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NYSTAGMUS
Nystagmus
 Periodic rhythmic biphasic ocular oscillation with slow
followed by fast or slow phase
 Slow eye movements ar...
Nystagmus
Initiated by a slow eye movement that drives the eye off
target, followed by
 Fast movement that is corrective ...
Mechanism of nystagmus
Aim of occular movements
 to maintain foveal centration of an object of interest
Nystagmus due to ...
Saccades
Pulse (a velocity command)
 Overcoming the resistance of the orbital tissues and the
inertia of the globe, chang...
Horizontal saccades
Pulse
 EBNs in the PPRF
↓
ipsilateral abducens nucleus
 IBNs in rostral medulla
↓
contralateral abdu...
Supra nuclear control
Horizontal saccades
Step
Neural Integrator
 Nucleus propositus hypoglossi (NPH) and the adjacent
MVN.
↕
vestibulocerebell...
Vertical saccades
Pulse
riMLF in the prerubral field of the ventral
diencephalomesencephalic junction
 upward and downwar...
Step
Neural Integrator
 Interstitial Nucleus of Cajal
lies caudal to the riMLF
↓ via the posterior commissure
C/L oculomo...
 Neural integrator depends on retinal inputs for its
calibration
 Bilateral blindness may also cause an inability to hol...
Pursuit system
Vestibulo ocular reflex
 vestibular system perceives head movement and makes
the eyeball move in the opposite direction
VOR
Connections from the anterior and posterior SCCs also
contact
 Nucleus of Cajal
 Important in eye head coordination ...
Causes of Nystagmus
Result from dysfunction of
 Vestibular endorgan
 Vestibular nerve
 Brainstem
 Cerebellum
 Cerebra...
Causes of nystagmus
 Symmetric, equal activity of the vestibular systems on
each side normally maintains the eyes in stra...
Symptoms
 Oscillopsia (absent in congenital nystagmus)
 Decreased acuity
 Nausea or vomiting
 Vertigo
 Coexisting neu...
Oscillopsia
Illusory perception of environmental movement
Four forms
1. associated with acquired jerk nystagmus (the
envir...
Nystagmus
physiological pathological
Vestibular
disorder
gaze-holding disorder
visual stabilization and pursuit
mechanisms...
Jerk Vs Pendular
Jerk nystagmus Pendular nystagmus
Slow phase drift with rapid
corrective saccade in
opposite direction
Si...
Direction of eye movement
 Direction of nystagmus determined by direction of the fast
phase
According to plane of eye mov...
Intensity of nystagmus: first, second, or third.
 First degree nystagmus is present only wnen the eyes are turned
in dire...
Amplitude of the nystagmus beat
 large amplitude, small amplitude or medium amplitude
depending upon the
excursion of eye...
congenital or acquired
 Acquired most often by abnormalities of vestibular input.
 Congenital form with afferent visual ...
Acquired VS congenital
Feature Acquired Congenital
Form Pure sinusoidal variable
Different in two eyes Frequent Rare
Direc...
Clinical classification of
nystagmus
Monocular
Binocular asymmetric
or dissociated
(Involve mainly one
eye)
Binocular symm...
Monocular and Asymmetric Binocular
Eye Oscillations
 Monocular visual deprivation or loss
 Monocular pendular nystagmus
...
Acquired Monocular Visual Loss
 small, slow vertical pendular oscillations in the primary
position of gaze
 may develop ...
Acquired monocular pendular
nystagmus
 Multiple sclerosis
 Neurosyphilis
 Brainstem infarct (thalamus and upper midbrai...
INO and in pseudo-INO syndromes
 nystagmus in the abducting eye contralateral to a MLF
lesion
 nystagmus beating in dire...
Epileptic Monocular Horizontal
Nystagmus
 Focal seizures originated in the occipital lobe contralateral
to the involved e...
Monocular DBN
 Acute infarction of the medial thalamus and upper
midbrain
 Pontocerebellar degeneration ( due to dysfunc...
Triad of
1. Head nodding
2. Nystagmus
3. Abnormal head
posture
Spasmus nutans
Spasmus nutans
 Onset in the first year of life
 Remits spontaneously within one month to several years
(up to 8 years) ...
Superior Oblique Myokymia
 Paroxysmal, rapid, smallamplitude, monocular torsional-
vertical oscillation
 Caused by contr...
Bilateral symmetric eye
oscillations
Disconjugate
(eyes moving in opposite
directions)
Vertical
disconjugate
See-saw
nysta...
See-saw Nystagmus
 cyclic movement : while one eye rises and intorts, the
other falls and extorts; the vertical and torsi...
See-saw Nystagmus
 Usually pendular
 See-saw jerk nystagmus → brainstem lesions affecting the
mesodiencephalon or latera...
See-saw Nystagmus
Congenital see-saw nystagmus
 lack the torsional component or even present with an
opposite pattern (i....
Etiologies of See-Saw Nystagmus
 Parasellar masses
 Brainstem and thalamic stroke
 Multiple sclerosis
 Trauma
 Arnold...
Convergence-retraction nystagmus
 repetitive adducting saccades accompanied by retraction
of the eyes into the orbit, occ...
Convergence nystagmus
 In dorsal midbrain stroke and arnold-chiari malformation
 Whipple's disease - ~ 1 hz (pendular ve...
Divergence nystagmus
 Occur with hindbrain abnormalities (e.G., Chiari
malformation)
 Associated with DBN
Repetitive divergence
 Slow divergent movement followed by a rapid return to
the primary position at regular intervals
 ...
Oculomasticatory Myorhythmia
 Acquired pendular vergence oscillations associated with
concurrent contraction of the masti...
Binocular
Symmetric
Conjugate Eye
Oscillations
pendular
nystagmus
Jerk nystagmus
saccadic
intrusions
Pendular conjugate eye oscillations
 Congenital nystagmus
 Acquired pendular nystagmus
 Oculopalatal myoclonus
 Spasmu...
Congenital nystagmus
 At birth or in early infancy, or may emerge or enhance in
teenage or adult life, often without appa...
Congenital nystagmus
 Slow phase with a velocity that increases exponentially as
the eyes move in the direction of the sl...
Latent nystagmus
 Generally congenital
 Appears when one eye is covered
 Usually associated with strabismus
 Marker fo...
Acquired Pendular Nystagmus
 may be wholly horizontal, wholly vertical, or have mixed
components (circular, elliptical, o...
Acquired Pendular Nystagmus
 Other causes of acquired binocular pendular nystagmus
include Pelizaeus-Merzbacher disease, ...
Windmill Nystagmus
 seen in Blind patients
 repeated oscillations in the vertical plane alternating with
repeated oscill...
Palatal myoclonus
 continuous rhythmic involuntary movement of the soft
palate
 association of pendular nystagmus (oculo...
Palatal myoclonus
 Damage to the dentatorubroolivary pathways (Guillain-
Mollaret triangle)
 most often caused by multip...
Binocular
Symmetric Jerk
Nystagmus
Spontaneous
present in
primary position
present
predominantly on
eccentric gaze
Induced
Spontaneous symmetric conjugate jerk nystagmus
that occurs in primary position
Horizontal
Congenital nystagmus
Latent nyst...
Vestibular Nystagmus
 Predominantly a horizontal or vertical unidirectional jerk
nystagmus, often with a slight torsional...
Vestibular Nystagmus
Results from unilateral destruction of
 Horizontal canal
 Total labyrinthine
 Torsional slow compo...
Vestibular Nystagmus
 Linear (constant velocity) slow phase toward the lesion
 Horizontal component is diminished when t...
Peripheral Central
Vary with head position
and movement
+ +
Latency + No
Fatigue + No
Direction Fixed Changing
Effect of f...
Periodic Alternating Nystagmus
 Eyes exhibit primary position nystagmus, which, after 60
to 120 seconds, stops for a few ...
Periodic Alternating Nystagmus
 Often caused by disease processes at the craniocervical
junction
 May be provoked by an ...
Mechanism
 Nodulus and uvula of the cerebellum maintain inhibitory
control over vestibular rotational responses by using ...
Drug-induced nystagmus
 Predominantly horizontal, vertical, rotatory, or, most
commonly, mixed
 Most often seen with tra...
Epileptic Nystagmus
 Usually horizontal
 Often associated with altered states of consciousness
 Epileptiform activity i...
Purely Torsional Nystagmus
 Rare form of central vestibular nystagmus
 Difficult to detect except by the observation of ...
Purely Torsional Nystagmus
 Seen with brainstem and posterior fossa lesions, such as
tumors, syringobulbia, syringomyelia...
DBN
 usually present in primary position, but is greatest when
the patient looks down (Alexander's law) and to one side
...
DBN
Causes
 Occur with cervicomedullary junction disease, midline
medullary lesions, posterior midline cerebellar lesions...
Mechanisms
 Deficient drive by the posterior SCCs
 Interruption of downward vestibulo-ocular
reflex pathways, which syna...
Etiologies of Downbeat Nystagmus
UBN
 Usually worse in upgaze (Alexander's law)
 Unlike DBN, it usually does not increase on lateral gaze
 Convergence m...
UBN
Causes
 Damage to the central projections of the
anterior SCCs
 Damage to the ventral tegmental
pathways
 Lesions o...
UBN
Primary position UBN increased in downward gaze
 Due to impairment of the vertical position-to-velocity
neural integr...
UBN
Primary position UBN combined with binocular elliptical
pendular nystagmus
 characteristic of Pelizaeus-Merzbacher di...
Both downbeat and upbeat nystagmus are poorly suppressed
by visual fixation and may be exacerbated by simply
placing patie...
Mechanism of spontaneous vertical
nystagmus
Primary dysfunction of the SVN-VTT pathway
Hypoactive after pontine or caudal
medullary lesions → UBN
 Hyperactive after floccular lesions → DBN
Binocular Symmetric Jerk Nystagmus
Present in Eccentric Gaze
 Gaze-evoked nystagmus
 Nystagmus due to brainstem/cerebell...
Gaze-evoked Nystagmus
 eyes fail to remain in an eccentric position of gaze but
drift to midposition
 velocity of the sl...
Gaze-evoked Nystagmus
 Leaky neural integrator or cerebellar (especially
vestibulocerebellar lesion )
 Side effect of me...
Bruns' nystagmus
 Cerebellopontine angle tumors
Combination of
 Ipsilateral large-amplitude, low-frequency nystagmus tha...
Physiologic or endpoint nystagmus
 Benign low-amplitude jerk nystagmus with the fast
component directed toward the field ...
Rebound nystagmus
 Brainstem and/or cerebellar disease (e.g., Olivocerebellar
Atrophy, Brainstem/Cerebellar Tumor Or Stro...
Convergence-evoked Nystagmus
 Usually vertical (upbeat is more common than downbeat)
 Seen most commonly with multiple s...
Induced Nystagmus
 Optokinetic nystagmus
 Rotational/caloric vestibular nystagmus
 Positional nystagmus
 Valsalva-indu...
OKN
 follow objects in motion when head remains stationary
 develops at 6 months of age
 slow pursuit movements on dire...
OKN
 Paradoxical reversal in congenital nystagmus
 With unilateral hemispheric lesions, especially parietal or
parietal-...
Positional Nystagmus
 Possibly related to degeneration of the macula of the
otolith organ or to lesions of the posterior ...
Caloric testing
 While in supine. Elevtes the head 30°; this brings the
horizontal semicircular canals in vertical plane
...
Nystagmus Induced By The Valsalva
Maneuver
 may occur with Arnold-Chiari malformation or perilymph
fistulas
Hyperventilation Induced Nystagmus
 Tumors of the eighth CN (e.G., Acoustic neuroma or
epidermoid tumors), after vestibul...
Head-shaking nystagmus
 nystagmus induced by head oscillation
 usually beats to the healthy side in unilateral periphera...
Perverted HSN
 nystagmus develops in the plane other than that being
stimulated, that is, downbeat or upbeat after horizo...
Superior SCC Dehiscence Syndrome
 Vertigo and nystagmus induced by sound (tullio
phenomenon) or changes of middle ear (he...
vibration induced nystagmus
 Bone conducted vibrations (BCV) of the head at low
frequencies ( 60-100 hz )
 Activating pr...
Saccadic Intrusions
 Interfere with macular fixation of an object of interest
Essential difference between nystagmus and ...
Lid Nystagmus
Rhythmic jerking movements of the upper eyelids
1. Synchronous with vertical ocular nystagmus
2. Synchronous...
Nystagmus Evaluation
 Does the nystagmus involve both eyes?
 Does the nystagmus involve both eyes symmetrically
 Does t...
 Low amplitude nystagmus mav be detected during
ophthalmoscopy; note that the direction of horizontal or
vertical nystagm...
Treatment of nystagmus
Pendular nystagmus
 central (brainstem or cerebellum
Jerk nystagmus
 either central or peripheral.
NYSTAGMUS SYNDROME an...
Jerk nystagmus
Linear (constant velocity) slow phase
 Peripheral vestibular dysfunction
Slow phase has a decreasing veloc...
NYSTAGMUS SYNDROME and
LOCALIZATION
Downbeat nystagmus
 Bilateral cervicomedullary junction (flocculus)
 Floor of the fo...
NYSTAGMUS SYNDROME and
LOCALIZATION
Pendular nystagmus
 Paramedian pons
 Deep cerebellar (fastigial) nuclei
Seesaw nysta...
NYSTAGMUS SYNDROME and
LOCALIZATION
Brun’s nystagmus
 Cerebellopontine angle
 AICA territory stroke
Torsional nystagmus,...
Thank you
 The oscillations may be sinusoidal and of approximately
equal amplitude and velocity (pendular nystagmus) or,
more commo...
 horizontal nystagmus usually (but not always) of
vestibular origin
 Vertical nystagmus is usually of CNS origin
 Direction -changing or direction-fixed
 change in direction of nystagmus. be it when the eyes are
in a specific positio...
 Manner of occurrence
 Effect of optic fixation on the nystagmus
 Due to peripheral vestibular pathology decreases
 Due to central vestibular...
 Although nystagmus described by direction of quick
phase, it is the slow phase that reflects underlying disorder
 differentiated from saccadic intrusions and oscillations
 rapid movements which take the eye away from the target
 Nystagmus mav be unilateral or bilateral, but when
unilateral its rather asymmetrical rather than truly
unilateral
 Localizing acquired central nystagmus: Jerk
 Downbeat nystagmus
 Upbeat nystagmus
 Periodic alternating nystagmus
 R...
 Localizing acquired central nystagmus: pendular
Occular bobbing
 intermittent often conjugate fast downward movement of
the eyes followed after a brief tonic interval by...
occular flutter
 intermittent bursts of conjugate horizontal saccades
without an intersaccadic interval.
 Impaired contr...
opsoclonus
 rare disorder of saccadic system
 involuntary arrhythmic, chaotic, multidirectional saccades
without intersa...
 harbinger of an occult malignancy, though manv cases are
postinfectious, toxic-metabolic or idiopathic
 usually neural ...
 Occulocephalic reflex
 from first week of life
 essentially represents a vestibulo-ocular reflex
 Gaze-provoked nystagmus
 The commonest form of nystagmus
 eyes moved into eccentric gaze, especially in lateral and
up...
 end point nystagmus
 usuallv unsustained, . of low frequency and amplitude,
and not accompanied by other ocular motor a...
 Pathological gaze evoked nystagmus
 sign of extraocular muscle weakness;, for example, in
patients with myasthenia grav...
Afferents to vestibular nuclei
• Semicircular canals → Superior and medial subnuclei
• Otolith organs → Lateral and inferi...
Ocular Connections
Vestibular
Nuclei
Mainly from superior and medial
nuclei
Superior nucleus projects to I/L
MLF; other nu...
Horizontal
semicircular canal
Anterior (superior) and
posterior canals
Abducens Nuclei &
Oculomotor Complex
Oculomotor &
T...
Nystagmus
Nystagmus
Nystagmus
Nystagmus
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Nystagmus

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Nystagmus

  1. 1. NYSTAGMUS
  2. 2. Nystagmus  Periodic rhythmic biphasic ocular oscillation with slow followed by fast or slow phase  Slow eye movements are responsible for its genesis and continuation
  3. 3. Nystagmus Initiated by a slow eye movement that drives the eye off target, followed by  Fast movement that is corrective (jerk nystagmus) or  Another slow eye movement in the opposite direction (pendular nystagmus)
  4. 4. Mechanism of nystagmus Aim of occular movements  to maintain foveal centration of an object of interest Nystagmus due to distubance of 1. Visual fixation 2. Occular movements - Neural integrator 3. vestibulo-ocular reflex
  5. 5. Saccades Pulse (a velocity command)  Overcoming the resistance of the orbital tissues and the inertia of the globe, changes the position of the eye in the orbit  Accomplished by burst neurons Step (a position command)  Change in tonic contraction of the orbital muscles, which, overcoming the elasticity of the orbital tissues, keeps the eye in the new position  Accomplished by neural integrators
  6. 6. Horizontal saccades Pulse  EBNs in the PPRF ↓ ipsilateral abducens nucleus  IBNs in rostral medulla ↓ contralateral abducens nucleus
  7. 7. Supra nuclear control
  8. 8. Horizontal saccades Step Neural Integrator  Nucleus propositus hypoglossi (NPH) and the adjacent MVN. ↕ vestibulocerebellum, especially the flocculus and paraflocculus
  9. 9. Vertical saccades Pulse riMLF in the prerubral field of the ventral diencephalomesencephalic junction  upward and downward saccades and I/L torsional saccades  lateral portion concerned with upgaze, the medial portion with downgaze ↓ B/L elevator muscles I/L depressor muscles
  10. 10. Step Neural Integrator  Interstitial Nucleus of Cajal lies caudal to the riMLF ↓ via the posterior commissure C/L oculomotor and trochlear subnuclei through the PC Vertical saccades
  11. 11.  Neural integrator depends on retinal inputs for its calibration  Bilateral blindness may also cause an inability to hold the gaze steady
  12. 12. Pursuit system
  13. 13. Vestibulo ocular reflex  vestibular system perceives head movement and makes the eyeball move in the opposite direction
  14. 14. VOR Connections from the anterior and posterior SCCs also contact  Nucleus of Cajal  Important in eye head coordination in roll and in vertical gaze holding  riMLF  Important in generating quick phases of vestibular nystagmus in the vertical and torsional planes
  15. 15. Causes of Nystagmus Result from dysfunction of  Vestibular endorgan  Vestibular nerve  Brainstem  Cerebellum  Cerebral centers for ocular pursuit
  16. 16. Causes of nystagmus  Symmetric, equal activity of the vestibular systems on each side normally maintains the eyes in straight-ahead, primary position. Vestibular imbalance causes the eyes to deviate toward the less active side  In an alert patient, the frontal eye fields generate a saccade to bring the eyes back toward primary position, creating the fast phase of vestibular nystagmus.
  17. 17. Symptoms  Oscillopsia (absent in congenital nystagmus)  Decreased acuity  Nausea or vomiting  Vertigo  Coexisting neurologic deficits
  18. 18. Oscillopsia Illusory perception of environmental movement Four forms 1. associated with acquired jerk nystagmus (the environment moves in the direction opposite the slow phase of the nystagmus) 2. associated with pendular nystagmus (perceived as a to- and-fro movement) 3. associated with SOM (jelly-like quivering) 4. associated with bilateral labyrinthine dysfunction (continuous environmental jumping, e.g., With the heartbeat)
  19. 19. Nystagmus physiological pathological Vestibular disorder gaze-holding disorder visual stabilization and pursuit mechanisms disorder
  20. 20. Jerk Vs Pendular Jerk nystagmus Pendular nystagmus Slow phase drift with rapid corrective saccade in opposite direction Sinusoidal oscillation with slow phase in both directions and no corrective saccades Direction is that of fast phase Horizontal or vertical
  21. 21. Direction of eye movement  Direction of nystagmus determined by direction of the fast phase According to plane of eye movement  Horizontal (right or left beating )or vertical (up or down beating) or rotatory (clock wise or anti clockwise) Types of nystagmus
  22. 22. Intensity of nystagmus: first, second, or third.  First degree nystagmus is present only wnen the eyes are turned in direction of nystagmus. This is the weakest form ot nystagmus.  second degree nystagmus is present when the eyes are in the midline, increases when the eves are turned towards the side of the slow phase.  In third degree nystagmus, nystagmus is present in all three eye positions Types of nystagmus
  23. 23. Amplitude of the nystagmus beat  large amplitude, small amplitude or medium amplitude depending upon the excursion of eyeball during the nystagmus.  Clinically irrelevant Types of nystagmus
  24. 24. congenital or acquired  Acquired most often by abnormalities of vestibular input.  Congenital form with afferent visual pathway abnormalities Types of nystagmus
  25. 25. Acquired VS congenital Feature Acquired Congenital Form Pure sinusoidal variable Different in two eyes Frequent Rare Direction Omnidirectional – vertical, circular, elliptical Horizontal, uniplanar, Rarely vertical or torsional OKN reversal Never Frequent Oscillopsia Frequent Mild
  26. 26. Clinical classification of nystagmus Monocular Binocular asymmetric or dissociated (Involve mainly one eye) Binocular symmetric (involve both eyes symmetrically)
  27. 27. Monocular and Asymmetric Binocular Eye Oscillations  Monocular visual deprivation or loss  Monocular pendular nystagmus  Internuclear ophthalmoplegia and its mimickers  Spasmus nutans and its mimickers  Partial paresis of extraocular muscles  Restrictive syndromes of extraocular muscles  Superior Oblique Myokymia
  28. 28. Acquired Monocular Visual Loss  small, slow vertical pendular oscillations in the primary position of gaze  may develop years after uniocular visual loss (Heimann- Bielschowsky phenomenon) and may improve if vision is corrected
  29. 29. Acquired monocular pendular nystagmus  Multiple sclerosis  Neurosyphilis  Brainstem infarct (thalamus and upper midbrain)
  30. 30. INO and in pseudo-INO syndromes  nystagmus in the abducting eye contralateral to a MLF lesion  nystagmus beating in direction of abduction  occurs in midline lesions in the dorsal part of the brain stem affecting MLF between the abducen nucleus on one side of the brain with the oculomotor nucleus  tumors and vascular lesions may also cause
  31. 31. Epileptic Monocular Horizontal Nystagmus  Focal seizures originated in the occipital lobe contralateral to the involved eye  forme fruste of the Sturge-Weber syndrome
  32. 32. Monocular DBN  Acute infarction of the medial thalamus and upper midbrain  Pontocerebellar degeneration ( due to dysfunction of the ipsilateral brachium conjunctivum)
  33. 33. Triad of 1. Head nodding 2. Nystagmus 3. Abnormal head posture Spasmus nutans
  34. 34. Spasmus nutans  Onset in the first year of life  Remits spontaneously within one month to several years (up to 8 years) of onset  Sinusoidal nystagmus intermittent, asymmetric or unilateral  High frequency and small amplitude with a shimmering quality  Usually horizontal but may have a vertical or torsional component  Must consider tumor of the optic nerve, chiasm, third ventricle, or thalamus
  35. 35. Superior Oblique Myokymia  Paroxysmal, rapid, smallamplitude, monocular torsional- vertical oscillation  Caused by contraction of the superior oblique muscle predominantly on the right side  Difficult to detect with the unaided eye and is more easily detected with a direct ophthalmoscope  Reported with adrenoleukodystrophy, lead poisoning, cerebellar astrocytoma, dural arteriovenous fistula, and microvascular Compression  Respond dramatically to carbamazepine or gabapentin
  36. 36. Bilateral symmetric eye oscillations Disconjugate (eyes moving in opposite directions) Vertical disconjugate See-saw nystagmus Horizontal disconjugate Convergence-retraction nystagmus (nystagmus retractorius) Divergence nystagmus Repetitive divergence Oculomasticatory myorhythmia Conjugate (both eyes moving in same direction)
  37. 37. See-saw Nystagmus  cyclic movement : while one eye rises and intorts, the other falls and extorts; the vertical and torsional movements are then reversed, completing the cycle
  38. 38. See-saw Nystagmus  Usually pendular  See-saw jerk nystagmus → brainstem lesions affecting the mesodiencephalon or lateral medulla  Represents sinusoidal oscillations involving central otolith connections, especially the INC  May also be partly due to an unstable visuovestibular interaction control system
  39. 39. See-saw Nystagmus Congenital see-saw nystagmus  lack the torsional component or even present with an opposite pattern (i.e., extorsion with eye elevation and intorsion with eye depression)
  40. 40. Etiologies of See-Saw Nystagmus  Parasellar masses  Brainstem and thalamic stroke  Multiple sclerosis  Trauma  Arnold-Chiari malformation  Hydrocephalus  Syringobulbia  Paraneoplastic encephalitis (with testicular cancer and anti-Ta antibodies)  Whole brain irradiation and intrathecal methotrexate  Septo-optic dysplasia, retinitis pigmentosa, and cone degeneration  Congenital see-saw nystagmus
  41. 41. Convergence-retraction nystagmus  repetitive adducting saccades accompanied by retraction of the eyes into the orbit, occur spontaneously or on attempted upgaze  elicited by Sliding an optokinetic tape downward in front of the patient's eyes  caused by Mesencephalic lesions affecting the pretectal region
  42. 42. Convergence nystagmus  In dorsal midbrain stroke and arnold-chiari malformation  Whipple's disease - ~ 1 hz (pendular vergence oscillations)
  43. 43. Divergence nystagmus  Occur with hindbrain abnormalities (e.G., Chiari malformation)  Associated with DBN
  44. 44. Repetitive divergence  Slow divergent movement followed by a rapid return to the primary position at regular intervals  Seen in coma from hepatic encephalopathy or related to seizures
  45. 45. Oculomasticatory Myorhythmia  Acquired pendular vergence oscillations associated with concurrent contraction of the masticatory muscles  Smooth, rhythmic eye convergence, which cycles at a frequency of approximately 1 hz, followed by divergence back to the primary position  Synchronous with rhythmic elevation and depression of the mandible  May also have paralysis of vertical gaze, progressive somnolence, and intellectual deterioration  Recognized only in whipple's disease
  46. 46. Binocular Symmetric Conjugate Eye Oscillations pendular nystagmus Jerk nystagmus saccadic intrusions
  47. 47. Pendular conjugate eye oscillations  Congenital nystagmus  Acquired pendular nystagmus  Oculopalatal myoclonus  Spasmus nutans  Visual deprivation nystagmus
  48. 48. Congenital nystagmus  At birth or in early infancy, or may emerge or enhance in teenage or adult life, often without apparent provocation  Seldom familial and most often idiopathic  Due to metabolic derangements and structural anomalies of the brain, including abnormalities of the eye or anterior visual pathways  Wholly pendular or have both pendular and jerk components
  49. 49. Congenital nystagmus  Slow phase with a velocity that increases exponentially as the eyes move in the direction of the slow phase  Visual fixation accentuates it and active eyelid closure or convergence attenuates it  Nystagmus decreases in an eye position (null region) that is specific for each patient  Quick phase of the elicited nystagmus generally follows the direction of the tape (reversed optokinetic nystagmus)
  50. 50. Latent nystagmus  Generally congenital  Appears when one eye is covered  Usually associated with strabismus  Marker for congenital ocular motor disturbance and does not indicate progressive structural brain disease
  51. 51. Acquired Pendular Nystagmus  may be wholly horizontal, wholly vertical, or have mixed components (circular, elliptical, or windmill pendular nystagmus)  most often caused by multiple sclerosis, stroke, or tumor of the brainstem or other posterior fossa structures  In multiple sclerosis → sign of cerebellar nuclear involvement or result from optic neuropathy  lesion in the dorsal pontine tegmentum, perhaps affecting the central tegmental tract
  52. 52. Acquired Pendular Nystagmus  Other causes of acquired binocular pendular nystagmus include Pelizaeus-Merzbacher disease, mitochondrial cytopathy, Cockayne's syndrome, neonatal adrenoleukodystrophy (a peroxisomal disorder), and toluene addiction
  53. 53. Windmill Nystagmus  seen in Blind patients  repeated oscillations in the vertical plane alternating with repeated oscillations in the horizontal plane
  54. 54. Palatal myoclonus  continuous rhythmic involuntary movement of the soft palate  association of pendular nystagmus (oculopalatal myoclonus )
  55. 55. Palatal myoclonus  Damage to the dentatorubroolivary pathways (Guillain- Mollaret triangle)  most often caused by multiple sclerosis or vascular lesions of the brainstem  MRI often shows enlargement of the inferior olivary nuclei
  56. 56. Binocular Symmetric Jerk Nystagmus Spontaneous present in primary position present predominantly on eccentric gaze Induced
  57. 57. Spontaneous symmetric conjugate jerk nystagmus that occurs in primary position Horizontal Congenital nystagmus Latent nystagmus Vestibular nystagmus PAN Drug-induced nystagmus Epileptic nystagmus Torsional Form of central vestibular nystagmus Vertical UBN DBN
  58. 58. Vestibular Nystagmus  Predominantly a horizontal or vertical unidirectional jerk nystagmus, often with a slight torsional component, that is evident when the eyes are close to the central position  Does not change with the direction of gaze  More prominent when visual fixation is eliminated
  59. 59. Vestibular Nystagmus Results from unilateral destruction of  Horizontal canal  Total labyrinthine  Torsional slow component causing the upper part of the globe to rotate toward the lesioned side
  60. 60. Vestibular Nystagmus  Linear (constant velocity) slow phase toward the lesion  Horizontal component is diminished when the patient lies with the intact ear down and is exacerbated with the affected ear down  Slow-phase velocity is greater when the eyes are turned in the direction of the quick component (Alexander's law)
  61. 61. Peripheral Central Vary with head position and movement + + Latency + No Fatigue + No Direction Fixed Changing Effect of fixation Suppresses No Pure vertical or torsional nystagmus No + Associated symptoms Subjective vertigo. Neurologic signs and symptoms of brainstem dysfunction
  62. 62. Periodic Alternating Nystagmus  Eyes exhibit primary position nystagmus, which, after 60 to 120 seconds, stops for a few seconds and then starts beating in the opposite direction
  63. 63. Periodic Alternating Nystagmus  Often caused by disease processes at the craniocervical junction  May be provoked by an attack of meniere's disease  Prominent finding in some patients with creutzfeldt-jakob disease
  64. 64. Mechanism  Nodulus and uvula of the cerebellum maintain inhibitory control over vestibular rotational responses by using the neurotransmitter GABA and over the course of postrotational nystagmus  following ablation of these structures, the postrotational response is excessively prolonged  So normal vestibular repair mechanisms act to reverse the direction of the nystagmus, which may result in PAN  Baclofen, a GABA-B agonist, may abolish PAN Periodic Alternating Nystagmus
  65. 65. Drug-induced nystagmus  Predominantly horizontal, vertical, rotatory, or, most commonly, mixed  Most often seen with tranquilizing medications and anticonvulsants  More often evident with eccentric gaze
  66. 66. Epileptic Nystagmus  Usually horizontal  Often associated with altered states of consciousness  Epileptiform activity ipsilateral or contralateral to the direction of the slow component of the nystagmus  Seizure-induced ipsilateral linear slow phases → smooth pursuit region in the temporo-occipital cortex  Seizure-induced contralateral quick phases → saccade- controlling regions of the temporo-occipital or frontal cortex
  67. 67. Purely Torsional Nystagmus  Rare form of central vestibular nystagmus  Difficult to detect except by the observation of the conjunctival vessels or by noting the direction of retinal movements on either side of the fovea
  68. 68. Purely Torsional Nystagmus  Seen with brainstem and posterior fossa lesions, such as tumors, syringobulbia, syringomyelia with arnold-chiari malformation, lateral medullary syndrome, multiple sclerosis, trauma, vascular anomalies, post-encephalitis, and sarcoidosis, and as part of the stiff-person syndrome
  69. 69. DBN  usually present in primary position, but is greatest when the patient looks down (Alexander's law) and to one side  convergence may increase, suppress, or convert the nystagmus to UBN
  70. 70. DBN Causes  Occur with cervicomedullary junction disease, midline medullary lesions, posterior midline cerebellar lesions, or diffuse cerebellar disease  Most lesions responsible for DBN affect the vestibulocerebellum (flocculus, paraflocculus, nodulus, and uvula) and the underlying medulla  Intermittent DBN, accompanied by episodic vertical oscillopsia, may be an early sign of arnold-chiari malformation
  71. 71. Mechanisms  Deficient drive by the posterior SCCs  Interruption of downward vestibulo-ocular reflex pathways, which synapse in the MVN and cross in the medulla  Cerebellar, especially floccular and uvulonodular, lesions by disinhibition of the cerebellar effect on the VN  Damage to the nuclei propositus hypoglossi and the medial VN (the neural integrator) in the medulla DBN
  72. 72. Etiologies of Downbeat Nystagmus
  73. 73. UBN  Usually worse in upgaze (Alexander's law)  Unlike DBN, it usually does not increase on lateral gaze  Convergence may increase or decrease the nystagmus, or convert DBN to UBN
  74. 74. UBN Causes  Damage to the central projections of the anterior SCCs  Damage to the ventral tegmental pathways  Lesions of the anterior cerebellar vermis, perihypoglossal and inferior olivary nuclei of the medulla, pontine tegmentum, brachium conjunctivum, midbrain, and brainstem diffusely
  75. 75. UBN Primary position UBN increased in downward gaze  Due to impairment of the vertical position-to-velocity neural integrator in the Nucleus Intercalatus Of Staderini  Structure in the paramedian caudal medulla located caudal to the VN and to the most rostral of the perihypoglossal nuclei (NPH and nucleus of roller)
  76. 76. UBN Primary position UBN combined with binocular elliptical pendular nystagmus  characteristic of Pelizaeus-Merzbacher disease Bow-tie nystagmus  quick phases are directed obliquely upward with horizontal components alternating to the right and left  probably a variant of UBN
  77. 77. Both downbeat and upbeat nystagmus are poorly suppressed by visual fixation and may be exacerbated by simply placing patient in head hanging position
  78. 78. Mechanism of spontaneous vertical nystagmus Primary dysfunction of the SVN-VTT pathway
  79. 79. Hypoactive after pontine or caudal medullary lesions → UBN
  80. 80.  Hyperactive after floccular lesions → DBN
  81. 81. Binocular Symmetric Jerk Nystagmus Present in Eccentric Gaze  Gaze-evoked nystagmus  Nystagmus due to brainstem/cerebellar disease  Bruns' nystagmus  Drug-induced nystagmus  Physiologic nystagmus  Rebound nystagmus  Convergence-induced nystagmus
  82. 82. Gaze-evoked Nystagmus  eyes fail to remain in an eccentric position of gaze but drift to midposition  velocity of the slow component decreases exponentially as the eyes approach midposition  more pronounced when the patient looks toward the lesion
  83. 83. Gaze-evoked Nystagmus  Leaky neural integrator or cerebellar (especially vestibulocerebellar lesion )  Side effect of medications, including anticonvulsants, sedatives, and alcohol  Adult-onset alexander's disease with the involvement of the middle cerebellar peduncles and dentate nuclei  Familial episodic vertigo and ataxia type 2
  84. 84. Bruns' nystagmus  Cerebellopontine angle tumors Combination of  Ipsilateral large-amplitude, low-frequency nystagmus that is due to impaired gaze holding  Contralateral small-amplitude, high-frequency nystagmus that is due to vestibular impairment
  85. 85. Physiologic or endpoint nystagmus  Benign low-amplitude jerk nystagmus with the fast component directed toward the field of gaze  Usually ceases when the eyes are brought to a position somewhat less than the extremes of gaze
  86. 86. Rebound nystagmus  Brainstem and/or cerebellar disease (e.g., Olivocerebellar Atrophy, Brainstem/Cerebellar Tumor Or Stroke, Marinesco-sjogren Syndrome, Dandy-walker Cyst, Gerstmann-straussler-scheinker Disease, Adult-onset Alexander's Disease, etc.)  Probably reflects an attempt by the brainstem or the cerebellar mechanisms to correct for the centripetal drift of gaze-evoked nystagmus
  87. 87. Convergence-evoked Nystagmus  Usually vertical (upbeat is more common than downbeat)  Seen most commonly with multiple sclerosis or brainstem infarction  Converting downbeat to upbeat, upbeat to downbeat, or pendular to upbeat
  88. 88. Induced Nystagmus  Optokinetic nystagmus  Rotational/caloric vestibular nystagmus  Positional nystagmus  Valsalva-induced nystagmus  Hyperventilation-induced nystagmus
  89. 89. OKN  follow objects in motion when head remains stationary  develops at 6 months of age  slow pursuit movements on direction of drum and then a quick saccade to opposite side
  90. 90. OKN  Paradoxical reversal in congenital nystagmus  With unilateral hemispheric lesions, especially parietal or parietal-occipital lesions show impaired OKN when the drum is rotated toward the side of the lesion  Each eye can be tested separately to exclude monocular blindness  Hysterical patients and malingerers who claim that they cannot see, and of neonates and infants
  91. 91. Positional Nystagmus  Possibly related to degeneration of the macula of the otolith organ or to lesions of the posterior SCC  After rapid head tilt toward the affected ear or following head extension, when the posterior SCC is moved in the specific plane of stimulation  Other causes of positional vertigo include trauma, infection, labyrinthine fistula, ischemia, demyelinating disease, arnold-chiari malformation, and, rarely, posterior fossa tumors or vascular malformations
  92. 92. Caloric testing  While in supine. Elevtes the head 30°; this brings the horizontal semicircular canals in vertical plane  Cold water instilled into the right ear causes the endolymph in the right semicircular canal to cool and sink.This movement is the same movement induced by a rotation or the head to the left, inducing a horizontal nystagmus directed to the left  Warm water in the same ear produces the opposite effect  Failure to respond to otolithic stimuli implies peripheral vestibular disease.
  93. 93. Nystagmus Induced By The Valsalva Maneuver  may occur with Arnold-Chiari malformation or perilymph fistulas
  94. 94. Hyperventilation Induced Nystagmus  Tumors of the eighth CN (e.G., Acoustic neuroma or epidermoid tumors), after vestibular neuritis, or central demyelinating lesions  Slow phase away from the side of the lesion (an excitatory or recovery nystagmus)  Due to the effect of hyperventilation upon serum PH and calcium concentration, which improves nerve conduction in a marginally functional, demyelinated nerve
  95. 95. Head-shaking nystagmus  nystagmus induced by head oscillation  usually beats to the healthy side in unilateral peripheral vestibulopathy
  96. 96. Perverted HSN  nystagmus develops in the plane other than that being stimulated, that is, downbeat or upbeat after horizontal head oscillation  in diffuse cerebellar degeneration, with focal caudal cerebellar stroke, or with medullary lesions  signifies central vestibular lesion
  97. 97. Superior SCC Dehiscence Syndrome  Vertigo and nystagmus induced by sound (tullio phenomenon) or changes of middle ear (hennebert sign) or intracranial pressure  Caused by bony dehiscence of the superior SCC
  98. 98. vibration induced nystagmus  Bone conducted vibrations (BCV) of the head at low frequencies ( 60-100 hz )  Activating probably only semicircular canals and not otolithic afferent neurons  High frequencv (500 hz) BCV is a selective means of activating otoliths  Delivered at the mastoids and at the midline of the forehead at the hairline
  99. 99. Saccadic Intrusions  Interfere with macular fixation of an object of interest Essential difference between nystagmus and saccadic intrusions Initial eye movement  Nystagmus → slow drift or slow phase  Saccadic intrusions → inappropriate saccadic movement that intrudes on steady fixation
  100. 100. Lid Nystagmus Rhythmic jerking movements of the upper eyelids 1. Synchronous with vertical ocular nystagmus 2. Synchronous with the fast phase of gaze-evoked horizontal nystagmus in some patients with the lateral medullary syndrome 3. Evoked by horizontal gaze in some patients with midbrain tumors that injure the m-group of neurons adjacent to the rimlf 4. During voluntary convergence (pick’s sign) in some patients with medullary or cerebellar disease
  101. 101. Nystagmus Evaluation  Does the nystagmus involve both eyes?  Does the nystagmus involve both eyes symmetrically  Does the nystagmus cause the eyes to move in same or opposite direction (conjugate or dysconjugate)  Docs the nystagmus occur spontaneously in primary position  Does the nystagmus onlv occur when gaze is directed to an eccentric gaze position
  102. 102.  Low amplitude nystagmus mav be detected during ophthalmoscopy; note that the direction of horizontal or vertical nystagmus is inverted when viewed through the ophthalmoscope.  Electronvstagmogram ENG for identifying nystagmus not present with eyes open  Dix-Hallpike or Barany maneuver for assessing positional nystagmus Nystagmus Evaluation
  103. 103. Treatment of nystagmus
  104. 104. Pendular nystagmus  central (brainstem or cerebellum Jerk nystagmus  either central or peripheral. NYSTAGMUS SYNDROME and LOCALIZATION
  105. 105. Jerk nystagmus Linear (constant velocity) slow phase  Peripheral vestibular dysfunction Slow phase has a decreasing velocity exponential  Brainstem neural integrator Increasing velocity exponential slow phase in the horizontal plane  Central in origin and is the usual form of congenital nystagmus NYSTAGMUS SYNDROME and LOCALIZATION
  106. 106. NYSTAGMUS SYNDROME and LOCALIZATION Downbeat nystagmus  Bilateral cervicomedullary junction (flocculus)  Floor of the fourth ventricle Periodic alternating nystagmus  Cervicomedullary junction (nodulus) Upbeat nystagmus  Bilateral pontomesencephalic junction  Bilateral pontomedullary junction  Cerebellar vermis
  107. 107. NYSTAGMUS SYNDROME and LOCALIZATION Pendular nystagmus  Paramedian pons  Deep cerebellar (fastigial) nuclei Seesaw nystagmus (SSN)  Mesodiencephalic junction, chiasm, disorders that disrupt central vision Rebound nystagmus  Cerebellum
  108. 108. NYSTAGMUS SYNDROME and LOCALIZATION Brun’s nystagmus  Cerebellopontine angle  AICA territory stroke Torsional nystagmus, jerk  Central vestibular system Torsional nystagmus, pendular  Medulla
  109. 109. Thank you
  110. 110.  The oscillations may be sinusoidal and of approximately equal amplitude and velocity (pendular nystagmus) or, more commonly, with a slow initiating phase and a fast corrective phase (jerk nystagmus)
  111. 111.  horizontal nystagmus usually (but not always) of vestibular origin  Vertical nystagmus is usually of CNS origin
  112. 112.  Direction -changing or direction-fixed  change in direction of nystagmus. be it when the eyes are in a specific position or when the position of the eye is changed indicates a lesion in the central nervous svstem.  • nystagmus due to vestibular lesion never changes direction irrespective of whether the eyes are in a fixed position or changed
  113. 113.  Manner of occurrence
  114. 114.  Effect of optic fixation on the nystagmus  Due to peripheral vestibular pathology decreases  Due to central vestibular pathology increases when eyes open and decreases when closed
  115. 115.  Although nystagmus described by direction of quick phase, it is the slow phase that reflects underlying disorder
  116. 116.  differentiated from saccadic intrusions and oscillations  rapid movements which take the eye away from the target
  117. 117.  Nystagmus mav be unilateral or bilateral, but when unilateral its rather asymmetrical rather than truly unilateral
  118. 118.  Localizing acquired central nystagmus: Jerk  Downbeat nystagmus  Upbeat nystagmus  Periodic alternating nystagmus  Rebound nystagmus  Bruns'nystagmus
  119. 119.  Localizing acquired central nystagmus: pendular
  120. 120. Occular bobbing  intermittent often conjugate fast downward movement of the eyes followed after a brief tonic interval by slower return to primary position.  associated with intrinsic pontine pathology, particularly heamorrhage tumours or infarction  in association with paralysis of spontaneous and reflex horizontal eve movements
  121. 121. occular flutter  intermittent bursts of conjugate horizontal saccades without an intersaccadic interval.  Impaired control by cerebellar fastigial nucleus especially of horizontal saccadic system
  122. 122. opsoclonus  rare disorder of saccadic system  involuntary arrhythmic, chaotic, multidirectional saccades without intersaccadic intervals  fixation continuously interrupted by multivectorial, back to back saccades  at times seen only with ophthalmoscope
  123. 123.  harbinger of an occult malignancy, though manv cases are postinfectious, toxic-metabolic or idiopathic  usually neural crest tumors in children and lung, breast or gynaecological cancer in adults  dysfunction of glycinergic omnipause neurons in nucleus raphe interpositus  disinhibition of occulomotor region of fastigial nucleus (FOR) in the cerebellum can generate opsoclonus opsoclonus
  124. 124.  Occulocephalic reflex  from first week of life  essentially represents a vestibulo-ocular reflex
  125. 125.  Gaze-provoked nystagmus  The commonest form of nystagmus  eyes moved into eccentric gaze, especially in lateral and up gaze
  126. 126.  end point nystagmus  usuallv unsustained, . of low frequency and amplitude, and not accompanied by other ocular motor abnormalities
  127. 127.  Pathological gaze evoked nystagmus  sign of extraocular muscle weakness;, for example, in patients with myasthenia gravis ("fatigue nystagmus").  result of central disorders that involve the gaze holding neural network, which includes the nucleus prepositus hvpoglossi and medial vestibular nucleus for horizontal gaze, the interstitial nucleus of Cajal for vertical gaze, and the vestibulocerebellum, which optimises gaze holding
  128. 128. Afferents to vestibular nuclei • Semicircular canals → Superior and medial subnuclei • Otolith organs → Lateral and inferior subnuclei • Cerebellovestibular fibers through the inferior cerebellar peduncle, primarily from the flocculonodular lobe • Spinal cord • Reticular formation
  129. 129. Ocular Connections Vestibular Nuclei Mainly from superior and medial nuclei Superior nucleus projects to I/L MLF; other nuclei to C/L MLF CNs III, IV, and VI Nuclei CN XI and upper cervical nerves nuclei Regulating movements of the eyes, head, and neck in response to stimulation of the semicircular canals MLF
  130. 130. Horizontal semicircular canal Anterior (superior) and posterior canals Abducens Nuclei & Oculomotor Complex Oculomotor & Trochlear Nuclei Medial Longitudinal Fasciculus Ocular Connections

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