Nystagmus is an uncontrollable, repetitive and rapid movement of the eyes. When affected by nystagmus, either one or both of the eyes can move in a circular motion, up and down, or from side to side, according to MedlinePlus. Dysfunction in the inner ear or the part of the brain that controls eye movements can cause nystagmus to develop, which has a variety of causes.
Alcohol Intoxication
Alcohol intoxication can cause horizontal gaze nystagmus, which is a jerking movement of the eye back to the midpoint after drifting to the side. The movement is involuntary and the intoxicated person is not aware of it, according to the National Highway Traffic Safety Administration. Observing for horizontal gaze nystagmus, or HGN, is a routine part of a field sobriety test conducted by law enforcement. A finding of HGN can be admitted as evidence of intoxication, along with other findings, in some trial courts.
Congenital Nystagmus
Congenital nystagmus exists at birth and is the most common type of nystagmus. It is not usually associated with any other disorder and is commonly so mild that the affected person is not aware of it, although careful observers may notice it, MedlinePlus states. The severity does not change over time. If the eye movements are large, visual sharpness may be reduced and surgical repair may be required. An eye doctor should evaluate all children with congenital nystagmus; in rare cases, it can result from an underlying eye disorder.
Benign Paroxysmal Positional Vertigo
Benign paroxysmal positional vertigo, or BPPV, is a disorder of the inner ear that causes short periods of dizziness along with nystagmus and nausea. It is believed to be caused by loose calcium carbonate crystals within the inner ear. Dizziness associated with BPPV is described as a spinning sensation of less than 60 seconds duration, according to The Merck Manuals Online Medical Library. BPPV is triggered by certain head positions. The disorder usually resolves in a few weeks or months. BPPV is treated with the Epley and Semont maneuvers, a series of head manipulations that move the loose crystals to another part of the ear.
Brain Tumor
Tumors located in the brain stem, the area that controls eye movement, can cause nystagmus to develop, according to an article titled "Primary Brain Tumors in Adults" in the May 15, 2008, issue of the journal "American Family Physician." Ataxia or the inability to coordinate movements and paralysis of one side of the body are other possible symptoms. The standard treatment for a primary brain stem tumor is radiation therapy, according to "American Family Physician."
