Nondominant Parietal Cortex Lesion Example

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First Aid USMLE Step 1: Neuropathology Questions with

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Frontal Lobe Lesion Presentation

Ans: Disinhibition and deficits in concentration, orientation, judgment

May have reemergence of primitive reflexes.

Frontal Eye Field Lesion Presentation

Ans: Eyes look toward lesion.

Paramedian Pontine Reticular Formation Lesion Presentation

Ans: Eyes look away from side of lesion

Medial Longitudinal Fasciculus Lesion Presentation

Ans: Internuclear ophthalmoplegia:

Impaired adduction of ipsilateral eye

Nystagmus of contralateral eye with abduction

Medial Longitudinal Fasciculus Lesion Example

Ans: MS

Dominant Parietal Cortex Lesion Presentation

Ans: Agraphia, acalculia

Finger agnosia

Left-right disorientation

Dominant Parietal Cortex Lesion Example

Ans: Gerstmann Syndrome

Nondominant Parietal Cortex Lesion Presentation

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Ans: Agnosia of the contralateral side of the world

Nondominant Parietal Cortex Lesion Example

Ans: Hemispatial Neglect Syndrome

Hippocampus (Bilateral) Lesion Presentation

Ans: Anterograde amnesia—inability to make new memories

Basal Ganglia Lesion Presentation

Ans: May result in tremor at rest, chorea, athetosis

Basal Ganglia Lesion Examples

Ans: Parkinson Disease

Huntingdon Disease

Mammillary Bodies (Bilateral) Lesion Presentation

Ans: Wernicke-Korsako Syndrome:

Confusion

Ataxia

Nystagmus

Ophthalmoplegia

memory loss – anterograde & retrograde amnesia

confabulation

personality changes

Mammillary Bodies (Bilateral) Lesion Example

Ans: Wernicke problems in a CAN O’ beer

Subthalamic Nucleus Lesion Presentation

Ans: Contralateral hemiballismus

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Amygdala (Bilateral) Lesion Presentation

Ans: Klüver-Bucy Syndrome:

Disinhibited behavior – hyperphagia, hypersexuality, hyperorality

Amygdala (Bilateral) Lesion Example

Ans: HSV-1 Encephalitis

Superior Colliculus Lesion Presentation

Ans: Parinaud Syndrome:

Paralysis of conjugate vertical gaze – rostral interstitial nucleus also involved

Superior Colliculus Lesion Examples

Ans: Stroke

Hydrocephalus

Pinealoma

Reticular Activating System (midbrain) Lesion Presentation

Ans: Reduced levels of arousal and wakefulness → coma

Cerebellar Hemisphere Lesion Presentation

Ans: Intention tremor

Limb ataxia

Loss of balance

Damage to cerebellum → ipsilateral deficits – fall toward side of lesion

Cerebellar Hemisphere Lesion Example

Ans: Cerebellar hemisphere are *lateral*ly located

Affect *lateral* limbs

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Cerebellar Vermis Lesion Presentation

Ans: Truncal ataxia

Dysarthria

Cerebellar Vermis Lesion Examples

Ans: Vermis is *central*ly located

Affects *central* body

Degeneration associated with chronic alcohol use

When does Irreversible Damage Begin with Ischemic Brain Disease/Stroke?

Ans: Irreversible damage begins within 5 minutes of hypoxia

What are the Most Vulnerable Structures During Hypoxia?

Ans: – Hippocampus

– Neocortex

– Cerebellum

– Watershed areas

Mnemonics for Knowing Vulnerable Structure

Ans: *Hipp*ocampus is most *vulnerable* to ischemic hypoxia

*Vulnerable Hippos*

What can be Caused by Ischemic Brain Disease/Stroke?

Ans: Irreversible neuron damage

How is CT Imaging used for Stroke?

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Ans: – Noncontrast CT to exclude hemorrhage (before tPA can be given)

– CT detects ischemic change in 6-24 hours

How is MRI Imaging used for Stroke?

Ans: Diffusion weighted MRI can detect ischemia within 3-30 minutes

What are the Histological Features of Ischemic Stroke 12-24 hours after?

Ans: Red neurons – eosinophilic cytoplasm with pyknotic nuclei

What are the Histological Features of Ischemic Stroke 24-72 hours after?

Ans: Necrosis & neutrophils

What are the Histological Features of Ischemic Stroke 3-5 days after?

Ans: Microglial (macrophages

What are the Histological Features of Ischemic Stroke 1-2 weeks after?

Ans: Reactive gliosis & vascular proliferation

What are the Histological Features of Ischemic Stroke >2 weeks after?

Ans: Glial scar

What is Ischemic Stroke?

Ans: Acute blockage of vessels → disruption of blood flow → subsequent

ischemia → liquefactive necrosis

What are the 3 Types of Ischemic Stroke?

Ans: 1. Thrombotic

2. Embolic

3. Hypoxic

What is the Etiology of a Thrombotic Stroke? (i.e. location and type of

plaque)