Progressive Bilateral Lower Extremity Weakness and Muscle Soreness in a 17-year-old Dancer

1. Gregory W. Kirschen, MD, PhD* 2. Roberta Seidman, MD, MS† 3. Maribeth Chitkara, MD‡ 4. Julie Cherian, MD‡ 1. *Gynecology and Obstetrics Residency, The Johns Hopkins Hospital, Baltimore, MD 2. †Department of Pathology, 3. ‡Department of Pediatrics, Stony Brook Medicine, Stony Brook, NY A 17-year-old previously healthy girl presents with complaints of progressive bilateral lower extremity weakness of 2 to 3 weeks’ duration. She is a competitive dancer who practices many hours each day. Upon initiation of intensive competition training, she notices increasing fatigue and loss of endurance, citing inability to kick her legs as high as usual. She describes generalized soreness in the quadriceps and hamstring muscles bilaterally, associated with weakness, occurring multiple times each day for the past 2 to 3 weeks. Acetaminophen and ibuprofen have had little effect. She takes no medications and has a family history of rheumatoid arthritis and Crohn disease in her maternal grandmother. She denies alcohol or other substance use. She denies fever, headaches, blurry vision, respiratory symptoms, abdominal pain, diarrhea, vomiting, dysuria, hematuria, rashes, visual changes, changes in speech or swallowing, facial weakness or weakness performing activities of daily living. Physical examination is unremarkable, with symmetrical 5/5 strength bilaterally in upper and lower extremities, proximal and distal muscle groups, normal tone, and full range of motion. She has no rash and a normal nailfold capillaroscopy. Laboratory results reveal creatine phosphokinase (CPK) 13,286 IU/L, aldolase 172.7 U/L, lactate dehydrogenase 698 IU/L, alanine aminotransferase 296 IU/L, and aspartate aminotransferase 319 IU/L, enzymes that are expressed by muscle tissue and are commonly used as markers of myocyte injury. (1) Urinalysis is within normal limits and negative for myoglobin. She is placed on intravenous fluids without significant improvement in her CPK or transaminase levels. Thyrotropin is 5.64 mIU/L. Magnetic resonance imaging (MRI) of the thighs without contrast shows extensive, diffuse bilateral muscle edema involving the gluteal, adductor, …