好色先生

好色先生

Explore the latest content from across our publications
Join The AAN

Log In

Forgot Password?
Create New Account

Loading... please wait

Abstract Details

Predictive Value of Single Fiber Electromyography in a Low Prevalence Cohort
Neuromuscular and Clinical Neurophysiology (EMG)
P4 - Poster Session 4 (8:00 AM-9:00 AM)
11-003
To calculate the predictive value of single fiber electromyography (SFEMG) in a referral population with a low prevalence of myasthenia gravis (MG).

SFEMG is considered the “gold standard” diagnostic test when there is clinical suspicion for seronegative MG due to its recognized high sensitivity. Changing referral patterns have resulted in a low prevalence of myasthenia in patients referred for SFEMG so the specificity of SFEMG is of particular concern as it affects the positive predictive value of an abnormal SFEMG result. False positive SFEMG studies may lead to inappropriate thymectomy and immunosuppression. Most studies analyzing the accuracy of SFEMG have been in the setting of high MG prevalence.

 
All relevant documentation from 50 consecutive patients referred for SFEMG was reviewed. The predictive values were calculated after excluding patients with other neuromuscular conditions or inadequate follow-up. 

  • The cohort had a mean age of 57.3 years and 68% were female. 86% had ocular symptoms which were often only superficially suggestive of MG. Mean follow up was 26 months.

  • Final clinical diagnoses were 9 MG patients, 4 other neuromuscular conditions, 4 non-neuromuscular neurologic conditions, 13 ophthalmological, 18 no determined diagnosis, and 2 had inadequate follow up. The prevalence of autoimmune MG was 19%.  

  • SFEMG was abnormal in all MG patients and in 2 patients with mechanical ptosis (false positive) for a 100% sensitivity and 94% specificity. This yields a positive predictive value of 82% and a negative predictive value of 100%.  Excluded from this analysis were 3 patients with abnormal SFEMG that had other neuromuscular diseases. 
Despite the low prevalence of myasthenia, SFEMG demonstrated very good accuracy similar to published cohorts with higher prevalence of MG. 36% of patients with abnormal results had conditions other than autoimmune MG. 
Authors/Disclosures
Yorjannys Gomez (Wake Forest Health Sciences)
PRESENTER 		Miss Gomez has nothing to disclose.
Araya Puwanant, MD (Wake Forest University School of Medicine) The institution of Dr. Puwanant has received research support from NIH/NINDS.
James B. Caress, MD, FAAN (Wake Forest School of Medicine) Dr. Caress has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Wiley Publishing Inc.. Dr. Caress has received personal compensation in the range of $0-$499 for serving as a Grant Reviewer with US Department of Defense.