Neuronal loss, demyelination and volume change in the multiple sclerosis neocortex

Aims Indices of brain volume [grey matter, white matter (WM), lesions] are being used as outcomes in clinical trials of patients with multiple sclerosis (MS). We investigated the relationship between cortical volume, the number of neocortical neurons estimated using stereology and demyelination. Methods Nine MS and seven control hemispheres were dissected into coronal slices. On sections stained for Giemsa, the cortex was outlined and optical disectors applied using systematic uniform random sampling. Neurons were counted using an oil immersion objective (× 60) following stereological principles. Grey and WM demyelination was outlined on myelin basic protein immunostained sections, and expressed as percentages of cortex and WM respectively. Results In MS, the mean number of neurons was 14.9 ± 1.9 billion vs. 24.4 ± 2.4 billion in controls (P