title: A test for the evaluation of the lateral cutaneous branch of the iliohypogastric nerve using somatosensory evoked potentials.
abstract: Iliohypogastric nerve (IHN) lesions are rare and usually due to abdominal surgery or trauma. There is no established electrophysiologic test for evaluating this nerve. A method is proposed to evaluate the IHN lateral cutaneous branch using somatosensory evoked potentials (SSEP). SSEP were elicited in 20 subjects using electrical stimulation from the greater trochanter up to 7 cm posterior to a point on the posterior axillary line, at the level of the greater trochanter. The active recording electrodes were placed 2 cm behind the Cz electrode in the midline, and the reference electrode midway between the Fpz and Fz electrodes in the midline. Stable responses were elicited in 19/20 subjects (12 male), aged 19-52 years (mean 32+/-6.6). Average positive peak onset latency was 32.5+/-3.7 msec, average amplitude 0.96+/-0.4 microV. Side-to-side latency difference range was 0-3.7 msec and amplitude difference range 0.06-1.04 microV. The technique proved sensitive in two cases with IHN injury following trauma, a 24-year-old male with a large hematoma over the right hip from the iliac crest to the greater trochanter tested twice one year apart, with stable repeat responses, and a 26-year-old female who sustained a crush injury to the right lateral pelvis. A side-to-side latency difference >3.7 msec or a unilateral absent response should be regarded as abnormal. This test may be useful for confirming the clinical picture of IHN lateral cutaneous branch lesions.
authors.affiliation: Department of Neurology and EMG Laboratory, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, 6, Weizmann St, 64239 Tel-Aviv, Israel.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Rabie
authors.forename: Vivian E
authors.initials: VE
authors.lastname: Drory
mesh_terms: D000063:Accidents, Traffic; D000328:Adult; D004566:Electrodes; D004568:Electrodiagnosis / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005269:Femur / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D025981:Hip Injuries / Q000503:physiopathology; D006801:Humans; D007085:Ilium / Q000293:injuries; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000293:injuries; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000503:physiopathology*