Nystagmus
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Introduction
Nystagmus is an involuntary back-forth, up-down, or rotating eye movement.
Nystagmus can also suggest problems with the vestibular system.
slow phase - deregulated vestibular stimulus cuases drift
fast phase - cortical correction (this is the direction of the nystagmus)
problem with vestibular input to eom system
paralytic nystagmus - right ear is busted
irritative nystagmus - right ear is overactive - slow drift to left, so right beating nystagmus
Can be caused by benign paroxysmal positional vertigo (BPPV)
The Case of...
Differential Diagnosis
Can be caused by
- vertigo
- alcohol
Rotatory nystagmus
CN IV or brain stem problems
Direction-changing nystagmus
CN III and VI and cerebellum
History and Physical Exam
- history
- physical exam
History
Physical Exam
It can be induced physiologically by turning the eyes far to one side: ask the person to follow a pen and ask them to hold the gaze for a few seconds at the end of the change.
or by injecting water into the ear canal.
caloric testing
- cold water in the canal causes a change in temperature
- COWS - cold opposite, warm same
- cheap
- can test each ear
- can't do if there's a hole in the eardrum
rotation chair testing
- tests both lateral canals
- ask patients to look straight at you
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
Management
Pathophysiology
Resources and References
Topic Development
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