What is one-and half syndrome?

One-and-a-half syndrome is a rare neurological disorder characterized by a specific type of eye movement impairment that affects the ability to move the eyes horizontally. This condition occurs when there is damage to specific parts of the brainstem, which is responsible for controlling eye movements, specifically the pons and the medial longitudinal fasciculus (MLF).

In one-and-a-half syndrome, one eye cannot move horizontally at all, while the other eye is restricted in its ability to move in the opposite direction. This results in double vision, or diplopia, in the affected eye, leading to difficulty with reading, driving, and other everyday activities. In addition to the eye movement impairment, individuals with one-and-a-half syndrome may also experience other symptoms such as difficulty with balance, coordination, and walking.

One-and-a-half syndrome can occur due to a variety of causes, including stroke, multiple sclerosis, brainstem hemorrhage, or other conditions or injuries that affect the brainstem. Treatment for this condition depends on the underlying cause and may include medication, physical therapy, and surgery in severe cases.