Subclinical skeletal muscle involvement in long-QT syndrome.

Deafness is said to be the only extracardiac manifestation of long-QT syndrome. Whether long-QT syndrome manifests in the skeletal muscle as well, has not been investigated so far. Six affected members of two families with long-QT syndrome without deafness (Romano-Ward syndrome) underwent a clinical neurological examination, nerve conduction studies and needle electromyography. The clinical neurological examination and nerve conduction studies were normal but abundant spontaneous activity (fibrillations and bursts of fibrillations) could be recorded from the right biceps brachii muscle (one patient) and the right abductor pollicis brevis muscle (all patients). Since all other causes were excluded, spontaneous discharges were interpreted to be related to the long-QT syndrome. In conclusion, long-QT syndrome does not seem to be confined to the heart but may involve the skeletal muscle subclinically as well.