Pyramidal system
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Clinic
- Pyramidal tracts are a system of efferent nerve fibers that carry signals from the cerebral cortex to either the brain-stem or the spinal cord.
- It divides into two tracts:
- Corticospinal tract: It starts at Primary motor cortex / Premotor areas and terminates on LMN / Spinal cord Interneurons.
- Corticobulbar / corticonuclear tract: It connects motor cortex to the medullary pyramids
Corticospinal tract
Sign / Symptoms
- Pyramidal tracts are part of the UMN system. Pyramidal signs are:
- Spasticity
- Weakness
- Slowing of rapid alternating movements
- Hyper reflexia
- Positive Babinski sign
These symptoms are all characteristic of an upper motor neuron lesion. However, certain symptoms are specific to a pyramidal tract lesion.
- More on lower extremities than upper ones.
- In presence of asymmetrical findings, ALS should be considered.
Clinical significance
- Parkinsonian-Pyramidal syndrome (PPS) is a combination of both pyramidal and parkinsonian signs
- Pyramidal tract lesions can occur from any type of damage to the brain or spinal cord such as meningitis, multiple sclerosis, or trauma.
- ALS: It causes symptoms of both upper and lower motor neuron syndrome.
- MS: In early MS stages, corticospinal tract integrity is already affected in the absence of WM lesions or brain atrophy. [1]
- Central Pontine Myelinolysis: It is a condition that involves damage to nerve cells in the pons.
Entity / Miasms
I suggest the same Entities / Miasms of UMN entity which are GSS, JE, CJD, NVCJD, HTLV-1 and WEE/ EEE.
- ↑ Pawlitzki M, Neumann J, Kaufmann J, Heidel J, Stadler E, Sweeney-Reed C, Sailer M, Schreiber S. Loss of corticospinal tract integrity in early MS disease stages. Neurol Neuroimmunol Neuroinflamm. 2017 Sep 25;4(6):e399. doi: 10.1212/NXI.0000000000000399. PMID: 28959706; PMCID: PMC5614727.