65 yr old right hand dominant male had an ischemic infraction. WOF clinical features corresponding to infracted areaa. Left homonymous hemianopia – R/S occipital lobe b. Acalculia – left parietal lobe c. R/S vigorous spasm – cerebellum d. Abnormal higher functions – frontal lobe e. L/S weakness & R/S 3rd nerve palsy – mid brain
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I now have enough information from the textbooks to give a thorough answer. Let me analyze each option carefully.
Answer: Clinical Features and Infarcted Areas
This question asks which option correctly pairs a clinical feature with its infarcted brain region. Here is a full analysis of each option:
a. Left homonymous hemianopia -- Right/Side occipital lobe ✅ CORRECT
The primary visual cortex (calcarine cortex) lies in the occipital lobe. Each occipital lobe receives input from the contralateral visual field via the optic radiations.
- A right occipital lobe infarct destroys the right visual cortex, causing left homonymous hemianopia (loss of the left visual field in both eyes).
- As confirmed by Harrison's: "Occlusion of the posterior cerebral artery supplying the occipital lobe is a common cause of total homonymous hemianopia."
- This pairing is anatomically correct.
b. Acalculia -- Left parietal lobe ✅ CORRECT
Acalculia (inability to perform calculations) is a feature of dominant (left) parietal lobe disease, specifically the inferior parietal lobule (angular gyrus area). It is part of Gerstmann's syndrome, which includes:
- Acalculia
- Agraphia (without alexia)
- Left-right disorientation
- Finger agnosia
Confirmed by Kanski's and Adams & Victor: "Associated features of dominant parietal lobe disease include acalculia, agraphia, left-right disorientation, finger agnosia."
This pairing is anatomically correct.
c. Right/Side vigorous spasm -- Cerebellum ❌ INCORRECT
The cerebellum does not produce spasticity or vigorous spasm. Cerebellar lesions cause:
- Ipsilateral ataxia, intention tremor, dysmetria, dysdiadochokinesia, nystagmus, hypotonia
- Not spasticity or spasm
Spasticity (increased muscle tone / "vigorous spasm") is a corticospinal (upper motor neuron) tract sign, caused by lesions in the motor cortex (frontal lobe), internal capsule, or corticospinal tracts in the brainstem/spinal cord.
This pairing is wrong -- cerebellum does not cause spasm/spasticity.
d. Abnormal higher functions -- Frontal lobe ✅ CORRECT
The frontal lobe (prefrontal cortex) governs executive functions, personality, judgement, insight, abstract reasoning, planning, and impulse control -- collectively called "higher functions." Frontal lobe infarcts or lesions classically produce:
- Disinhibition, personality change
- Poor judgement and planning
- Perseveration
- Working memory deficits
This pairing is anatomically correct.
e. Left/Side weakness AND Right/Side 3rd nerve palsy -- Midbrain ✅ CORRECT
This is the classic Weber's syndrome -- a midbrain (cerebral peduncle) infarct involving:
- The ipsilateral oculomotor (3rd) nerve fascicles (exit ventrally through the peduncle) -- causing ipsilateral 3rd nerve palsy
- The contralateral corticospinal tract in the cerebral peduncle -- causing contralateral (opposite side) hemiplegia/weakness
So: Right midbrain infarct → Right 3rd nerve palsy + Left-sided weakness (contralateral).
From Adams & Victor: "With midbrain lesions there is a third nerve palsy (Weber syndrome)."
From Harrison's: "A third nerve palsy with contralateral hemiplegia (Weber's syndrome) may result [from midbrain infarction]."
This pairing is anatomically correct.
Summary Table
| Option | Feature | Stated Location | Correct? | Reason |
|---|---|---|---|---|
| a | Left homonymous hemianopia | Right occipital lobe | ✅ Yes | Right visual cortex = left visual field loss |
| b | Acalculia | Left parietal lobe | ✅ Yes | Dominant parietal lobe = Gerstmann's syndrome |
| c | Vigorous spasm (spasticity) | Cerebellum | ❌ No | Cerebellum → ataxia/hypotonia, NOT spasticity |
| d | Abnormal higher functions | Frontal lobe | ✅ Yes | Prefrontal cortex governs executive function |
| e | L/S weakness + R/S 3rd nerve palsy | Midbrain | ✅ Yes | Weber's syndrome -- midbrain peduncle infarct |
The odd one out / incorrect pairing is option (c): Vigorous spasm (spasticity) is NOT a feature of cerebellar infarction -- it is an upper motor neuron (corticospinal tract) sign. The cerebellum produces cerebellar signs (ataxia, intention tremor, dysmetria), not spasticity.
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