This document defines and describes different types of nystagmus, including their neuroanatomical basis and localizing value. It discusses congenital and acquired nystagmus, differentiating between peripheral and central causes. Key points covered include the mechanisms underlying gaze holding and different forms of pathological nystagmus associated with lesions in various areas of the brainstem and cerebellum. The document emphasizes the importance of characterizing nystagmus to guide further neurological or medical evaluation and identifies potential treatment options.

1. Overview of NYSTAGMUS
Vivek Patel MD

2. OBJECTIVES
 Definition, description
 Neuroanatomical basis
 Instrinsic localizing value
 Representative cases

3. DEFINITION
 Disorder of ocular motor instability resulting in
spontaneous, involuntary, rhythmic oscillations
of the eyes
 Congenital vs. acquired
 “jerk” nystagmus vs. pendular
 “true” nystagmus vs. nystagmoid movements

4.  Conjugate vs. disconjugate vs. dissociated
 Trajectory may be horizontal, vertical, torsional,
or mixed
 Description of amplitude, frequency, velocity,
and intensity
 may vary with changes in gaze position
 May be influenced by the integrity of the
afferent visual system
 May exhibit a “null” point

5.  3 main mechanism of maintaining steady
gaze:
 1) fixation: a) prevent retinal image drift
b) suppress unwanted saccades
 2) VOR
 3) eccentric gaze holding

6.  Pulse (phasic) and step (tonic) outputs must be
balanced for appropriate gaze-holding.
 Significant cerebellar (vermis) calibration
 Horizontal: phasic = PPRF
tonic = NPH, MVN = neural integrators
Vertical: phasic = riMLF
tonic = iNC = neural integrator

7. NEUROANATOMICAL BASIS
Leigh & Zee, Neurology of Eye Movements, 3rd
ed., 1998Leigh & Zee, Neurology of Eye Movements, 3rd
ed., 1998

8. Not always a sign of disease…
 Physiological:
 Usually conjugate
 Preserves clear vision during self-rotation
 unsustained end-point nystagmus
 Vestibular nystagmus (brief sustained rot.)
 OKN (visually driven….uses pursuit mech.)

9. CHILDHOOD NYSTAGMUS
 Congenital nystagmus:
 usually recognized in first few months of life – life long
 May have good vision or poor vision
 Most often occurs in isolation (motor), but may be associated
with albinism, LCA, achromatopsia, or optic atrophy
 Uniplanar, horizontal trajectory irrespective of gaze position
 No oscillopsia
 Reversal of OKN direction
 Exponential increase in slow phase velocity
 Conjugate
 Null point (may have resultant head turn)
 Amplified by attempted fixation (distant)
 Dampened by convergence and darkness
 Absent in sleep
 Association with esotropia

10.  Latent nystagmus:
 Usually appears within first few months of life
 Horizontal jerk nystagmus appearing only
under monocular viewing conditions
 Fast phase beats away from occluded eye
 Strong association with esotropia
 Usually poor stereopsis
 May explain subnormal visual acuity tested
monocularly
 Manifest latent nystagmus:
 Present even when both eyes are open
 Loss of peripheral fusion

11.  Monocular nystagmus of childhood:
 Usually monocular, vertical, low amplitude oscillation
 Eye with nystagmus may have afferent visual dysfunction
 Requires neuroimaging (chiasmal glioma)
 Spasmus Nutans:
 Asymmetric or monocular low-amplitude oscillations
 May be horizontal, vertical or torsional
 Head nodding
 Torticollis or abnormal head posture
 Begins in infancy, usually resolved by age 3 to 5
 Requires neuroimaging

12. ACQUIRED NYSTAGMUS

13. PERIPHERAL VS. CENTRAL
VESTIBULAR NYSTAGMUS
PERIPHERAL
 Severe vertigo
 Days to weeks duration
 Hearing loss, tinnitus
associated
 Usually horizontal with
torsion
 Very rarely purely vertical or
torsional
 Dampened with visual
fixation
 Commonly peripheral
vestibular organ dysfunction:
labyrynthitis, meniere’s
CENTRAL
• None or mild vertigo
• Often chronic
• May be purely vertical or
torsional
• visual fixation usually has no
effect
• Etiologies commonly
vascular, demyelination,
pharmacologic, toxic
• Downbeat, upbeat, torsional

14.  Gaze evoked nystagmus:
 One of the most common forms of central
nystagmus
 Inability to maintain eccentric gaze
 “leaky integrator” -- miscalibration between pulse
and step inputs
 Symmetric
 cerebellar flocculus implicated
 Age, anti-convulsant therapy, alcoholic
degeneration, stroke, demyelination
 Baclofen effective

15.  Downbeat nystagmus:
 Defect in vertical gaze holding
 Asymmetric inputs from vertical semi-circular
canals produce upward slow drift of eyes
 Defect in fastigial nuclei calibration
 Secondary downward corrective fast phase
 Obeys Alexander’s law
 Localizes to cervico-medullary junction
 Arnold-Chiari malformation
 Treatment with baclofen, clonazepam, base-out
prisms

16.  Upbeat nystagmus:
 Present in primary position or upgaze
 Classically localizes to a lesion of anterior cerebellar
vermis
 More generally implicates posterior fossa disease
 Etiologies include stroke, cerebellar degeneration,
demyelination, toxic exposures
 Periodic alternating nystagmus:
 Horizontal oscillation characterized by a periodic reversal
in the direction of nystagmus due a shift in the null point
 Duration of cycles from 30 seconds to 6 minutes
 Classically a lesion of the cerebellar nodulus
 MS, drugs, ethanol, paraneoplastic syndromes
 Baclofen effective

17. •Bruns nystagmus:
• associated with CPA tumors
• high frequency, low amplitude
nystagmus (fast-phase away from lesion)
• low frequency, large amplitude
nystagmus on ipsilateral gaze (fast phase
toward lesion)
• shift from eye movement response to
vestibular imbalance to that of defective
gaze holding

18.  See-saw nystagmus:
 Disconjugate vertical nystagmus (pendular vs. jerk)
 Upward moving eye intorts while downard eye extorts
 Localizes to lesions of diencephalon
 Visual fields may be useful (disruption of afferents to cerebellum)
 Ocular flutter/opsoclonus:
 Burst-like, incoordinated saccadic excursions with high frequency,
low amplitude
 No intersaccadic latency
 Purely horizontal: ocular flutter
 Multiplanar: opsoclonus
 Reflect pause cell dysfunction (pons)
 Must consider paraneoplastic etiology: SCC of lung, ovarian,
breast CA
 Neuroblastoma in children

20. Acquired pendular nystagmus:
 Can be vertical, horizontal, torsional, or any
combination (usually one predominates)
 Usually disconjugate or dissociated
 Oscillopsia ++
 MS, whipple’s, oculopalatal myoclonus
 Combination of afferent dysfunction and
cerebellar calibration

21.  Oculopalatal myoclonus:
 Vertical pendular eye movements associated with rhythmic
upward movement of palate
 Caudal brainstem pathology: red nucleus, inferior olive, and
dentate nuc.
 Convergence-retraction nystagmus:
 Commonly associated with dorsal midbrain syndrome
 May be associated with other Parinaud’s findings
 Not a true nystagmus: co-contraction of horizontal recti on
attempted upgaze
 Localizes to pretectal area, posterior commissure, INC
 Pineal cyst or tumor, demyelination, stroke

22. SUMMARY
 Recognize physiologic vs. pathological
 Appropriate characterization important
 Presence of nystagmus may correlate with significant
afferent visual dysfunction
 Recognition of nystagmus may facilitate subsequent
neurological or medical investigations (know where to
look)
 Treatment options do exist