Neuro Review Part 2

8/12/2019 Neuro Review Part 2

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OSCE | Batch 2014

The estimated amount of glucose used by an adult human brain each day,

expressed in M&Ms: 250 Harpers Index

Keshia Lourdes Duyongco


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NOTE: Neurology will NOT be included in the Identification

Exam.

Case 1: The Teacher Case 2: The Businessman

Case 3: The Brave Policeman


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A 55 year-old high school teacher develops sudden

weakness of her left arm and leg, and over the next 30

mins, these limbs become even weaker.

When she looks at herself in the mirror, she finds that thelower half of her face appears to sag, and with

vocalization, there is less movement on the lower left than

on the lower right side of her face.


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Her medical records reveal the ff info:

BP: 140/90

FBS: 110 mg/dl

LDL: 120 mg/dl

Total cholesterol: 250 mg/dL

Question1: What is your interpretation of the data?

Stage 1 HypertensionDiabetes mellitus

High LDL (desirable:


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When she is seen in the emergency room 1 hour later, she

has almost complete paralysis of the lower part of the left

side of her face and left arm and leg, with an

approximately equal degree of weakness in the face, arm,

and leg.


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Question 2: Where is the lesion that is responsible for her symptoms?(a) Right internal capsule

(b) Left internal capsule

(c) Upper brainstem

(d) Cerebral cortex

ANSWER: A

The most likely location is the right internal

capsule. This is because the corticobulbar

and corticospinal fibers innervating the

contralateral face, arm, and leg are close

together in this location.

These fibers are also close in the upper

brainstem but the patient has no clinical signs

suggesting brainstem disease.

The lesion is less likely to be in the cerebral

cortex because the representation of the

face, arm, and leg are distributed over a

very large region.


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Corticospinal Tract Aka: pyramidal tract

Origin:

1/3 Primary motor cortex (area 4)

1/3 premotor and supplementary motor

regions (area 6)

1/3 parietal/primary somatosensory area(areas 3,1,2)

Passes through

Posterior limb of internal capsule

Decussation:

Medullary pyramids (90% of the

corticospinal fibers cross at this level and

descend through the spinal cord as the

lateral corticospinal tract) to innervate the

muscles in the distal parts of the extremities,

i.e. hands and feet

10% do not decussate and descend as the

ventral corticospinal tract


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Corticobulbar Tract Terminates in the brainstem to supply the motor nuclei of

the cranial nerves III, IV, V, VI, VII, IX, X, XI, XII NOTE: cranial nerve motor nuclei receive innervation from both

cerebral hemisphere, and in most cases, the muscles they control

cannot be contracted voluntarily on one side only.

Both the lower facial nucleus, which innervates facialmusculature below the eye, and the hypoglossal nucleusreceive innervation from the opposite cerebral cortex that

is much heavier than the innervation from the ipsilateralcortex. Thus, these muscles can be controlled rather independently on the

two sides (try it! ), and a lesion of one cerebral hemisphereresults in weakness primarily on the contralateral side.


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Nerve CN Function Type PEARLS

Olfactory I Smell S

Optic II Sight S

Oculomotor III Eye movt (SR, IR, MR, IO), pupillary

constriction, accommodation, eyelid opening

(levator palpebrae)

M

Trochlear IV Eye movt (SO) M

Trigeminal V Mastication, facial sensation (VI ophthalmic,

V2 maxillary, V3 mandibular)

B Jaw deviates toward

side of lesion

Abducens VI Eye movt (LR) M

Facial VII Facial movement, taster from anterior 2/3 of

tongure, lacrimation, salivation

(submandibular, sublingual glands), eyelid

closing (orbicularis oculi), stapedius muscle in

ear

B


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Nerve CN Function Type PEARLS

Vestibulocochlear VIII Hearing, balance S

Glossopharyngeal IX Taste from posterior 1/3 of tongue,salivation (parotid), carotid body and sinus

chemo- and baroreceptos, and

stylopharyngeus (elevates pharynx and

larynx)

B

Vagus X Taste from epiglottic region, swallowing,palate elevation, midline uvula, talking,

coughing, thoracoabdominal viscera, aortic

arch chemo- and baroreceptors

B Uvula deviates away

from side of lesion

Accessory XI Head turning (SCM), shoulder shrugging(trapezius) M Weakness turning head tocontralateral side oflesion (SCM), shoulder

droop on side of lesion

(trapezius)

Hypoglossal XII Tongue movement M Tongue deviates towardside of lesion


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Question 3: Which artery supplies the involved area?(a) Anterior cerebral artery

(b) Middle cerebral artery

(c) Deep branches of MCA

(d) Deep branches of ACAANSWER: C

The internal capsule is supplied

by the deep branches of the

middle cerebral artery.

Review of cortical distribution:

ACA (Anteromedial surface)

MCA (lateral surface)

PCA (posteroinferior surface)


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Question 4: What has happened to Ms. S?

ANSWER:

Clinical evaluation led to the diagnosis of ischemic

infarction (stroke) because of cerebrovasculardisease resulting from diabetes mellitus andhypertension. An MRI study verified the localizationand diagnosis.

She was treated with tissue plasminogen activator

in an attempt to dissolve the clot in vesselsperfusing the internal capsule.


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A 55 year old man develops a feeling of stiffness and

clumsiness of his left hand, and when sitting still, he

observes a tremor involving the wrist and fingers of this

hand.

About the same time, he also begins to scuff his left foot on

the floor occasionally while walking.

About 1 year later, the tremor has become constant, and

he trips occasionally because of the misplacement of hisleft foot.


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What is the most likely diagnosis?

(a) Huntingtons disease

(b) Parkinsons disease

(c) Cerebellar disease

(d) Cerebral Palsy

ANSWER: B

The patient described has a movement

disorder resulting from disease in the

basal ganglia.

The history and findings are

characteristic of Parkinsons disease.

Patients develop bradykinesia, rigidity,

gait instability and tremors, usually

beginning on one side of the body, then

affecting the other. The lines of the face

become smooth and the expression

becomes fixed (masked-like facies)


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The neurologist he consulted noticed that he has somewhat

an immobile face and that he blinks frequently.

Additional findings: A 4-6 cycle/second tremor of the left

wrist and fingers, mild rigidity on passive manipulation of

the left arm and left, and slowness of the finger movements

of both hands.


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Characteristics Helpful Mnemonics

Parkinsons Disease Lewy bodies

Depigmentation of

substantia nigra pars

compacta (loss of

dopaminergic neurons)

TRAP = Tremor (at rest

eg pill-rolling tremor),

cogwheel Rigidity, Akinesia,

and Postural instability

Huntingtons Disease Autosomal dominant

trinucleotide repeat

disorder

Chorea, depression,

progressive dementia

Expansion of CAG.

Caudate loses Ach and

GABA.


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Characteristics Mnemonics

Hemiballismus Sudden, wild flailing of 1 arm +/- leg

Contralateral subthalamic nucleus lesion

(e.g. lacunar stroke in pt with

hypertension)

Loss of inhibition of thalamus thru globus

pallidus

Half ballistic (as in throwing

a baseball)

Chorea Sudden, jerky, purposeless movement

Characteristic of basal ganglia lesion.

Choreadancing (Greek)

Think choreography

AthetosisSlow, writhing

movementCharacteristic of basal gangial lesion. Athetosnot fixed (Greek)Think snakelike

Myoclonus Sudden, brief muscle contraction Jerks, hiccups

Dystonia Sustained, involunatry muscle

contractions

Writers cramp


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TREMORS

Essential/postural tremor

action tremor (worsens when holding posture), autosomaldominant.

Often self medicate with alcohol (decreases tremors) Tx: Beta blockers

Resting tremor

Most noticeable distally

Parkisons

disease (pill-rolling tremor) Intention tremor

Slow, zigzag motion when pointing toward a target

Cerebellar dysfunction


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APHASIAS

Higher-order inability to speak (vs. dysarthria: motor

inability to speak)

Brocas

Nonfluent aphasia with intact comprehension( to remember: Brocas Broken Boca)

Brocas area: inferior frontal gyrus

Wernickes

Fluent aphasia with impaired comprehension

( to remember: Wernickes is Wordy but makes no sense!)

Wernickes area: superior temporal gyrus

Global

BOTH affected: Nonfluent aphasia with impaired comprehension


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A gunman shoots a 25 year-old policeman in the abdomenduring an armed robbery. The policeman is quickly transported

to the hospital, where he is awake and alert.

PE shows moderate blood loss from wound but stable BP and

pulse


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Neurologic exam:

Weakness of R leg with decreased DTR

No response to plantar stimulation of R foot

Loss of position sense and vibration sense in entire R leg Loss of pain and temp sensation in L leg and L lower abdomen

X-ray:

Bullet lodged in lower thoracic spine

He is taken to surgery, where the abdominal wound is explored and the

bleeding is stopped. No major organ injury has been sustained, and noattempt is made to remove the bullet.

Over the next several months, the patient recovers most of his strength in the

R leg, but it is stiff when he moves.

Examination 6 mos post-op reveals:

increased DTRs in the R leg

a right extensor plantar response

diminished position sense and vibration sense in the R leg

diminished pinprick sensation in the L leg and lower abdomen.


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Question 1: What structures in this man spinal cord have

been damaged to cause the neurologic abnormalities?

Matching Type! (letters may be repeated)1. Weakness of R leg with decreasedDTR

2. Loss of position sense and vibration

sense in entire R leg

3. Loss of pain and temp sensation in L

leg and L lower abdomen

(a) Right lateral column

(b) Right dorsal column

(c) Left lateral column

(d) Left dorsal column


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ANSWER: A. Right Lateral Column

Right corticospinal tract

Note that a lesion caudal/distal to the

decussation causes signs on the ipsilateral side.

results in UMN signs (see next slide)

1. Weakness of R leg with decreased

DTR

2. Loss of position sense and vibration

sense in entire R leg

3. Loss of pain and temp sensation in L

leg and L lower abdomen

ANSWER: B. Right Dorsal Column

Loss of position sense, vibration sense, and

tactile discrimination on the ipsilateral side

below the level of injury. Because of the paralysis, sensory ataxia,

which may otherwise occur, cannot be

demonstrated readily,

ANSWER: A. Right Lateral ColumnRight lateral spinothalamic tract

Loss of pain and temp on contralateral side

beginning one or two dermatomes below the

level of injury


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The policeman received an

injury to the right lateral part of

the lower thoracic spinal cord.


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Question 2: Is this an UMN or a LMN lesion? ANSWER: UMN


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Question 2: What condition does the policeman have?

(a) Syringomyelia

(b) Amyotrophic lateral sclerosis

(c) Brown-Sequard Syndrome

ANSWER: C

Lateral hemisection of the spinal cord (e.g. From a bullet or knife wound)

Brown-Sequard. The specific effects in the patient with a chronic lesion can be

understood by considering the fiber tracts and roots affected by the lesion

discussed in the previous slide.

Syringomyelia damages the anterior white commissure of the spinothalamic tract

resulting in bilateral loss of pain and temp sensation.

ALS: both UMN and LM signs; no sensory deficits


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Documents

Neuro Review Part 2