Myotonia is a neuromuscular condition characterized by the inability of muscles to relax after contraction. This leads to stiffness and difficulty in movement, especially after periods of rest. It can affect various muscle groups, causing discomfort and impacting daily activities. The condition is often associated with genetic disorders, such as myotonic dystrophy and congenital myotonia. Diagnosis typically involves clinical evaluation and tests like electromyography (EMG). Treatment may include medications and physical therapy to help manage symptoms and improve muscle function.