Facioscapulohumeral muscular dystrophy. Multimodal evoked potentials and electroretinogram

Clinical or subclinical abnormalities of the central nervous system (CNS) have been reported in a range of primary muscle diseases, including the muscular dystrophies.

To ascertain by neurophysiologic techniques evidence of CNS dysfunction in a relatively large, homogeneous group of patients with facioscapulohumeral muscular dystrophy (FSHD).

Standard evoked potential (EP) and electroretinogram techniques were used to study the visual, auditory and somatosensory pathways in 20 patients with FSHD.

Abnormal values were recorded in 70% (14/20) of patients, specifically of visual pathways (4/20), brainstem auditory pathways (4/20), median (5/20) and tibial nerve (2/20) somatosensory pathways, and of the retina (2/18). Abnormal results did not correlate with clinical parameters of patient age, disease duration and degree of weakness.

Any process that caused CNS conduction delays was tentatively associated with FSHD. Sensorineural hearing deficit and vascular retinopathy were rare causes of abnormal EPs. Peripheral conduction delay of the arms was ascribed to mechanical factors secondary to shoulder girdle weakness. Progress in genetics and molecular pathogenesis of FSHD may shed further insight into the association between the myodystrophic process and nervous system abnormalities.