Motor involvement in acute herpes zoster

Area of Science:

• Neurology
• Infectious Diseases
• Clinical Electrophysiology

Background:

• Motor involvement in acute herpes zoster is traditionally considered rare.
• The actual incidence and extent of motor nerve involvement in herpes zoster remain largely unknown.
• Acute herpes zoster can potentially affect the nervous system beyond the affected dermatome.

Purpose of the Study:

• To investigate the incidence and characteristics of motor involvement in patients with acute herpes zoster.
• To determine the extent and duration of subclinical motor abnormalities using electromyography (EMG).
• To explore potential associations between EMG findings and clinical presentation of herpes zoster.

Main Methods:

• Electromyography (EMG) was performed on 40 patients diagnosed with acute herpes zoster.
• EMG assessed for abnormalities such as fibrillation potentials, positive sharp waves, and high-frequency discharges.
• Repeat EMG examinations were conducted over several months in a subset of patients.

Main Results:

• Abnormal EMG findings, indicative of motor unit involvement, were detected in 53% of patients.
• Motor abnormalities were widespread, extending beyond the rash-affected segment both cranially and caudally, and bilaterally.
• In 13% of patients, EMG changes progressed over months; no correlation was found between EMG findings and rash severity, pain, or postherpetic neuralgia.

Conclusions:

• Widespread subclinical motor involvement is a relatively common complication of acute herpes zoster.
• EMG is a sensitive tool for detecting these subclinical motor abnormalities, which can persist for months.
• The findings suggest a broader neurological impact of herpes zoster than clinically apparent.