Exertional Stiffness ??? Football, Basketball

Abstract

1919 HISTORY: A 16-year-old high school football and basketball player presents with progressively worsening exertional stiffness. He reports the onset of symptoms around age 9. The patient complains of a tendency for his muscles to stiffen up when he initially engages in sudden movements or athletic activities. He reports that after the initial warm-up phase the symptoms somewhat subside. This occurs while participating in basketball, football and everyday activities such as going up stairs or rising after sitting for a prolonged period. He reports that these symptoms are very restrictive in his ability to perform athletic activities. The patient denies any weakness, paresthesias or sensory loss. Coordination and balance are normal. Patient denies any diplopia, ptosis, bowel or bladder dysfunction or speech and swallowing difficulties. PHYSICAL EXAMINATION: Examination revealed a well-developed, wellnourished, muscular 16-year-old male. Patient with full ROM of the neck, back, shoulders, elbows, wrists, hands, hips, knees, ankles, feet and toes. Good strength symmetrically of the upper and lower extremities. Cranial nerves II through XII grossly intact. Deep tendon reflexes are 2+ globally. Sensation is intact throughout. Patient noted to have a bilateral grip myotonia on exam. Remainder of examination within normal limits. DIFFERENTIAL DIAGNOSIS: Myotonic Muscular Dystrophy Myotonia Congenita Periodic Paralysis Muscle Cramps Muscle Spasticity McArdle's Disease or other Metabolic Muscle Disease Neuroleptic Malignant Syndrome Pseudomyotonia Inflammatory Myopathy (polymyositis) TESTS AND RESULTS: CBC, CMP: Within normal limits. ESR: Slightly elevated at 26. CPK, CRP: Within normal limits. HLA B-27, RF, ANA: All negative. Radiographs of the Knees, Pelvis, Hips: No abnormalities noted. EMG: Widespread myotonic discharges induced by needle movement and muscle contraction. No definite motor unit potential abnormalities were noted. FINAL WORKING DIAGNOSIS: Myotonia Congenita. TREATMENT AND OUTCOMES: Referred to the Muscular Dystrophy Association Clinic. Begun on Mexilitine 150 mg P.O. BID. Good response to medication with decrease in exertional stiffness, however still present with heavy exertion such as running. Mexilitine increased to 300 mg P.O. TID, with excellent results one month later. CBCs and LFTs monitored and found to be within normal limits. Patient allowed to resume organized athletic activities five months after beginning medication. Patient is presently doing well on the medication four years later without any physical limitations.