Clinical and pathological characteristics of riboflavin-reactive lipid storage myopathy / 临床神经病学杂志

ABSTRACT

Objective To investigate the clinical and pathological features of riboflavin-reactive lipid storage myopathy.Methods Clinical material of 4 patients with riboflavin-reactive lipid storage myopathy were analyzed retrospectively.Results All the patients were subacute onset and presented proximal and axial muscle weakness accompanied by intolerance to excise.Amyotrophy and weakness involved in neck and paraspinal muscle were found in 3 cases,and chewing muscle weakness in 2 cases.Electromyogram showed myogenic changes in 2 cases and reduced conductive velocity of tibial nerves in 1 case.Muscle Biopsy study showed markedly increased lipid droplets in muscle fibers.The ragged red fibers,succinate dehydrogenase strongly reactive vessels and COX deficiency fibers which supported mitochondrial myopathy were not detected.Electromicroscope observation revealed that the structure and quantity of mitochondria were normal.All the patients had a dramatic response to riboflavin treatment.Two cases were cured and the other two were improved significantly.Two cases relapsed 1 year and 5 years later,respectively,and riboflavin was still effective for them.Conclusions Riboflavin-reactive lipid storage myopathy is a myopathy characterized by preferential involvement of neck,paraspinal and chewing muscles.The distinct pathological features are lipid accumulation in muscle fibers without any abnormalities of mitochondrial structure and quantity.Riboflavin alone is effective for this myopathy and this is distinguished from other myopathies.