Motor Involvement in Herpes Zoster Using EMG Study

ABSTRACT

Herpes zoster(HZ) is well known as a benign viral infection affecting the sensory nerves. That this disease may also cause motor paralysis is less well known. We performed this study to evaluate the exact prevalence of motor involvement and to compare the extent of EMG abnormality with that of skin lesions. Ninety patients with HZ who did not sho w clinical motor weakness except 4 patients with Ramsay-Hunt syndrome were studied prospectively for 2 years using EMG which is generally known to be very sensitive method for detection of motor involvement. The results turned out as follows. I.. In patients with Herpes zoster, motor involvement(denervation m EMG study) is 56.67%(51/90 patients) and subclinical motor involvement is 54.65%(47/86 patients). 2. There was no statistically significant difference m the rates of motor involvement among the cranial, cervical, thoracic & lumbosacral regions. 3. There was no statistically significant difference in the rates of motor involvement between the male and female, although the positivity were higher in male. 4. The subclnical motor involvement was gradually increased by aging, as seen in clinical motor paralysis of other report. 5. There was significant statistic difference between the number of dermatome involved by skin lesion(mean 1.88) and that of myotome with motor involvement (mean 2.55). In conclusion, it is suggested that subclnical motor involvement in Herpes zoster is rather frequent and extensive than generally expected.