramen ovale

foramen spinosum

Foramen Rotundum

= canal within greater sphenoid wing connecting middle cranial fossa +

pterygopalatine fossa

Location: inferior and lateral to superior orbital fissure

Course: extends obliquely forward + slightly inferiorly in a sagittal direction

parallel to superior orbital fissure

Contents:

nerves: V2 (maxillary nerve)

(b) vessels:

artery of foramen rotundum

emissary vv.

best visualized by coronal CT

Foramen Ovale

= canal connecting middle cranial fossa + infratemporal fossa

Location: medial aspect of sphenoid body, situated posterolateral to foramen

rotundum (endocranial aspect) + at base of lateral pterygoid plate (exocranial

aspect)

Contents:

nerves:

V3 (mandibular nerve)

lesser petrosal nerve (occasionally)

vessels:

accessory meningeal artery

emissary vv.

Foramen Spinosum

Location: on greater sphenoid wing posterolateral to foramen ovale

(endocranial aspect) + lateral to eustachian tube (exocranial aspect)

Contents:

nerves:

recurrent meningeal branch of mandibular nerve

lesser superficial petrosal nerve

vessels:

middle meningeal a.

middle meningeal v.

Foramen Lacerum

Fibrocartilage cover (occasionally), carotid artery rests on endocranial aspect

of fibrocartilage

Location: at base of medial pterygoid plate

Contents: (inconstant)

nerve: nerve of pterygoid canal (actually pierces cartilage)

vessel: meningeal branch of ascending pharyngeal a.

Foramen Magnum

Contents:

nerves:

medulla oblongata

cranial nerve XI (spinal accessory n.)

vessels:

vertebral a.

anterior spinal a.

posterior spinal a.

Pterygoid Canal

= VIDIAN CANAL

= within sphenoid body connecting pterygopalatine fossa anteriorly to foramen

lacerum posteriorly

Location: at base of pterygoid plate below foramen rotundum

Contents:

nerves: vidian nerve = nerve of pterygoid canal = continuation of greater

superficial petrosal nerve (from cranial nerve VII) after its union with deep

petrosal nerve

vessel: vidian artery = artery of pterygoid canal = branch of terminal portion of

internal maxillary a. arises in pterygopalatine fossa + passes through foramen

lacerum posterior to Vidian n.

Hypoglossal Canal

= ANTERIOR CONDYLAR CANAL

Location: in posterior cranial fossa anteriorly above condyle starting above

anterolateral part of foramen magnum, continuing in an anterolateral direction

+ exiting medial to jugular foramen

Contents:

nerves: cranial nerve XII (hypoglossal nerve)

vessels:

pharyngeal artery

branches of meningeal artery

Jugular Foramen

Location: at the posterior end of petro-occipital suture directly posterior to

carotid orifice

anterior part:

inferior petrosal sinus

meningeal branches of pharyngeal artery + occipital artery

intermediate part:

cranial nerve IX (glossopharyngeal nerve)

cranial nerve X (vagus nerve)

cranial nerve XI (spinal accessory nerve)

posterior part: internal jugular vein

Craniovertebral junction

Craniometry:

LATERAL VIEW

Chamberlain line = line between posterior pole of hard palate + opisthion

(= posterior margin of foramen magnum)

P.195

tip of odontoid process usually lies below / tangent to Chamberlain line

tip of odontoid process may lie up to 1 6.6 mm above the Chamberlain line

McGregor line = line between posterior pole of hard palate + most caudal

portion of occipital squamosal surface

Substitute to Chamberlain line if opisthion not visible

tip of odontoid

Skull Base Lines on Lateral View

Open-Mouth Odontoid View

Bimastoid line = line connecting the tips of both mastoid processes

tip of odontoid

Normal Relationship of Craniovertebral Junction

(range of the two extreme normal positions of the basion is drawn in dashes)

P.196

Meninges of spinal cord

PERIOSTEUM

= continuation of outer layer of cerebral dura mater

EPIDURAL SPACE

= space between dura mater + bone containing rich plexus of epidural veins,

lymphatic channels, connective tissue, fat

cervical + thoracic spine: spacious posteriorly, potential space anteriorly

normal thickness of epidural fat 36 mm at T7

lower lumbar + sacral spine: may occupy more than half of cross-sectional area

DURA

= continuation of meningeal / inner layer of cerebral dura mater; ends at 2nd

sacral vertebra + forms coccygeal ligament around filum terminale; sends

tubular extensions around spinal nerves; is continuous with epineurium of

peripheral nerves

Attachment: at circumference of foramen magnum, bodies of 2nd + 3rd

cervical vertebrae, posterior longitudinal ligament (by connective tissue

strands)

SUBARACHNOID SPACE

= space between arachnoid and pia mater containing CSF, reaching as far

lateral as spinal ganglia

dentate ligament partially divides CSF space into an anterior + posterior

compartment extending from foramen magnum to 1st lumbar vertebra, is

continuous with pia mater of cord medially + dura mater laterally (between

exiting nerves)

dorsal subarachnoid septum connects the arachnoid to the pia mater

(cribriform septum)

PIA MATER

= firm vascular membrane intimately adherent to spinal cord, blends with dura

mater in intervertebral foramina around spinal ganglia, forms filum terminale,

fuses with periosteum of 1st coccygeal segment

Meninges of Spinal Cord

Typical Cervical Vertebra

(cranial aspect)

Thoracic spine

12 load-bearing vertebrae

posterior arch (= pedicles, laminae, facets, transverse processes) handles

tensional forces

vertebral bodies:

height of vertebrae anteriorly 23 mm less than posteriorly = mild kyphotic

curvature

AP diameter: gradual increase from T1 to T12

transverse diameter: gradual increase from T3 to T12

Thoracolumbar spine (T11L2)

anterior column = anterior longitudinal ligament, anterior annulus fibrosus,

anterior vertebral body

middle column = posterior longitudinal ligament, posterior annulus fibrosus,

posterior vertebral body margin

Integrity of the middle column is synonymous with stability!

posterior column = posterior elements + ligaments

Transitional vertebra

= vertebra retaining partial features of segments below and above; total

number of vertebrae usually unchanged

Prevalence: 20%

incidental finding

Location:

often at sacrococcygeal + lumbosacral junction

P.197

sacralized L5 = L5 incorporated into sacrum

Cross Sections through 5th Lumbar Vertebra

Anatomy of Diskovertebral Junction

anterior longitudinal ligament attaches to anterior surface of vertebral

body; it is less adherent to intervertebral disk;

posterior longitudinal ligament is applied to back of intervertebral disk

and vertebral bodies

lumbarized S1 = S1 incorporated into lumbar spine

Cx: confusion over labeling / assignment of vertebral levels during treatment

planning

Normal position of conus medullaris

Vertebral bodies grow more quickly than spinal cord during fetal period of

L1L2 level: normal (range T12 to L3)

L2L3 or higher: in 97.8%

L3 level: indeterminate (in 1.8%)

L3L4 / lower: abnormal

by 3 month: above inferior endplate of L2 (in 98%)

N.B.: If conus is at / below L3 level, a search should be made for tethering

mass, bony spur, thick filum!

P.198

Joints and Ligaments of Occipito-Atlanto-Axial Region

P.199

Skull and Spine Disorders

Arachnoiditis

Etiology: trauma, back surgery, meningitis, subarachnoid hemorrhage,

pantopaque myelography (inflammatory effect potentiated by

blood), idiopathic

Associated

with:

syrinx

Myelo:

blunting of nerve root sleeves

blocked nerve roots without cord displacement (2/3)

streaking + clumping of contrast

CT:

fusion / clumping of nerve roots

intradural pseudomass

intradural cysts

empty thecal sac = featureless empty-looking sac with individual nerve roots

adherent to wall (final stage)

Arachnoid Cyst of Spine

Location: dorsal to cord in thoracic region

Site:

extradural cyst secondary to congenital / acquired dural defect

intradural secondary to congenital deficiency within arachnoid (= true

arachnoid cyst) / adhesion from prior infection or trauma (= arachnoid

loculation)

oval sharply demarcated extramedullary mass

immediate / delayed contrast filling depending upon size of opening between

cyst + subarachnoid space

local displacement + compression of spinal cord

higher signal intensity than CSF (from relative lack of CSF pulsations)

Arachnoid Diverticulum

= widening of root sheath with arachnoid space occupying >50% of total

transverse diameter of root + sheath together

Cause: ? congenital / traumatic, arachnoiditis, infection

Pathogenesis: hydrostatic pressure of CSF scalloping of posterior margins of

vertebral bodies myelographic contrast material fills diverticula

Arteriovenous Malformation of Spinal Cord

Classification:

True intramedullary AVM

= nidus of abnormal intermediary arteriovenous structure with multiple shunts

Age: 2nd3rd decade

Cx: subarachnoid hemorrhage, paraplegia

Prognosis: poor (especially in midthoracic location)

Intradural arteriovenous fistula

= single shunt between one / several medullary arteries + single perimedullary

vein

Dural arteriovenous fistula

= single shunt between meningeal arteries + intradural vein

Metameric angiomatosis

Atlantoaxial Rotary Fixation

history of insignificant cervical spine trauma / upper respiratory tract

infection

limited painful neck motion

head held in cock-robin position + inability to turn head atlanto-odontoid

asymmetry (open mouth odontoid view):

decrease in atlanto-odontoid space + widening of lateral mass on side

ipsilateral to rotation

increase in atlanto-odontoid space + narrowing of lateral mass on side

contralateral to rotation

atlantoaxial asymmetry remains constant with head turned into neutral

position

Types:

5 mm anterior displacement

posterior displacement of atlas on axis

DDx: torticollis (atlantoaxial symmetry reverts to normal with head turned

into neutral position)

Brachial Plexus Injury

Erb-Duchenne: adduction injury affecting C5-6 (downward displacement of

shoulder)

Klumpke: abduction injury at C7, C8, T1 (arm stretched over head)

pouchlike root sleeve at site of avulsion

asymmetrical nerve roots

contrast extravasation collecting in axilla

metrizamide in neural foramina (CT myelography)

Caudal Regression Syndrome

= SACRAL AGENESIS = CAUDAL DYSPLASIA SEQUENCE

= midline closure defect of neural tube with a spectrum of anomalies including

complete / partial agenesis of sacrum + lumbar vertebrae and pelvic deformity

Etiology: disturbance of caudal mesoderm

Musculoskeletal anomalies

@ Lower extremity

symptoms from minor muscle weakness to complete sensorimotor paralysis

of both lower extremities

hip dislocation

hypoplasia of lower extremities

flexion contractures of lower extremities

foot deformities

@ Lumbosacral spine = SACRAL AGENESIS

Spectrum:

P.200

Type 1

=

unilateral partial agenesis localized to sacrum / coccyx

Type 2

=

bilateral partial symmetric defects of sacrum + iliosacral

articulation

Type 3

=

total sacral agenesis + iliolumbar articulation

Type 4

=

total sacral agenesis + ilioilial fusion posteriorly

nonossification of lower spine

fusion of caudal-most 2 or 3 vertebrae

spina bifida (lipomyelomeningocele often not in combination with Arnold-

Chiari malformation)

narrowing of spinal canal rostral to last intact vertebra

hypoplastic iliac wings

Spinal cord anomalies

characteristic club- / wedge-shaped configuration of conus medullaris

(hypoplasia of distal spinal cord)

tethered spinal cord

dural sac stenosis with high termination

spinal cord lipoma, teratoma, cauda equina cyst

syrinx

Genitourinary anomalies

neurogenic bladder (if >2 segments are missing)s

malformed external genitalia

bilateral renal aplasia with pulmonary hypoplasia

+ Potter facies

Hindgut anomalies

lack of bowel control

anal atresia

OB-US:

normal / imperforate anus

short crown-rump length in 1st trimester (diabetic embryopathy)

normal / mildly dilated urinary system

normal / increased amniotic fluid

2 umbilical arteries

2 hypoplastic nonfused lower extremities

sacral agenesis, absent vertebrae from lower thoracic / upper lumbar spine

caudally

N.B.: brain, proximal spine, and spinal cord are notably spared!

Sirenomelia

= fused lower extremities resembling a mermaid (siren)

Cause: aberrant vessel that shunts blood from the high abdominal aorta to the

umbilical cord (steal phenomenon) resulting in severe ischemia of

caudal portion of fetus

CRS Sirenomelia

umbilical

artery

two one

lower limb two hypoplastic single / fused

renal anomaly nonlethal renal agenesis / severe

dysgenesis

anus imperforate / normal absent

amniotic fluid polyhydramnios /

normal

oligohydramnios

NOT associated with maternal diabetes mellitus!

pulmonary hypoplasia + Potter facies

absence of anus

absent genitalia

bilateral renal agenesis / dysgenesis (lethal)

marked oligohydramnios

single aberrant umbilical artery

two-vessel umbilical cord

single / fused lower extremity often with fewer leg bones than normal

sacral agenesis, absent pelvis, lumbosacral tail, lumbar rachischisis

Prognosis: incompatible with life

Chordoma

Chordoma is the most common primary malignant tumor of the spine in

adults excluding lymphoproliferative neoplasms!

Prevalence: 1:2,000,000; 124% of all primary

malignant neoplasms of bone; 1% of

all intracranial tumors

Etiology: originates from embryonic remnants

of notochord / ectopic cordal foci

(notochord appears between 4th and

7th week of embryonic development,

extends from Rathke pouch to coccyx

and forms nucleus pulposus)

Age: 3070 (mean, 50) years (peak age in

6th decade); M:F = 2:1; highly

malignant in children

Path: lobulated tumor contained within

pseudocapsule

Histo:

typical chordoma: cords + clusters of

large bubblelike vacuolated

(physaliferous) cells containing

intracytoplasmic mucous droplets;

abundant extracellular mucus

deposition + areas of hemorrhage

chondroid chordoma: cartilage

instead of mucinous extracellular

matrix

Location:

50% in sacrum

35% in clivus

15% in vertebrae

other sites (5%) in mandible, maxilla,

scapula amorphous calcification (50

75%) heterogeneous enhancement

CT:

low-attenuation within soft-tissue mass (due to myxoid-type tissue)

higher attenuation fibrous pseudocapsule

MR (modality of choice):

low to intermediate intensity on T1WI, occasionally hyperintense (due to high

protein content):

heterogeneous internal texture due to calcification, necrosis, gelatinous mucoid

collections

very high signal intensity on T2WI (due to physaliferous cells similar to

nucleus pulposus with high water content)

Angio:

prominent vascular stain

NUC:

cold lesion on bone scan

no uptake on gallium scan

Metastases (in 543%)

to:

liver, lung, regional lymph node, peritoneum, skin

(late), heart

Prognosis: almost 100% recurrence rate despite radical surgery

P.201

Sacrococcygeal Chordoma (5070%)

Most common primary malignant sacral tumor;

24% of all malignant osseous neoplasms!

Peak age: 4060 years; M:F = 2:1

low back pain (70%)

constipation / fecal incontinence

rectal bleeding (42%)

sciatica

frequency, urgency, straining on micturition

sacral mass (17%)

Location: esp. in 4th + 5th sacral segment

presacral mass with average size of 10 cm extending

superiorly + inferiorly; rarely posterior location

displacement of rectum + bladder

solid tumor with cystic areas (in 50%)

osteolytic midline mass in sacrum + coccyx

amorphous peripheral calcifications (1589%)

secondary bone sclerosis in tumor periphery (50%)

honeycomb pattern with trabeculations (1015%)

may cross sacroiliac joint

Prognosis: 810 years average survival; 66% 5-year survival rate (adulthood)

DDx: Giant cell tumor, plasmacytoma, lymphoma, metastatic

adenocarcinoma, aneurysmal bone cyst, atypical hemangioma,

chondrosarcoma, osteomyelitis, ependymoma

Sphenooccipital Chordoma (1535%)

Age: younger patient (peak age of 2040 years); M:F - 1:1

orbitofrontal headache

visual disturbances, ptosis

6th nerve palsy / paraplegia

Location: clivus, spheno-occipital synchondrosis

bone destruction (in 90%): clivus > sella > petrous bone > orbit >

floor of middle cranial fossa > jugular fossa > atlas > foramen

magnum

reactive bone sclerosis (rare)

calcifications / bone fragments (2070%)

soft-tissue extension into nasopharynx (common), into sphenoid +

ethmoid sinuses (occasionally), may reach nasal cavity + maxillary

antrum

variable degree of enhancement

MR:

large intraosseous mass extending into prepontine cistern, sphenoid sinus,

middle cranial fossa, nasopharynx

posterior displacement of brainstem

usually isointense to brain / occasionally inhomogeneously hyperintense on

T1WI

hyperintense on T2WI

Prognosis: 45 years average survival

DDx: meningioma, metastasis, plasmacytoma, giant cell tumor, sphenoid

sinus cyst, nasopharyngeal carcinoma, chondrosarcoma

Vertebral / Spinal Chordoma (1520%)

More aggressive than sacral / cranial chordomas

Age: younger patient; M:F = 2:1

low back pain + radiculopathy

Location: cervical (8%particularly C2), thoracic spine (4%), lumbar spine

(3%)

Site: midline centra sparing posterior elements; arising in perivertebral

musculature (uncommon)

solitary midline spinal mass

tumor calcification in 30%

sclerosis / ivory vertebra in 4362%

total destruction of vertebra, initially unaccompanied by collapse

expansile growth:

violates disk space to involve adjacent bodies (1014%) simulating

infection

variable extension into epidural space of spine

exophytic anterior soft-tissue mass

expansion into neural foramen mimicking nerve sheath tumor

Cx: complete spinal block

Prognosis: 45 years average survival

DDx: metastasis, primary bone tumor, primary soft-tissue tumor,

neuroma, meningioma

CSF Fistula

Cause:

Trauma to skull base (most commonly) 2% of all head injuries develop CSF

fistula

Tumor: especially those arising from pituitary gland

Congenital anomalies: encephalocele

traumatic leak: usually unilateral; onset within 48 hours after trauma, usually

scanty; resolve in 1 week

nontraumatic leak: profuse flow; may persist for years

anosmia (in 78% of trauma cases)

Location: fractures through frontoethmoidal complex + middle cranial fossa

(most commonly)

high-resolution thin-section CT in coronal plane followed by

rescanning after low-dose intrathecal contrast material instilled into

lumbar subarachnoid space

Cx: infection (in 2550% of untreated cases)

Degenerative Disk Disease

Therapeutic decision-making should be based on clinical assessment alone!

There are no prognostic indicators on images in patients with acute lumbar

radiculopathy!

35% of individuals without back trouble have abnormal findings (HNP, disk

bulging, facet degeneration, spinal stenosis)

Imaging is only justified in patients for whom surgery is considered!

Pathophysiology:

loss of disk height leads to stress on facet joints + uncovertebral joints (=

uncinate process), exaggerated joint motion with misalignment (= rostrocaudal

subluxation) of facet joints, spine instability with arthritis, capsular

hypertrophy, hypertrophy of posterior ligaments, facet fracture

Plain film:

intervertebral osteochondrosis = disease of nucleus pulposus (desiccation

= loss of disk water):

narrowing of disk space

vacuum disk phenomenon = radiolucent interspace accumulation of nitrogen

gas at sites of negative pressure

disk calcification

bone sclerosis of adjacent vertebral bodies

P.202

spondylosis deformans = degeneration of the outer fibers of the annulus

fibrosus:

endplate osteophytosis growing initially horizontally + then vertically several

millimeters from disko-vertebral junction (2 to displacement of nucleus

pulposus in anterior + anterolateral direction producing traction on osseous

attachment of annulus fibrosus [= fibers of Sharpey])

enlargement of uncinate processes

osteoarthritis = degenerative disease of synovium-lined apophyseal /

costovertebral joints:

degenerative spondylolisthesis

cartilaginous node = intraosseous disk herniation

Myelography:

delineation of thecal sac, spinal cord, exiting nerve roots

CT (accuracy >90%):

facet joint disease (marginal sclerosis, joint narrowing, cyst formation, bony

overgrowth)

uncovertebral joint disease of cervical spine (osteophytes project into lateral

spinal canal + neuroforamen)

MR:

scalloping of cord (T2WI FSE / GRE images):

anterior encroachment by disk / spondylosis posterior encroachment by

ligamentum flavum hypertrophy

loss of disk signal (due to desiccation secondary to a decrease in water-

binding proteoglycans + increase in collagen within nucleus pulposus)

grade 1

=

slight decrease in signal intensity of nucleus on T2WI

grade 2

=

hypointense nucleus pulposus on T2WI + normal disk

height

grade 3

=

hypointense nucleus pulposus on T2WI + disk space

narrowing

annular tear:

(1) concentric tear - separation of annular lamellae

(2) transverse tear

(3) radial tear - crossing multiple annular lamellae with greater vertical

dimension + more limited horizontal extent

diskogenic pain

does not imply disk herniation

Location: inferior / superior insertion at posterior margin of annulus

gap near middle of annulus

cleft of high signal intensity in a normally hypointense outer annulus on T2WI

contrast enhancement (secondary to granulation tissue / hyperemia /

inflammation)

Annular Tears of Disk

reduction in disk height (late):

Schmorls node

moderate linear uniform enhancement on T1WI

vacuum phenomenon with low signal on T1WI

endplate + marrow changes (Modic & DeRoos):

= linear signal alterations paralleling adjacent endplates

Type I (4%) = edema pattern

Cause: replacement of bone marrow with hyperemic fibrovascular tissue +

edema

in acute disk degeneration hypointense on T1WI + hyperintense on T2WI

contrast-enhancement of marrow

Type II (16%) = fatty marrow pattern

Cause: replacement of bone marrow with fat

in chronic disk degeneration

hyperintense marrow signal on T1WI

iso- to mildly hyperintense on T2WI

Type III = bony sclerosis pattern

Cause: replacement of bone marrow with sclerotic bone

in chronic disk degeneration after a few years hypointense marrow signal on

T1WI + T2WI

juxtaarticular synovial cyst in posterolateral spinal canal (most frequently at

L4-5):

smooth well-defined extradural mass adjacent to facet joint

variable signal pattern (due to serous, mucinous, gelatinous fluid components,

air, hemorrhage)

hypointense perimeter (= fibrous capsule with calcium + hemosiderin) with

contrast enhancement

NUC:

SPECT imaging of vertebrae can aid in localizing increased uptake to vertebral

bodies, posterior elements, etc.

eccentrically placed increased uptake on either side of an intervertebral space

(osteophytes, diskogenic sclerosis)

Sequelae:

Disk bulging

Disk herniation

Spinal stenosis

Facet joint disease

Instability

dynamic slip >3 mm on flexion-extension

static slip >4.5 mm

traction spurs

vacuum phenomenon

DDx: Idiopathic segmental sclerosis of vertebral body (middle-aged /

young patient, hemispherical sclerosis in anteroinferior aspect of lower

lumbar vertebrae with small osteolytic focus, only slight narrowing of

intervertebral disk; unknown cause)

Grade Description

0 contrast confined within nucleus pulposus

1 contrast extends to inner third of annulus

2 contrast extends to middle third of annulus

3 outer third of annulus + 30 of circumference

5 extension of contrast beyond annulus

P.203

Bulging Disk = Disk Bulge

= concentric smooth expansion of softened disk material beyond the confines

of endplates with disk extension outward involving >50% of disk

circumference

Cause: weakened and lengthened but intact annulus fibrosus + posterior

longitudinal ligament

Age: common finding in individuals >40 years of age

Location: L4-5, L5-S1, C5-6, C6-7

rounded symmetric defect localized to disk space level

smooth concave indentation of anterior thecal sac

encroachment on inferior portion of neuroforamen

accentuated by upright myelography

MR:

nucleus pulposus hypointense on T1WI + hyperintense on T2WI (desiccation

= water loss through degeneration + fibrosis)

Herniation of Nucleus Pulposus

= HNP = protrusion of disk material >3 mm beyond margins of adjacent

vertebral endplates involving

Site:

posterolateral (49%) = weakest point along posterolateral margin of disk at

lateral recess of spinal canal (posterior longitudinal ligament tightly adherent to

posterior margins of disk)

posterocentral (8%)

bilateral (on both sides of posterior ligament)

lateral / foraminal (

Disk Bulge & Herniations

Location Descriptor for HNP on Axial Image

Location Descriptor for HNP on Sagittal Image

deviation of nerve root / root sleeve

enlargement of nerve root secondary to edema (trumpet sign)

amputated / truncated nerve root (nonfilling of root sleeve)

MR:

herniated disk material of low signal intensity displaces the posterior

longitudinal ligament and epidural fat of relative high signal intensity on T1WI

squeezed toothpaste effect = hourglass appearance of herniated disk at

posterior disk margin on sagittal image

asymmetry of posterior disk margin on axial image

Cx:

spinal stenosis

mild = 2/3

neuroforaminal stenosis

Prognosis:

conservative therapy reduces size of herniation by

050% in 11% of patients,

5075% in 36% of patients,

75100% in 46% of patients

(secondary to growth of granulation tissue)

Broad-based Disk Protrusion

triangular shape of herniation with a base wider than the radius of its depth

2550% of disk circumference

P.204

Focal Disk Protrusion

triangular shape of herniation with a base wider than the radius of its depth

toothpaste sign

Disk Sequestration

= Free Fragment Herniation

= complete separation of disk material from parent disk with rupture through

posterior longitudinal ligament into epidural space

Missed free fragments are a common cause of failed back surgery!

migration superiorly / inferiorly away from disk space with compression of

nerve root

Documents

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