Peripheral nystagmus occurs as a result of either normal or diseased functional states
of the vestibular system and may combine a rotational component with vertical or
horizontal eye movements and may be spontaneous, positional, or evoked.
Positional nystagmus occurs when a person's head is in a specific position. An example
of disease state in which this occurs is Benign paroxysmal positional vertigo (BPPV).
Gaze Induced nystagmus occurs or is exacerbated as a result of changing one's gaze
toward or away from a particular side which has an affected vestibular apparatus.
Post rotational nystagmus occurs after an imbalance is created between a normal side
and a diseased side by stimulation of the vestibular system by rapid shaking or rotation
of the head.
Spontaneous nystagmus occurs randomly, regardless of the position of the patient's
head.
Central nystagmus occurs as a result of either normal or abnormal processes not related
to the vestibular organ. For example, lesions of the midbrain or cerebellum can result
in up- and down-beat nystagmus.
Nystagmus in MS -A condition in which the eyes are seen to move in a more or less
rhythmical manner, from side to side, up and down, or in a rotary manner from the
original point of fixation. This sometimes goes unnoticed by the person with MS but
is clearly seen by a health professional or optician. To others it resembles the
eye movements when someone is looking at the scenery from the window of a moving
vehicle.
It can occur in one eye or both and, if in both of them, simultaneously or separately.
Horizontal nystagmus is usually due to a disturbance in the vestibular system. It
typically causes general poor vision and, often, loss of balance and may contribute
to dizziness or nausea.
It is often caused by a lesion in an area of the brain called the medial longitudinal
fasciculus (MLF), but also by lesions in the cerebellum, the area of the brainstem
where the vestibular cranial nerve arises, or further along the vestibular pathways.
Although quite a common symptom, it can be a difficult symptom to treat. Depending
on the severity i.e. if it interferes enough with daily life then drug therapy may
help and very recently the use of a muscle relaxant injection (botulinum) into the
eye muscles has been shown to be effective but apart from immunomodulating drugs
and steroids, there are no other treatments for nystagmus. NICE
Guideline for management of MS states that "any person who has nystagmus that causes
reduced visual acuity or other visual symptoms should be offered a time-limited trial
of treatment with oral gabapentin. This should be initiated and monitored by a suitable
specialist".
A small study also suggest that memantine is also effective and very recently the
use of a muscle relaxant injection (botulinum) into the eye muscles can show benefit.
If it is a troubling condition it may be a good idea to experiment with different
lighting levels or tinted lenses. As with most symptoms of MS, fatigue and heat (Uhthoff's
Syndrome) usually make the condition worse and temporarily reduce vision.
Fortunately, the prognosis for recovery from many vision problems associated with
MS is good. There is work being done on optical devices to stabilise the ‘wiggling’
visual environment of those with nystagmus and moreover, the brain eventually learns
to ignore the ‘wiggling’ type of vision disturbance.
