The absolute number of nerve cells in substantia nigra in normal subjects and in patients with Parkinson's disease estimated with an unbiased stereological method.
Level 4 - case-series / case-control
Post-mortem case-control study
PubMed 2010756 · doi:10.1136/jnnp.54.1.30
What was done
Total numbers of pigmented and non-pigmented neurons in the substantia nigra were estimated post-mortem in 7 patients with Parkinson's disease and 7 control subjects using an unbiased stereological counting method independent of nerve cell size, section thickness, and tissue shrinkage.
What was found
In controls, the average total number of pigmented neurons was 550,000 and non-pigmented neurons was 260,000. In Parkinson's disease patients, pigmented neurons were reduced by 66% and non-pigmented neurons were reduced by 24%. A significant correlation was observed between pigmented and non-pigmented neuron totals in controls (r = 0.81), whereas the correlation in patients (r = 0.72) fell just short of statistical significance.
Why it matters
This study provides precise, unbiased stereological estimates of absolute neuronal loss in the substantia nigra in Parkinson's disease, showing that neurodegeneration affects both pigmented and non-pigmented neuronal populations.
Limits
The sample size was very small (7 patients and 7 controls). The abstract does not report patient age, disease duration, clinical severity, post-mortem intervals, or medication exposure.
Cited by
- contradicts There are approximately 80,000 dopamine neurons per side (about 160,000 total) in the human brainstem.