Diagnostic value of electrophysiological tests in patients with sciatica Albeck MJ, Taher G, Lauritzen M, Trojaborg W. Diagnostic value of electrophysiological tests in patients with sciatica. Acta Neurol Scand 2000: 101: 249±254. # Munksgaard 2000. Objectives ± To assess the diagnostic value of electrophysiological tests in patients with sciatica. Materials and methods ± The diagnostic value of electrophysiological tests were evaluated in 25 patients with mono- radicular sciatica. The electrophysiological study included dermatomal somatosensory evoked potentials, electromyography, F-wave latencies, H-re¯exes and motor and sensory nerve conduction determinations. The results of the electrophysiological examinations were evaluated blindly, and the test results were analysed separately by a receiver operating characteristic (ROC) analysis. Furthermore, the 5 modalities were evaluated jointly and analysed by a decision-analytic regret function. Results ± A high predictive value was found for the H-re¯ex examination, but low for the other modalities. When the 5 modalities were evaluated jointly, a non-signi®cant decrease in expected regret from the pre-test situation of 0.96 to a value of 0.93 in post-test situation was revealed. Conclusion ± Electrophysiological testing is not suf®cient as stand-alone examination in patients with sciatica. M. J. Albeck 1 , G. Taher 2 , M. Lauritzen 2 , W. Trojaborg 2 1 University Clinic of Neurosurgery, and 2 Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark Key words: electrophysiological test; evoked potential; intervertebral disc displacement; diagnostic test Michael J. Albeck, Department of Neurosurgery, A Ê rhus Kommunehospital, University of Aarhus, DK-8000 A Ê rhus C, Denmark Accepted for publication November 10, 1999 The diagnosis of lumbar disc herniation is mainly based on clinical examination in combination with imaging studies. Electrophysiological tests have been suggested as substitutes for, or as a supple- ment to, imaging examinations. Several electro- physiological methods are available to evaluate nerve root function: needle electromyography aims to identify the affected myotome, F wave latency measurements may reveal slowing of proximal motor conduction, H re¯ex studies are particularly useful to examine afferent and efferent pathways of the S 1 root. In addition somatosensory evoked potentials from the lumbosacral dermatomes may be of use, especially in patients with only sensory symptoms. Electrophysiological tests are especially valuable in patients with negative ®ndings at myelography or CT, or in patients with uncharacteristic clinical ®nd- ings. In such patients, electrophysiological assess- ment gives clues to nerve function, and may reveal the site of the lesion. The aim of the present report was to determine whether multimodality electro- physiological tests are valuable to reveal a disc herniation in patients with monoradicular sciatica and suspicion of low lumbar disc herniation. A comprehensive electrophysiological test battery was used. In the operated patients the intra- operative ®nding of a disc herniation was used as the ®nal diagnosis. In the 5 patients without operation the clinical examination and course of symptoms, myelography or CT ruled out the presence of a disc herniation. Material and methods Patient selection and ®nal diagnosis Twenty-®ve consecutively recruited patients (16 males, 9 females, aged 23±58 years, median 40 years) with clinically suspected low lumbar disc herniation, were included in the prospective study. All patients had monoradicular sciatica correspond- ing to the L 5 (16 patients) or the S 1 (9 patients) root distribution. All but one had low back pain. The actual pain had lasted for 1±36 months (median 4 months). Six patients had diminished Achilles Acta Neurol Scand 2000: 101: 249±254 Printed in UK. All rights reserved Copyright # Munksgaard 2000 ACTA NEUROLOGICA SCANDINAVICA ISSN 0001-6314 249