nistagmo

Nistagmo, or nystagmus, is a condition characterized by involuntary, rhythmic oscillation of the eyes. The eye movements typically have a slow phase in one direction and a fast corrective phase in the opposite direction. Nistagmo can be horizontal, vertical, pendular (equal speed in both directions), or rotary, and it may be congenital (present from infancy) or acquired later in life.

Causes include congenital nistagmo, often associated with reduced visual input, and acquired forms resulting from brainstem or cerebellar disease, vestibular disorders, retinal or optic nerve disease, intoxication, multiple sclerosis, stroke, tumors, or trauma. The condition may occur in isolation or as part of a broader neurological syndrome.

Symptoms vary by form but commonly include involuntary eye movements, reduced visual acuity, oscillopsia (perceived movement of the visual field), and visual instability. Gaze-evoked nystagmus may worsen when looking to a particular direction. Diagnosis relies on clinical observation and objective testing of eye movements, such as video-oculography or electronystagmography, often supplemented by caloric testing or rotary chair assessments and, when indicated, MRI to identify structural causes. Comprehensive visual and refractive evaluation is frequently performed.

Treatment focuses on the underlying cause when possible. Optical aids (refractive correction, prisms) can improve vision. Pharmacologic options, including baclofen or gabapentin, may reduce movement in some cases. Botulinum toxin injections into extraocular muscles and various surgical procedures to reposition muscles to shift the null point are used in selected patients. Rehabilitation and gaze-stabilizing exercises can aid some individuals.

Prognosis depends on etiology and subtype; congenital nistagmo is typically lifelong but may remain stable, while acquired forms may improve or worsen with the underlying condition.