NeuroTeach 22 - Nystagmus Part I (Basic principles)

Nystagmus series – Part I

(Basic principles)


“the two neuro-ophthalmology legends”

Richard John Leigh And David Samuel Zee


2) Sight’s line
“a disturb in any of the sight’s line components may cause nystagmus” I) vestibulo-ocular reflex II) eccentric position III) fixation IV) recalibration


3) Quick vs slow phase
-quick-phase defines nystagmus direction - slow-phase defines underlying disorder


4) Slow-phase waveforms
A) vestibulo-ocular reflex (central&peripheral) constant velocity, sawtooth appearance B) eccentric position gaze-evoked nystagmus, unsustained eye position C) fixation gaze-holding, increasing velocity D) recalibration pendular nystagmus


5) Axis of rotation & direction of gaze
- vestibular (peripheral/central) nystagmus ➡️ no change w/ gaze - central nystagmus ➡️ can change w/ gaze

6) Terminology - dissociated ≠ oscillation size - disconjugated ≠ oscillation direction - oscillopsia "illusion of motion of the seen world" nystagmus cause excessive motion of image on the retina - nystagmus, pursuits, saccades


7) Physical exam
a) eye movement-vestibular (vestibulo-ocular reflex) b) smooth-pursuits c) saccades d) vergence e) nystagmus exam
8) Nystagmus exam
“remove fixation because it can affect nystagmus presence” 1st eyes closed, palpate globe and observe corneal bulge moves - lid closure can affect nystagmus 2nd eyes open a) Frenzel goggles b) direct ophthalmoscopy


9) How can we make nystagmus more noticeable?
a) Alexander’s law b) change head position, head shaking c) valsalva & hyperventilation


10) Vestibular (central & peripheral) imbalance
Peripheral vestibular imbalance - mixed horizontal-torsional Central vestibular imbalance - downbeat (most common central vestibular nystagmus) - upbeat - torsional - seesaw - periodic alternating nystagmus (PAN)