Myotonia congenita
ICD-10 G71.12 is a billable code used to indicate a diagnosis of myotonia congenita.
Myotonia congenita is a genetic neuromuscular disorder characterized by delayed relaxation of skeletal muscles after voluntary contraction. It is primarily caused by mutations in the CLCN1 gene, which encodes a chloride channel essential for muscle function. Patients typically present with muscle stiffness, particularly after periods of inactivity, and may experience muscle hypertrophy. The condition can be classified into two main types: Thomsen disease, which is the milder form, and Becker myotonia congenita, which is more severe. Symptoms often improve with repeated muscle use, a phenomenon known as 'warm-up' effect. Myotonia congenita is distinct from other neuromuscular disorders such as myasthenia gravis, which involves the neuromuscular junction and presents with muscle weakness rather than stiffness. Diagnosis is typically confirmed through clinical evaluation, electromyography (EMG), and genetic testing. Management focuses on symptom relief, with medications such as mexiletine being used to reduce myotonia. Understanding the genetic basis and clinical presentation is crucial for accurate diagnosis and treatment.
Comprehensive neurological examination findings, including muscle strength and reflexes.
Patients presenting with muscle stiffness, especially after inactivity.
Documentation should include family history and any genetic testing performed.
Genetic test results and family pedigree analysis.
Patients with a family history of myotonia or unexplained muscle symptoms.
Ensure that genetic counseling notes are included in the documentation.
Used to confirm diagnosis of myotonia congenita.
EMG results must be documented in the medical record.
Neurologists should ensure detailed EMG findings are included.
Common symptoms include muscle stiffness after periods of inactivity, muscle cramps, and in some cases, muscle hypertrophy. Symptoms may improve with repeated use of the affected muscles.
