A 65-year-old hypertensive man presents with a witnessed seizure characterized by forceful leftward deviation of head and eyes, followed by left arm clonic jerking and secondary generalization. Postictally, his head and eyes remain deviated to the right, and he cannot voluntarily look to the left for several hours. MRI shows an acute ischemic infarct in the right posterior middle frontal gyrus. EEG shows the pattern marked **B** in the diagram—focal delta slowing and intermittent sharp waves over the right frontal region, with versive electrographic seizure activity recorded during the event. Which of the following best explains the postictal rightward gaze deviation and inability to look left?

Question

Accepted Answer

A. Destructive lesion in the right frontal eye field (Brodmann area 8) causing contralateral gaze palsy—the eyes deviate toward the side of the lesion and cannot look to the contralateral hemispace. ## Why option 1 is correct

The frontal eye field (FEF) in Brodmann area 8 of the posterior middle frontal gyrus controls voluntary conjugate horizontal eye movements to the **contralateral** side. A destructive lesion (such as ischemic stroke) in the right FEF produces a contralateral gaze palsy: the patient cannot look toward the left (contralateral hemispace), and the eyes deviate **toward the side of the lesion** (rightward, toward the right frontal infarct). During the ictal phase, seizure discharge from the FEF drives contraversive deviation (eyes away from the discharging hemisphere—leftward in this case). During the postictal period, Todd's paralysis of gaze develops, and the eyes deviate toward the side of the seizure focus (rightward) because the underlying structural lesion (the infarct) now dominates, producing the classic destructive lesion pattern: gaze toward the lesion, away from the hemiplegia. The EEG pattern marked **B**—focal delta slowing and intermittent sharp waves over the right frontal region—is the hallmark of a structural frontal lesion with seizure activity, confirming FEF involvement. (Harrison's Principles of Internal Medicine, Cortical Eye Movement Control; Aminoff & Daroff, Neurology in Clinical Practice)

## Why each distractor is wrong

- **Option 2**: A pontine paramedian reticular formation (PPRF) lesion produces the **opposite** pattern: the eyes deviate **away from** the side of the lesion. In this case, a right PPRF lesion would cause leftward gaze deviation, not rightward. Additionally, the MRI shows a frontal infarct, not a pontine lesion, and the EEG shows frontal sharp waves, not brainstem localization.

- **Option 3**: An occipital hemorrhage would cause homonymous hemianopia (loss of the contralateral visual field), not gaze deviation. Occipital lesions do not produce conjugate gaze palsies. The clinical presentation and imaging clearly indicate a frontal lesion, not an occipital one. Rightward gaze deviation would not be explained by left occipital pathology.

- **Option 4**: Bilateral thalamic infarction affecting the dorsomedian nuclei would impair arousal and consciousness but would not produce a consistent, lateralized gaze deviation pattern. The gaze deviation in this case is clearly related to a unilateral right frontal lesion producing a contralateral gaze palsy, not a diffuse thalamic process. The EEG shows focal frontal abnormality, not diffuse thalamic dysfunction.

**High-Yield:** FEF lesion → eyes deviate **toward** the lesion (destructive pattern); FEF seizure → eyes deviate **away** from the lesion (irritative pattern); postictal Todd's paralysis → eyes deviate **toward** the seizure focus (destructive lesion dominates).

[cite: Harrison's Principles of Internal Medicine—Cortical Eye Movement Control; Aminoff & Daroff, Neurology in Clinical Practice]

Answer

B. Irritative lesion in the right pontine paramedian reticular formation causing ipsilateral gaze deviation away from the lesion

Answer

C. Bilateral thalamic infarction affecting the dorsomedian nuclei and disrupting arousal, resulting in random eye deviation

Answer

D. Acute hemorrhage in the left occipital lobe disrupting visual processing and causing homonymous hemianopia with forced gaze to the right

Explanation

Why option 1 is correct

Why each distractor is wrong

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