Stapedius reflex decay test in diagnosis of myasthenia gravis (MG).
Stapedius reflex decay test (SRDT) was attempted in 30 patients with suspected myasthenia gravis (MG). In 43% of the sample measurement of the decay was not possible because of an audiologic abnormality, reflex threshold too high for safe testing or absence of the reflex with no obvious cause. A control group of 24 normal subjects showed a large variance and thus only a decay, after 5 minutes of stimulation, greater than 50% of the original value was considered abnormal. Out of 17 patients in whom SR decay was successfully measured, 7 (41%) had an abnormal value. Sensitivity of the test was found at 80%, specificity at 75%, when the clinical diagnosis of MG, upheld in follow-up, was taken as a criterion. The percentage of concordant abnormal findings was 50% for repetitive electrical stimulation of a peripheral nerve, 60% for positive effect of anticholinesterase drugs, 100% for presence of ACh receptor antibodies.
Department of Medical Physics, Leicester Royal Infirmary, U.K.
M J
MJ
Smith
V
V
Brezinova
D000158:Acoustic Impedance Tests; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000503:physiopathology; D012022:Reflex, Acoustic / Q000502:physiology*