From the Guidelines
Peripheral gaze nystagmus is a normal physiological eye movement that occurs when a person looks far to the side, but it can also be a sign of a neurological disorder if it occurs before reaching 45 degrees of lateral gaze, persists for more than a few seconds, or is accompanied by other symptoms like vertigo or visual disturbances. When testing for peripheral gaze nystagmus, have the patient follow your finger to the extreme lateral position and hold their gaze there for several seconds. A few beats of nystagmus in this extreme position is normal due to fatigue of the extraocular muscles attempting to maintain the extreme position, as noted in the context of vestibular disorders 1. The quick phase of the nystagmus typically beats toward the direction of gaze.
Some key points to consider when evaluating peripheral gaze nystagmus include:
- Nystagmus findings that more strongly suggest a central cause of vertigo rather than a peripheral cause such as BPPV include downbeating nystagmus on the Dix-Hallpike maneuver, direction-changing nystagmus occurring without changes in head position, or baseline nystagmus manifesting without provocative maneuvers 1.
- Among the central causes of vertigo that should be distinguished from BPPV are vestibular migraine, brainstem and cerebellar stroke or transient ischemic attacks, and intracranial tumors or disorders, such as multiple sclerosis 1.
- Failure to respond to conservative management such as CRP or vestibular rehabilitation should raise concern that the underlying diagnosis may not be BPPV 1.
In terms of diagnosis and management, it is essential to differentiate BPPV from other causes of imbalance, dizziness, and vertigo, and to question patients with BPPV for factors that modify management, including impaired mobility or balance, CNS disorders, lack of home support, and increased risk for falling 1. The most recent and highest quality study 1 suggests that clinicians should diagnose posterior semicircular canal BPPV when vertigo associated with nystagmus is provoked by the Dix-Hallpike maneuver, and that particle repositioning maneuvers (PRM) should be used to treat patients with posterior canal BPPV.
From the Research
Definition and Types of Nystagmus
- Nystagmus is defined as rhythmic, most often involuntary eye movements 2
- It normally consists of a slow (pathological) drift of the eyes, followed by a fast central compensatory movement back to the primary position (refixation saccade) 2
- The direction is reported according to the fast phase 2
- There are two major categories: spontaneous nystagmus and nystagmus induced or modified by certain factors, such as gaze-evoked nystagmus, head-shaking nystagmus, positional nystagmus, and hyperventilation-induced nystagmus 2
Peripheral Gaze Nystagmus
- Gaze-evoked nystagmus is a type of nystagmus that occurs when the eyes are moved from the primary position to an eccentric position 2, 3
- It is often associated with peripheral vestibular disorders, such as vestibular neuritis or Meniere's disease 3, 4
- Treatment of gaze-evoked nystagmus depends on the underlying cause, but may include pharmacological treatment with aminopyridines, baclofen, or gabapentin 5, 4
Treatment Options
- Treatment of nystagmus depends on the type and underlying cause, and may include pharmacological, surgical, or optical devices 6, 2, 5
- Aminopyridines, such as 4-aminopyridine, are effective in treating downbeat and upbeat nystagmus 2, 5, 4
- Baclofen is effective in treating periodic alternating nystagmus 2, 5, 4
- Gabapentin and memantine are effective in treating pendular and infantile nystagmus 2, 5, 4