Electro-oculographic findings in Machado-Joseph disease

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is an inherited neurodegenerative disorder.
• Ophthalmoparesis and other oculomotor abnormalities are common clinical manifestations of MJD.
• Early detection of MJD is crucial for timely intervention and genetic counseling.

Purpose of the Study:

• To evaluate the utility of electro-oculography (EOG) in detecting eye movement abnormalities in patients with Machado-Joseph disease (MJD) or at genetic risk.
• To determine the sensitivity of EOG in identifying subclinical MJD in individuals with normal or equivocal neurological examinations.

Main Methods:

• Electro-oculographic recordings (EOG) were performed on 26 patients with clinically apparent MJD or at genetic risk.
• Patients underwent a battery of eye movement tests, including caloric response, sinusoidal tracking, opticokinetic nystagmus (OKN), refixation saccades, and assessment for gaze paretic nystagmus.
• Neurological examinations were conducted to assess clinical signs of MJD.

Main Results:

• All patients with clinically apparent MJD exhibited abnormal eye movements on EOG.
• The frequency of EOG abnormalities in clinically apparent MJD was: caloric response, sinusoidal tracking, OKN, refixation saccades, and gaze paretic nystagmus.
• Among 14 subjects at genetic risk but with normal or equivocal neurological exams, 9 showed abnormal EOG findings.
• Abnormalities in sinusoidal tracking, caloric response, refixation saccades, OKN, and gaze paretic nystagmus were observed in this at-risk group, in that order.

Conclusions:

• Electro-oculography (EOG) is a sensitive tool for detecting oculomotor dysfunction in Machado-Joseph disease.
• EOG can identify individuals with MJD or at genetic risk who may have normal or subtle neurological findings.
• EOG may serve as a valuable diagnostic aid for early case detection and can inform genetic counseling for MJD.