Lect 11-27-23 Clinic ANS PDF

Autonomic Nervous System dysfunction after CNS injury Fernando Gomez-Pinilla, Ph.D. Dr. Paul Vespa, Professor of Neurosurgery helped prepare presentation 1 Coordination among organs and tissues Heart rate varies in conjunction with respiration Inspiration: increase in heart rate Expiration: decre...

Autonomic Nervous System dysfunction after CNS injury Fernando Gomez-Pinilla, Ph.D. Dr. Paul Vespa, Professor of Neurosurgery helped prepare presentation 1 Coordination among organs and tissues Heart rate varies in conjunction with respiration Inspiration: increase in heart rate Expiration: decrease in heart rate Inspiration Expiration Inspiration Expiration 3 Integrative ANS response across organs Posture changes triggers changes in heart rate and blood pressure Standing causes a time dependent increase in heart rate and a decrease in blood pressure Tilt table test is useful to diagnose autonomic control of blood pressure Standing HR or BP 150 100 BP 50 HR 0 15 30 60 90 120 150 180 210 240 seconds Fainting is due to abnormalities of one or more segments of the ANS, often working as a protective mechanism The heart or end-organ is affected and cannot increase in rate when standing up Heart doesn’t work Nerves don’t work Pacemaker can correct some of the problem 5 Symptoms of Autonomic Dysfunction A drop in blood pressure on standing (orthostatic hypotension), which can cause dizziness and fainting Cardiovascular problems, such as heart rate abnormalities Trouble with urination, including diminished sensation, overflow incontinence and inability to empty your bladder completely, which can lead to urinary tract infections Heat intolerance, especially during exercise, and abnormal — usually decreased — sweating Male impotence Exercise intolerance Sluggish pupil reaction to light and dark Vaginal dryness and difficulties with arousal and orgasm in women Difficulty digesting food (gastroparesis), which can cause diarrhea, constipation, abdominal bloating, nausea, vomiting, heartburn, feeling full after eating little and loss of appetite 6 Many health conditions can cause autonomic neuropathy. It can also be a side effect of treatments for other diseases, such as cancer. Some common causes of autonomic neuropathy include: •Diabetes, especially when poorly controlled, is the most common cause of autonomic neuropathy. Diabetes can gradually cause nerve damage throughout the body. •Abnormal protein buildup in organs (amyloidosis), which affects the organs and the nervous system. •Autoimmune diseases, in which your immune system attacks and damages parts of your body, including your nerves. Examples include Sjogren's syndrome, systemic lupus erythematosus, rheumatoid arthritis and celiac disease. Guillain-Barre syndrome is an autoimmune disease that happens rapidly and can affect autonomic nerves. •An abnormal attack by the immune system that occurs as a result of some cancers (paraneoplastic syndrome) is another possible cause. •Certain medications, including some drugs used in cancer treatment (chemotherapy). •Some viruses and bacteria, such as HIV and those that cause botulism and Lyme disease. •Certain inherited disorders also can cause autonomic neuropathy. • Loss of temperature control and blood pressure are the most common symptoms of autonomic dysfunction • There is an integrative response to preserve temperature and blood pressure involving the Hypothalamus- Pituitary – Adrenal Axis (HPA) • A decrease in SNS activity promotes vasodilation and temperature reduction while an increase in SNS tone promotes vasoconstriction preserving heat under cold conditions • Pathological response occurs such as high grade fever when there is loss of homeostatic control 8 Brain injury elicits adaptations in ANS control • Types of injuries: – brain trauma – Stroke: subarachnoid and – intracerebral hemorrhage – hemorrhage – acute seizures 9 Leakage of blood into the brain results in an increase in BP 10 Brain injury disrupts autonomic control (cardiovascular regulation) • Injury leads to an increased intracranial pressure (ICP) • Increase in ICP leads to reduction of electrical and neurochemical changes • Increase in BP and reduction in heart rate (Cushing Response) 11 Increase in systemic blood pressure (SBP) after blood brain leakage SBP 120 Time 12 Increased ICP elicits a cardiac and pulmonary response • Sudden onset pulmonary edema – increase in hydrostatic pressure in the pulmonary arterioles and venules – increased capillary permeability with leakage of proteins and fluids into the alveoli – impaired oxygenation – respiratory distress • Cardiac injury: EKG changes, necrosis 13 Neurogenic Pulmonary Edema: Increased SNS activity (catecholamine surge (HR, BP, leaky blood vessels) causes increase in ICP and pulmonary edema 14 Sepsis caused by bacterial release of endotoxins promotes systemic illness and ANS instability • • • • • • Bacteria release of endotoxin Activation of immune response (TNFa, IL-1, IL-6 release) Reduction in peripheral vascular resistance Diffuse increase in capillary permeability Extracellular edema hypotension, increased heart rate, impaired microvascular perfusion HR Temp BP 15 Treatment of Sepsis is aimed at overcoming autonomic failure • Medication to mimic sympathetic tone – norepinephrine infusions (alpha and beta) • Fluids to expand the vascular space • Antibiotics to suppress bacterial toxins 16 Disruption of autonomic nervous system in diabetes • Diabetes Mellitus: endocrine disease of insulin resistance and hyperglycemia – peripheral neuropathy: numb feet, ulcers – autonomic neuropathy: loss of concsciousness with standing up (syncope), gastroparesis – poor heart variability 17 Demyelination of peripheral nerves in diabetic patients promotes autonomic insufficiency Diabetic Patient Mohan et al 2001 Control- age matched 18 Loss of sweat gland control: Iodine Sweat Test for Sympathetic Dysfunction 19