Cortical and striatal neurone number in Huntington's disease.

The total cortical and striatal neurone and glial numbers were estimated in five cases of Huntington's disease (three males, two females) and five age- and sex-matched control cases. Serial 500-microns-thick gallocyanin-stained frontal sections through the left hemisphere were analysed using Cavalieri's principle for volume and the optical disector for cell density estimations. The average cortical neurone number of five controls (mean age 53 +/- 13 years, range 36-72 years) was 5.97 x 10(9) +/- 320 x 10(6), the average number of small striatal neurones was 82 x 10(6) +/- 15.8 x 10(6). The left striatum (caudatum, putamen, and accumbens) contained a mean of 273 x 10(6) +/- 53 x 10(6) glial cells (oligodendrocytes, astrocytes and unclassifiable glial profiles). The mean cortical neurone number in Huntington's disease patients (mean age 49 +/- 14 years, range 36-75 years) was diminished by about 33% to 3.99 x 10(9) +/- 218 x 10(6) nerve cells (P < or = 0.012, Mann-Whitney U-test). The mean number of small striatal neurones decreased tremendously to 9.72 x 10(6) +/- 3.64 x 10(6) (-88%). The decrease in total glial cells was less pronounced (193 x 10(6) +/- 26 x 10(6)) but the mean glial index, the numerical ratio of glial cells per neurone, increased from 3.35 to 22.59 in Huntington's disease. Qualitatively, neuronal loss was most pronounced in supragranular layers of primary sensory areas (Brodmann's areae 3,1,2; area 17, area 41). Layer IIIc pyramidal cells were preferentially lost in association areas of the temporal, frontal, and parietal lobes, whereas spared layer IV granule cells formed a conspicuous band between layer III and V in these fields. Methodological issues are discussed in context with previous investigations and similarities and differences of laminar and lobar nerve cell loss in Huntington's disease are compared with nerve cell degeneration in other neuropsychiatric diseases.