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The unbearable lightness of the extrapyramidal system
Ricardo de Oliveira-Souza1, Fernanda Tovar-Moll
1D'Or Institute for Research & Education, Rio de Janeiro, Brazil.
Journal of the History of the Neurosciences
|June 26, 2012
Summary
The extrapyramidal system concept has evolved significantly, often misapplied to human basal ganglia or movement disorders. It accurately describes specific brainstem motor nuclei projecting to the spinal cord.
Area of Science:
- Neuroscience
- Anatomy
- Clinical Neurology
Background:
- The term "extrapyramidal system" has a complex history, leading to semantic confusion among neuroscientists and clinicians.
- Its original meaning has been obscured by subsequent interpretations and applications.
Observation:
- This review traces the evolution of the extrapyramidal concept from its origins in the late 1890s to the 1980s neuroimaging era.
- Historical usage often incorrectly equated "extrapyramidal" with the basal ganglia, movement disorders, or spastic hemiplegia in humans.
Findings:
- The misapplication of the extrapyramidal concept in humans stems from animal experimentation, flawed clinical-anatomic deductions, and speculative phylogenetic ideas.
- The study identifies the unwarranted translation of animal study results into human clinical interpretations as a key issue.
Implications:
- The extrapyramidal concept is anatomically valid when restricted to descending fibers from specific brainstem tegmental motor nuclei to the spinal cord.
- Clarifying the definition is crucial for accurate understanding in neuroscience and clinical neurology, avoiding past misinterpretations.
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