Which condition is characterized by delayed muscle relaxation, such as difficulty releasing a handshake?

The condition characterized by delayed muscle relaxation, resulting in difficulty releasing a handshake, is grip myotonia. This phenomenon occurs due to a disorder in muscle excitability and results in an inability to relax the muscles after prolonged contraction. Patients may experience a noticeable delay in muscle relaxation, which can be particularly evident during activities that require grip strength, leading to the described difficulty when trying to release a handshake.

Grip myotonia is commonly seen in myotonic dystrophy, where the muscle fibers exhibit abnormal electrical characteristics, causing the muscles to remain contracted for an unusually long time after the initial contraction. This delayed relaxation is distinct from other neuromuscular disorders, where muscle fatigue, weakness, or atrophy may be present instead, but not the specific symptom of delayed muscle relaxation. Understanding this mechanism helps in distinguishing grip myotonia from other neuromuscular diseases that present with different features or muscle involvement.