[Lateral femoral cutaneous neuropathy: paresthetic meralgia. Neurophysiological diagnosis]

The neurophysiological approach to meralgia paresthetica (MP) deals with the possible abnormalities demonstrated in the peripheral nerve conduction and/or somatosensory evoked potentials (SEP) of the lateral femoral cutaneous nerve (LFCN).

To ascertain the diagnostic value of these methods, a group of 23 patients with unilateral MP symptoms has been studied; SEP of LFCN was also evaluated in a series of normal people.

LFCN conduction was abnormal on the symptomatic side in 47.6% of the cases and nerve potential was absent on both sides in all the rest. SEPLFCN showed some impairment in 91% of the cases on the symptomatic side and responses were obtained on the asymptomatic side in every case; the most common abnormality was the delay of the response followed by its followed by its absence. In the normal group, the amplitude of potentials registered on the contralateral scalp to the stimulated side was usually higher than that registered on the median line, where they eventually lacked. Methodologically, this fact supports the need of a multiple recording of the SEPLFCN on the scalp.

The SEPLFCN should be considered as the main technique for the objective diagnosis of MP and although LFCN conduction can supply useful information in individual cases, its exclusive use may lead to rather many positive false results.