Jamir Pitton Rissardo
MD | Neurology | Writer | Reviewer | Illustrator | Guitarist ♬
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NeuroTeach 21 - Nystagmus (general)
Nystagmus – Moving eyes!!!
“rhythmic, involuntary, rapid, oscillatory movement of the eyes”
Austrian otologist Robert Bárány (1976–1936)
Nobel prize physiology of vestibular apparatus
2) Differences
nystagmus - byphasic
pursuits – only slow phase
saccades – only fast phase
3) Nystagmus classification
4) Physiological nystagmus
“normal nystagmus variant of oculomotor function”
5) Physiologic end-point nystagmus
“horizontal jerks nystagmus results from testing oculomotor movements too far laterally”
6) Per-rotational nystagmus
“horizontal jerk nystagmus that occurs with sustained head rotations, with fast phases ipsilateral to the rotation”
7) Post-rotational nystagmus
“reflexive horizontal nystagmus that occurs with a rapid brake to a unidirectional head rotation”
- contralateral fast phase
8) Optokinetic or pendular nystagmus
“multi-direction nystagmus in response to moving or rotating visual fields or objects”
- slow phase ipsilateral to visual stimuli
- no fast phase
- parietal-occipital cortex lesion
9) Optokinetic after-nystagmus
“persisting ipsilateral optokinetic nystagmus after the visual stimulus has extincted”
“a slow, pursuit phase and a fast ‘reflex’ or ‘refixation’ phase”
10) Vestibular-ocular reflex
“seen when the patient sees a fixed image, and a rapid head rotation is elicited bilaterally”
- controlled by semicircular canals
11) Caloric nystagmus
“VOR reflex elicited by stimulating the tympanic membrane and horizontal semicircular canals with either warm or cold water”
12) Magnetic vestibular stimulation-induced nystagmus
“occurs while the patient is undergoing an MRI”
- depends on the strength and direction of the field
- interaction of MRI field currents and ionic currents in the endolymph
“abnormal nystagmus from central or peripheral nervous system damage to the vestibular-oculocephalic and/or cortical areas affecting the oculomotor function”
15) Waveform classification
Jerk versus pendular
16) Jerk nystagmus
subdivided by trajectory and the conditions under which it occurs
trajectory – downbeat, upbeat, horizontal, torsional, and mixed
conditions – primary position, gaze-evoked, positional, dissociated, others
- oculopalatal myoclonus
- vertical-torsional and asymmetric or purely vertical and symmetric
23) See-saw nystagmus
“combination of a conjugate torsional motion and a dysconjugate but synchronized vertical component: as one eye goes up, the other descends”
- most freq parasellar mass
24) Oculomasticatory myorhythmia
continuous rhythmic movements of eye convergence with concurrent contractions of the masticatory or other muscles
- pathognomonic Whipple's disease
25) Why is it important to know waveforms?
waveforms are correlated with nystagmus localization
26) Algorithm for the approach of nystagmus
27) Nystagmus features
Direction- fast phase
Plane- horizontal, vertical, torsional, mix
Intensity- amplitude, frequency
Normal eye movs- pursuits, saccades, VOR
Conjugacy- dis&conjugate
Associations- strabismus, head posture
Cover- monocular vs binocular
Convergence- effect
28) Central vs peripheral
Peripheral
- usually horizontal and jerk
- fast beat away from side of lesion
- relieved by gaze fixation
29) How to approach nystagmus?
1st, is this nystagmus?
≠ pursuits & saccades
2nd, is this pathological?
≠ physiological & infantile
3rd, is this central or peripheral?
≠ remember peripheral features
4th, waveform characteristics
≠ remember waveforms
30) Central versus peripheral vestibular nystagmus
