Diagnostic and prognostic value of electrophysiologic tests in meralgia paresthetica. Electrophysiologic diagnosis of unilateral meralgia paresthetica is usually assessed by side-to-side comparison of SNAP amplitudes, SNCVs, and SEP latencies following stimulation of lateral femoral cutaneous nerves. To determine the relevance for diagnosis of these tests and side-to-side comparison, the results were compared in patients with unilateral meralgia paresthetica and normal subjects. The long-term outcome was also considered, in order to determine whether electrophysiologic findings contribute to the prognosis. In our study, SNAP amplitude comparison was found to be more useful for diagnosis than SNCV and SEP latency comparisons. However the value of the SNAP amplitude on the affected side, just as the results of the other tests, was not found to be predictive of the outcome. Also the results of the tests depend on the methods used and on the nerve's route. 