Skeletal muscle involvement in tropical endomyocardial fibrosis

Evidence for neuromuscular dysfunction was sought in 20 consecutive, angiographically proven cases of tropical endomyocardial fibrosis (Group I). Statistical comparison was made with equal number of age, sex and weight-matched normal healthy volunteers (Group II), as well as similarly matched cases of consecutive heart failure (Group III). A myopathic pattern in the EMG was found in 85% of Group I and 65% of Group III patients. However, the severity and global extent of the EMG changes was much more marked in Group I than in Group III. The summed motor unit potential duration was reduced by 20.1% in Group I and by 9.5% in Group III. Corresponding figures for summed motor unit potential amplitude were 27.9% and 15.4%. the summed frequency of polyphasic potentials was significant in Group I and in Group III. Involvement of 3 or 4 muscles in the same patient was found in 80% of Group I, n 10% of Group III. The upper limb muscles were affected in 80% of Group I and 50% of Group III. The motor nerve conduction velocity and distal latency time were normal in all the patients. It is suggested therefore that the myopathic EMG changes in Group I patients may be related to the disease process itself, rather than a reflection of long standing CHF alone. Light-microscopic study of the quadriceps muscles in 8 patients of Group I did not reveal any abnormality.