Characteristics of the neuropathy induced by thoracotomy: a 4-month follow-up study with psychophysical examination

Objectives To explore the role of neuropathy in persistent pain after thoracotomy, combining a clinical follow-up and a psychophysical examination of the operated area. Methods Seventy-three patients were followed and examined at their discharge from hospital, 6 weeks and 4 months after pneumonectomy under thoracotomy. Spontaneous and evoked pain was assessed by clinical examination, a 7-day pain score, and the Neuropathic Pain Symptom Inventory. At the fourth month follow-up, pain and tolerance thresholds to pinprick, heat, and warm sensation threshold were measured on both sides of the thorax. Results The rate of spontaneous pain was 40% at discharge and went up to 59% at the sixth week follow-up. Evoked pain was rare at discharge (11%), most cases appearing at the sixth week follow-up (47%). The evolution profiles of pain between the sixth week and the fourth month follow-up were heterogeneous with a tendency to decrease. Young age, female sex, and spontaneous pain observed at discharge from hospital were identified as early predictive factors of spontaneous pain persisting at the fourth month follow-up. On the side of operation, thresholds tended to increase for warm and hot stimuli, and to decrease for mechanical stimuli. At the fourth month follow-up, spontaneous pain and evoked pain were associated to static hyperalgesia, persisting hypoesthesia, low mechanical thresholds, altered sensation of heat, and impaired quality of life. Discussion Peripheral neuropathy is common after thoracotomy, with variant characteristics, ranging from subclinical disturbances to severe pain. The process seems to develop between the discharge from hospital and the sixth week after thoracotomy.