Severity of skin lesions of herpes zoster at the worst phase rather than age and involved region most influences the duration of acute herpetic pain

Abstract

Duration of acute herpetic pain (AHP) in 1431 patients for whom treatment was begun within 14 days after the onset of herpes zoster (HZ) was analyzed with respect to age, involved region, and severity of skin lesions. All patients were treated with repeated sympathetic nerve blocks until their pain was almost nil. Severity of the skin lesions at the worst phase was defined as mild when they covered less than one-quarter of the primary dermatome, as severe when they covered more than three-quarters of the primary dermatome, and moderate if they were between mild and severe. Without taking into account the severity of skin lesions, the duration of AHP for those aged 60 years or over and for those with trigeminal involvement was significantly longer than for patients aged under 40 years (P < 0.01 and P < 0.001) and for patients with thoracic (P < 0.001) and lumbosacral (P < 0.01) involvement, respectively. However, duration of AHP was significantly longer with increase in the severity of skin lesions in all age groups (the mild group versus the moderate group, P < 0.01 and P < 0.001; the moderate group versus the severe group, P < 0.01 and P < 0.001). The mean duration of AHP for patients aged 60 years or over with mild skin lesions ranged from 17.4 to 22.9 days, while that for patients aged 30-59 years with severe skin lesions ranged from 37.2 to 50.1 days. In addition, duration of AHP was significantly longer with increase in the severity of skin lesions in all regions (the mild group versus the moderate group, P < 0.01 and P < 0.001; the moderate group versus the severe group, P < 0.05 and P < 0.001). The mean duration of AHP for those with trigeminal involvement with mild skin lesions was 19.5 days, while the range was from 51.3 to 55.0 days for patients with severe skin lesions involving regions other than the trigeminal area. The frequency of severe skin lesions was significantly higher (P < 0.001) in patients aged 60 years or over and in those with trigeminal involvement. Multiple stepwise regression analysis revealed that the most important factors influencing the duration of AHP were the severity of skin lesions of HZ at the worst phase (r = 0.412), age (r = 0.277) and the involved region (r = -0.101). Thus, AHP in the elderly and in cases of trigeminal involvement is longer because of higher frequencies of severe HZ in the elderly and in trigeminal involvement rather than "being aged' and "trigeminal involvement' itself. We propose that one needs to analyze the results of treatment of AHP with respect to the severity of skin lesions at the worst phase.