Pain and sensory dysfunction 6 to 12 months after inguinal herniotomy

Inguinal hernia repair is associated with a 5%-30% incidence of chronic pain, but the pathogenesis remains unknown. We therefore evaluated pain and sensory dysfunction by quantitative sensory testing 6-12 mo after open herniorrhaphy. Before sensory testing, all patients (n = 72) completed a short-form McGill Pain Questionnaire and a functional impairment questionnaire. Sensory dysfunction in the incisional area was evaluated by quantification of thermal and mechanical thresholds, by mechanical pain responses (von Frey/pressure algometry), and by areas of pinprick hypoesthesia and tactile allodynia. The incidence of chronic pain was 28% (20 of 72). Quantitative sensory testing and pressure algometry did not demonstrate differences between the pain and nonpain groups, except for a small but significant increase in pain response to von Frey hair and brush stimulation in the pain group. Hypoesthesia, or tactile allodynia, in the incisional area was observed in 51% (37 of 72) of the patients, but the incidence did not differ significantly between the pain group and the nonpain group (14 of 20 versus 23 of 52; P > 0.3). We concluded that cutaneous hypoesthesia, or tactile allodynia, is common after inguinal herniotomy but has a low specificity for chronic postherniotomy pain. Factors other than nerve damage maybe involved in the development of chronic postherniotomy pain.