CLINICAL AND NEUROPHYSIOLOGIC RESPONSE OF MYOPATHY AND NEUROPATHY IN LONG-CHAIN L-3-HYDROXYACYL-COA DEHYDROGENASE-DEFICIENCY TO ORAL PREDNISONE

The purpose of this study was to evaluate the clinical and neurophysio logic responses to oral prednisone therapy in a boy with enzymatically confirmed long-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency in biopsied muscle and cultured skin fibroblasts, This boy presented with progressive limb girdle myopathy, recurrent myoglobinuria, peripheral sensorimotor axonopathy, and intraventricular conduction delays, Prio r to prednisone therapy, at age 8 years, he exhibited marked distal we akness greater than proximal weakness with a waddling and high-steppag e gait, Gowers' maneuver (10 s to rise from the floor), fatigue after 3-20 yards of walking and the ability to climb only 2 stairs, Serum le vels of creatine kinase rose from 34 to 4,124 U/L following mild exert ion, Nerve conduction studies revealed progressive axonopathy with sec ondary demyelination. Four weeks after initiation of oral prednisone ( 0.75 mg/kg/day) therapy, there was approximately a 100% increase in po wer and endurance, He was able to walk at least 100 yards before tirin g, could rise from sitting on the floor in 3-4 s, and was able to clim b 20 steps in 30 s, There was concurrent improvement in nerve conducti on studies, Prednisone was gradually withdrawn over the next 4 months to 0.19 mg/kg/day; lower doses of 0.08 mg/kg/day resulted in a marked deterioration in power to the prior state, Although 0.19 mg/kg/day did not maintain the peak power achieved at 0.75 mg/kg/day, it provided a dequate baseline power and endurance, It is concluded that there was a significant clinical and neurophysiologic response to prednisone at a dosage greater than or equal to 0.16 mg/kg/day, Prednisone may stabil ize muscle and neuronal plasma membranes, as well as the fatty acid ox idation enzyme complex in the mitochondrial membrane.