Visual hallucinations in recovery from cortical blindness - Imaging correlates

Objective: To investigate the cerebral metabolic and functional patterns du ring recovery from cortical blindness. Design: Follow-up study with serial clinical, metabolic, and functional ima ging and visual evoked potentials. Case Presentation: A 24-year-old woman suffered from cortical blindness aft er cardiac arrest and recovered over a 6-month period. During recovery, she experienced complex visual hallucinations that could be initiated by visua l imagery. Results: Initially, the regional cerebral metabolic rate of glucose was sev erely reduced in the visual and parietooccipital cortex bilaterally but rec overed almost completely. Visual hallucinations led to significant increase s of the regional cerebral blood flow in the initially severely hypometabol ic parieto-occipital and temporo-lateral cortex. Conclusions: Recovery of vision was related to normalization of the postles ionally dysfunctional cortex. Visual hallucinations appeared as the clinica l correlate of the electrophysiological hyperexcitability of the recovering partially damaged visual cortex.