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NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins Nancy Long Sieber, Ph.D. September 27, 2010.

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Presentation on theme: "NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins Nancy Long Sieber, Ph.D. September 27, 2010."— Presentation transcript:

1 NEUROPATHOPHYSIOLOGY III Trauma, Stroke and Toxins Nancy Long Sieber, Ph.D. September 27, 2010

2 Disease and Trauma of the Peripheral Nerves

3 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.

4 Guillain-Barre Syndrome involves demyelinization of peripheral nerves

5 Adaptation to Sensory Loss: Blindness See link:

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7 Anatomy of the Visual System

8 The Braille Alphabet

9 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.

10 Injury and Trauma to the CNS

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12 from Injury to the spinal cord causes loss of function below the lesion site. Causes: 45% motor vehicle 18% falls 17% violence 13% sports, esp. diving Who: 80% male Avg age 31.5 yrs.

13 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.

14 Sensory pathways cross to the opposite side of the spinal cord or medulla before ascending to the cortex. course/bsen1.gif

15 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.

16 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

17 Stroke: Hemorrhagic and Ischemic

18 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.

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22 Neurotoxins Organophosphates Strychnine poisoning Tetanus toxin Heavy Metals –Lead –Mercury

23 Organophosphate pesticides inhibit acetylcholinesterase.

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25 Strychnine Strychnine blocks the activity of glycine, an inhibitory neurotransmitter.

26 Tetanus A soldier dying from tetanus. Painting by Charles Bell in the Royal College of Surgeons, Edinburgh.

27 Heavy Metals Lead Mercury –Elemental mercury (quicksilver) –Methylmercury

28 Intelligence quotient as a function of lifetime average blood lead concentration. Koller, et al. Recent Developments in Low-Level Lead Exposure and Intellectual Impairment in Children. Envtl. Health Persp. VOLUME 112 | NUMBER 9 | June 2004

29 Elemental mercury is used in artisanal gold mining

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32 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. /a_corner/a03.html

33 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.

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