In patients with mild clinical symptoms, drug treatment is often unnecessary.

Life style

• Relaxation techniques and stress avoiding (well known provocative factor) are beneficial
• Avoiding periods of longer rest or maintenance of same position helps with muscle stiffness control
• Sudden movements after prolonged rest should be avoided in order to prevent muscle injuries and falls
• Warm up phenomenon
• Exercise and stretching is recommended to improve flexibility, especially in Achilles tendons which frequently require surgical lengthening

 Drug treatment

 Mexiletine

• Mexiletine is most often the first choice for treatment of myotonia, based on its efficacy and mostly benign adverse effect profile. It is a antiarrhythmic agent, which acts on fast-acting voltage-gated sodium channels. Its half-life is 10 to 12 h.
• Standard dosage is 150 mg to 200 mg  in adults and 1 to 8 mg/kg per day given two to three times a day given with meal in order to prevent gastrointestinal side-effects.
• Treatment starts with lowe dose which increases over time. Patients are advised to stop tretament every few years to sure that treatment is still warranted
• Because rapid discontinuation can cause a rebound in myotonia and stiffness, the drug should be tapered in 50-mg increments every few days.
• Contraindications: patients with severe cardiac arrhythmias, cardiomyopathy, or coronary artery disease. It should also not be used in patients with an allergic response to lidocaine or lidocaine derivatives
• Side-effects: epigastric symptoms (20% of patients) that can be alleviated if the drug is taken with food, lightheadedness (10%,), skin rash (3%). Other side-effects are anxiety, headaches, and coordination difficulties.

 Tocainide

• Tocainide is a lidocaine derivative that acts on the sodium channel. It has been shown to be as effective as mexiletine in controlling myotonia. However, because it has a depressive effect on bone marrow, it is considered a second-line agent for the treatment of myotonia congenita. Its half-life is 15 h.
• Standard dosage is 200 mg twice a day. It can be increased up to 1,200 to 1,600 mg/d divided in two or three doses
• Contraindications: patients with severe cardiac arrhythmias, cardiomyopathy, or coronary artery disease and patients allergic to lidocaine and its derivates. Tocainide should be avoided in any patient with a history of bone marrow suppression.
• Side effects: dizziness (11%), lymphadenopathy (3%), nausea, anxiety, and tremor.

 Carbamazepine

• Carbamazepine works by reducing post-tetanic potentiations and is thought to stabilize the muscle membrane. Its half-life is 12 to 17 h.
• Contraindications: hypersensitivity to tricyclic antidepressants or a history of recent use of monoamine oxidase inhibitors. It also should be avoided in patients with a history of increased intraocular pressure, liver and kidney disease
• Side effects : somnolence, changes in ECG, dizziness, blurred vision, lack of coordination, increased liver enzymes

Phenytoin

• Phenytoin works as voltage-dependent sodium and calcium channel modulator

Drugs to avoid

• Beta-agonists, beta-blockers, acetilcholiesterase inhibitors – worsen myotonia
• Colchicin- causes muscle weakness

 Anesthesia in patients with myotonia

• Patients with congenital myotonia have an increased risk for development of malignant hyperthermia
• Suxamethonium, succinylcholine, and propofol can induce myotonia
• It should be taken into consideration that patients should be kept warm during surgery