We report the case of a 74-year-old patient who presented with an anterior inflexion of the trunk which increased during the day. His past medical history included treatment for hypothyroidism, a cure of cataracts and an increase of gammaGT. This camptocormic attitude revealed a proximal myotonic myopathy (PROMM). Clinical and paraclinical arguments (hypothyroidism, cataracts, weakness, EMG, muscle biopsy, biology) led to diagnosis.