Cortical blindness after correction of symptomatic hyponatremia: dynamic cerebral dysfunction visualized using serial SPECT scanning.

A 70-yr-old woman developed cortical blindness after correction of hyponatremia. Regional hyperperfusion was noted on SPECT scans obtained in the acute phase. One month later when symptoms had largely resolved, a repeat examination was normal. This regional hyperperfusion, which was not associated with any apparent structural damage, may have represented either luxury perfusion or a transient increased metabolic requirement of the dysfunctional cortical area. SPECT scanning may be a useful method to study cerebral dysfunction resulting from an osmotic disturbance.