Thought ripples on muscle waves: recognition of rippling muscle disease

We report on a 16-year-old Dutch patient in whom rippling muscle disease (RMD) was diagnosed years after his mother had been falsely diagnosed with acid maltase deficiency. The autosomal dominant mode of inheritance of the neuromuscular symptoms in this family had led to a re-evaluation of the diagnosis of acid maltase deficiency. Physical examination revealed the three key features leading to the clinical diagnosis of RMD: rippling, mounding, and percussion-induced rapid muscle contraction. Mutation analysis revealed a novel heterozygous missense mutation in the caveolin-3 gene (c.79C > G; p.Arg27Gly) in both the index patient and his mother. This case report stresses the importance of adhering to the mode of inheritance in the diagnosis of neuromuscular disorders. It also indicates that typical RMD phenomena are not easily acknowledged among paediatricians or neurologists. We therefore present an overview of these clinical characteristics of rippling muscle disease RMD.