eMedicine Specialties > Ophthalmology > Extraocular Muscles

Nystagmus, Acquired

Christopher M Bardorf, MD, MS, Ophthalmology, Children's Eye Physicians, Denver, CO
Gregory P Van Stavern, MD, FACP, Assistant Professor, Departments of Ophthalmology and Neurology, Wayne State University; Enrique Garcia-Valenzuela, MD, PhD, Clinical Assistant Professor, Department of Ophthalmology, University of Illinois Eye and Ear Infirmary; Consulting Staff, Vitreo-Retinal Surgery, Midwest Retina Consultants, SC, Parkside Center

Updated: Aug 18, 2009

Introduction

Background

Nystagmus may be defined as a periodic rhythmic ocular oscillation of the eyes. 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).¹

Nystagmus may be unilateral or bilateral, but, when the nystagmus appears unilateral, it is more often asymmetric rather than truly unilateral. Nystagmus may be conjugate or disconjugate (dissociated). It may be horizontal, vertical, torsional (rotary), or any combination of these movements superimposed upon each other.

Nystagmus may be congenital or acquired. When acquired, it most often is caused by abnormalities of vestibular input. Congenital forms may be associated with afferent visual pathway abnormalities (sensory nystagmus).²

To understand the mechanisms by which nystagmus may occur, it is important to discuss the means by which the nervous system maintains position of the eyes. Foveal centration of an object of regard is necessary to obtain the highest level of visual acuity. Three mechanisms are involved in maintaining foveal centration of an object of interest: fixation, the vestibulo-ocular reflex, and the neural integrator.

Fixation in the primary position involves the visual system's ability to detect drift of a foveating image and signal an appropriate corrective eye movement to refoveate the image of regard. The vestibular system is intimately and complexly involved with the oculomotor system.

The vestibulo-ocular reflex is a complex system of neural interconnections that maintains foveation of an object during changes in head position. The proprioceptors of the vestibular system are the semicircular canals of the inner ear. Three semicircular canals are present on each side, anterior, posterior, and horizontal. The semicircular canals respond to changes in angular acceleration due to head rotation.

The third mechanism is the neural integrator. When the eye is turned in an extreme position in the orbit, the fascia and ligaments that suspend the eye exert an elastic force to return toward the primary position. To overcome this force, a tonic contraction of the extraocular muscles is required. A gaze-holding network called the neural integrator generates the signal. The cerebellum, ascending vestibular pathways, and oculomotor nuclei are important components of the neural integrator.

Pathophysiology

A disorder affecting any of the 3 mechanisms that control eye movements may result in nystagmus. Both focal and diffuse disorders may cause nystagmus. The characteristics of the nystagmus, as well as associated signs and symptoms help to localize the lesion and suggest possible etiologies.

Vestibular nystagmus

Vestibular nystagmus may be central or peripheral. Important differentiating features between central and peripheral nystagmus include the following: peripheral nystagmus is unidirectional with the fast phase opposite the lesion; central nystagmus may be unidirectional or bidirectional; purely vertical or torsional nystagmus suggests a central location; central vestibular nystagmus is not dampened or inhibited by visual fixation; tinnitus or deafness often is present in peripheral vestibular nystagmus, but it usually is absent in central vestibular nystagmus. According to Alexander's law, the nystagmus associated with peripheral lesions becomes more pronounced with gaze toward the side of the fast-beating component; with central nystagmus, the direction of the fast component is directed toward the side of gaze (eg, left-beating in left gaze, right-beating in right gaze, up-beating in upgaze).

Downbeat nystagmus

Downbeat nystagmus is defined as nystagmus with the fast phase beating in a downward direction.³ The nystagmus usually is of maximal intensity when the eyes are deviated temporally and slightly inferiorly. With the eyes in this position, the nystagmus is directed obliquely downward. In most patients, removal of fixation (eg, by Frenzel goggles) does not influence slow phase velocity to a considerable extent; however, the frequency of saccades may diminish.

The presence of downbeat nystagmus is highly suggestive of disorders of the craniocervical junction (eg, Arnold-Chiari malformation). This condition also may occur with bilateral lesions of the cerebellar flocculus and bilateral lesions of the medial longitudinal fasciculus, which carries optokinetic input from the posterior semicircular canals to the third nerve nuclei. It may also occur when the tone within pathways from the anterior semicircular canals is relatively higher than the tone within the posterior semicircular canals. Under such circumstances, the relatively unopposed neural activity from the anterior semicircular canals causes a slow upward pursuit movement of the eyes with a fast, corrective downward saccade.

Upbeat nystagmus

Upbeat nystagmus is defined as nystagmus with the fast phase beating in an upward direction. Daroff and Troost described 2 distinct types.⁴ The first type consists of a large amplitude nystagmus that increases in intensity with upward gaze. This type is suggestive of a lesion of the anterior vermis of the cerebellum. The second type consists of a small amplitude nystagmus that decreases in intensity with upward gaze and increases in intensity with downward gaze. This type is suggestive of lesions of the medulla.⁵

This condition may occur when the tone within the pathways of the posterior semicircular canals is relatively higher than the tone within the anterior semicircular canals, and it can occur from lesions of the ventral tegmental tract or the brachium conjunctivum, which carry optokinetic input from the anterior semicircular canals to the third nerve nuclei.

Torsional (rotary) nystagmus

Torsional (rotary) nystagmus refers to a rotary movement of the globe about its anteroposterior axis. Torsional nystagmus is accentuated on lateral gaze. Most nystagmus resulting from dysfunction of the vestibular system has a torsional component superimposed on a horizontal or vertical nystagmus.

This condition occurs with lesions of the anterior and posterior semicircular canals on the same side (eg, lateral medullary syndrome). Lesions of the lateral medulla may produce a torsional nystagmus with the fast phase directed away from the side of the lesion. This type of nystagmus can be accentuated by otolithic stimulation by placing the patient on their side with the intact side down (eg, if the lesion is on the left, the nystagmus is accentuated when the patient is placed on his right side).

Pendular nystagmus

Pendular nystagmus is a multivectorial nystagmus (ie, horizontal, vertical, circular, elliptical) with an equal velocity in each direction that may reflect brain stem or cerebellar dysfunction. Often, there is marked asymmetry and dissociation between the eyes. The amplitude of the nystagmus may vary in different positions of gaze.⁶

Horizontal nystagmus

Horizontal nystagmus is a well-recognized finding in patients with a unilateral disease of the cerebral hemispheres, especially with large, posterior lesions. It often is of low amplitude. Such patients show a constant velocity drift of the eyes toward the intact hemisphere with fast saccade directed toward the side of the lesion.

Seesaw nystagmus

Seesaw nystagmus is a pendular oscillation that consists of elevation and intorsion of one eye and depression and extorsion of the fellow eye that alternates every half cycle. This striking and unusual form of nystagmus may be seen in patients with chiasmal lesions, suggesting loss of the crossed visual inputs from the decussating fibers of the optic nerve at the level of the chiasm as the cause or lesions in the rostral midbrain. This type of nystagmus is not affected by otolithic stimulation.

Gaze-evoked nystagmus

Gaze-evoked nystagmus is produced by the attempted maintenance of an extreme eye position. It is the most common form of nystagmus. Gaze-evoked nystagmus is due to a deficient eye position signal in the neural integrator network. Thus, the eyes cannot be maintained at an eccentric orbital position and are pulled back toward primary position by the elastic forces of the orbital fascia. Then, corrective saccade moves the eyes back toward the eccentric position in the orbit.⁷

Gaze-evoked nystagmus may be caused by structural lesions that involve the neural integrator network, which is dispersed between the vestibulocerebellum, the medulla (region of the nucleus prepositus hypoglossi and adjacent medial vestibular nucleus [NPH/MVN]), and the interstitial nucleus of Cajal (INC). Patients recovering from a gaze palsy go through a period where they are able to gaze in the direction of the previous palsy, but they are unable to sustain gaze in that direction; therefore, the eyes drift slowly back toward primary position followed by a corrective saccade. When this is repeated, a gaze-evoked or gaze-paretic nystagmus results.

Gaze-evoked nystagmus often is encountered in healthy patients; in which case, it is called end-point nystagmus. End-point nystagmus usually can be differentiated from gaze-evoked nystagmus caused by disease, in that the former has lower intensity and, more importantly, is not associated with other ocular motor abnormalities.

Spasmus nutans

Spasmus nutans is a rare condition with the clinical triad of nystagmus, head nodding, and torticollis. Onset is from age 3-15 months with disappearance by 3 or 4 years. Rarely, it may be present to age 5-6 years. The nystagmus typically consists of small-amplitude, high frequency oscillations and usually is bilateral, but it can be monocular, asymmetric, and variable in different positions of gaze.

Periodic alternating nystagmus

Periodic alternating nystagmus is a conjugate, horizontal jerk nystagmus with the fast phase beating in one direction for a period of approximately 1-2 minutes. The nystagmus has an intervening neutral phase lasting 10-20 seconds; the nystagmus begins to beat in the opposite direction for 1-2 minutes; then, the process repeats itself. The presumed mechanism is disruption of the vestibulo-ocular tracts at the pontomedullary junction.⁸

Abducting nystagmus of internuclear ophthalmoplegia

Abducting nystagmus of internuclear ophthalmoplegia (INO) is, as the name implies, nystagmus in the abducting eye contralateral to a medial longitudinal fasciculus (MLF) lesion.

Mortality/Morbidity

Dependent upon etiology

Age

Onset of spasmus nutans is in infants aged 3-15 months with disappearance by age 3 or 4 years. Rarely, it may be present until children are aged 5-6 years.

Clinical

History

A thorough history is important to help determine the etiology of the nystagmus. Important aspects of the history include the following:

• Age of onset of the nystagmus, whether it is constant or intermittent, the presence of any aggravating or alleviating factors (eg, head position)
• Presence or absence of vertigo, oscillopsia (an illusory motion of the seen world),⁶ and sensation of disequilibration suggest a lesion of the vestibular system.
• Deafness or tinnitus is present with peripheral lesions of the vestibular system.
• Presence of diplopia, particularly in certain positions of gaze: Patients with INO may report diplopia only on lateral gaze or intermittent blurring of vision.
• Ask questions regarding the presence of any associated symptoms, such as symptoms related to demyelinating disease (eg, a history of loss of vision, eye pain, or numbness or weakness of the extremities), symptoms related to cerebrovascular accident (eg, hemiplegia).

Physical

A complete neuro-ophthalmic examination is imperative in patients with nystagmus. Aside from a complete ophthalmic examination, including visual acuity, measurement and reactivity of the pupils to light and accommodation, measurement of intraocular pressure, testing the function of extraocular muscles, and anterior and dilated posterior segment examination, other important aspects of the examination include the following:

• Observing the nystagmus with regard to type (eg, horizontal, vertical), frequency, amplitude, direction, and conjugate/disconjugate is important. Pure vertical, pure horizontal, or pure rotary nystagmus almost always represents central vestibular dysfunction.
• Note whether the character of the nystagmus changes in certain directions of gaze.
  • Nystagmus due to vestibular disease increases in intensity when the eyes are turned in the direction of the saccade (fast phase), ie, Alexander law.
  • A horizontal nystagmus due to peripheral vestibular imbalance remains horizontal on upward and downward gaze.
• Note the presence or absence of head nodding or torticollis (spasmus nutans).
• Note whether the nystagmus dampens with fixation. Fixation inhibits nystagmus and vertigo due to peripheral lesions of the vestibular system.
• Optokinetic nystagmus (OKN) drum: The optokinetic reflex allows us to follow objects in motion when the head remains stationary (eg, observing individual telephone poles on the side of the road as one travels by them in a car). The reflex develops at about age 6 months. The normal eye movements that one observes depend upon the orientation of the drum in front of the patient. If the drum is held in front of the patient with the bars directed vertically and is spun to the left (the patient's right), one would observe a slow pursuit movement of the eyes to the patient's right as a moving bar is followed, then a quick saccade to the patient's left as the patient searches for the next moving bar to fixate on and again follows that bar with a slow pursuit movement to the patient's right.
  • This reflex is abnormal in patients with congenital nystagmus. One may observe a paradoxical reversal of the optokinetic nystagmus response.
  • Patients with horizontal nystagmus with unilateral hemispheric lesions, especially parietal or parietal-occipital lesions, show impaired optokinetic nystagmus when the drum is rotated toward the side of the lesion.
  • The OKN drum may be used as an estimate of visual acuity. The striped drum is equivalent to a vision of counting fingers when held at a distance of 3-5 feet from the patient. The further the drum is from the patient, the better the visual acuity must be to respond normally to the moving drum.
• Confrontational visual field testing may reveal gross field defects that may help determine the presence and/or location of an intracranial lesion.
• For Romberg testing have the patient stand with eyes closed and feet together. If a defect in the vestibular system is present, the patient tends to fall toward the side of the lesion.
• Oculocephalic reflex (doll's head phenomenon)
  • The oculocephalic reflex develops within the first week of life and essentially represents a vestibulo-ocular reflex normally suppressed in a conscious individual that attempts to turn the head to fixate on an object.
  • This test consists of the rapid rotation of the patient's head in a horizontal or vertical direction. With intact vestibular nuclei and medial longitudinal fasciculi, the eyes move conjugately in the opposite direction of the head turn. Alternatively, the test may be performed by having the patient extend the arm out in front of the body and fixate on the outstretched thumb. Patients should be instructed to rotate their torso back and forth about their longitudinal axis such that the thumb remains in front of the body at all times.
  • Patients with the ability to suppress the oculocephalic reflex should be able to maintain fixation on their thumb while rotating. An abnormal test result would show the patient continuously losing fixation of the thumb.
  • Inability to suppress the oculocephalic reflex is common in patients with vestibular imbalance.
• Caloric testing
  • Instilling cold or warm water into the external auditory canal can reproduce the same movement of endolymph in the semicircular canals produced by rotations of the head. Instillation of water into the external auditory canal causes endolymph convection currents that in turn induce nystagmus.
  • While sitting erect, the patient tilts the head back 60°. While in supine, the patient elevates the head 30°; this brings the horizontal semicircular canals into the vertical plane.
  • The external auditory canal is irrigated with cold or hot water. Cold water instilled into the right ear causes the endolymph in the right semicircular canal to cool and sink. This movement of endolymph is the same movement induced by a rotation of the head to the left, inducing a horizontal nystagmus directed to the left (ie, to the opposite side the water was placed). Warm water in the same ear produces the opposite effect (ie, a horizontal nystagmus directed to the right or toward the same side the water was placed); ie, cold-opposite, warm-same (COWS).
• Note whether the character of the nystagmus changes with otolithic stimulation. Failure to respond to otolithic stimuli implies peripheral vestibular disease.

Causes

• Seesaw nystagmus
  • Rostral midbrain lesions
  • Parasellar lesions (eg, pituitary tumors)
  • Visual loss secondary to retinitis pigmentosa
• Downbeat nystagmus
  • Lesions of the vestibulocerebellum and underlying medulla, including the following:
    • Arnold-Chiari malformation
    • Demyelination (eg, multiple sclerosis)
    • Microvascular disease with vertebrobasilar insufficiency
    • Brain stem encephalitis
    • Tumors at the foramen magnum (eg, meningioma, cerebellar hemangioma)
    • Trauma
    • Drugs (eg, alcohol, lithium, antiseizure medications)
    • Nutritional (eg, Wernicke encephalopathy, parenteral feeding, magnesium deficiency)
  • Heat stroke
  • Approximately 50% have no identifiable cause.
• Upbeat nystagmus
  • Medullary lesions, including perihypoglossal nuclei, the adjacent medial vestibular nucleus, and the nucleus intercalatus (structures important in gaze holding)
  • Lesions of the anterior vermis of the cerebellum
  • Benign paroxysmal positional vertigo
• Periodic alternating nystagmus
  • Arnold-Chiari malformation
  • Demyelinating disease
  • Spinocerebellar degeneration
  • Lesions of the vestibular nuclei
  • Head trauma
  • Encephalitis
  • Syphilis
  • Posterior fossa tumors
  • Binocular visual deprivation (eg, ocular media opacities)
• Pendular nystagmus
  • Demyelinating disease
  • Monocular or binocular visual deprivation
  • Oculopalatal myoclonus
  • Internuclear ophthalmoplegia
  • Brain stem or cerebellar dysfunction
• Spasmus nutans
  • Usually occurs in otherwise healthy children
  • Chiasmal, suprachiasmal, or third ventricle gliomas may cause a condition that mimics spasmus nutans.
• Torsional - Lateral medullary syndrome (Wallenberg syndrome)
• Abducting nystagmus of internuclear ophthalmoplegia
  • Demyelinating disease
  • Brain stem stroke
• Gaze evoked
  • Drugs - Anticonvulsants (eg, phenobarbital, phenytoin, carbamazepine) at therapeutic dosages
  • Alcohol

Differential Diagnoses

Nystagmus, Congenital

Other Problems to Be Considered

Ocular flutter
Ocular bobbing
Opsoclonus
Repetitive square wave jerks
Macrosaccadic oscillations
Superior oblique myokymia

Workup

Imaging Studies

• Any patient who develops nystagmus without an identifiable cause (eg, Ménière disease, drug toxicity) or with localizing neurologic deficits should undergo neuroimaging. A complete history and neuro-ophthalmic examination are crucial to localizing an intracranial disorder. Communication with the neuroradiologist regarding such localization is important in ensuring that regions of the brain suggestive of a disorder are imaged adequately.
• Central vestibular forms of nystagmus are always pathologic and deserve a thorough evaluation. MRI is the preferred method of neuroimaging.
• Congenital forms of nystagmus typically appear at birth or during infancy and usually are pendular rather than jerk. Visual loss, if present, is stable and not progressive. Any child who develops nystagmus in early childhood should be evaluated carefully. The presence of a pale optic disk, or a history of progressive visual loss, should suggest that the nystagmus is acquired and possibly due to a neoplasm involving the visual system. Such patients require neuroimaging with MRI.
• Optic chiasm or third ventricle gliomas can cause a condition that mimics spasmus nutans. All children with spasmus nutans should undergo a complete neuro-ophthalmic examination. Signs suggestive of a neoplastic etiology include decreased visual acuity, afferent pupillary defect, optic disc pallor, failure to thrive, age of onset before 12 months, and vertical or seesaw nystagmus. All such children should undergo an MRI. If the decision is made to delay MRI in children without neurologic deficit, they should be observed closely for onset of such neurologic deficits.

Other Tests

• Electronystagmographs record eye muscle contractions to evaluate the direction and velocity of nystagmus. It may be used to evaluate low-amplitude nystagmus that is difficult to discern on examination. This study can help determine the type and velocity of the nystagmus, which is important in directing therapy.

Treatment

Medical Care

• Any medications that may be causing the nystagmus should be discontinued in conjunction with the patient's internist, neurologist, and/or pediatrician.
• Significant refractive errors should be corrected. Contact lenses may be preferred over spectacles because the patient may continue to look through the optical center of the contact lens if a head turn secondary to the presence of a null zone exists. Although, this usually applies only to congenital nystagmus.
• Base-out prisms (to induce convergence) can be used to treat downbeat nystagmus. Prisms may be useful prior to considering surgery for a face turn. Fresnel prisms directed with the base opposite the null zone (eg, for a right face turn with a null zone in left gaze, the prism over the right eye would be base out and a prism over the left eye would be base in). Null zones are more characteristic of congenital nystagmus; thus, prisms may not be applicable to most forms of acquired nystagmus.

Surgical Care

• Removing the inciting etiology if possible (eg, intracranial tumors, ocular media opacities)
• Botulinum toxin may be used to treat patients with acquired nystagmus to dampen the nystagmus and to improve visual acuity and to decrease oscillopsia.
  • The toxin may be injected into the rectus muscles (2.5 U per muscle) or may be given as a retrobulbar injection⁹ (10-25 U in 0.1-1 cm³).
  • Multiple injections usually are necessary as the effect of the toxin wears off.
  • Patients whose symptoms improve with botulinum toxin injection may be able to discern when the effect of the toxin begins to diminish as the symptoms may begin to recur.
  • A disadvantage of this treatment option is that botulinum toxin impairs all types of eye movement (eg, saccades, smooth pursuit).
  • Complications of toxin injection include ptosis, diplopia, and increase of nystagmus in the noninjected eye.
• Extraocular muscle surgery for correction of nystagmus is based on surgically shifting the null zone into primary position. Again, null zones are more characteristic of congenital nystagmus; thus, they may not be applicable to most forms of acquired nystagmus. Retroequatorial rectus muscle recessions have been shown to be effective in treating acquired nystagmus without a null point.¹⁰

Consultations

• Neurologic or neuro-ophthalmic consultation should be considered.
• Neurosurgical or oncologic consultation should be sought in cases with a neoplastic etiology.
• Otolaryngologic consultation should be considered in cases of benign positional vertigo or other peripheral vestibular disorders.

Medication

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Muscle relaxants, GABA agonists

Use for periodic alternating nystagmus, downbeat and upbeat nystagmus, and seesaw nystagmus.¹¹

Baclofen (Lioresal)

Periodic alternating oscillopsia may be a major complaint in patients with periodic alternating nystagmus and may be cured by the use of baclofen.

Dosing

Adult

5 mg PO tid; not to exceed 80 mg qd

Pediatric

<2 years: Not established
2-8 years: 10-40 mg/d PO divided tid/qid
Start: 2.5-5 mg PO tid x 3d; increase by 5-15 mg/d q3d prn; 40 mg/d maximum
8-12 years: 10-60 mg/d PO divided tid/qid
Start: 2.5-5 mg PO tid x 3d; increase by 5-15 mg/d q3d prn; 60 mg/d maximum
>12 years: 20-80 mg/d PO divided tid/qid
Start: 5 mg PO tid x 3d; increase by 5-15 mg/d q3d prn; 80 mg/d maximum

Interactions

Increased risk of depression with alcohol, antipsychotics, anxiolytics, MAOIs, narcotics, and tricyclic antidepressants; insulin and oral hypoglycemics may increase blood glucose levels

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in renal impairment or patients with seizure disorder

Anticonvulsants

Increases GABA synthesis and release and decreases GABA degradation. Used for acquired pendular nystagmus.

Gabapentin (Neurontin)

May reduce nystagmus, improve visual acuity, and reduce oscillopsia in patients with acquired pendular nystagmus.

Dosing

Adult

300-1200 mg PO in divided doses

Pediatric

Not established

Interactions

Antacids may decrease absorption

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in renal impairment and in elderly persons; avoid abrupt withdrawal

Clonazepam (Klonopin)

Used for downbeat nystagmus. Suppresses muscle contractions by facilitating inhibitory GABA neurotransmission and other inhibitory transmitters.

Dosing

Adult

0.5-5 mg PO tid; not to exceed 20 mg PO qd

Pediatric

<10 years or <30 kg: 0.01-0.03 mg/kg PO divided bid/tid; increase by 0.25-0.5 mg q3d; not to exceed 0.1-0.2 mg/kg/d
>10 years or >30 kg: 0.5 mg PO tid; increase by 0.5-1 mg q3d; not to exceed 20 mg/d

Interactions

Carbamazepine, phenytoin, and phenobarbital decrease clonazepam levels; cimetidine, itraconazole/ketoconazole, and ritonavir increase clonazepam levels; CNS depressants increase risk of CNS depression; valproic acid increases risk of absence seizures

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Caution in patients with impaired respiratory function; avoid abrupt withdrawal

Neuromuscular blocker agents

Blocks neuromuscular transmission at cholinergic junctions by preventing release of acetylcholine from nerve terminals. Decreases nystagmus and improves visual acuity.

Botulinum toxin A (BOTOX®)

Treats excessive, abnormal contractions associated with blepharospasm. Binds to receptor sites on motor nerve terminals and inhibits release of acetylcholine, which, in turn, inhibits transmission of impulses in neuromuscular tissue.
Reexamine patients 7-14 d after initial dose to assess for response. Increase doses 2-fold over previous one for patients experiencing incomplete paralysis of target muscle. Do not exceed 25 U when giving it as single injection or 200 U as cumulative dose in 30-day period.

Dosing

Adult

Rectus muscles: 2.5 U/muscle
Retrobulbar injection: 10-25 U in 0.1-1 cm³

Pediatric

Not established

Interactions

Aminoglycosides or drugs that interfere with neuromuscular transmission may potentiate effects of botulinum toxin

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Systemic side effects have not occurred; however, electrophysiologic studies have shown that large doses produce subclinical effects on neuromuscular transmission in distant muscles

Follow-up

Further Outpatient Care

• Regular office visits are useful to monitor nystagmus.

Prognosis

• Prognosis is dependent upon etiology.

Miscellaneous

Medicolegal Pitfalls

• The principal medical/legal pitfall in the management of acquired nystagmus is related to misdiagnosis of a serious or life-threatening etiology. Life-threatening causes of nystagmus should first be ruled out with a pertinent history and physical examination. Appropriate consultation and/or imaging should be obtained without delay if a serious underlying cause is suspected.

Special Concerns

• Bruns nystagmus
  • The first manifestation of slow-growing cerebello-pontine angle tumors (eg, acoustic neurinoma, exophytic brain stem glioma, cerebellar tumors, metastases) may be a vestibular nystagmus associated with peripheral vestibular symptoms. Peripheral vestibular nystagmus has a horizontal jerk component with the fast phase directed away from the side of the lesion. In addition, an ipsilateral, slow, gaze-evoked nystagmus with gaze to the side of the lesion may be seen as the tumor expands to compress the brain stem. A small amplitude rapid jerk nystagmus in primary position with the fast phase directed away from the side of the lesion in combination with a slow, gaze-evoked nystagmus directed toward the side of the lesion suggests a mass compressing the brain stem with peripheral vestibular nerve involvement. This is known as Bruns nystagmus.
  • Acquired nystagmus most often is a result of vestibular dysfunction. A resting tone is present in the vestibular system, even when the head is at rest. Therefore, any loss of neural activity on either side from a pathologic process (eg, mass lesion, ischemia) results in a relative overexcitation of the contralateral side, causing the eyes to drift toward the side of the lesion (ie, nystagmus with the fast phase away from the lesion).

References

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Keywords

acquired nystagmus, downbeat nystagmus, upbeat nystagmus, periodic alternating nystagmus, horizontal nystagmus, vertical nystagmus, optokinetic nystagmus, rotary nystagmus, vestibular nystagmus, oscillopsia, congenital nystagmus, spasmus nutans

Contributor Information and Disclosures

Author

Christopher M Bardorf, MD, MS, Ophthalmology, Children's Eye Physicians, Denver, CO
Christopher M Bardorf, MD, MS is a member of the following medical societies: American Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Gregory P Van Stavern, MD, FACP, Assistant Professor, Departments of Ophthalmology and Neurology, Wayne State University
Gregory P Van Stavern, MD, FACP is a member of the following medical societies: American Academy of Neurology and North American Neuro-Ophthalmology Society
Disclosure: Nothing to disclose.

Enrique Garcia-Valenzuela, MD, PhD, Clinical Assistant Professor, Department of Ophthalmology, University of Illinois Eye and Ear Infirmary; Consulting Staff, Vitreo-Retinal Surgery, Midwest Retina Consultants, SC, Parkside Center
Enrique Garcia-Valenzuela, MD, PhD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Retina Specialists, Association for Research in Vision and Ophthalmology, Retina Society, and Society for Neuroscience
Disclosure: Nothing to disclose.

Medical Editor

Michael J Bartiss, OD, MD, Medical Director, Ophthalmology, Family Eye Care of the Carolinas
Michael J Bartiss, OD, MD is a member of the following medical societies: American Academy of Ophthalmology, American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus, and North Carolina Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Brian R Younge, MD, Professor of Ophthalmology, Mayo Clinic School of Medicine
Brian R Younge, MD is a member of the following medical societies: American Medical Association, American Ophthalmological Society, and North American Neuro-Ophthalmology Society
Disclosure: Nothing to disclose.

CME Editor

Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.

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