What are the signs and symptoms of a posterior cerebral artery (PCA) territory infarct?

PCA Territory Infarct Signs and Symptoms

Posterior cerebral artery (PCA) territory infarcts most commonly present with visual field defects (84% of cases), but the clinical presentation varies significantly based on whether the infarct involves superficial cortical territories alone or extends to deep structures (thalamus/midbrain). 1, 2

Core Clinical Features

Visual Manifestations (Most Common)

• Homonymous hemianopia is the hallmark finding, present in the vast majority of patients 3, 2
• Patients typically describe the visual loss as a negative phenomenon (darkness/absence of vision) in 87% of cases 3
• 66% of patients can correctly lateralize their visual symptoms to a hemifield affecting both eyes 3
• Isolated visual perceptual abnormalities may occur, including:
  • Palinopsia (visual perseveration)
  • Cerebral dyschromatopsia (defective color vision)
  • Cortical blindness (in bilateral PCA infarcts) 4, 5

Non-Visual Symptoms (Present in 43%)

The following symptoms suggest more extensive ischemia involving deep structures 3:

• Sensory deficits (numbness, tingling) - strongly linked to concurrent thalamic infarction 3
• New-onset headache - common presenting symptom, often unilateral 6
• Motor weakness (typically mild and reversible, present in 25%) 2
• Ataxia (25%) 2

Neuropsychological and Behavioral Deficits

These occur primarily with cortical involvement:

• Left PCA infarcts: Reading disorders (alexia) 4
• Right PCA infarcts: Spatial disorientation, visual neglect 4
• Bilateral PCA infarcts: Amnesia, cortical blindness with anosognosia (patient denies blindness) 4

Location-Specific Syndromes

Deep Territory Involvement (P1-P2 Segments)

Thalamomesencephalic infarcts present with the classical triad 4:

1. Hypersomnolence/decreased consciousness
2. Cognitive deficits
3. Vertical oculomotor paresis

Thalamogeniculate artery territory: Severe contralateral hypesthesia and ataxia 4

Posterior choroidal artery territory: Sectoranopia with lateral geniculate body involvement 4

Combined Cortical and Deep Infarcts (38% of cases)

• More severe sensory deficits
• Motor weakness (usually mild)
• Neuropsychological impairments
• Associated with worse outcomes 7

Critical Clinical Pitfalls

Non-Specific Presentation

90% of PCA strokes occur without preceding warning symptoms 3, making diagnosis challenging. The presentation can be subtle and easily missed:

• Symptoms may be limited to headache, vertigo, and nausea only
• Patients can have NIHSS score of 0 despite significant stroke 1
• Truncal ataxia may be the only neurological sign 1
• Maintain high clinical suspicion even with minimal findings 1

Delayed Recognition

• PCA strokes are frequently misdiagnosed as complicated migraine due to unilateral headache presentation 6
• Door-to-needle time for IV tPA is significantly longer than anterior circulation strokes 1
• 10% have prodromal warning symptoms that are retrospectively identified 3

Procedure-Related Strokes

20% of PCA strokes occur within 72 hours of a medical/surgical procedure or newly identified medical condition 3 - consider this temporal relationship when evaluating postoperative patients with visual complaints.

Prognostic Indicators

Poor outcomes are associated with:

• Consciousness disturbances at onset (RR 66.6) 7
• Mesencephalic and/or thalamic involvement (RR 3.79) 7
• Proximal large-artery disease (RR 2.71) 7
• Basilar artery disease (RR 5.94) 7

Overall mortality is relatively low (7%), but long-term behavioral and cognitive deficits are frequently underestimated 4, 7. Stroke recurrence occurs in 16% during 6-month follow-up 7.