In simple words: Myotonia congenita is a genetic condition where your muscles have trouble relaxing after they tense up. This can make them feel stiff and sometimes weak. There are two main types, one milder (Thomsen disease) and one more severe (Becker disease). Symptoms usually start in childhood but can sometimes appear later. While it can make everyday tasks harder, most people with this condition live full and healthy lives.

Myotonia congenita (MC) is an inherited neuromuscular disorder. It is characterized by the inability of muscles to relax quickly after a voluntary contraction, causing muscle stiffness and sometimes temporary weakness. MC encompasses different forms, including acetazolamide-responsive myotonia congenita, dominant myotonia congenita (Thomsen disease), myotonia levior, and recessive myotonia congenita (Becker disease). Thomsen disease, less common and less severe, often starts in childhood (up to age 10), affecting leg muscles more than arm or hand muscles. Becker disease, more common and more severe, typically starts between ages 4 and 12, sometimes in adulthood, mainly affecting lower limbs and proximal muscles. General MC symptoms include muscle stiffness, pain, weakness, difficulty walking, grasping objects, swallowing, and balancing.Muscle hypertrophy, resembling a bodybuilder's physique, might be observed, resulting from fat buildup around the muscles.MC doesn't involve systemic disorders.

Example 1: A 7-year-old child experiences persistent muscle stiffness, especially in the legs, making it difficult to run and play. After a period of rest, the stiffness worsens. The child's pediatrician suspects MC and refers them to a neurologist for further evaluation and diagnosis., A teenager experiences muscle stiffness and cramping after exercise, particularly in the arms and legs. Additionally, they report episodes of weakness after periods of rest.These symptoms interfere with their ability to participate in sports. A physician performs a thorough examination and orders diagnostic tests, including EMG and genetic testing, leading to a diagnosis of Becker disease (a type of MC)., An adult with a long history of mild muscle stiffness and occasional cramps notices increased difficulty with everyday activities like climbing stairs and grasping objects.They consult a physician who, based on their medical history and physical exam, suspects MC and recommends EMG and genetic testing to confirm the diagnosis.

Documentation should include details about the onset, duration, and location of muscle stiffness, any associated symptoms like weakness or hypertrophy, family history of similar conditions, and results of diagnostic tests such as EMG, muscle biopsy, and genetic testing.

** Treatment for MC can range from conservative measures like exercise and physical therapy for mild cases to medication (e.g., mexiletine, carbamazepine) for moderate to severe cases. Genetic counseling is often recommended.