Differential neuronal responses between brain nuclei after blunt head‐injury

Abstract

Introduction: Stereological evidence for loss of neurons after human blunt head‐injury is lacking. A quantitative analysis of total numbers of neurons in two different brain regions in nonhead‐injured control (n = 10) and severely head‐injured patients (n = 24) (age range 18–64) was undertaken.Material and methods: 8 µm paraffin sections of the left and right thalami and of the left hippocampus from all patients were cut and cresyl violet stained. The neuronal size in subfields of the hippocampus, and dorsomedial, lateral and ventral thalamic nuclei was measured to determine the size of the counting box and, within this, the total number of neurons was counted. Statistical analysis used the Student's t‐test.Results: At 1 week, pyramidal neurons were lost from hippocampal subfields CA1 (P = 0.012), CA3 (P = 0.003) and CA4 (P = 0.002), but not from CA2. Further loss occurred at 6 months but only in CA1 (P = 0.033) and CA4 (P = 0.013). No evidence for loss of neurons from any thalamic nucleus was obtained.Conclusions: Loss of neurons from different nuclei of the brain after blunt head‐injury occurs both with a different timescale and to a different extent. Anecdotal evidence of damage to thalamic nuclei after head‐injury has not been supported using stereology.