Hearing loss in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the muscular dystrophy syndromes; unlike the X-linked syndromes such as Duchenne muscular dystrophy, the gene for facioscapulohumeral muscular dystrophy is dominant and is located on an autosomal chromosome (rather than a sex chromosome). The autosomal dominant muscular dystrophies are named according to the groups of affected muscles; FSHD affects muscles of the face, shoulders, and upper arms. FSHD may be especially benign, and many patients may be unaware of any symptoms. A variety of symptoms may be present in addition to muscular symptoms, and some researchers have considered the possibility that FSHD might be a heterogeneous collection of disorders. One of the symptoms which may accompany FSHD is neurosensory hearing loss. A study was therefore undertaken to evaluate the hearing in 56 patients from 9 FSHD families. Seventy-two healthy family members were also evaluated. Normally, the ability to hear a faint tone depends upon the pitch, or sound frequency, of the tone. When the hearing of the family members was evaluated, it was found that the differences between affected family members and controls were minimal. However, the fall-off in hearing as the tone increased in frequency from 4,000 to 6,000 Hz (hertz; cycles per second) was significantly greater among the patients. Although this fall-off is far from a significant hearing loss, these findings suggest that the cases of sensorimotor hearing loss associated with FSHD may simply represent the extreme end of a spectrum of effects on the auditory system. The demonstration of this hearing deficit in all families tested provides evidence that the underlying genetic cause is likely to be similar among all families with FSHD. (Consumer Summary produced by Reliance Medical Information, Inc.)