This document provides an overview of ocular motility disorders, including: 1. The anatomy and function of the extraocular muscles and neural control centers. 2. Classification of abnormal eye movements including types (e.g. saccades, smooth pursuit) and causes (e.g. myopathies, nerve palsies). 3. Specific disorders are described in detail such as internuclear ophthalmoplegia, Parinaud's syndrome, and progressive supranuclear palsy. 4. Nystagmus is classified and mechanisms are discussed.

1. Ocular Motility Disorders
By : Wudie G(NRII)
Moderator :Dr.Meron A( MD , Consultant Neurologist)

2. Outlines
• EOM Anatomy and function
• Regulatory Mechanisms of eye movement
• Different types of eye movement
• Classification of abnormal eye movement
• References

3. Anatomy of EOMs
• Six extraocular muscles
– 4 recti + 2 oblique
• Origin of extraocular muscles
– All recti extraocular muscles originate from the orbital apex –
annulus of Zinn( common tendinous ring ).
– IQ originates from medial side of orbital floor
– SO originates from sphenoid bone

5. CN III Nuclei complex
• Lesion of occulomotor nucleus results bilateral ptosis
and dilated pupil
• Lesions of the occulomotor nucleus affect the
contralateral superior rectus

6. • Eye movement =to bring and maintain the image on to the
fovea by finding, fixating ,maintaining on to the retina
• Systems to hold eyes steady on the fovea
– Ocular fixation
– Vestibular system
– Optokinetic
– CNS Neural integrator

7. • Ocular fixation
– Helps to keep the image of the object remain stationary on
the fovea when the head is not moving
– Also suppresses any unwanted saccades
– Occipital lobe
• Vestibular system
– holds image still on the retina during brief head movement
– VOR

8. • Optokinetic
– holds image still on the retina during sustained head movement
– Driven by visual system
• Neural integrator
– Helps to maintain the eye position during d/f gazes
– Against the pull of suspensory ligaments and the EOM that tends
to bring the eye back to the central position

9. Law
• Hering’s law
– The law of equal innervation
– States that the muscles yoked for conjugate eye movement
receives equal innervation .
• Sherrington’s law/Law of reciprocal innervation
– An agonist muscles receive a neural impulse to contract
– an equivalent inhibitory impulse is sent to the neurons
supplying the appropriate antagonist muscle resulting in
relative relaxation of the antagonists

10. Eye Movement Control Center
 Supranuclear
• Cortical
– Frontal lobe –FEF,SEF
,DMFC
– Parietal lobe –PEF
– Occipital lobe –Visual
Cortex
• Basal ganglia
• Thalamus
• Cerebellum
 Nuclear
• Midbrain
--Superior colliculus
--nucleus of Cajal
---riMLF
--Nuclei of CN-III & IV
• Pons
---PPRF
---Nuclei of CN-VI
----Vestibular nuclei
Infranuclear
•Oculomotor nerve
•EOM

11. Vestibular system
• Consists of semicircular canal ,otholith organs and vestibular
nuclei

12. Horizontal Conjugate Eye Movement

13. • PTO cortex are primarily responsible for smooth pursuit
movements in the ipsilateral direction, via connections with
the vestibular nuclei, cerebellum, and PPRF,

14. Vertical Conjugate Eye Movements
• riMLF equivalent to PPRF and
INC to Step cells
• The upgaze centers lie more
dorsally
• The downgaze centers lie more
ventrally

15. Types of Eye movement
 Eye movement can be classified according to several systems:
• Duction =movement of one eye
• Version =movement of two eyes in same direction(conjugate )
• Vergence =Binocular dysconjugate movement

16. • Morphological classification

17. Functional Classification

18. Saccade
• Saccades are fast movements of the eyes used to quickly bring
an object onto the fovea.
• shift gaze from one object to another.
• normally under voluntary control.
• are generated by the burst neurons of the pons (horizontal
movements) and midbrain (vertical movements).
• Voluntary saccades are generated in the contralateral frontal
cortex and reflexive saccades in the contralateral parietal cortex

19. Smooth Pursuit
• refers to the voluntary movement of the eyes used to track a
target moving at a low velocity
• It functions to keep the moving object on the fovea to
maximize vision
• Patients with impaired smooth pursuit require frequent small
saccades to keep up with the target ===saccadic pursuit

20. Abnormal eye movements
• Disorders can be broadly divided into
– i) peripheral (infranuclear and nuclear) and
– ii) central (internuclear and supranuclear).

21. PERIPHERAL DISORDERS OF OCULAR
MOTILITY
• Disturbances of ocular motility may result from processes
involving the
– Orbit-- causing mechanical limitation of eye movement
– From ocular myopathies
– Neuromuscular transmission disorders
– A palsy of an individual ocular motor nerve.

22. Muscle Disease
 Ocular myopathies causes
– Weakness of EOM
– Ptosis
– Weakness of eye closure
• Due to myopathic involvement of facial muscles
– The common causes
• Chronic progressive external ophthalmoplegia (CPEO)
• Oculopharyngeal muscular dystrophy.
– Rarely
• Inflammatory myositis

23.  Restrictive orbitopathies
– Restriction of movement
– Most common restrictive orbitinopathy is TED ( thyroid eye
disease)
– Restrictive myopathy is easily confused with weakness of
antagonist muscle (e.g.. restrictive myopathy of MR mimic
weakness of LR)==do Forced duction test
– Abnormal forced duction
• Inferior rectus muscle is the most commonly involved muscle
in TED followed by medial rectus and superior rectus

24. CPEO
• Is a syndrome that has numerous etiologies,
– It is most often due to mitochondrial myopathy.
• Progressive ptosis and symmetric eye muscle
weakness(immobility),painless ,pupil spared
• Patients do not typically have diplopia.
• Examination shows loss of both voluntary and reflex eye
movements;

25. Oculopharyngeal dystrophy
• Rare autosomal dominant
• Causes marked progressive bilateral ptosis and dysphagia ±
proximal muscle weakness
• Usually begin in the fifth or sixth decade.
• The signature of the disease
– Ocular myopathy + pharyngeal weakness.

26. Neuromuscular Transmission
Disorders
• MG
– Frequently involve EOMs(50-70% early,,90% late)
– Typically present with fluctuating binocular diplopia, ptosis
, opthalmoparesis or both
– Can mimic gaze palsy or the pattern of any individual nerve.
– On tensilon test hypermetric saccade due to central
adaptation
• LEMS
– Rarely involve extraocular muscles except mild ptosis
• Botulism
– Ophthalmoplegia + Fixed dilated pupils

27. INDIVIDUAL NERVE PALSIES
• Most common cause of 4th nerve palsy is trauma
• Most common cause of 3rd & 6th nerve palsy
– Microangiopathic vascular disease
– Followed by trauma

28. Oculomotor Nerve Palsy
 Results varying degree and combination of EOM weakness ,
ptosis and pupil involvement
• Opthalmoplagia
– Internal -- Limited to the pupillary sphincter and ciliary
muscle
– external --- Only the extraocular muscles
– complete -- Both
• Ptosis

29. Signs
• Nuclear/ sub nuclei
– Contralateral superior rectus weakness
• Fascilar
– Lesion from interpedencular fossa to point of division
– Paralysis of all functions
• Divisional
– Superior division-ptosis & upgaze palsy
– Inferior division- IR,MR & pupil ,inability to look nasally ,
inferiorly

30. • The most common identifiable etiologies are
– Ischemia –Pupil sparing
– Aneurysm (P communicating A & distal ICA) & trauma=
pupil involving
• Aberrant re-innervation is common
– Tumor
– Some 20% remain unexplained.

31. Trochlear Nerve Palsy
• Vertical or diagonal diplopia , maximal in down gaze
• On examination
– Extortion and impairment of depression of the adducted
eye.
Right fourth nerve palsy
– Head tilt forward and to the opposite side of weak eye

32. Abducens Nerve Palsy
• Horizontal diplopia worse at distance.
• Concomitant strabismus, worse in the direction of action of the
involved muscle.
• Lesion involving the nucleus causes an ipsilateral horizontal
gaze palsy rather than a sixth nerve palsy
– CN VI nucleus contains both lateral rectus motor neurons
and interneurons that project up the MLF

34. Central Disorders Of Ocular Motility
• Supranuclear disorders
– Those that affect the supranuclear gaze centers in the
hemispheres and brainstem
– Areas that influence eye movements, such as the basal
ganglia and cerebellum.
• Internuclear disorders affect the connections between the
ocular motor nerve nuclei in the brainstem.

35. Saccadic Dysfunction
• Lesions or degeneration of saccadic center or lesions of the
ocular motor neurons / extraocular muscles leads to slowing of
saccades
• Overshooting saccades (missing the target and then needing to
correct) indicates a lesion of the cerebellum
• Undershooting saccades are less specific and often occur in
normal subjects

36. • PPRF lesion can cause a horizontal saccadic gaze palsy and a
lesion in the RIMLF can cause a vertical and torsional
saccadic gaze palsy
• The clinical hallmark of a supranuclear gaze palsy is
– Disproportionate involvement of saccades
– OKN lost
– Smooth pursuit may be affected, but usually to a lesser
extent than saccades
– Vestibular eye movements are typically spared
• Nuclear and infranuclear processes affect saccades, smooth
pursuit, and vestibular reflexes equally

37. Pursuit Dysfunction
• Abnormal smooth pursuit is non localizing
• The lesion can be anywhere
– Cortex, basal gangila,mid brain, pons ,cerebellum
• Asymmetry is more specific than symmetry
• Poor initiation – frontal/Parietal lobe lesions
• Deficits found usually in both vertical and horizontal planes

38. Internuclear ophthalmoplegia
• Lesion of the MLF
• Manifest with
– impaired adduction of the eye ipsilateral to the lesion
– contralateral abducting “nystagmus” upon abduction in the
contralesional eye
– Convergence may be preserved
– When convergence is impaired INO classified as
rostral(anterior),if preserved classified as caudal (posterior)

39. Causes of INO
• INO may occur with a variety of disorders affecting the
brainstem
• Common conditions are MS and brainstem stroke
– Child : Suspect tumor
– Young : Demyelinating disease (MS)
– Elder : ischemic lesions
• INO must be distinguished from the many (primarily peripheral
infranuclear) causes of pseudo-INO

40. WEBINO Syndrome
• Lesion is in bilateral MLF
• Both eye will be slightly abducted –giving rise to appearance
call as ‘’Wall eyed’’(bilateral exotrophia)

41. Pseudo-INO
• Feature of INO but lesion is not in MLF
• Imaging is normal
• Most common cause : Myasthenia Gravis
• Other(rare) cause Miller Fisher Syndrome

42. One-and-half syndrome.
• Lesion involving both the PPRF (or the abducens nucleus) and
the crossed MLF on one side of the pons
• Manifest with ipsilateral horizontal gaze palsy(PPRF lesion)
and ipsilateral INO lesion
• Abduction of the eye contralateral to the lesion is intact
• E.g. : Right sided lesion –Rt sided MLF and PPRF are non
functional
– Right INO
– Right PPRF involved –involve right 6th nerve and left 3rd
nerve
Spared =C/L 6th nerve

43. CON…
• Paralytic pontine exotropia occurs because of the preserved
abduction
• Vertical movement and convergence is spared
• Common causes are infarction , demyelination in the median
pontine region (dorsomedian region)
• MG can cause a pseudo– one-and-a-half syndrome

44. Horizontal Gaze Deviation
• The FEFs move the eyes into contralateral conjugate
horizontal gaze.
– Destructive Frontal lobe lesion --gaze preference to side of
the lesion
– Irritative lesion --gaze deviation away from the lesion
• The PPRF governs ipsilateral, conjugate horizontal gaze &
draws the eyes ipsilaterally
– Destructive lesions - resulting in a gaze deviation toward
the intact side as the normal PPRF pulls the eyes over.
• Pontine gaze palsies that involve the PPRF affect all functions,
voluntary and reflex.

45. • Patients with destructive frontal
lesions
– gaze away from the side of the
hemiparesis;
• Patients with pontine strokes
– gaze toward the hemiparesis.
• Patients with irritative frontal lesion
– Gaze away from the side of
lesion

46. Vertical Gaze Abnormalities
• Vertical gaze center
– riMLF
• Two common disorders affecting vertical gaze
– Parinaud’s syndrome
– PSP.

47. Parinaud’s Syndrome
• AKA dorsal midbrain syndrome /Syndrome of posterior
commissure
• Cortical pathway for conjugate upward eye movements runs in
the tegmentun dorsal to pathways for downward movements
• Caused by compression of vertical gaze center (riMLF)
– Mass lesion commonly pinealoma
– Stroke
– Hydrocephalus (Obstructive)

48. Clinical features
• Up gaze palsy
• Convergence-retraction “nystagmoid reaction” (often elicited
by attempted up gaze)
• Bilateral lid retraction (Collier sign)
• Pupillary light-near dissociation

49. Progressive Supranuclear Palsy
• Degenerative changes in the rostral brainstem and thalamus
(thalamomecencephalic area)
• Result in impairment first of downgaze then of upgaze and
eventually in global gaze paresis.
• Reflex eye movements are preserved until late in the disease.
• The gaze abnormalities are accompanied by parkinsonian signs

50. • Late in the disease course, saccades and smooth pursuit may
be lost both vertically and horizontally
• Other Oculomotor findings= saccadic intrusions (square wave
jerks),loss of OKN (particularly in the vertical direction),loss
of convergence ,eyelid opening apraxia

51. Nystagmus
• It is a rhythmic , biphasic , involuntary movement of the eyes.
• The slow phase of nystagmus is the pathological component
responsible for the initiation and generation of the nystagmus.
• Direction defined by fast phase
• Can be physiological or pathological

52. Classification of Nystagmus
• Nystagmus is classified in multiple ways
– Jerk Vs. Pendular Nystagmus
– Central versus peripheral
– Spontaneous /gaze evoked or positional
– Physiologic vs. pathologic
– Congenital versus acquired

53. • Slow phases of jerk nystagmus may have linear, decreasing, or
increasing velocity
– correct identification of this may assist with diagnosis
• Acquired forms of nystagmus tend to have linear or decreasing
slow-phase velocities
• Congenital nystagmus slow phases in the infantile nystagmus
syndrome are typically of increasing velocity although these
are not pathognomonic

54. • Described by
– Amplitude –extent of excursion of the nystagmus
• Fine : less than 5⁰
• Moderate: 5-15⁰
• Large/coarse : greater than 15⁰
– Frequency - is the number of complete to and fro
movements in one second
• Slow : (1-2 Hz)
• Medium : (3-4 Hz)
• Fast: (5 Hz or more)

55. • Plane : horizontal ,vertical or rotatory or combination
• Direction : unidirectional /Bidirectional
• Null zone of nystagmus:
– position where nystagmus intensity is minimized
– Patient assumes a head posture, such that the eyes are in
null zone

56. • 1st degree
– nystagmus present only with eccentric gaze
• 2nd degree
– Nystagmus present in primary gaze and increase in
intensity with gaze in the direction of fast component
• 3rd degree
– fast component opposite to the direction of gaze
– Most common in vestibular nystagmus

57. Mechanism /Etiology
• Disturbance or abnormality of three mechanisms
– Fixation
– VOR
– Ocular neural integrator (brainstem and cerebellum)

58. • Neuropathologic nystagmus: common types include
– vestibular , positional ,gaze evoked , gaze paretic nystagmus
• Non neuropathologic nystagmus
– Physiologic nystagmus
– Nystagmus due to ocular disease (poor vision) or other
conditions
– Voluntary nystagmus

59. Physiologic Nystagmus
o End point nystagmus
– observed on extremes of lateral gaze ,absent in upgaze
– Typically low amplitude ,symmetric ,poorly sustained and
fatigues overtime ,horizontal
– Abolished on primary position
– No other neurologic abnormality
o Optokinetic nystagmus
o Induced vestibular nystagmus
– Caloric test

60. Optokinetic Nystagmus
• It is normal ,physiologic phenomenon
• Nystagmus stimulated by watching moving object
– When one is looking out the window of a moving train
• Has initial smooth pursuit followed by saccade back to
primary gaze
• Normally should have symmetric OKN
• Cogan’s rule
– Homonymous hemianopia +asymmetric OKN –Parietal
lobe lesion probably mass lesion
– Homonymous hemianopia + Symmetric OKN- Ocipital lobe
lesion ,most likely vascular lesion

61.  Clinical testing –OKN strip
• Fast phase is opposite to drum rotation and slow pursuit is
towards drum rotation

62. Childhood Nystagmus
Childhoo
d
nystagmu
s
Infantile
forms
Infantile
nystagmus
syndrome
Latent
and
manifest
latent
nystagmu
s
Infantile
forms of
adult
nystagmu
s
Acquired
forms
Spasmus
nutans
Nystagmu
s with
intracrani
al disase
Nystagmu
s with
ipsilateral
visual loss

63. Congenital /Infantile nystagmus
syndrome
• Seen in < 6 months /at birth or appear later shortly
• Mostly due to ocular disease /congenital or acquired in the 1st
month of life
• Usually horizontal, pendular (in primary position) ,
jerk(eccentric gaze)
• Not suppressed by fixation
• 3 common causes are congenital cataract , Albinism and optic
nerve hypoplasia

64.  Mnemonic “CONGENITAL”
• Convergence dampens or decrease the nystagmus
• Oscillopsia is absent
• Null point is in primary position
• Gaze is uniplanar
• Equal amplitude in all direction called pendular nystagmus
• Inverted OKN
• Turn face
• Abolished in sleep

65. Pendular Nystagmus
• Has a sinusoidal wave form and usually is horizontal
• Generally does not have a fast phase including saccade , but
composed of entirely slow eye movements
• Can be either congenital or acquired
• Acquired pendular nystagmus typically has horizontal ,
vertical or torsional component

66. Acquired pendular nystagmus
• MS most common cause followed by brainstem vascular
disease
• Probably results from disruption of normal feedback from
cerebellar nuclei to neural integrator
• In demyelinating diseases, APN most often is horizontal
and/or elliptical in trajectory, with a frequency of 3 to 5 Hz

67. • Vertical /Vertical-torsional pendular nystagmus
– Results from lesions in the deep cerebellar nuclei and their
connections (dentatorubroolivary pathways= Gullian
Mollaret triangle)
– Associated with palatal myoclonus
==oculopalatal myoclonus syndrome

68. Pathologic Gaze Evoked Nystagmus
• AKA Gaze paretic nystagmus
• Nystagmus present in less than extreme gaze ,absent in the primary
position
• Most common type of nystagamus
• Usually symmetric ,sustained ,large amplitude and /present in upgaze
• Causes
– Drugs toxicities (i.e Anticonvulsants , Alcohol ,sedatives)
– Brainstem lesions
– Cerebellar lesions/ Floccules

69. Vestibular Nystagmus
• Jerk nystagmus
• Vestibular nystagmus:
– Central ( brainstem nuclei)
– Peripheral ( labyrinths, VIII CN)
• May occur spontaneously or be produced by various
maneuvers.

70. Features Peripheral Central
Onset & duration Abrupt onset ,lasts short
min(intermittent)
Can be gradual
onset/sudden onset and
continuous
Cause Dysfunction of Vestibular
end organ or vestibular
nerve
Disease of the brainstem
nuclei
Type of nystagmus Horizontal-rotatory
/upbeat-torsional
Pure vertical or pure
torsional
Visual Fixation Inhibits the nystagmus No inhibition
Direction of nystagmus Fixed /unidirectional May change with gaze
/bidirectional
Severity of vertigo Severe Mild
Associated finding Vertigo ,tinnitus , nausea
,vomiting ,hearing loss
Headache ,ataxia, diplopia
,pyramidal tract signs

71. Localizing Nystagmus/ Ocular
oscillations

74. Saccadic Intrusions
• Saccadic intrusions are brief, unwanted involuntary saccadic
interruptions of fixation
• Saccadic intrusions with an intersaccadic interval include
– square-wave jerks, macro–square-wave jerks, and macro
saccadic oscillations ,square wave pulses ,saccadic pulses
• Saccadic intrusions without an intersaccadic interval
– ocular flutter and opsoclonus

75. Saccadic intrusion with normal
intersaccadic interval
Square wave jerks
Macro square wave jerks
Macrosaccadic oscillation
Intersaccadic interval is more used over
saccadic intrusion amplitude to
distinguish SWP from SWJ

76. o Opsoclonus/dancing eyes
• Continuous succession of multidirectional conjugate
saccadic eye movements
• Most common cause is encephalitis
• Post viral ,metastasis or neuroblastoma
• Occurs due to interruption of cerebellar connections to
brainstem
o Ocular flutter,
• Similar to Opsoclonus but confined to horizontal plane

77. Non nystagmus ocular oscillations
• There are ocular movements which mimic nystagmus
o Ocular bobbing
• Sudden conjugate downward deviation of eye followed
by slow return to normal
• Paralysis of spontaneous & reflex horizontal eye
movement
• Seen in comatose patient
• Pontine dysfunction

78.  Superior oblique myokymia
• A paroxysmal ,rapid, small-amplitude monocular torsional-
vertical oscillation caused by contraction of the superior
oblique muscle
• Consider when the patient reports episodes of rapid
monocular torsional or vertical oscillopsia

79. • Ocular dysmetria
– is an over- or undershooting of the eyes on rapid refixation
of gaze toward either side or on returning to the primary
position that requires corrective saccades;
– There may also be overshooting in following movements
when the object of regard is suddenly stopped.
– Cerebellar System dysfunction(always)

80. • Oculogyric crisis
– Refers to attacks of involuntary conjugate upward deviation
of the eyes, which may be transient or last for hours( typical
attack lasts for about 2 hrs).
– A dystonic reaction to drugs(neuroleptics) or medical
condition(MS , syphilis).
– Post encephalitic parkinsonism

81. References
• De Jong clinical examination,8th edition:2020
• Bradley’s neurology in clinical practice 8th edition ,2021
• Neuro ophthalmology Continuum
• Demyers neurologic examination
• Neuroanatomy through clinical cases,2nd edition
THANK YOU!!!!!

82. • A 71-year-old Rt handed man patient with a history of
diabetes collapsed on the street and was unable to stand up &
brought to the ER by ambulance.
• On exam, awake but lethargic , rightward gaze preference, and
was unable to move either eye past the midline toward the left.
• Rt SNFP and Rt sided hemiparesis , Rt up going plantar
– Where is the lesion ?
– Most likely dx?