Facioscapulohumeral muscular dystrophy. Multimodal evoked potentials and electroretinogram

Area of Science:

• Neuroscience
• Neuromuscular Disorders
• Clinical Neurophysiology

Background:

• Central nervous system (CNS) abnormalities are documented in various primary muscle diseases, including muscular dystrophies.
• Facioscapulohumeral muscular dystrophy (FSHD) is a primary muscle disease with potential CNS involvement.

Purpose of the Study:

• To investigate CNS dysfunction in a homogeneous cohort of facioscapulohumeral muscular dystrophy (FSHD) patients.
• Utilize neurophysiologic techniques to identify subclinical CNS abnormalities in FSHD.

Main Methods:

• Employed standard evoked potential (EP) and electroretinogram techniques.
• Studied visual, auditory, and somatosensory pathways in 20 FSHD patients.
• Assessed retinal function via electroretinogram.

Main Results:

• 70% (14/20) of FSHD patients exhibited abnormal neurophysiologic findings.
• Abnormalities were noted in visual pathways (4/20), auditory pathways (4/20), somatosensory pathways (median 5/20, tibial 2/20), and retina (2/18).
• No correlation found between abnormal results and patient age, disease duration, or muscle weakness severity.

Conclusions:

• CNS conduction delays are tentatively associated with facioscapulohumeral muscular dystrophy (FSHD).
• Sensorineural hearing deficits and vascular retinopathy were infrequent causes of abnormal evoked potentials.
• Peripheral arm conduction delays may stem from mechanical factors related to shoulder girdle weakness; further research into FSHD genetics and pathogenesis is warranted.