Subcortical afferent projection systems in Huntington's chorea.

The number and nucleolar volume of nerve cells within the nucleus basalis of Meynert, locus caeruleus, substantia nigra and dorsal raphe were examined in five patients with Huntington's chorea. No significant changes in nerve cell number were noted in any area in any patient and, although nucleolar volume was reduced in nerve cells of locus caeruleus and substantia nigra in four patients, this was considered to reflect medication rather than to be related to the disease process itself. It is concluded that the subcortical afferent projection systems of the mid-brain and brain stem are unaffected in Huntington's chorea and that the dementia in such patients most likely relates to changes within the cerebral cortex and/or damage to corticopetal pathways within the basal ganglia.