The Diagnostic Validity of Samatosensory Evoked Potentials in Meralgia Paresthetica

ABSTRACT

BACKGROUND: Meralgia paresthetica(MP) is clinically benign entrapment neuropathy which is characterized by paresthesias and sensory impairment in the cutaneous distribution of the lateral femoral cutaneous nerve(LFCN). The diagnosis of MP is mostly based on clinical symptoms. Sensory nerve conduction study of the LFCN have been of limited value because frequently they could not be recorded in able-bodied persons and also because lesions of the nerve may be localized proximally from the segment that is accessible to nerve conduction study. For these reasons, I studied simple bilateral somatosensory evoked potentials(SSEP) of LFCN to evaluate this clinical symptoms objectively. METHODS: 16 MP patients (mean age+/-SE 50+/-3.21yrs) and 15 disease free adults(49+/-4.47yrs) were studied bilateral SSEP of LFCN. The stimulation site was anterolateral aspect of thigh and the recording site was Cz'. RESULTS: The mean latencies of P0 and N1 were prolonged on the affected side(P<0.05), The mean latency differences of P0 and N1 between two sides were increased in the patients with MP compare with those of controls.(P<0.001) The mean amplitude difference between two sides were increased in the patients with MP compare with that of controls(P<0.05). CONCLUSION: SSEP of LFCN can be used as a objective test to support the diagnosis of MP. I suggest more than 2.4msec difference for P0 latency between affected and unaffected side could be abnormal.