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The Autonomic Nervous System Keith Sequeira MD, FRCPC Assistant Professor UWO Objectives 1. Anatomy of ANS 2. Physiology of ANS 3. Elicit a Hx. From a SCI individual 4. Identify Autonomic Dysreflexia (A.D) 5. Treat A.D. Format Didactic Meet the patients/groups Opportunity to talk to a patient Informal Autonomic Nervous System Innervation of INVOLUNTARY structures such as the heart, smooth muscle and glands Distributed throughout the central and peripheral nervous system ANS Blood vessels Viscera Secretion of glands (secretomotor) Endocrine system (homeostasis) Differences Somatic Cell bodies inside CNS Axons extend to skeletal muscle All excitatory Autonomic Synapse outside CNS First and second order axons Autonomic System Thought to travel alongside somatic fibers Autonomic Nervous Systems Sympathetic Parasympathetic Both have afferent and efferent fibers Length of pre and postganglionic fibers differs Afferent Peripheral receptors in wall of viscera and blood vessels Cell bodies in dorsal root ganglia or Cranial Nerve Ganglia Central processes end in dorsal grey column or spinal cord or brainstem Efferent Smooth muscles in walls of hollow viscera and blood vessels Excitatory or inhibitory General layout Efferent pathway – 2 neurons: Preganglionic neuron (myelinated) in spinal cord or brainstem, synapsing with; Postganglionic neuron (unmyelinated) in autonomic ganglion General Layout Sympathetic ganglia are further from the target organs Parasympathetic are located near or in the walls of target organs Autonomic Nervous System Parasympathetic Long pre-ganglionic Sympathetic Short pre-ganglionic Chemical transmission in the ANS Pre-gang fibers Post-gang Effector fibers organs Parasymp Acetylchol Acetylchol Heart, Sm. Muscle, lac/sal glands Chemical transmission in the ANS Pre-gang Fibers Sympath Post-gang Effector organs Fibers Acetylchol Acetylchol Sweat glands Norepi Heart, Sm muscle, Vessels, Glands ANS Parasympathetic Muscarinic Nicotinic Sympathetic Alpha adrenergic Beta adrenergic Sympathetic T1-L3 Cardiac Blood vessels, sweat glands, hair follicles Larynx, trachea, viscera Parasympathetic CN 3, 7, 9, 10 Spinal cord segments S2-4 Parasympathetic Supplies heart, glands and smooth muscles of the viscera NOT sweat glands, blood vessels or erector pilorum muscles Sympathetic Nervous System Fright, Fight or Flight reaction Sympathetic Nervous System Redistributes blood from skin and intestine to the brain, heart and skeletal muscle Closes sphincters, inhibits peristalsis Sympathetic Nervous System Chief transmitter at the end organ is norepinephrine Hormone which circulates along with epinephrine, especially in states of alarm or defense Released by the adrenal medulla Adrenal Medulla Cells of the adrenal medulla behave as neurons in sympathetic ganglia without axons Mostly epinephrine Parasympathetic Aim at conserving and restoring energy Slows the heart rate, increases peristalsis of the intestines and glandular activity and opens the sphincters Heart Carotid baroreceptor Aortic arch receptor Heart Parasympathetic Cardiac inhibition Vasoconstriction of the coronary arteries Sympathetic Cardiac acceleration Dilation of the coronary arteries Cardiac Arteries Veins sympathetic Bladder Body Parasympathetic Base, sphincters Sympathetic – alpha1 Bladder Treatment Sexual Function Parasympathetics S2-S4 originate in the intermediolateral column In males, fibers end in erectile tissue, prostate, vas deferens, seminal vesicles, ejaculatory ducts In females, fibers go to vagina and erectile tissue Sexual Function Sympathetic In females, nerves originate from splanchnic nerves of the ovarian plexus, T10-L2 In males, nerves originate in the hypogastric nerves, T10-L2 Sexual Function “Point and Shoot” P – Parasympathetic S – Sympathetic Brief Review Sympathetic Increases HR and ventricular contraction, dilates blood vessels in skeletal muscles, constricts blood vessels in skin and gut, increases blood sugar level, stimulates sweating, dilates pupils, inhibits gut and gastric secretion Parasympathetic More active at rest Slows down heart rate, constricts pupils, increases gastric secretion and intestinal motility Autonomic Dysreflexia Syndrome of massive imbalanced reflex sympathetic discharge with SCI above the splanchnic outflow (T5-T6) 48-85% of all T6 and above8 Autonomic Dysreflexia SCI subjects with a lesion level above T6 Also been reported in other conditions CVA, MS Autonomic Dysreflexia Noxious stimulus below the level of the lesion Reflex release of the SNS below the level of the lesion Descending input to SNS is interrupted cannot provide interruption of SNS firing Autonomic Dysreflexia Parasympathetic above lesion Flushing of face Pounding headache Stuffy nose Blurred vision Slow heart rate Autonomic Dysreflexia Sympathetic below lesion Elevated blood pressure Jitteriness Goosebumps Pallor of the skin Sweating (above lesion) Autonomic Dysreflexia Systolic of 250-300 and diastolic of 200220 have been reported9 Autonomic Dysreflexia Triggering factors Bladder distention Bowel distention/impaction Ulcer Ingrown toenail Sex/Orgasm Pregnancy/Delivery Cystoscopy Electrostimulation, vibratory stimulation Pregnancy 2/3 of women, T6 and above during labour Consideration for epidural Need skilled staff Electrostimulation Electro-ejaculation and vibrator stimulation FES to legs but not arms16 Autonomic Dysreflexia Complications include: Retinal hemorrhage Subarachnoid hemorrhage Intracerebral hemorrhage MI Seizure Death Autonomic Dysreflexia Very important Life threatening Most serious complication of spinal cord injuries Treatment Acutely Sit the patient upright Prevents further increase in blood pressure Rapid survey of triggering factors If pressure doesn’t begin to improve after 1 minute, consideration for pharmacological treatment “Boosting” The intentional induction of autonomic dysreflexia to try and enhance athletic performance Summary Parasympathetics Anatomy Transmitters Function Summary Sympathetics Anatomy Transmitters Exceptions Function Summary Autonomic Dysreflexia Which patients Level of injury Treatment Summary Questions Summary Thank you