[Myopathy caused by propoxyphene: report of 2 cases with muscle histochemistry]

The cases of a 43 years old-man with gout and a 24 years-old woman with severe back pain who developed dextro-propoxyphene addiction during pain treatment are reported. They had severe edema and fibrosis of skin, subcutaneous tissue and muscle involving the upper and lower limbs. ESR was elevated, CPK and LDH were normal. EMG in proximal muscles showed decreased duration and voltage of potentials, excess of short polyphasics and increased recruitment (BSAP), with positive waves and fibrillations; distal muscles had fasciculations, fibrillations, positive waves, normal voluntary potentials, decreased recruitment. Lymphography indicate delayed progression of contrast media and obstruction in the thighs. Muscle biopsy on fresh-frozen section and histochemistry showed extensive connective tissue proliferation with intense acid and alkaline phosphatase activity in the perimysial and endomysial area, infiltration of lymphocytes near and around small vessels and capillaries. There were perifascicular and type II fiber atrophy. After discharge the patients returned to propoxyphene addiction and the symptoms who subsided during drug withdrawal come back again. New admission, new drug withdrawal and they were discharged free of symptoms and pathologic changes.