What is the management of cortical blindness?

Management of Cortical Blindness

Visual rehabilitation with perceptual training is the cornerstone of management for cortical blindness, particularly when initiated within 6 months of onset, as it can improve visual sensitivity in the blind field and maximize remaining vision.

Definition and Etiology

Cortical blindness refers to vision loss caused by damage to the primary visual cortex (V1) or its postchiasmal afferents, rather than damage to the eyes themselves. Common causes include:

• Cerebrovascular disease (most common cause) 1
• Cardiac surgery complications 1
• Cerebral angiography 1
• Bilateral occipital lobe infarctions in the posterior cerebral artery territory 2
• In children: hypoxia, status epilepticus, intracranial hemorrhage, cerebral thrombosis, and head trauma 3

Diagnostic Evaluation

When evaluating a patient with suspected cortical blindness:

• Assess for neurological symptoms beyond vision loss, including seizures, lethargy, and coma 4
• Perform fundoscopic examination to rule out retinal causes
• Order neuroimaging:
  • CT or MRI to identify occipital lesions (bioccipital lucencies on CT indicate poor prognosis) 1
  • CTA or MRA for suspected vertebrobasilar insufficiency (94% sensitivity, 95% specificity) 5
• EEG typically shows abnormal findings with absent alpha rhythm 1
• Visual evoked potentials are often abnormal but don't reliably correlate with prognosis 1

Management Approach

Acute Management

1. Address the underlying cause:

   • For stroke-related cortical blindness, follow standard stroke protocols
   • For vertebrobasilar insufficiency:
     • Antiplatelet therapy (aspirin plus dipyridamole) for secondary prevention 5
     • Anticoagulation for acute ischemic syndromes with thrombus in extracranial vertebral artery 5
     • Consider revascularization procedures in appropriate cases 5

2. Manage risk factors:

   • Blood pressure control
   • Lipid management
   • Diabetes management
   • Smoking cessation 5

Visual Rehabilitation

1. Timing is critical:

   • Begin rehabilitation as early as possible, ideally within the first 6 months (subacute period) 5, 6
   • After 6 months, the visual deficit is traditionally considered stable, though recent evidence suggests improvements may still be possible 6

2. Perceptual training approaches:

   • Localized, repetitive perceptual training to improve visual sensitivity in the blind field 6, 7
   • Saccadic localization training to improve oculomotor adaptations 6
   • Visual training programs that target specific deficits 5

3. Optical aids:

   • Prismatic spectacle correction 5
   • Other optical systems to maximize remaining vision 5

Prognosis

Prognosis varies significantly based on:

1. Etiology:

   • Poor prognosis: Spontaneous stroke (all 8 patients in one study had poor recovery) 1
   • Better prognosis: Non-stroke causes, especially hypotensive episodes after cardiac surgery 3

2. Patient factors:

   • Better outcomes in patients under 40 years of age 1
   • Better outcomes in those without hypertension or diabetes 1
   • Better outcomes in those without associated cognitive, language, or memory impairments 1

3. Imaging findings:

   • Bioccipital abnormalities on CT scan are associated with poor prognosis 1
   • Cerebral atrophy on CT is a poor prognostic sign 3

4. Recovery timeline:

   • In children with good outcomes, recovery typically occurs within 2 weeks to 5 months 3

Follow-up Considerations

• Regular follow-up is essential, as patients with unilateral occipital infarction have risk of developing delayed contralateral occipital infarction leading to worsening cortical blindness 5
• Monitor for improvement in visual function during rehabilitation
• Assess for development of other neurological symptoms
• Continue management of underlying vascular risk factors

Special Considerations in Children

• Congenital cortical blindness has a poorer prognosis than acquired forms 3
• EEG findings with focal or multifocal spike-wave discharges indicate poor prognosis 3
• Visual evoked potentials: abnormal or absent responses predict poor recovery (only 14% had normal vision) 3