Chapter 10


Eric R. Eggenberger

This chapter discusses the diagnosis, localization, and treatment of nystagmus. Despite most clinicians’ fear of nystagmus, it is a logical branch of neuro-ophthalmology, and an understanding of nystagmus provides the clinician with valuable information regarding this commonly encountered problem.

The most common chief complaint in patients with nystagmus is either oscillopsia or one of the symptoms associated with the underlying disease (e.g., diplopia, vertigo, dysarthria, weakness, etc.). Although the history and examination are crucial to an understanding of the pathology of nystagmus, this chapter assumes you have examined the patient and can describe the abnormal eye movements. Next, review the definitions and basic concepts (see Sidebar: Definitions and Nomenclature) required to categorize examination findings. Then go through the questions in Table 10–1, starting at the top. The first question that can be answered affirmatively helps guide you to the likely category of nystagmus.



Coma results from either bilateral hemispheric lesions or brainstem lesion. Eye movements in coma help to localize the lesion (see also Broad Category 2: Induced Nystagmus, below).



Broad Category

Is the patient in a coma?

1: nystagmus and abnormal eye movements in coma

Is the nystagmus present only when induced by an external maneuver?

2: induced nystagmus

Is the nystagmus primarily present only in one eye?

3: dissociative eye movement abnormality

Is the nystagmus associated with convergence or divergence movements?

4: convergence/divergence nystagmus

Does the direction of nystagmus change over a few minutes?

5: direction-changing nystagmus

Are there only back-to-back slow movements, without fast phases?

6: pendular nystagmus

Are there just fast phases, without slow phases?

7: saccadic intrusion

Did the nystagmus begin in infancy or early childhood?

8: childhood or infantile-onset nystagmus

Is the nystagmus reduced with fixation?

9: peripheral vestibular nystagmus

Is the nystagmus present only on gaze away from primary position?

10: gaze-evoked nystagmus

Is the nystagmus present in primary position?

11: central vestibular nystagmus

Is there oscillopsia in the absence of nystagmus?

12: vestibular ocular reflex abnormality



Classic Presentation

• This most commonly occurs in hypoxic ischemic encephalopathy, such as after rescue from cardio-pulmonary arrest.

• Sustained up- or downgaze in hypoxic-ischemic encephalopathy typically indicates a poor prognosis for general neurologic recovery.

• Sustained upgaze may be associated with sustained eye opening.

Red Flags

image Beware drug overdose effects.

image Beware of the possibility of seizure inducing abnormal eye movements after a central nervous system (CNS) insult, which can also occur in hypoxic-ischemic encephalopathy.

image Beware locked-in syndrome with retained vertical gaze; the upgaze in locked-in syndrome is not sustained, but typically intermittent and voluntary because the patient is still conscious.


Classic Presentation

• Ocular bobbing is a repetitive, vertical eye movement noted in coma, with fast downward deviation followed by slower return to primary position.

• Typical ocular bobbing denotes an abnormal response to vestibulo-ocular reflex (VOR) stimulation in addition to bobbing.

• The VOR may be checked with either head rotation or cold caloric stimulation.

• With an intact VOR in the comatose patient, the eyes deviate right with head movement left, and vice versa; the eyes deviate tonically (no resetting fast phase) toward the ear undergoing cold-water stimulation.

• Typical ocular bobbing indicates a destructive lesion of the pons and is a very poor prognostic sign for recovery.

Red Flags

image Other variants of bobbing have very little localizing or prognostic value.

image These variants include reverse bobbing (eyes demonstrating a slow downward movement followed by rapid return to primary) or dipping (slow or rapid upward movement followed by slow or rapid return to primary).

image These variants of bobbing are associated with diffuse cerebral dysfunction and may result from any of several pathophysiologies including hypoxicischemic insult or drug overdose.

image Beware locked-in syndrome, with a brainstem lesion that spares consciousness and vertical gaze; vertical eye movements in locked-in syndrome are volitional and not rhythmic but need to be specifically assessed because most locked-in patients are on a ventilator, nonverbal, and quadriplegic.


Classic Presentation

• Sustained right or left gaze generally signifies any of three possibilities:

image Gaze preference: indicates lesion of the ipsilateral hemisphere.

image Supranuclear lesion: generally able to move the eyes to the opposite side with vestibular ocular reflex (either head rotation or cold caloric testing).


oscillopsia The illusion of movement of the environment. This is related to instability of the object of regard on the retina. Oscillopsia generally results from one of two mechanisms: nystagmus, or an impaired vestibular ocular reflex (VOR).

nystagmus Regular to-and-fro oscillation of the eye. Nystagmus always has a slow phase. Nystagmus produces oscillopsia because the unwanted eye movements move the object of regard across the retina, and prohibits retinal stability of the object.

nystagmus categories Nystagmus is easy to name. Merely observe the waveform of the abnormal eye movement. Jerk nystagmus has a slow phase followed by a fast resetting phase, whereas pendular nystagmus has back-to-back slow phases. Jerk nystagmus is named for the fast phase (e.g., down beat has slow phases upward with fast downward corrective phase), but pay attention to the direction of the slow phase because this indicates the region of the pathology. Pendular nystagmus is named for the plane of movement (vertical pendular, torsional, elliptical pendular, etc.).

saccadic intrusions Interruptions of fixation by abnormal saccadic components. In contrast to nystagmus, saccadic intrusions have no slow phase, but rather only fast phases. Some common saccadic intrusions are asymptomatic and merely noted on examination, such as square wave jerks (see saccadic intrusion section).

vestibular ocular reflex (VOR) The reflex that keeps the eyes on the object of regard during head movement. Inputs from the vestibular organ of the ear sense head acceleration and transmit this information to the ocular motor nuclei to move the eyes in an appropriate compensatory fashion. This is by necessity a rapid reflex, and dysfunction may be heralded by oscillopsia with head movements.

VOR abnormalities If the VOR is weak on one side (or vestibular asymmetry), nystagmus is present acutely. Over hours to days, central compensation occurs and the spontaneous nystagmus resolves. Despite the disappearance of nystagmus, with rapid head moments (especially toward the side of the lesion) the patient may report fleeting oscillopsia. This is usually not a major problem, and most patients are not particularly aware of this symptom; however, if vestibular weakness is bilateral, then a more consistent sense of oscillopsia develops with head movements. If bilateral weakness is severe, even the small-amplitude head movements caused by the patient’s own heartbeat (which produces minimal vertical head displacement) may produce oscillopsia, even though there is no nystagmus.

In addition to VOR weakness, inability to suppress the VOR may also produce oscillopsia. The VOR functions to keep the eyes locked on a stationary target during head movements; however, if the eyes are locked on a target that is moving in synchrony with head movements, then the VOR needs to be suppressed. This operates when the head follows a moving target. Patients with cerebellar system dysfunction often have difficulty suppressing the VOR and may note oscillopsia with head turns under certain circumstances (e.g., turning the head to scan traffic).

image Gaze palsy: indicates contralateral brainstem lesion

image Unable to move eyes into the opposite field of gaze with vestibular ocular reflex maneuvers.

• Seizure or postictal state: during the ictus, the eyes often deviate contralateral to a hemispheric seizure focus and may demonstrate nystagmus-like movements, then deviate ipsilateral to the focus in the postictal period.

Red Flag

image Misdiagnosis of the actual pathophysiology may lead to inappropriate investigations.


Classic Presentation

• Ping-pong gaze consists of rapid conjugate side-to-side eye movements with gaze shifting every several seconds.

• This typically indicates bilateral hemispheric lesions, most commonly stroke.

Red Flags

image Beware more rapid eye movements deviating the eyes to one side, producing nystagmus-like movements related to seizure (lesion within the contralateral hemisphere). Following the seizure, the eyes may then deviate to the other side (ipsilateral to the seizure focus), but this will not be as rhythmic or predictable as ping-pong gaze.

image Slower conjugate eye deviations with direction change every 1 to 3 minutes has been reported in hepatic encephalopathy.

image Do not confuse with slower direction changing eye movements such as periodic alternating nystagmus.


Classic Presentation

• Slow, conjugate, roving horizontal eye movements in coma are common and indicate the brainstem structures for horizontal gaze are intact.

• Generally only partial horizontal excursion

• Similar to the eye movements in light sleep

Red Flags

image Needs to be distinguished from other horizontal gaze deviations in coma such as periodic alternating gaze deviation and ping-pong gaze

image Spontaneous roving horizontal eye movements are generally smaller amplitude and less rhythmic or predictable.


Classic Presentation

• Conjugate periodic horizontal eye movements that change direction with an ~2-minute cycle

• Associated with persistent vegetative state or hepatic encephalopathy

Red Flag

image Needs to be distinguished from the other periodic horizontal eye movements above by the slower cycle


Classic Presentation

• Rare, 2- to 3-Hz vertical oscillations

• Reported in association with pontine infarction

Red Flag

image Beware locked-in syndrome, with a brainstem lesion that spares consciousness and vertical gaze; vertical eye movements in locked-in syndrome are volitional and not rhythmic but need to be specifically assessed because most locked-in patients are on a ventilator, nonverbal, and quadriplegic



Classic Presentation

• This type of nystagmus is seen with cold or warm irrigation into the ear.

• “COWS,” refers to cold opposite, warm same; denotes the direction of the fast phase in an awake patient when cold or water is irrigated into the ear.

• Caloric testing is done in coma to help decide if the cause of coma is the brainstem or bilateral hemispheric dysfunction (the latter is much more common than the former as a cause of coma, e.g., post cardiac arrest hypoxic-ischemic encephalopathy).

• When cold caloric testing is done in a patient in coma, there is no fast phase (because the cerebral cortex is not functioning properly).

• If the brainstem components for generation of eye movements are intact, then there is a slow phase toward the side of cold irrigation (the eyes deviate toward the side of cold irrigation because there is no resetting fast phase).

Red Flag

image If the brainstem components related to eye movements are damaged (the coma is likely related to brainstem dysfunction), then cold water irrigated into the ear produces no eye movements (same as cold water irrigation into a cadaver would produce) or there are abnormal movements, such as internuclear ophthalmoplegia


Classic Presentation

• OKN is a type of physiologic nystagmus induced by smooth movement of the environment across the retina.

• OKN consists of saccades and pursuit movements when stimulated by smaller rotating targets such as OKN drum or repeating pattern strip (e.g., a striped neck tie).

• OKN should be symmetric left- and rightward.

• OKN is diminished or absent when stimuli are rotated toward a temporal-parietal lesion [medial superior temporal (MST) area].

• OKN generation requires a combination of fairly good visual acuity and field; with poor visual acuity or a very constricted field, OKN may be lost. One cannot accurately discern the exact visual acuity and visual field from the responses generated by most OKN targets used at the bedside.



Dissociative eye movement abnormalities have a different waveform in each eye or are monocular.


The most common form of eye movement abnormality is abducting nystagmus associated with internuclear ophthalmoplegia (INO). Abducting nystagmus with INO likely results from Hering’s law applied to weakened adduction. The weakened adductor increased innervation to both eyes, and this produces overshoot in the intact contralateral abductor.

Classic Presentation

• Usually presents with diplopia and oscillopsia, whereas occasional patients report gaze-evoked oscillopsia only

• Abducting nystagmus with contralateral INO (e.g., left INO produces abducting nystagmus OD in right gaze with impaired adduction OS)

Red Flag

image If abducting nystagmus is present on exam, carefully observe horizontal saccades to look for an associated INO; adduction paresis may not be evident with simple assessment of versions, and may only be apparent as a slowing of the adducting saccade.


Classic Presentation

• Often pendular

• Generally indicative of upper brainstem-midbrain disease

• In adults, acquired monocular pendular nystagmus often related to multiple sclerosis

• May be highly asymmetric rather than absolutely unilateral/monocular

• Monocular oscillopsia

• May be associated with other ocular motor symptoms such as diplopia

Red Flag

image Beware the small amplitude monocular intermittent “shimmering” seen in children with ipsilateral anterior pathway gliomas.


Classic Presentation

• Onset in childhood

• Often very small amplitude

• May be intermittent

• Indicative of anterior pathway lesion, most commonly optic nerve glioma

Red Flags

image May be confused with other forms of monocular nystagmus

image May be confused with spasmus nutans, but typically doesn’t have the head tilt/turn, binocular involvement (although often very asymmetric), or head nystagmus associated with spasmus nutans. Some authors feel these two disorders are difficult to differentiate, and advocate imaging in all suspected cases to rule out an anterior pathway glioma.


Classic Presentation

• Spasmus nutans presents in early childhood (usually in the first year)

• Classic triad includes asymmetric or monocular nystagmus, head tilt, and head shaking or head nystagmus.

• Nystagmus is small amplitude, pendular, rapid, and often highly asymmetric, and may change in amplitude and phase relationship between the two eyes over seconds to minutes.

• Typically spontaneously resolves with time (usually within 2 years of onset)

Red Flag

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Jun 4, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Nystagmus

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