NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins Nancy Long Sieber, Ph.D. September 27, 2010.
NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins
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Transcript of NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins
NEUROPATHOPHYSIOLOGY IIITrauma, Stroke and Toxins
Nancy Long Sieber, Ph.D.
September 27, 2010
Disease and Trauma of the Peripheral Nerves
Dermatomes are the regions on the body that
correspond with specific cranial or spinal nerves.
Damage to a nerve will cause loss of sensation and motor function in that region of the body.
Guillain-Barre Syndrome involves demyelinization of peripheral nerves
http://www.monografias.com/trabajos37/sindrome-guillain-barre/Image8645.jpg
Adaptation to Sensory Loss:
Blindness
See link: http://www.the-scientist.com/blog/display/55315/
Anatomy of the Visual System
http://www.kellogg.umich.edu/theeyeshaveit/anatomy/visual-pathway.html
The Braille Alphabet
Governor Paterson of New York is legally blind. He does not read Braille, but he does have a tremendous memory.
To be legally blind, a person must have vision worse than 20/200 in their best eye, or a visual field of 20 degrees or less.
Injury and Trauma to the CNS
http://dailyme.com/gallery/medical-condition/head-injury.html
from http://www.cureparalysis.org/faq/spine.gif
Injury to the spinalcord causes loss offunction below the lesion site.
Causes:45% motor vehicle18% falls17% violence13% sports, esp. diving
Who:80% maleAvg age 31.5 yrs.
Sequence of events following spinal cord injury
• Spinal shock – transient (hours to days) loss of reflexes in area below lesion. Muscles become flaccid, motor function lost due to injury & inflammation. May lose sympathetic tone.
• Reflexes gradually return over the next few days to weeks. – Axons of surviving cells begin to recover
• Patient may experience hyperreflexia, as normal inhibitory signals that descend down the spinal cord are blocked by the injury. Gradually stabilizes.
Sensory pathways cross to the opposite side of the spinal cord or
medulla before ascending to the cortex.
http://thalamus.wustl.edu/course/bsen1.gif
From: McPhee, Lingappa, Ganong & Lange Pathophysiology of Disease 1995
Injury to one side of the spinal cord can cause loss of function on both sides of the body.
Concerns with spinal cord injury
• Loss of function below site of lesion – may be complete or partial, depending on the injury.
• Loss of thermoregulation
• Pressure wounds
• Autonomic dysreflexia
Stroke:Hemorrhagic and Ischemic
Adaptations to Maintain Brain Blood Flow
• Anastomoses – interconnections between blood vessels, compensate for blocked vessels.
• Autoregulation:– Myogenic autoregulion brain blood vessels dilate in
response to a fall in blood pressure, and constrict in response to an elevation in blood pressure
– Metabolic autoregulation – matches brain bloodflow to metabolic activity
– Helps maintain blood flow if vessel is partially occluded.
http://ww2.heartandstroke.ca/images/english/stroke_isc_web.jpg
http://ww2.heartandstroke.ca/images/english/stroke_hem_web.jpg
Neurotoxins
• Organophosphates
• Strychnine poisoning
• Tetanus toxin
• Heavy Metals– Lead– Mercury
http://www.environmentalhealthnews.org/ehs/newscience/depressed-about-pesticides/
Organophosphate pesticidesinhibit acetylcholinesterase.
http://www.drugstoremuseum.com/sections/level_info2.php?level=1&level_id=74
Strychnine
http://animalpetdoctor.homestead.com/PoisonRat.html
Strychnine blocks the activity of glycine, an inhibitory neurotransmitter.
Tetanus
A soldier dying from tetanus. Painting by Charles Bell in the Royal College of Surgeons, Edinburgh.
Heavy Metals
• Lead
• Mercury– Elemental mercury (quicksilver)– Methylmercury
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1247191/pdf/ehp0112-000987.pdf
Intelligence quotient as a function of lifetime average blood lead concentration.
Koller, et al. Recent Developments in Low-Level Lead Exposure and IntellectualImpairment in Children. Envtl. Health Persp. • VOLUME 112 | NUMBER 9 | June 2004
http://www.ghana-mining.org/ghweb/en/pmu-mssp/mer-abate.html
Elemental mercury is used in artisanal gold mining
http://www.worstpolluted.org/projects_reports/display/56
http://www.nimd.go.jp/archives/english/tenji/a_corner/a03.html
1. Gait disturbance, loss of balance (ataxia), speech disturbance (dysarthria)
2. Constriction of the visual fields
3. Stereo anesthesia
4. Muscle weakness, muscle cramp
5. Loss of hearing
6. Disturbance of sense of pain, touch or temperature.
Adverse effects to nervous system caused by methylmercury.
http://www.nimd.go.jp/archives/english/tenji/a_corner/a03.html
Lupus and the nervous system
• About 10-15% of people with lupus have CNS effects, typically fatigue, headaches, disorientation.
• More common: peripheral neuropathy, typically as a result of vasulitis. Pain, loss of function of extremities, esp. feet. Sometimes autonomic systems is affected as well.
Spi
nal
Cor
d
Organ
{
NT= acetylcholine receptor= nicotinic
Neurotransmitters and receptors of the autonomic nervous system
Parasympathetic (cholinergic)Sympathetic (adrenergic)
Preganglionic neuron
Organ
Preganglionic neuron
Postganglionic neuron
NT= acetylcholine receptor= nicotinic
Spi
nal
Cor
d NT = acetylcholine receptor = muscarinic
NT = norepinephrine receptor= or ß adrenergic
Postganglionic neuron