The duration of the disease is about 15 years. Grossly, the brain in Huntington s disease is characterized by atrophy of the caudate nucleus which is visible on CT scans. The normally rounded head of the caudate becomes flattened, then concave. Microscopically, there is loss of the small and medium-sized neurons of the caudate and putamen with corresponding gliosis. Milder changes occur in the cortex, thalamus, substantia nigram, brainstem and spinal cord.
Age of onset is usually mid to late life.
Males are affected twice as often as females. Gait disorder, limb weakness, dysarthria or dysphagia, and loss of muscle bulk are common initial complaints. The immediate cause of death is often respiratory failurre. Early on, the symptoms may mimic those of a treatable spinal cord lesion. There may be focal swellings of the axons and dendrites of affected neurons.