Eye movements in amyotrophic lateral sclerosis

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Amyotrophic lateral sclerosis (ALS) involves degeneration of upper motor neurons and spinal cord motor neurons.
• Ocular motor systems and cranial nerve nuclei (III, IV, VI) are typically considered unaffected in ALS.
• Previous clinical assessments suggest normal eye movements in most ALS patients.

Purpose of the Study:

• To investigate potential subclinical abnormalities in the ocular motor system of ALS patients.
• To determine if eye movement abnormalities are more prevalent in ALS than previously recognized.

Main Methods:

• Utilized electro-oculography (EOG) to assess eye movement velocities.
• Evaluated saccadic and smooth pursuit eye movements in ten patients diagnosed with ALS.

Main Results:

• Four out of ten ALS patients exhibited decreased saccadic or smooth pursuit velocities.
• One patient displayed unidirectional saccadic pursuit.
• Another patient showed progressively decreasing saccadic velocities during testing.

Conclusions:

• The ocular motor system may be more frequently affected in ALS than previously assumed.
• Observed defects are likely supranuclear, indicating higher-level brain involvement.
• Electro-oculography can detect subtle ocular motor deficits in ALS patients.