Complete fatty degeneration of lumbar erector spinae muscles caused by a primary dysferlinopathy.

Magnetic resonance imaging of the thoracolumbar spine showed complete fatty degeneration of the lumbar erector spinae muscles in a woman who had complained of chronic lower back pain for 5 years and of progressive weakness of the lower limbs for 1 year. Neuromuscular examination of the lower limbs showed no obvious anomaly, and there was no camptocormia. Serum creatine kinase levels were increased (six- to ninefold); electrodiagnostic examination revealed no activity at rest or during effort in the erector spinae muscles and was normal in proximal and distal muscles of the limbs. Muscle computed tomography revealed mild fatty degeneration of thigh and gastrocnemius muscles, and histopathology of the deltoid muscle showed dystrophic features and complete lack of dysferlin. Molecular analysis identified a homozygous disease-causing mutation in the gene encoding dysferlin. Because there were no similar cases in the family, the final diagnosis was sporadic limb-girdle muscular dystrophy type 2B. Overall, this case report shows that the lumbar and lower thoracic of erector spinae muscles may display complete fatty degeneration without the occurrence of camptocormia, with primary dysferlin deficiency as a possible cause.