Feasibility of Integrated Human Performance Testing in a Patient with Lambert-Eaton Myasthenia Gravis Syndrome (LEMS)

Abstract

2099 PURPOSE: LEMS is a rare autoimmune neurological disorder of the neuromuscular junction. To the best of our knowledge, integrated human performance testing has not been previously reported in patients with LEMS. METHODS: Body composition and bone density (BMD) were measured by DEXA. Pulmonary function (PFT), maximal inspiratory muscle strength (MIPS); isokinetic strength testing (elbow and knee fiexors and extensors); and a maximal cardiorespoiratory exercise test (CPET) were performed before and after ingestion of 20mg 3–4 diaminopyridine (current medication standard) in a 48yr old male (69.9kg, 177.8cm, BMI 22.1(kg/cm2), diagnosed with LEMS 13 years ago. RESULTS: The patent tolerated all procedures well and did not complain of pain or undue fatigue. Body Composition: percent fat 35.6%; and lean body mass 41.9kg. Femoral BMD: 0633g/cm2, Z-score −2.3. Results are listed as pre and post medication respectively. PFT: FVC and FEV1 were reduced 73 and 75% predicted; PEF: 66 and 69% predicted; but PImax was 82 and 93% predicted. CPET Peak Values – WR: 21 and 28% predicted; VO2 (L/min): 29 and 32% predicted; HR: 95 and 100% predicted. CONCLUSIONS: Impaired exercise performance, as expected, was observed. Lung function was mildly reduced save for highly respiratory muscle dependent PEF results which were markedly reduced. BMD demonstrated osteoporosis. Although, BMI was relatively low, high fat percentage with decreased lean body mass was observed. Medications led to minor changes in strength and PFT's. Integrated human performance testing is feasible in patients with LEMS and may prove useful for staging the degree of impairment and for documenting the effect of medications. Multi-center studies are needed to create human performance data base for this rare disease. Supported by the National GCRC Applied Physiology and Human Performance Consortium