A comparison of nerve conduction studies and somatosensory evoked potentials in the diagnosis of meralgia paresthetica

Nerve conduction studies of lateral femoral cutaneus nerve (LFCN) and somatosensory evoked potentials (SEP) evoked by electrical stimulation of LFCN are main electrophysiological methods used in the diagnosis of meralgia paresthetica (MP). However, the reliability of these methods is disputatious. The aim of this study is to compare the diagnostic sensitivities of sensory nerve conduction studies of LFCN and LFCN SEPs in patients with MP. Fifteen patients with clinically defined MP and 20 control subjects were studied with both methods. The onset latency, peak to peak amplitude and interside differences of sensory nerve action potential (SNAP) of LFCN, peak latency, peak to peak amplitude and interside differences of first cortical component of SEP (Fz/Cz derivation recording) (P0) were analyzed. All patients showed NCS abnormalities. Unrecordable SNAPs and alterations in the amplitude of LFCN SNAP was more frequently observed abnormalities in patients with MP. SEP abnormalities were observed in 12/15 patients (80%). Increased interside differences of peak latency of P0 component was most useful parameter among the SEP parameters. Our results suggest that nerve conduction study of LFCN is a more reliable parameter in the diagnosis of MP.