The presence of neuropathic pain predicts postoperative neuropathic pain following trigeminal nerve repair

Purpose: The risk for the continuation or recurrence of neuropathic pain following trigeminal nerve repair has never been examined. The objective of this study was to determine which risk factors might be associated with the continuation or recurrence of neuropathic pain following trigeminal nerve microneurosurgery.

Patients and methods: An ambispective study design was used to assess subjects who underwent trigeminal nerve repair of the inferior alveolar nerve and lingual nerve between 2000 and 2010. The primary outcome was the presence or absence of neuropathic pain at 3, 6, and 12 months after surgery. Explanatory variables, including age at surgery, gender, presence of neuropathic pain before surgery, site of nerve injury, etiology of nerve injury, classification of nerve injury, duration of nerve injury, and type of repair performed, were abstracted from patient charts. Fisher exact tests were used to compare the demographic and injury characteristics of patients who presented with pain before surgery and those who did not. The McNemar test was used to assess whether there was a significant change in neuropathic pain report from before to after surgery. The level of significance was set at .50.

Results: Of the 65 patients analyzed, two-thirds were women; the average age was 36±16.1 years, and the median time between the injury and surgery was 6.4 months (interquartile range, 6.7 months). Lingual nerve injury type was the most frequent (62%). There was no statistically significant change in pain status from before to after surgery (P=.104). Only 1 patient had pain after surgery who had not had pain before surgery, while 67% of those with pain before surgery continued to have pain after surgery. Pain prior to surgery as a predictor of pain after had sensitivity of 91%, specificity of 88%, positive predictive value of 67%, and negative predictive value 97%.

Conclusions: The presence of neuropathic pain prior to trigeminal microneurosurgery is the major risk factor for the continuation or recurrence of postoperative neuropathic pain. These findings suggest that trigeminal nerve surgery is not a risk factor for developing neuropathic pain in the absence of neuropathic pain before surgery.