Diagnostic yield of single fiber electromyography and other electrophysiological techniques in myasthenia gravis. II. Jitter and motor unit fiber density studies. Clinical remission and thymectomy evaluation
Cruz Martinez, A.; Ferrer, M.T.; Perez Conde, M.C.; Diez Tejedor, E.; Barreiros, P.; Ribacoba, R.
Electromyography and Clinical Neurophysiology 22(5): 395-417
1982
ISSN/ISBN: 0301-150X PMID: 6284473 Document Number: 195024
Results of single fiber electromyography (SFEMG) performed in extensor digitorum communis (EDC) and frontalis muscles in 26 patients with myasthenia gravis (MG) are described. The highest diagnostic yield in MG corresponds to SFEMG. Increased jitter and impulse blocking in EDC muscle are found in 88% of the patients and in 96% of the cases if SFEMG is performed in frontalis muscle. In the ocular form of the disease, jitter study in facial muscles is the best method to confirm the diagnosis of MG. SFEMG is also the most sensitive method to study the improvement after thymectomy. After complete clinical remission SFEMG still showed subclinical neuromuscular transmission abnormalities in all but 1 of 8 patients tested. Increased motor unit fiber density is found in some patients. The possible significance of this finding is discussed.