Could visual changes be associated with a right posterior cerebral artery lesion?

Visual Changes Associated with Right Posterior Cerebral Artery Lesions

Yes, visual changes are definitively associated with right posterior cerebral artery (PCA) lesions, most commonly presenting as left homonymous hemianopia, though the specific manifestations depend on the exact location and extent of the infarction within the PCA territory. 1, 2

Primary Visual Manifestations

Visual Field Defects

• Left homonymous hemianopia is the hallmark presentation of right PCA territory infarction, occurring because the right occipital cortex processes visual information from the left visual field of both eyes 1, 2
• Visual field defects were documented in 74% (23 of 31) of patients with PCA strokes in systematic evaluation 1
• Macular sparing may occur when the occipital pole receives collateral perfusion from the middle cerebral artery, preserving central vision up to 10° despite hemianopia 3
• Superior or inferior quadrantanopia can occur with partial PCA territory involvement affecting specific portions of the calcarine cortex 4

Transient Visual Symptoms

• Transient ischemic attacks (TIAs) in the PCA territory predominantly manifest with visual symptoms rather than completed strokes, distinguishing PCA stenosis from embolic occlusion 2
• The most common visual TIA symptom is "difficulty seeing to one side" rather than complete vision loss 2
• Flashing lights (photopsias) can occur as a manifestation of PCA TIAs 2
• Monocular temporal hemianopia, though rare, has been documented with left occipital lobe infarction 5

Higher-Order Visual Processing Deficits

Visual Agnosia

• Agnosic visual disorders following PCA infarcts are more frequent than traditionally recognized, requiring dedicated testing batteries to identify 1
• Right PCA lesions can produce deficits in recognizing faces (prosopagnosia), houses, and objects, depending on which occipitotemporal regions are affected 1
• In systematic testing, 65% (20 of 31) of PCA stroke patients demonstrated visual processing deficits for at least one category of stimuli (faces, houses, objects, or words) 1
• Six patients (19%) had category-specific deficits affecting only a single type of visual stimulus, which can easily escape clinical detection 1

Perceptual Abnormalities

• Palinopsia (persistence or recurrence of visual images after the stimulus is removed) represents a rare but documented manifestation of right occipito-temporal PCA infarction 4
• Cerebral dyschromatopsia (impaired color perception) can occur with occipito-temporal involvement 4
• These isolated perceptual abnormalities may present without obvious visual field defects, making diagnosis challenging 4

Clinical Presentation Patterns

Acute Stroke vs. TIA

• PCA atherostenosis produces more TIAs and fewer completed infarcts compared to embolic PCA occlusion 2
• Visual and sensory symptoms often occur together during TIAs, with paresthesias typically involving the arm and hand 2
• The risk of stroke is highest within the first few days following onset of visual symptoms, necessitating urgent evaluation 6

Sensory Accompaniments

• Sensory spells are common with PCA TIAs, always presenting as paresthesias rather than numbness 2
• Combined visual and sensory symptoms occurred in 50% (3 of 6) of patients with symptomatic PCA stenosis 2

Diagnostic Approach

Urgent Evaluation Required

• Any patient presenting with new visual field defects or unexplained visual phenomena requires immediate brain MRI with diffusion-weighted imaging to identify acute ischemia 6
• Vascular imaging with MRA or CTA should be performed to evaluate the posterior circulation 6
• Perimetric examination coupled with urgent neuroimaging enables prompt diagnosis of neurological events causing visual symptoms 4

Anatomical-Clinical Correlation

• The spatial relationship between lesion location and functionally specialized visual areas (face area, place area, word form area) predicts the nature of specific visual deficits 1
• Right hemisphere lesions produce stronger correlations for face and spatial recognition deficits, while left hemisphere lesions more reliably produce word recognition deficits due to stronger lateralization 1

Management Implications

Stroke Prevention

• Patients with PCA TIAs require anticoagulation with warfarin or modern anticoagulants to prevent progression to completed stroke 2
• In follow-up of treated PCA stenosis patients (4 months to 4 years), no patients developed new strokes in the PCA territory with anticoagulation 2
• Immediate referral to specialized stroke centers is mandatory, with treatment following the same protocols as cerebral TIAs 6

Common Diagnostic Pitfalls

• Macular sparing can create false reassurance, as patients may appear to detect stimuli in their blind hemifield through surveillance saccades during inadequate fixation control 3
• Isolated visual perceptual abnormalities without obvious field defects may be misdiagnosed as ophthalmologic rather than neurological conditions 4
• Nonspecific symptoms like headache with vision changes require neuroimaging consideration rather than dismissal as benign entities 5