Ahd neuro-opthalmology - v. patel - nystagmus (1)
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Transcript of Ahd neuro-opthalmology - v. patel - nystagmus (1)
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