Rippling muscle disease (RMD) is a rare condition that primarily affects the muscles. It belongs to a group of conditions known as caveolinopathies. Signs and symptoms of the condition generally begin during late childhood or adolescence, although the age of onset can vary widely. It is characterized by signs of increased muscle irritability, including percussion-induced rapid contractions (repetitive tensing of the muscle), percussion-induced muscle mounding ("bunching up" of the muscle), and/or visible rippling of the muscles. Fatigue, cramps, and/or muscle stiffness are common, especially after strenuous activity or exposure to cold temperatures. Some affected people may also have hypertrophy (overgrowth) of some muscles and an unusual gait. Treatment is said to be supportive and based on the signs and symptoms present in each person.

Rippling muscle disease can be caused by changes (mutations) in the CAV3 gene. Inheritance is usually autosomal dominant, but can be autosomal recessive. In addition to RMD, CAV3 gene mutations can cause features of the other caveolinopathies, even within the same family. The other caveolinopathies are: limb-girdle muscular dystrophy 1C, isolated hyperCKemia, CAV3-related distal myopathy, and hypertrophic cardiomyopathy.

There have also been reported cases of an acquired, autoimmune form of RMD that occurs concurrently with myasthenia gravis. In this form, there is no family history of RMD and CAV3 testing is negative.

• Weight control to avoid obesity
• Physical therapy and stretching exercises to promote mobility and prevent contractures
• Use of mechanical aids such as canes, walkers, orthotics, and wheelchairs as needed to help ambulation and mobility
• Social and emotional support and stimulation to maximize a sense of social involvement and productivity and to reduce the sense of social isolation common in these disorders

Only case reports from the 1980s report the benefit of dantrolene (a muscle relaxant)and calcium channel antagonists in two patients. However, we are unaware of any current, well-documented treatment options.

For people with immune-mediated RMD associated with myasthenia gravis (an acquired, autoimmune form of RMD), immunosuppressive therapy has reportedly been effective in improving the symptoms of both conditions. For this reason, it is important to recognize when RMD and myasthenia gravis occur together.

To our knowledge, there is limited information in the medical literature about the long-term outlook associated with rippling muscle disease (RMD). While it has been described as a generally benign, non-progressive condition with relatively mild symptoms, muscle cramping or stiffness may be painful. People with autosomal recessive RMD (who have 2 genemutations) may be more severely affected. Additionally, because some people with RMD also have features of other caveolinopathies (which may be more severe), the outlook may depend on the specific symptoms present. We are not aware of reports noting shortened life expectancy in individuals with RMD.