Progressive Weakness in Adulthood: Lipid Storage Myopathy With Suspected Sertraline-Associated Etiology.

Lipid storage myopathies (LSMs) are uncommon metabolic disorders that are not always considered during routine evaluations for weakness. We describe a 51-year-old woman with progressive proximal weakness. The patient's initial studies included electromyography (EMG), spine imaging, and serologies, all of which were unrevealing. A muscle biopsy revealed lipid accumulation, and genetic testing suggested a deficiency in multiple acyl-CoA dehydrogenase (MADD) or a defect in the riboflavin transporter. Riboflavin supplementation was recommended, and a sertraline taper was initiated after concern that prolonged selective serotonin reuptake inhibitor (SSRI) exposure might be contributing to her mitochondrial dysfunction. This case demonstrates the importance of considering metabolic myopathies in patients with unexplained progressive weakness, particularly when conventional diagnostics are inconclusive.