Unusual monocular pendular nystagmus in multiple sclerosis

Area of Science:

• Ophthalmology
• Neuroscience
• Neurology

Background:

• Multiple sclerosis (MS) can cause various ocular motor abnormalities.
• Acquired pendular nystagmus (APN) is a rare but significant visual disturbance.

Observation:

• Two unique cases of monocular pendular nystagmus (MPN) in MS patients are detailed.
• Case 1: Right eye horizontal oscillations in abduction with abduction paresis.
• Case 2: Left eye oscillations in adduction with partial internuclear ophthalmoplegia.

Findings:

• The observed MPN was dependent on eye position.
• This suggests a combination of muscle paresis and neural feedback loop dysfunction in the ocular motor system.
• These findings challenge existing hypotheses on APN pathogenesis.

Implications:

• Provides novel insights into the pathogenic mechanisms of acquired pendular nystagmus.
• Highlights the complex interplay between motor deficits and neural network dysfunction in MS-related eye movements.
• May inform future diagnostic and therapeutic strategies for ocular motor disorders in neurological conditions.