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Approach to Macro and Microcephaly
Dr. Kalpana MallaMD Pediatrics
Manipal Teaching Hospital
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• Head circumference ( occipito frontal ) > 2 standard deviation above the mean for age and sex
MACROCEPHALY
Head circumference > 3 standard deviations below the mean for age and sex
MICROCEPHALY
1 SD = 1.25 CM
Macrocephaly > 2 SD i.e. 2.5 cm
Microcephaly < 3 SD i.e 3.75 cm
Take 50 centile as base line
• Familial• Congenital : Achondroplasia, Cranioskeletal
dysplasia, Hydrocephalus, Porencephaly.• Degenerative : white matter degeneration• Infectious : Hydrocephalus, sudural
effusion/empyema
CAUSES OF LARGE HEAD
• Metabolic : GM1 gangiosidosis, mucopolysaccharidosis, hypoparathyroid.
• Space occupying : tumors, hematoma• Neurocutaneous defects : tuberous sclerosis,
neurofibroma• Thickened Skull: Rickets, hemolytic anaemia,
fibrous dysplasia of bone
CAUSES OF LARGE HEAD
Head circumference
• Normal head circumference growth velocity:
• Birth-35cm • 0-3 months : +2 cm/mon(41cm)• 3-6 months :+ 1 cm/mon(44cm)• 6-12 months :+ 0.5cm/mon• 1-3 year : 0.25 cm/ mon• 3-6 year : 1 cm/year
• Pathological increase in ventricular volume due to abnormal CSF accumulation
• Imbalance between CSF production and flow leading to ventricular enlargement
HYDROCEPHALUS
• CSF secreted @ 500ml/day @ 20 ml/hr
• Total CSF volume in infant = 50 mlin adult = 150ml.
• 80% CSF – produced from choroid plexus of lateral, 3rd and 4th ventricle.
• 20% CSF – from cerebrum and spinal cord
Physiology of CSF
CSF DRAINAGECSF Lateral Ventricles
Interventricular Foramen of MONRO
3rd VENTRICLE
AQUEDUCT OF SYLVIUS
4th VENTRICLE
MEDIAN FORAMEN OF MAGENDIE
Paired Lateral FORAMEN OF LUSCHKA
80 % Enters into CISTERNAL SYSTEM
20 % Enters Subarachnoid Space OF SPINAL CORD
Then flows into VENOUS SINUSES Due to increased HYDROSTATIC PRESSURE Through ARACHNOID VILLI AND GRANULATIONS
1. Obstruction to flow2. Decreased absorbtion3. Increased production- rarely by choroid
plexus papilloma
Pathophysiology:
• Obstructive/ Non Communicating/ Internal:• Obstruction is within ventricular system upto
and including outlet foramina of 4th ventricle.• SAS is compressed - ventricles can’t
communicate with subarachnoid space
CLASSIFICATION OF HYDROCEPHALUS
• Aqueductal stenosis: - 70% of congenital - 2% are inherited, mostly secondary to IVH,
meningitis.• Arnold chiari malformation esp. type 2• Dandy walker syndrome• Chromosomal anomalies
OBSTRUCTIVE/ NON COMMUNICATING - causes
• Intra uterine infections• Midline brain tumors - Cerebellar tumors• Vein of Galen malformation• Posterior fossa subdural hematoma• Congenital septa or membrane block at outlet of
4th ventricle
OBSTRUCTIVE/ NON COMMUNICATING/ INTERNAL:
• Non Obstructive/ Communicating/ External:
• Obstruction is distal to 4th ventriclular outlet - foramina in cisterns, subarachnoid space or arachnoid villi
• Patent ventricular system - SAS space is enlarged
• Post infectious - Meningitis ( TB COMMONEST, also pnemococcal), Intra uterine infections – toxoplasma, CMV,
• Sub arachnoid hemorrhage • Meningeal leukemic infiltrates• Secondary to excessive CSF production-papilloma
of choroid plexus• Mucopolysacchridosis, achondroplasia• Craniosynostosis
NON OBSTRUCTIVE/ COMMUNICATING – causes
• Congenital :
Eg. IUI, IVH AV-malformations Cong. tumors
• Acquired :
Eg . TBM, meningitis,
Post. fossa tumor,
CLASSIFICATION
• 50% may be asymptomaticSymptoms• Vomiting, headache• Drowsiness• Failure to thrive, poor appetite• Shrill cry, irritability, lethargy• Delayed motor milestones – mainly motor• Progressive enlargement of head• Abnormal shape of head – inverted triangle• Slow mental deterioration
Clinical Features
Signs• Progressive increase in OFC (>1cm/wk )• Head shape abnormal, forehead is broad,
frontal bossing• Ant fontanel: wide open and bulging, non
pulsatile• Open squamo parietal suture
• Macrocephaly• Skin of skull – shiny, tense,
dilated veins• Transillumination test: • MacEwen Sign: percussion of
the skull produces a “cracked pot” sound
Signs
Trans illumination of headWhen Translucency extends beyond 2 CM in frontal area and over 1 CM in occipital area is abnormal and S/O – sub dural effusion Hematoma, hydrocephalus , Hydranencephaly
SOME PART OF SKULL LIGHTED- HYDROCEPHALUS
ENTIRE SKULL IS LIT UP - HYDRANENCEPHALY.
MACEWEN’S SIGN
Aka. Crack pot signElicited by percussion of skullAmplified sound can be heard from Steth from other end - Indicative of separated sutures due to raised intra cranial tension
Physiologically present if AF is open
• Ocular signs: eyes deviated downward “sun setting sign”- due to pressure of 3rd ventricle supra pineal recess on mesencephalic tectum , causing impairment of upward gaze
• Squint - 6th n. palsy• Nystagmus, ptosis, Optic atrophy• Chorioretinitis (I.U. infec)• Papilledema
Eyes signs
• Pyramidal signs: spasticity, brisk tendon reflexes, clonus, Babinski sign due to compression & stretching of myelienated para central corticospinal fibers arising from leg area of motor cortex
• Others: mental retardation, gait anomaly, epilepsy
Signs
• Presents as difficulty in feeding, sucking, drooling, aspiration
• Due to - - Disruption of B/L cortico bulbar fibers - Can be due to arnold chiari malformation
Pseudo bulbar palsy
• Multiple café au- lait spots – NF• Cranial bruit – Vein of Galen malformation• NTD – Arnold chiari• DANDY WALKER - prominent occiput
Look for
• USG: when ant fontanelle is open. Assesses ventricular size, detects IVH
• Plain skull films- shows sign of ICP:- separation of sutures- erosion of the post. Clinoid process- increased convolutional markings (beaten silver appearance)
-Flat enlarged sella tursica
Investigation:
• CT: helps to identify the cause• MRI: better visualization of post fossa
pathologies• Opthalmological evaluation• Psychomotor assessment: using different dev
scales
Investigation:
• Medical :aims to decrease ICP&CSF formation1.MANNITOL 20% - 5ML/KG stat followed by
2ml/kg 6th hourly for 2 days.2.ACETAZOLAMIDE 50-100mg/kg/day to reduce
CSF production3.ORAL GLYCEROL4.FRUSEMIDE
TREATMENT
VENTRICULO PERITONEAL SHUNT • SILASTIC one way low pressure valve shunt –
Upadhya shunt• Indications for surgery:Papilledema/ periventricular ooze on
fundoscopy/CT.Cortical mantle < 2.5cm on initial neuroimagingProgressive thinning of mantle despite medical
treatment.
SURGICAL
• Pump the reservoir by finger pressure • Normally shunt empties and refills on release• IF FAILS TO REFILL = Proximal block = Due to
choroid plexus tissue• IF RESISTANCE TO EMPTYING= Distal block =
Omental block
EVALUATION OF SHUNT
• SHUNT FAILURE CAN OCCUR DUE TO:Shunt infection, calcifications, malposition.• Shunt infection - mostly due to staph
epidermis, staph aureus.
• “arrested hydrocephalus” - may undergo spontaneous arrest • Untreated : 50% mortality• These children are at an increased risk of:
– Dev. Disabilities with less IQ– Visual problems: visual field defects, strabismus, optic
atrophy– Behavioral problems: – Accelerated pubertal dev- due to increased
gonadotropin secretion in response to raised ICP
Prognosis
Post Meningitis with enlarging head
CT, CSF EXAM, FUNDOSCOPY
LOOK FOR CSF CELLS PROTEINS, INTRA CRANIAL PRESSURE PERIVENTRICULAR OOZE
RAISED ICTLOW CELLSLOW PROTEIN
SHUNT
Mild hydro,ICT NOT RAISED
MEDICAL
Significant hydroc.Ooze +, high cells,protein
Externaldrainage
High cellsHigh proteins
Try to avoid Shunts. Treat medically
POST TBM HYDROCEPHALUS
IN Acute Stage not indicated as high PROTEINS - GREATER SHUNT BLOCK also it responds well to ATT AND STEROIDS.
INDICATION FOR SURGERY BEING – Persistent decerebration no improvement in sensorium in 10days
• 1,3,6 months then yearly.• Check – HC, neurological signs, Fundus, shunt
function, IQ testing.
Follow up
Hydranencephaly
• The cerebral hemispheres are replaced by a thin-walled, fluid-filled cyst
• The aqueduct is usually atretic, and increased fluid pressure causes the cyst to enlarge
• The empty cranial cavity transilluminates
Is defined as head circumference > 3 standard deviations below the mean for age and sex
MICROCEPHALY
PRIMARY ( Genetic ) MICROCEPHALY
Refers to group - associated with specific genetic syndromes.
USUALLY have slanting forehead.Identified at birth itself
Causes for primary• Familial - AR• Autosomal dominant• Syndromes : Down, Cri du
chat, Edward, Cornelia de Lange, Rubinstein Tyabi, Smith Lemli Opitz.
• Results from noxious agents that may affect a fetus in utero or an infant during periods of rapid brain growth, particularly the first 2 years of life
Secondary ( non genetic) Microcephaly
• Radiation• Congenital infections – rubella, CMV, toxo• Drugs – fetal alcohol, fetal hydantoin• Meningitis/encephalitis
Causes for secondary microcepahaly
• Metabolic – maternal diabetes• Hypoxic ischemic encephalopathy• Malnutrition• Hyperthermia
Causes for secondary microcepahaly
Microcephaly • Shape of skull
usually normal• Suture line -
normal
Craniosynostosis • Shape of skull -
abnormal• Suture line –
ridged.
• Familial microcephaly needs exclusion• Detail birth history• OFC of siblings and parents should be
recorded• Examine for associated dysmorphism
Developmental assessment• Detailed neurological evaluation - seizures,
spasticity
Evaluation of microcephaly
• X ray skull -determine suture patency, overriding, fusion and calcification
• TORCH serology-• KARYOTYPE- if dysmorphism• Metabolic screening
Investigations
• CT Head- for evidence of HIE sequelae, and intracranial calcifications
• MRI- in cases of familial microcephaly and suspected migrational disorders
• Usually supportive• Treat neurological & sensory deficits• Treat seizures• If MR present, special schools may be
needed• Genetic councelling
Treatment and Prognosis
Thank youDownload more documents and slide shows on The Medical Post
[ www.themedicalpost.net ]