Abstract Details

Title Predictors of Muscle Biopsy Outcomes in a Tertiary Neuromuscular Center

Topic Muscle Disease/Neuromuscular Junction

Presentation(s) P05 - (-)

Poster/Presentation
Number 087

Objective

Background BACKGROUND: As far as we know, no rigorous studies have been conducted to evaluate the predictive power of different tests currently in use to approach patients with suspected muscle diseases. Such an evaluation can significantly help clinicians in their decisions to perform muscle biopsies on these cases.

Design/Methods DESIGN/METHODS: Muscle biopsy reports for 409 biopsies performed at a tertiary neuromuscular clinic between 2002 and 2012 were randomly selected, reviewed and classified as normal, non-specific myopathy, specific myopathy, and neurogenic atrophy. Medical records of these patients were subsequently reviewed and information was derived about the highest CK level, proximal strength and EMG findings. CK levels were studied at 200-600, 600-1000, and above 1000 IU/L. Proximal strength was classified as present or absent and EMG findings were classified as myopathic or non- myopathic. All muscle biopsies were stained according to the laboratory protocol. We calculated the sensitivity, specificity and predictive value of each and combinations of these tests for diagnosing and predicting myopathic biopsy outcomes.

Results RESULTS: There were specific changes in 36.2% of biopsies, while 27.9% were non-specific, 16.9% were neurogenic, and 19.1% were normal. Isolated plasma CK level 200-600mg/dl was only 11.6% predictive for diagnosing specific myopathies. Likewise, isolated proximal weakness on examination was only 20.9% predictive of specific myopathies. A combination of CPK level 600-1000 mg/dl with proximal weakness and myopathic EMG changes had the highest predictive value for muscle biopsies positive for both overall myopathies and specific myopathies (90.2% and 70.7%, respectively).

Conclusions CONCLUSIONS: Being common indications of referral to neuromuscular clinics, isolated plasma CK level 200-600 and isolated proximal weakness are poor predictors for myopathies. A constellation of tests is needed to predict the presence of myopathic biopsy changes.

Authors/Disclosures
Chia Arif, MD PRESENTER	No disclosure on file
	No disclosure on file
Aziz I. Shaibani, MD, FAAN (Houston Neurocare, PA)	Dr. Shaibani has nothing to disclose.
Uwe Zettl	Uwe Zettl has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Merck Serono. Uwe Zettl has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion . Uwe Zettl has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bayer. Uwe Zettl has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Roche. Uwe Zettl has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Teva. The institution of Uwe Zettl has received research support from BMBF(Government).

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