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 fibers Effector organs ParasympAcetylchol Heart, Sm. Muscle, lac/sal glands

Chemical transmission in the ANS Pre-gang Fibers Post-gang Fibers Effector organs SympathAcetylchol Sweat glands NorepiHeart, 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

Oculomotor Constricts the pupil

Facial Salivary and lacrimal glands Chorda tympani branch

Glossopharyngeal Parotid gland Secretomotor to the oropharynx

Vagus Larynx, pharynx, cardiac, smooth muscles glands, viscera of thorax, neck and abdomen

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

Smooth Muscles of the Eye and Orbital Cavity Parasympathetic Miosis Sympathetic Mydriasis

Glands in the Head Parasympathetic Stimulation of secretion watery Sympathetic Secretion Mucous like

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

Lungs Parasympathetics Bronchoconstriction Stimulation of secretion Sympathetic Bronchodilation Inhibition of secretion

Sweat glands Parasympathetic with respect to the chemical transmitter, although sympathetic anatomically

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 above 8

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 and diastolic of have been reported 9

Bradycardia Part of the clinical scenario, but: Kewalramani et al, found 10% bradycardia, 38% tachycardia during AD episodes

Autonomic Dysreflexia Triggering factors Bladder distention Bowel distention/impaction Ulcer Ingrown toenail Sex/Orgasm Pregnancy/Delivery Cystoscopy Electrostimulation, vibratory stimulation

Iatrogenic Causes Cystoscopy Chancellor et al. described 6/39 developed AD with flexible cystoscopy 14 Lithotripsy Conflicting reports of AD 1995 Robert et al. described 15 patients without AD

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 arms 16

Autonomic Dysreflexia Given no AD with lungs and FES to arms: Afferent stimuli below T6 that may trigger dysreflexia reaction and not all stimuli below lesion level?

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

Treatment The goal is a: balanced bladder

“Boosting” The intentional induction of autonomic dysreflexia to try and enhance athletic performance

“Boosting” Burnham et al. studied 8 elite quads with 7.5 km road race Blood pressure, O 2 utilization, noradrenaline concentration were higher during boosted conditions, lower SV Metabolic parameters (glucose, lactate, FFA utilization), cardiac output not affected Improved race time by 9.7% Peripheral mechanism? Lipolysis?

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