SATELLITE POTENTIALS AS A MEASURE OF NEUROMUSCULAR DISORDERS

The study was carried out to investigate the characteristics of satell ite potentials and their validity in clinical electromyography. Conven tional needle electromyography was applied to the right biceps brachii and tibialis anterior muscles of 41 controls, 22 neuropathies, and 17 myopathies. Satellites were defined as small extrapotentials, precedi ng/following the main motor unit action potential (MUAP) component and separated from it by an isoelectrical interval of >1 ms. The normal m ean satellite rate was 1.6% (biceps brachii) and 1.2% (tibialis anteri or). In the biceps brachii (tibialis anterior) muscle it was 5 (5) tim es higher for neuropathies (P = 0.005, P = 0.006) and 5 (6) times high er for myopathies (P = 0.006, P = 0.003). MUAP parameters were not sig nificantly different, whether satellites were considered or ignored. E valuation of the satellite rate increased detection rates of neuromusc ular disorders by up to 13%. The satellite rate proved a valuable and easily available, supplemental electromyographic parameter for the dis crimination and detection of neuromuscular disorders. (C) 1997 John Wi ley & Sons, Inc.