This is one of multiple hereditary disorders in which there is progressive deterioration of the nervous system. Many of them have signs and symptoms involving the visual system. There is considerable variation in the age of onset and in the rate of progression of symptoms.
Early symptoms of eye disease include some loss of vision and color perception. The eyes often exhibit a to-and-fro motion (nystagmus). Later many patients are unable to move the eyes normally in all directions (ophthalmoplegia). Examination of the eye may show changes in the retina and degeneration of the optic nerve.
General unsteadiness (ataxia) and lack of coordination are common. Speech is often slurred and explosive. Loss of balance and difficulty walking are prominent symptoms. Swallowing may be difficult. It is not unusual for individuals to have loss of muscle as well as numbness and tingling in the arms and legs. The mean age of onset is about age 40 years but there is considerable variation and onset in childhood has even been observed. In general, the disease is more severe and progresses more rapidly in individuals with onset of symptoms in childhood or adolescence.
An MRI may show some loss of brain tissue (atrophy).
This is an autosomal dominant disorder in which the condition is passed from parent to child. It also tends to occur earlier in succeeding generations. Children born to affected fathers tend to have an earlier onset of symptoms and they often progress more rapidly.
Neurologists and ophthalmologists working together usually can make this diagnosis, especially if there is a family history. No treatment is available for this disease but low vision aids and mobility training can be helpful in early stages.
The prognosis is poor. Individuals with adult onset disease may live from 10-30 years whereas those whose symptoms appear before the age of 13 years often do not live beyond the age of 16. No effective treatment is available.