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Stimulated single fiber EMG of the frontalis muscle in the diagnosis of ocular myasthenia
Author(s) -
VallsCanals J.,
Montero J.,
Pradas J.
Publication year - 2000
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(200005)23:5<779::aid-mus16>3.0.co;2-z
Subject(s) - frontalis muscle , myasthenia gravis , electromyography , medicine , jitter , repetitive nerve stimulation , anesthesia , surgery , physical medicine and rehabilitation , ptosis , electronic engineering , engineering
We performed single fiber electromyography by axonal stimulation (SFEMG‐AS) of the frontalis muscle of 16 patients with ocular myasthenia gravis (OM) and 33 controls. In the controls, values of mean consecutive differences (MCD) ranged from 5 to 55 μs (average, 14.7 ± 2.8 μs) and mean MCD of individual MPs was 14.6 ± 6.8 μs. All the OM patients showed abnormal SFEMG‐AS jitter before prostigmine was administered (mean MCD: 49.19 ± 21.82 μs, percentage of blocks: 20.97 ± 18.53). Twenty or 30 min after prostigmine had been administered, we saw a significant improvement in jitter: mean MCD was 36.38 ± 22.49 μs ( P = 0.005), and percentage of blocks was 10.16 ± 18.87 ( P = 0.008). The method was well tolerated. We conclude that SFEMG‐AS of the frontalis muscle is a sensitive technique for the diagnosis of OM and is easy to carry out. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 779–783, 2000