Abstract
Objective: To study retrospectively the thermograms of patients who suffered from postherpetic pain (PHP) or postherpetic neuralgia (PHN) of thoracic nerve (s) over two weeks.
Methods: Average temperatures of the affected skin in 31 patients with PHP or PHN were compared with those of the contralateral normal skin by thermographic measurement; ΔT (difference of average temperatures)=(average temperature of affected side)-(that of normal side), and their sensory disturbances (either hypesthesia or hyperesthesia) of affected segment (s) were checked. The suffering periods were classified into group A (<31 days), B (31-60 days), C (61-180 days) and D (>180 days) according to the days from the onset of herpes zoster to first visit to our clinic. Also the treatment periods during our participation as to nerve block therapy were classified into group a (<31 days), b (31-90 days) and c (>90 days). Three relations were examined; between sensory disturbances and ΔT, between suffering period and ΔT and between treatment period and ΔT.
Results: The mean±standard deviation (SD) of ΔT of group A (n=7) was 0.20±0.35°C. The mean±SD of ΔT of group B (n=13), C (n=6) and D (n=5) were -0.26±0.32°C, -0.13±0.25°C and -0.20±0.14°C, respectively. The data of group A were significantly different from group B. There were no meaningful differences, however, among three groups of a, b, c as to ΔT. On the other hand, the patients with hypesthesia visited our clinic significantly later than those with hyperesthesia. The majority (96%) of patients after a month from onset of the disease didn't show warm thermographic pattern in the affected area. The ΔT of 48% of all patients were within±0.2°C.
Conclusion: The thermograms of patients with postherpetic pain suffering within a month revealed different patterns from those suffering for more than one but less than two months; the former were warmer than the latter. There was no correlation between ΔT and sensory disturbance and between ΔT and treatment period.
