From the Research
Myotonic dystrophy patients who cannot release their grip during a handshake should be treated with mexiletine, starting at 150mg three times daily, as it has been shown to be effective in reducing myotonia symptoms. This condition, characterized by delayed muscle relaxation, can be managed with medication, and sodium channel blockers like mexiletine are the first-line treatment for myotonia 1. The most recent and highest quality study, a randomized, double-blind, placebo-controlled trial, demonstrated that mexiletine improved hand grip myotonia in patients with myotonic dystrophy type 1, with no significant effects on cardiac conduction measures 2.
Treatment Options
- Mexiletine: starting at 150mg three times daily, potentially increasing to 200mg three times daily
- Alternative medications: phenytoin, carbamazepine, or procainamide
- Practical strategies: warning others before handshakes, using a gentle grip, and employing distraction techniques like wiggling fingers before the handshake to temporarily reduce myotonia
- Physical therapy: focusing on hand exercises to maintain function
Pathophysiology
Myotonia occurs due to abnormal chloride and sodium channel function in muscle cell membranes, causing prolonged electrical activity and delayed relaxation after contraction. While treatment can reduce the severity of myotonia, patients should understand that complete elimination of symptoms is unlikely, and management is focused on reducing the impact on daily activities 3.
Safety and Efficacy
Long-term safety and efficacy of mexiletine in myotonic dystrophy types 1 and 2 have been demonstrated, with 96% of patients reporting some improvement in myotonia symptoms, and no clinically relevant cardiac adverse events associated with long-term use 1.