Thermal and tactile perception thresholds in acute herpes zoster

This study was conducted to determine somatosensory perception thresholds in 97 immunocompetent patients with herpes zoster (HZ), and to evaluate their associations with the development of post-herpetic neuralgia (PHN). Warm, cold and heat pain thresholds were tested by Thermotest (SOMEDIC) and tactile thresholds by Semmes-Weinstein monofilaments. To establish reference values, 103 healthy subjects underwent somatosensory testing, from which values were calculated for both genders for four age groups (<60, 60-69, 70-79 and >/=80years) in five dermatomal levels (VI, C3, T3, T10 and S1). Patients with HZ underwent quantitative somatosensory testing within the affected dermatome, its mirror image dermatome and an adjacent dermatome bilaterally. The follow-up visits with somatosensory testing took place at 2 weeks, 6 weeks, 3 months and 6 months. When evaluated as means of the results, warm and cold thresholds were significantly elevated in the affected dermatome from the initial visit until 3 and 6 months, respectively. By contrast, heat pain thresholds were lowered at the initial visit but normalized by 2 weeks, and tactile thresholds remained unchanged. These threshold changes were associated neither with further development of PHN nor each other. It is concluded that measurement of somatosensory perception thresholds in early stages of HZ shows evidence of impaired neural function but is not helpful in predicting which patient will go on to develop PHN. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.