Overview of NYSTAGMUS Overview of NYSTAGMUS

Vivek Patel MDVivek Patel MD

OBJECTIVESOBJECTIVES

Definition, description

Neuroanatomical basis

Instrinsic localizing value

Representative cases

Definition, description

Neuroanatomical basis

Instrinsic localizing value

Representative cases

DEFINITIONDEFINITION

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

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

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

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

3 main mechanism of maintaining steady gaze:

1) fixation: a) prevent retinal image drift

b) suppress unwanted saccades

2) VOR

3) eccentric gaze holding

3 main mechanism of maintaining steady gaze:

1) fixation: a) prevent retinal image drift

b) suppress unwanted saccades

2) VOR

3) eccentric gaze holding

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

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

NEUROANATOMICAL BASISNEUROANATOMICAL BASIS

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

Not always a sign of disease…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.)

Physiological: Usually conjugate Preserves clear vision during self-rotation

unsustained end-point nystagmus Vestibular nystagmus (brief sustained rot.) OKN (visually driven….uses pursuit mech.)

CHILDHOOD NYSTAGMUSCHILDHOOD 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

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

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

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

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

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

ACQUIRED NYSTAGMUSACQUIRED NYSTAGMUS

PERIPHERAL VS. CENTRAL VESTIBULAR NYSTAGMUSPERIPHERAL 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

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

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

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

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

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

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

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

•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

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

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

Acquired pendular nystagmus: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

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

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

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

SUMMARYSUMMARY

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

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