Premium
Single fiber EMG in the frontalis muscle in ocular myasthenia: Specificity and sensitivity
Author(s) -
Rouseev R.,
Ashby P.,
Basinski A.,
Sharpe J. A.
Publication year - 1992
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/mus.880150322
Subject(s) - medicine , electromyography , myasthenia gravis , abnormality , ocular myasthenia , extraocular muscles , ophthalmology , surgery , physical medicine and rehabilitation , psychiatry
Patients ( n = 41) with isolated weakness of the eyelids or extraocular muscles, who had been referred for single fiber electromyography (SFEMG), were followed up after 4 to 24 months, At follow‐up the patients were classified as “definite ocular myasthenia gravis” (MG), “definite other diagnosis,” or “no definite diagnosis” on the basis of the completed investigations and subsequent course. The original SFEMG findings in the frontalis muscle were then reviewed. The specificity and sensitivity of SFEMG for “definite ocular MG” could be maximized by using as criteria for abnormality >8/20 pairs with jitter >45 μs, or a mean jitter of 20 pairs of >50 μs. Patients with abnormal SFEMG according to these criteria have MG, and are likely to require treatment in the immediate future. Patients who have normal SFEMG according to these criteria (and no other demonstrated disorder) may have MG, but it is so mild that they are unlikely to require treatment. Two patients whose final diagnosis was progressive external ophthalmoplegia had normal SFEMG according to these criteria.