In a patient with a suspected artery of Percheron infarct, can ptosis and nystagmus be expected findings?

Artery of Percheron Infarction: Expected Neurological Findings

Ptosis and nystagmus are NOT typical or expected findings in artery of Percheron (AOP) infarction. The classic triad consists of altered mental status, memory impairment, and vertical gaze palsy—not ptosis or nystagmus 1, 2, 3.

Core Clinical Presentation of AOP Infarction

The most common clinical manifestations in AOP infarction are:

• Decreased level of consciousness (73% of cases) – the most frequent presenting feature 1
• Ocular movement disorders (57-80% of cases) – specifically vertical gaze palsy, NOT nystagmus 1, 2
• Behavioral and memory impairment – prominent in bilateral paramedian thalamic infarcts without midbrain involvement 2
• Disorientation (42% of cases) 1
• Diplopia (57% of cases) – due to vertical gaze abnormalities, not nystagmus 1, 4

Why Ptosis and Nystagmus Are Atypical

Ptosis is not a recognized feature of AOP infarction in any of the published case series or clinical descriptions 1, 2, 3, 5, 4, 6, 7, 8. The bilateral paramedian thalamic and rostral midbrain territory supplied by the AOP does not include the oculomotor nucleus or fascicle in a pattern that would produce ptosis.

Nystagmus is similarly not described as a characteristic finding. The ocular movement disorder in AOP infarction is specifically vertical gaze palsy (inability to look up or down), which is distinct from nystagmus 2, 3, 4. One case report described bilateral internuclear ophthalmoplegia, but not nystagmus 5.

Clinical Subtypes Based on Imaging Patterns

Bilateral Paramedian Thalamic with Rostral Midbrain Infarction (BPTRMI)

• Ocular movement disorders and mental status disturbance are the dominant features 2
• Vertical gaze palsy is the specific ocular finding 2, 3
• Poorer long-term outcome (only 25% achieve mRS ≤2) 2

Bilateral Paramedian Thalamic Without Midbrain Infarction (BPTWMI)

• Behavioral/amnesic impairment and mental status disturbance predominate 2
• Better prognosis (67% achieve mRS ≤2) 2

Critical Diagnostic Pitfalls

If ptosis and nystagmus are present, strongly consider alternative diagnoses:

• Ptosis suggests third nerve involvement – consider top-of-the-basilar syndrome, posterior communicating artery aneurysm, or midbrain lesions affecting the oculomotor nucleus/fascicle 9
• Nystagmus suggests brainstem or cerebellar pathology – consider lateral medullary syndrome, cerebellar infarction, or more extensive posterior circulation stroke 10, 11
• Direction-changing nystagmus or downbeat nystagmus are red flags for central pathology requiring urgent MRI 10, 11

Diagnostic Approach

Head CT is frequently normal or nondiagnostic in AOP infarction, particularly in the first 9.5 hours (570 minutes) from symptom onset 1. In the largest recent series, CT was only diagnostic when obtained >570 minutes from time last known well 1.

MRI with diffusion-weighted imaging (DWI) is diagnostic at all time points and demonstrates the characteristic bilateral paramedian thalamic hyperintensity with or without rostral midbrain involvement 1, 2, 3, 4, 6, 8.

Common Presenting Features to Recognize

• Systolic blood pressure >140 mmHg (80% of cases) 1
• Sudden onset severe drowsiness or altered consciousness 1, 8
• Vertical gaze abnormalities – specifically inability to look upward 2, 3, 4
• Acute cognitive or memory disturbance 1, 2
• Dysarthria (28% of cases) 1, 2

The median time from ED arrival to stroke diagnosis was 519 minutes (8.6 hours) in one series, highlighting the diagnostic challenge 1. Maintain high clinical suspicion when patients present with altered consciousness and vertical gaze abnormalities, even if initial CT is normal 1, 4, 8.