Myotonia congenita is a congenital neuromuscular channelopathy that affects skeletal muscles (muscles used for movement). It is a genetic disorder. The hallmark of the disease is the failure of initiated contraction to terminate, often referred to as delayed relaxation of the muscles (myotonia) and rigidity. Symptoms include delayed relaxation of the muscles after voluntary contraction (myotonia), and may also include stiffness, hypertrophy (enlargement), transient weakness in some forms of the disorder (from certain genetic mutations), severe masseter spasm, and cramping. The condition is sometimes referred to as fainting goat syndrome, as it is responsible for the eponymous fainting seen in fainting goats when presented with a sudden stimulus. Of note, myotonia congenita has no association with malignant hyperthermia (MH). Symptoms and signs
The prolonged muscle contractions, which occur most commonly in the leg muscles in recessive mutations, and more commonly in the hands, face, and eyelids in dominant mutations, are often enhanced by inactivity, and in some forms are relieved by repetitive movement known as "the warm-up effect". This effect often diminishes quickly with rest. Some individuals with myotonia congenita are prone to falling as a result of hasty movements or an inability to stabilize themselves after a loss of balance. During a fall, a person with myotonia congenita may experience partial or complete rigid paralysis that will quickly resolve once the event is over. However, a fall into cold water may render the person unable to move for the duration of submergence.
In addition to its helpful effects in treating AU, it can have side effects that can be very serious, such as severe dermatitis.Topical and intralesional corticosteroids, such as clobetasol propionate, have also shown to be an effective treatment for AT and AU patients. A controlled study comprising 28 patients found positive terminal hair growth in eight of the patients (28.5%) using a 0.05% clobetasol propionate ointment. This is very similar to the results obtained from immunotherapy treatment trials. Additionally, studies suggest that intralesional applications are much more effective than topical applications of steroids. However, the main side effect is increased risk of cutaneous atrophy at the site of treatment; folliculitis is also an occasional complication.Janus kinase inhibitors, previously used in the treatment of cancer and other diseases, such as arthritis, have successfully shown to be effective in the initial trials of treatment for alopecia patients. Multiple cases of treatments have been successful, one of them being of a 22-year-old man with a history of AU and atopic dermatitis (AD). This man was treated with JAK inhibitor tofacitinib, and after ten months, he experienced hair regrowth on all of his affected body parts and subsequent improvement of his AD. Current research and findings suggest that systemic JAK inhibitors eliminate and prevent the development of AA, while topical JAK inhibitors promote hair regrowth and reverse the established disease. Many clinical trials are ongoing involving JAK inhibitors such as ruxolitinib and tofacitinib. See also
Alopecia areata
Alopecia totalis

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