Nerve cell loss in the thalamic mediodorsal nucleus in Huntington's disease.

We estimated the total neurone number, glial number, and glial index (ratio glial cells/neurone) in the thalamic mediodorsal nucleus (MD) in seven patients suffering from Huntington's disease (HD; four males, three females, mean age 52.4 +/- 13.6 years) and age- and sex-matched controls (four males, three females, mean age 53.6 +/- 12.1 years) by means of a stereological protocol. The mean total neurone number (N(T)) in the MD of controls was 2,985,188 +/- 174,710, the mean glial number (G(T); astrocytes, oligodendrocytes) 21,785,008 +/- 2,986,678, and the glial index 7.29 +/- 0.88. In HD, the average neurone number was decreased by 23.8% to 2,275,321 +/- 247,162 (Mann-Whitney U-test P < 0.05), the mean glial number by 29.7% to 15,318,895 +/- 1,722,524 (Mann-Whitney U-test P < 0.05), the glial index was slightly reduced to 6.81 +/- 1.06. Gallyas' impregnation for the demonstration of fibrous astroglia gave strongly positive results in all cases with HD and negative results in the controls. The morpho-functional correlation of the results is complicated because individual variability, presence of segregated and parallel neuronal circuits, and plasticity of the adult human CNS must be considered.