Myotonia
Pronunciation: my-oh-TOE-nee-ah
Delayed muscle relaxation after voluntary contraction, causing muscle stiffness. A key clinical finding in myotonic disorders requiring careful documentation.
Full Definition
Myotonia is the delayed relaxation of skeletal muscle after voluntary or involuntary contraction, resulting in prolonged muscle stiffness. This phenomenon occurs due to abnormal membrane excitability and is characteristic of myotonic dystrophy and other channelopathies. Clinically, it manifests as difficulty releasing grip or opening eyes after forceful closure. The degree and distribution of myotonia should be precisely documented in patient assessments, as it varies significantly between conditions and can fluctuate with temperature and activity.
Usage
Usage note: Distinguish from myokymia (continuous muscle fiber activity) and ordinary muscle cramping.
In Context
- "The patient exhibited pronounced myotonia in the hand muscles, requiring 3-4 seconds to release grip after handshake." — Clinical examination note
- "Percussion myotonia was elicited at the thenar eminence, with visible muscle ridge persisting for several seconds." — Neurological assessment