Evaluation of the Occurrence Valus of Post - herpetic Neuralgia in the Patients with Herpes Zoster by using the Electrodiagnostic Tests

Park, Yeon Ho; Park, Young Min; Kim, Hyung Ok

Abstract

BACKGROUND: Post-herpetic neuralgia is the most serious one of herpes zoster complications and its incidence becomes higher as the age of the patient increases. Nevertheless, besides considering the age and onset time of treatment, there is no more objective factor estimating the prognosis of post- herpetic neuralgia.
OBJECTIVE
The aim of this study is to understand the progression of herpes zoster and estimate the prognosis of post-herpetic neuralgia by practicing electrodiagnostic tests to patients with herpes zoster.
METHODS
We evaluated the pain scales in 26 patients with herpes zoster on the first visit and 2 months later. We also performed electrodiagnostic tests, more objective and reproducible methods, including somatosensory evoked potentials and motor nerve conduction studies on both the involved and uninvolved sites of 32 lesions in 26 patients with herpes zoster, and then compared the results with the change of pain scales.
RESULTS
1. The pain category scale and visual analogue scale on the second examination were significantly decreased compared with those on the first examination (P<0.05). 2. Latencies of intercostal somatosensory evoked potentials recorded on scalp and spine were significantly delayed in involved sides compared with those in uninvolved sides (P<0.05). 3. In the latencies and conduction velocities of motor nerve conduction studies, no significant differences were seen between involved sides and uninvolved sides. 4. On the second examinataion, latency differences of somatosensory evoked potentials were significantly improved compared with those on the first examination (P<0.05). 5. Among the various somatosensory evoked potentials parameters, P1 latency difference of cortical somatosensory evoked potentials between involved and uninvolved sides correlated significantly with pain category scale ard visual analogue scale on second examination (r=0.48, P<0.05; r =0.51, P<0.05, respectively). N1 latency difference of spinal somatosensory evoked potentials between involved and uninvolved sides correlated significantly with a visual analoge scale on the first examination and pain category scale on the second examination (r=0.61, P<0.05; r=0.78, P<0.05, respectively).
CONCLUSION
Intercostal somatosensory evoked potentials can be a useful and reliable technique to predict the development and severity of post-herpetic neuralgia.