Effects of acyclovir on sensory axonal neuropathy, segmental motor paresis and postherpetic neuralgia in herpes zoster patients

The effect of oral treatment with acyclovir (ACV) on sensory axonal neuropathy, segmental motor paresis and postherpetic neuralgia (PHN) was studied in 105 patients with herpes tester. Forty-seven patients were treated with ACV at a dose of 4 g/day in 5 doses for at least a week; the others did not undergo any kind of treatment. Electrodiagnostic examination of the nerves and muscles corresponding to the dermatomeric lesions was performed, including sensory and motor nerve conduction studies, blink reflex and electromyography (EMG). The patients treated with ACV showed a significant reduction in the number of cases in which there was electrophysiological evidence of axonal damage in afferent fibres of nerves arising from roots corresponding to affected dermatomes. The treated group also showed a smaller incidence of segmental motor neuritis, clinically evident or only detectable by EMG as denervation. However, there was no significant difference between groups as far as the incidence of PHN was concerned. Oral treatment with ACV therefore reduces peripheral sensory axonopathy due to ganglion damage and prevents the possibility of spread to anterior roots and spinal motoneurones. In this way it reduces the incidence of segmental motor neuritis, but does not reduce the incidence of PHN.