What would be the typical clinical presentation of a patient with proximal left posterior cerebral artery occlusion, a diminutive right vertebral artery occluding before the intradural segment, proximal right subclavian stenosis, and moderate bilateral internal carotid artery stenosis?

Clinical Presentation of Proximal Left PCA Occlusion with Posterior Circulation Compromise

This patient will most likely present with visual field deficits (homonymous hemianopia or quadrantanopsia), potentially accompanied by sensory symptoms, and possibly altered consciousness or motor deficits if thalamic involvement occurs from the proximal PCA occlusion. The compromised posterior circulation from the vertebral artery abnormalities may add symptoms of vertebrobasilar insufficiency including vertigo, ataxia, diplopia, or nausea. 1, 2

Primary Clinical Features from Left PCA Occlusion

Visual Symptoms (Most Common)

• Homonymous hemianopia or quadrantanopsia occurs in approximately 77% of PCA territory strokes, representing the most frequent presenting symptom 2
• Patients describe difficulty seeing to one side, or in some cases may report flashing lights 3
• Visual field defects from PCA occlusion rarely improve even with good survival outcomes 4

Motor and Sensory Deficits

• Hemiparesis occurs in approximately 29% of PCA strokes overall, but increases dramatically to 63% with proximal P1 segment occlusions (as in this case with proximal left PCA involvement) 2
• Sensory symptoms are characteristically paresthetic, typically involving the arm and hand, occasionally extending to face and leg 3
• Visual and sensory symptoms frequently occur together in the same patient 3

Thalamic Involvement

• Proximal P1 occlusions cause thalamic infarction in 65% of cases, which explains the higher rate of motor deficits and worse outcomes 2
• This anatomic involvement can produce altered consciousness, somnolence, or cognitive changes 1

Additional Posterior Circulation Symptoms

Vertebrobasilar Insufficiency Manifestations

• The diminutive right vertebral artery occluding before the intradural portion, combined with right subclavian stenosis creating potential subclavian steal, may produce symptoms of posterior cerebral circulatory insufficiency 1
• Symptoms include lightheadedness, syncope, vertigo, ataxia, diplopia, nausea, vomiting, dizziness, hearing loss, and imbalance 1
• These symptoms may be aggravated by left upper extremity exercise if subclavian steal physiology is present 1

Brainstem Signs

• Physical examination may reveal ataxia, nystagmus, cranial nerve deficits, or skew deviation 1
• The bilateral ICA stenosis adds anterior circulation vulnerability but is less likely to be symptomatic acutely 1

Critical Diagnostic Considerations

NIHSS Limitations

• The NIHSS significantly underestimates posterior circulation stroke severity because it emphasizes limb and speech impairments while minimizing cranial nerve lesions, vertigo, and dysphagia 1
• Patients with pc-ELVO can present with NIHSS scores of 0 despite significant symptoms, with truncal ataxia being the most common neurological sign in such cases 1
• The baseline NIHSS cut-off for favorable 3-month outcome is significantly lower in posterior circulation strokes compared to anterior circulation strokes 1

Prognostic Factors

• Proximal P1 occlusions carry significantly worse prognosis, with 70% showing poor outcome (mRS >2) at discharge compared to 29% for more distal occlusions 2
• Predictors of poor outcome include older age, higher NIHSS score, lack of recanalization, atrial fibrillation, intracranial hemorrhage, and pc-ASPECTS ≤8 1
• Overall mortality for posterior circulation large vessel occlusions ranges from 45% to 86%, with good clinical outcomes occurring in only approximately 20% despite advanced care 1

Common Clinical Pitfalls

• Do not dismiss subtle symptoms: Headache, vertigo, and nausea alone may represent pc-ELVO, requiring high clinical suspicion and urgent imaging 1
• Do not rely solely on NIHSS: A low score does not exclude devastating posterior circulation stroke 1
• Consider the prodrome: Unlike anterior circulation strokes, basilar artery occlusion can have an extended prodrome lasting days to months, and may mimic other clinical conditions 1
• The presence of bilateral ICA stenosis and subclavian stenosis suggests systemic atherosclerosis, making embolic versus in situ thrombosis considerations important for acute management 1