Vertical nystagmus is a type of involuntary eye movement in which the eye moves both rapidly and slowly on a vertical axis. The eye might either move upwards rapidly, then downwards slowly, or vice versa. Depending on how severe the condition is, it can lead to vision impairment and vertigo. Nystagmus can be either congenital or acquired.
The most common causes of this condition are congenital. The condition is noticeable even in infancy and usually lasts the individual's lifespan. Fortunately, congenital nystagmus is often milder than acquired nystagmus and is more manageable. Congenital nystagmus is usually also non-progressive, so the severity of the condition is static.
Acquired nystagmus, on the other hand, is often more severe. While some individuals with acquired nystagmus might report feelings of dizziness due to the involuntary eye movement, others might find the condition debilitating enough to have extremely impaired vision. Other than the physiological discomfort, the condition can also lead to emotional distress for individuals concerned about their appearance. Vertical nystagmus can be acquired through a variety of means, including diseases, nervous system disorders, and exposure to toxins.
The condition can be a symptom of some serious diseases. It can be a sign of brain tumors, Whipple's disease, or multiple sclerosis. Less serious conditions that lead to vertical nystagmus include albinism and Ménière's disease. Nystagmus might also be a symptom of thiamine deficiency.
It is also possible that vertical nystagmus is a result of several disorders of the nervous system. One common cause of acquired nystagmus, for example, is the nerve damage suffered during a stroke. Severe head trauma can also lead to the development of nystagmus. The condition can be a symptom of antidepressant withdrawal as well.
Exposure to certain toxins can also cause vertical nystagmus. Common toxic causes of nystagmus include lithium and salicylic acids. Use of illegal drugs such as Lysergic acid diethylamide (LSD) and ketamine can cause enough damage to the nervous system to cause nystagmus. In rare cases, alcohol intoxication might also be a cause of nystagmus.
Although vertical nystagmus is traditionally considered untreatable, several developments have shown promise for curing the condition. The drugs baclofen and gabapentin have both been found to show significant improvement in patients with nystagmus. Other notable treatments include acetazolamide, levetiracetam, and memantine. Several professionals are also attempting to develop a surgical treatment for nystagmus, although favorable results are too few to consider significant.