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Inclusion body myositis mimicking motor neuron disease
R Dabby1, D J Lange, W Trojaborg
1Neurological Institute, Columbia-Presbyterian Medical Center, Box 150, 710 W 168th St, New York, NY 10032, USA.
Archives of Neurology
|August 31, 2001
Summary
Inclusion body myositis can mimic motor neuron disease. Early muscle biopsy and quantitative EMG are crucial for accurate diagnosis, especially with atypical presentations.
Area of Science:
- Neurology
- Pathology
Background:
- Inclusion body myositis (IBM) is a rare inflammatory myopathy.
- It can present with symptoms overlapping with motor neuron disease (MND), leading to misdiagnosis.
Purpose of the Study:
- To identify clinical and electrophysiologic features distinguishing IBM from MND.
- To highlight diagnostic challenges in differentiating these conditions.
Main Methods:
- Retrospective review of 70 pathologically confirmed IBM cases.
- Selection of patients initially diagnosed with MND or amyotrophic lateral sclerosis (ALS).
- Analysis of clinical, electrophysiologic, laboratory, and morphologic data.
Main Results:
- Nine (13%) IBM patients were initially diagnosed with MND.
- Common features included asymmetric weakness, distal arm involvement, finger flexor weakness, and preserved reflexes.
- Muscle biopsy confirmed IBM, while routine EMG showed neurogenic changes; quantitative EMG was myopathic in most cases.
Conclusions:
- IBM can clinically mimic MND.
- Muscle biopsy and quantitative electromyography are essential for diagnosing atypical MND cases, particularly those with slow progression or disproportionate finger flexor weakness.