Clinical and pathological features of lipid storage myopathy caused by primary carnitine deficiency

Objective To analyze the clinical and pathological features of lipid storage myopathy (LSM) caused by primary carnitine deficiency (CD).Methods The clinical data of 4 cases of possible LSM caused by primary CD were analyzed retorspectively.Results The clinical features of the 4 patients were subacute or chronic onset, proximal muscle weakness and exercise intolerance. Elevated levels of creatases were measured in serum and myogenic damage was found by EMG examination. Frozen sections of muscle biopsy samples showed many fibers contained numerous vacuoles which was stained by oil red O. No ragged red fiber (RRF) was seen in MGT stain. Type I fibers were more severely affected. In electron microscopy, the prominent abnormality was the presence of excessive amounts of fatty droplets in muscle fibers and subsarcolemmal regions with mild increased mitochondria.Treatment with glucocorticoid and energy supplement had been clinically beneficial. Conclusions Fatigue and muscle weakness are prominent manifestations in LSM caused by primary CD. The main changes are accumulation of lipid droplets in muscle specimen without prominent abnormality in structure in mitochondria. Good clinic effect may be caused by therapy with glucocorticoid.