The accuracy of clinical neurosensory testing for nerve injury diagnosis

The accuracy of the clinical neurosensory test to diagnose trigeminal nerve injuries has never been statistically evaluated. The purpose of this study was to determine the statistical efficacy of the clinical neurosensory test using surgical findings as the "gold" standard, and to determine whether a correlation existed between the sensory impairment score obtained by preoperative testing and the degree of nerve injury found at surgery.

A multisite, randomized, prospective, blinded, clinical trial was conducted on 130 patients with inferior alveolar nerve (IAN) and lingual nerve (LN) injuries. Preoperatively, patients were provided a sensory impairment score using a three-level drop-out clinical neurosensory test (NST), and blind comparisons were made with the surgical findings postoperatively.

The positive predictive and negative predictive values for LN-injured patients were 95% and 100%, respectively. The positive predictive and negative predictive values for IAN patients were 77% and 60%, respectively. There were statistically significant differences in the distribution of age, duration of injury, cause of injury, presence of neuropathic pain, presence of trigger pain, and degree of injury between the IAN and LN patient populations. There was a statistically significant positive relationship found between the sensory impairment score and the degree of nerve injury.

The NST is a clinically useful method to diagnose IAN and LN injuries. However, the NST results are less efficient for IAN injuries than LN injuries, and have a high incidence of false-positive (23%) and false-negative (40%) results when testing patients with IAN injuries. The different rates of statistical efficiency between the two groups of patients may be attributable to differences in prevalence and biologic covariates.