Unusual causes of stiffness in two hockey players

To describe two cases of competitive hockey players whose performance was impaired by generalized painless muscle stiffness. They were each found to have a separate type of myotonia.

The first hockey player experienced stiffness only when initiating activity after a period of inactivity. He had a family history of muscle stiffness, grip myotonia clinically, and electrophysiologic findings of myotonic discharges. He had myotonia congenita. The stiffness in the second case was episodic and occurred during bouts of intense physical activity. The legs, arms, and neck were affected. Myotonia fluctuans was the probable diagnosis. Both cases responded well to Mexiletine.

The etiology, classification, and clinical presentation of myotonia are discussed.

Because of the musculoskeletal nature of our practice, sport medicine clinicians should be aware of myotonic disorders so they can be recognized and appropriately treated.