myotonia
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Introduction
Delayed relaxation of a muscle after an initial contraction.
Etiology
- myotonia congenita
- myotonic dystrophy (myotonia dystrophica)
- chondrodystrophic myotonia
- paramyotonia congenica
- hyperkalemic periodic paralysis
- Schwartz-Jampel syndrome
Pathology
- sustained muscle tensing that prevents muscles from relaxing normally
- impairment of muscle relaxation is due to increased membrane excitability
Clinical manifestations
- generally painless
- muscle stiffness that can interfere with movement
- in some people the stiffness is very mild, while in others it may be severe enough to interfere with walking, running, & other activities of daily life
- may interfere with fine hand movements
Laboratory
- EMG shows myotonic discharges with insertional activity
Management
More general terms
Additional terms
References
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 131
- ↑ Electrodiagnosis in Diseases of Nerve and Muscle, Principles and Practice, Kimura, J. FA Davis, Philadelphia, 1983
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015