P357 Rippling muscle disease: Two cases not associated with myopathy and review of the literature

Abstract

Objective/ background Muscle Rippling can be described as waves of involuntary muscular contractions, occurring spontaneously or induced after mechanical percussion. We present two cases of rippling muscle disorders associated with: (a) myasthenia gravis and (b) with neurogenic disorders. Case 1 Male patient, age 70 presented 7 years ago with dysphagia and mild dysarthria was diagnosed with (AchR +) myasthenia gravis. Neurophysiology confirmed the diagnosis with repetitive stimulation. He responded to pyridostigmine and after 4 years of treatment he developed muscle rippling (lower > upper limbs). CPK levels were mildly elevated. EMG revealed widespread spontaneous activity in the form of continuous fasciculations while recruitment and MUAP’s were normal. Morvan’s syndrome was excluded after negative anti- VGKC testing. The patient responded well to pyridostigmine’s dose decrease with the aid of immunosuppressive azathioprine, manifesting only limited fasciculations after exercise. Case 2 Male patient, age 55, presented with 5-year history of muscle rippling, a mild increase of CPK. Nerve conduction studies revealed a neuropathy, with decreased or absent sensory action potentials and EMG showed widespread spontaneous activity, in the form of fasciculations, with concomitant chronic denervation (MUAP’s of prolonged duration and increased amplitude with decreased recruitment). Genetic testing excluded Kennedy’s disease and the patient was diagnosed as peripheral polyneuropathy. Discussion Rippling of muscle is usually associated to myopathies and most cases are connected to caveolin mutations. However, muscle rippling should only be considered as a sign of muscular hyperexcitability. Abnormalities in calcium homeostasis in the sarcoplasmic reticulum have been proposed as the most probable causes.