Huntington's Disease and Ocular Motor Abnormalities

Huntington's chorea is a chronic, progressive, fatal, degenerative disorder of the central nervous system. It is characterized by mental deterioration and a motility disturbance best described as choreiform. It is inherited as an autosomal dominant with complete penetrance. Although described earlier, the landmark report by George Sumner Huntington of chorea in certain families of his father's practice in Easthampton, Long Island led its current eponym. The largest familial kindred (more than 1,000 patients) in the United States has been traced back to 3 immigrants who sailed from Burs, England, in 1630 to Salem, Massachusetts. Because of the progressive nature of the disease, the cost and care of these patients has often been out of proportion to their numbers. The onset of motility disturbance peaks early in the fifth decade but up to 10% of patients may have their first symptoms in their early teens or younger. The earlier the onset, the more severe and rapidly progressive the disease tends to be. Late on set is often associated with a relatively ‘benign' course. Previous attempts at early detection of those patients ‘at risk' for the development of Huntington's disease have been unrewarding. In particular, CT scanning and EEG analysis have been unable to select those patients who will develop the disease. The discovery of specific neuron transmitter disorders has led to experimentation with provocative testing (using oral L-dopa). The possibility of provoking, inducing, or hastening the onset of the disease has raised ethical questions on its use (L-dopa is capable of inducing chore form movements in some patients who eventually develop Huntington's disease). The frequency of ocular motor disturbances in patients with Huntington's disease has spurred detailed analysis of these findings in an attempt to better understand the ocular motor supranuclear connections and potentially provide an early method of determining those patients at risk for disease development.