Jerk nystagmus | Pendular nystagmus |
Alternation of slow phase drift followed by a rapid corrective saccade in the opposite direction | Sinusoidal oscillation with slow phases in both directions and no corrective saccades |
Right- or left-beating horizontal nystagmusa Upbeat or downbeat nystagmus Torsional or rotary nystagmus (clockwise or counterclockwise) | May be horizontal or vertical but would not be characterized as right-, left-, up-, or downbeating because there is no fast phase |
aDirection of jerk nystagmus = direction of the fast phase. | |
Acquired | Infantile (congenital) | |
Form | Pure sinusoidal | Variable waveforms |
Different in the two eyes | Frequent | Rare |
Direction | Omnidirectional (vertical, circular, elliptical) | Horizontal, uniplanar Rarely vertical or torsional |
OKN reversal | Never | Frequent |
Oscillopsia | Frequent | Mild (if any) |
Abbreviation: OKN, optokinetic nystagmus. | ||
Peripheral | Central | |
Feature | Unilaterala disease of vestibular organ or nerve Usually benign disease: Labyrinthitis Ménière disease | Disease of the brainstem and its connections with the vestibulocerebellum Any CNS disorder |
Direction | Horizontal componentb Mixed: horizontal/torsional, sometimes vertical component Fast phase away from lesion | Torsional pure Vertical pure Horizontal purec |
Visual fixation | Inhibits nystagmus | No inhibition |
Frenzel goggles or darkness (inhibition of fixation) | Peripheral nystagmus increases in intensity | Central nystagmus is not changed |
Severity of vertigo | Severe | Mild (except for Wallenberg syndrome) |
Induced by head movements | Often | Rare |
Associated eye movement deficits | None | May have pursuit or saccadic defects |
Other findings | Hearing loss | May have cranial nerve or long tract signs No tinnitus or hearing loss |
Abbreviation: CNS, central nervous system. aBilateral disease of vestibular organ and nerve (typically from drug toxicity) does not give nystagmus but produces loss of the vestibulo-ocular reflex. bIntensity increases when the eyes are turned in the direction of the quick phase. cDirection of nystagmus may change with gaze. | ||
Findings | Peripheral | Central |
Latency | Present | Absent |
Duration | < 1 min | > 1 min |
Fatigability | Yes | No |
Reversal with upright position | Yes | No |
Jerk nystagmus | |
Downbeat | Cervicomedullary junction Vestibulocerebelluma Medulla |
Upbeat | Medulla Cerebellar vermis Midbrain |
Periodic alternating | Cervicomedullary junction Cerebellum |
Rebound | Cerebellum Medulla |
Brun | Cerebellopontine angle |
Dissociated jerk | Internuclear ophthalmoplegia (MLF in brainstem) |
Pendular nystagmus | |
Monocular (often vertical) | Visual loss |
Seesaw | Parasellar lesions Septo-optic dysplasia |
Oculopalatal myoclonus | Mollaret triangle (connecting red nucleus to inferior olive and dentate nucleus) |
Oculomasticatory myorhythmia | Whipple disease |
Abbreviation: MLF, medial longitudinal fasciculus. aVestibulocerebellum includes the flocculus, paraflocculus, nodulus, and uvula. | |
Most patients with nystagmus complain of oscillopsia (oscillating vision with illusion that objects are moving), and in most cases, nystagmus can be recognized clinically without eye movement recording. However, eye movement recording allows far more accurate characterization of the nystagmus by analyzing the slow phase (velocity, amplitude, and frequency) (▶ Fig. 16.1 and ▶ Fig. 16.2).
Fig. 16.1 a, b Jerk nystagmus. (a) Right-beating nystagmus (fast phase beats to the right, slow phase drifts to the left). (b) Left-beating nystagmus (fast phase beats to the left, slow phase drifts to the right).
Fig. 16.2 Pendular nystagmus. Sinusoidal wave (there is no fast phase).
▶ Fig. 16.1 and ▶ Fig. 16.2 show the waveforms of horizontal jerk and pendular nystagmus.
16.1.1 Patient Evaluation
The goals of the evaluation are to decide whether there is a central or peripheral pattern of nystagmus and to determine if localization is possible based on the findings (▶ Table 16.3 and ▶ Table 16.4).
Symptoms include oscillopsia (absent in congenital nystagmus), decreased acuity, nausea or vomiting, and vertigo. There may be coexisting neurologic deficits.
The examination (in primary position as well as all positions of gaze) differentiates jerk from pendular nystagmus. If the finding is jerk nystagmus, look for the direction of the fast phase—watch for a few minutes, as nystagmus may occasionally alternate directions. Look for coexisting head oscillations or head turns, the effect of convergence on nystagmus, the presence of a null point (eye position where nystagmus is least prominent), and subtle nystagmus or vestibular nystagmus that is suppressed by fixation. The last can be assessed by performing ophthalmoscopy in one eye while the patient fixates at distance, then covering the fixating eye. Nystagmus may then be viewed through the ophthalmoscope (the fast phase direction is the opposite of what it appears through the direct ophthalmoscope). Frenzel goggles may be used to assess nystagmus in the absence of fixation. Electronystagmography
(ENG) is another method of identifying nystagmus not present with eyes open. Finally, the Dix–Hallpike or Bárány maneuver can be done to look for positional nystagmus in patients who complain of positional vertigo (see ▶ Table 16.4; ▶ Fig. 16.3).
16.1.2 Infantile (Congenital) Nystagmus
Infantile (congenital) nystagmus is usually not noted at birth but becomes apparent during the first few months of life.
Characteristics
Horizontal nystagmus (mixed pendular and jerk); may have a rotary component.
There are bilateral conjugate movements of the eyes.
Nystagmus is not present during sleep.
There may be associated latent nystagmus.
Null point (the preferred eye position for the patient to fixate) usually results in a head turn.
Convergence decreases the nystagmus, and fixation increases it.
Patients may have a head tremor that in some cases improves visual acuity.
Reverse response to optokinetic stimulus may be seen (fast phase in direction of moving optokinetic nystagmus [OKN] tape).
Nystagmus may be seen in isolation (also called congenital motor nystagmus), or it may be associated with strabismus or afferent visual system defects (e.g., albinism (see ▶ Fig. 16.4), congenital stationary night blindness, or optic nerve hypoplasia).
There is no oscillopsia, but there is decreased visual acuity (related to associated afferent conditions and to the nystagmus present in primary gaze).
