Nystagmus is rapid, involuntary movements of the eyes which is often unnoticeable to people with the complaint. To others it resembles the eye movements when someone is looking at the scenery from the window of a moving train. Usually it occurs in the horizontal plane but it can also affect the vertical.

Nystagmus can be caused by a variety of underlying conditions, including multiple sclerosis of which it is quite a common symptom. Most presentations of a type of nystagmus called Acquired Pendular Nystagmus are associated with multiple sclerosis.

In MS, nystagmus is often associated with internuclear ophthalmoplegia - which is a loss of coordination between the two eyes caused by a lesion in an area of the brain called the medial longitudinal fasciculus (MLF). Nystagmus can also be caused by lesions in the cerebellum, the area of the brainstem where the vestibular cranial nerve arises or further along the vestibular pathways.

Apart from immunomodulating drugs and steroids, there are no treatments for nystagmus. If it is a troubling condition it may be a good idea to experiment with different lighting levels. As with most symptoms of MS, fatigue and heat (Uhthoff's symptom) usually make the condition worse.

Nystagmus Links:
Multiple Sclerosis Video Page-Nystagmus
American Nystagmus Network

MS Glossary
All About Multiple Sclerosis