SUBCORTICAL TYPE COGNITIVE IMPAIRMENT IN HERPES-ZOSTER ENCEPHALITIS

Nine immunocompetent patients with acute herpes tester encephalitis (H ZE) were studied with the help of neurological, neuroradiological and neuropsychological investigations. All patients were treated with acyc lovir. Neuropsychological performance was compared with that of a grou p of 16 healthy controls. Computed tomography of the head showed infar ct-like hypodense lesions in two patients, involving the internal caps ule in one case and the temporoparietal cortex and white matter in ano ther. Hypoperfusion shown by single photon emission computed tomograph y, mostly involving the frontal areas bilaterally, was seen in six of the seven patients examined. Hyperperfusion as seen in herpes simplex encephalitis was not encountered. One patient remained mildly demented , but all the other patients recovered relatively well. Neuropsycholog ical examination after acyclovir treatment showed a decline in memory and speed of cognitive processes, without circumscribed neuropsycholog ical deficits. Six of the nine patients showed behavioural disinhibiti on, and mood changes were also observed. Memory impairment in HZE was not as global or as severe as is described after encephalitis due to h erpes simplex virus. In HZE both the brain perfusion pattern and the n europsychological test profile showed features compatible with subcort ical dysfunction.