Exam 1 (Nystagmus) Flashcards
what is nystagmus
involuntary rhythmic oscillation of the eys
to and from motion is generally involuntary
nystagmus can be ____ or ______
Can be normal physiological (end point) response or pathological issue
what are normal physiological (end point) responses
Fatigue nystagmus, unsustained end point nystagmus, sustained end point nystagmus
how is nystagmus characterized
by a slow and fast phase
how is nystagmus measured and described
Measured by the magnitude of the slow phase (deg/s) and described by the direction of the fast phase (UB, DB, LB, RB, etc.)
describe the slow phase
generated by the peripheral vestibular system; reflects how the vestibular system is operating and provides a reflexive response with a fast onset (about 5-10ms)
describe the fast phase
Generated by the central system; reflects a coordinated response and does not provide information about the vestibular system and has a slower onset (about 70ms)
description
direction of fast phase
RB, LB, UB, DB, torsional
measured by
magnitude of slow phase
deg/s
slope
what are the directional characteristics of nystagmus
Beats towards stimulated ear & away from inhibited ear
Beats ______ from a paretic lesion (e.g., peripheral vestibular loss, except for superior semicircular canal dehiscence [SSCD], migraine, Meniere’s disease, etc.)
away
Beats ______ the side with an irritative lesion (e.g., Meniere’s disease, vestibular migraine)
toward
what are the types of nystagmus
pendular and jerk
what is pendular nystagmus
Equal speed of oscillation in both directions
Speed of motion of the eyes is the same in both directions
No distinct fast and slow phases (sinusoidal pattern)
Measured in cycles per second
Causes: congenital or acquire
what is jerk nystagmus
movements in one direction is faster than in the other
Slow and fast phase → Eyes move slowly in one direction and then jerk back in the other direction
Types → DB (down-beating), UP (up-beating), LB (left-beating), RB (right-beating).
what is torsional/rotary nystagmus
Shows movement in both horizontal and vertical channels
Eye rotates around the central axis and is central or mixed which can indicate peripheral issues
peripheral nystagmus
Horizontal or mixed
Typically beats toward the stimulated ear or healthy ear
central nystagmus
Often vertical or torsional
May result from brainstem or cerebellar pathology, indicating more serious issues
how do you describe nystagmus
Direction: Right-beating, left-beating, up-beating, down-beating.
Intensity: Measured by amplitude (size of movement) and frequency (speed of oscillations).
Gaze Position: Intensity may change based on the direction of gaz
Left-sided vestibular loss results in ______ nystagmus
right-beating
