The Autonomic Nervous System Keith Sequeira MD, FRCPC Assistant Professor UWO.

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/groupsOpportunity 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

SomaticCell bodies inside CNSAxons extend to skeletal muscleAll excitatory

AutonomicSynapse outside CNSFirst and second order axons

Autonomic System

Thought to travel alongside somatic fibers

Autonomic Nervous Systems

Sympathetic

ParasympatheticBoth have afferent and efferent fibersLength 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

ParasympatheticLong pre-ganglionic

SympatheticShort pre-ganglionic

Chemical transmission in the ANS

Pre-gang

fibers

Post-gang

fibers

Effector

organs

Parasymp Acetylchol Acetylchol Heart, Sm. Muscle, lac/sal

glands

Chemical transmission in the ANS

Pre-gang

Fibers

Post-gang

Fibers

Effector organs

Sympath Acetylchol Acetylchol Sweat glands

Norepi Heart, Sm muscle, Vessels, Glands

ANS

ParasympatheticMuscarinicNicotinic

Sympathetic Alpha adrenergicBeta adrenergic

Sympathetic

T1-L3CardiacBlood vessels, sweat glands, hair folliclesLarynx, 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


Redistributes blood from skin and intestine to the brain, heart and skeletal muscle

Closes sphincters, inhibits peristalsis


Chief transmitter at the end organ is norepinephrineHormone 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

ParasympatheticCardiac inhibitionVasoconstriction of the coronary arteries

SympatheticCardiac accelerationDilation of the coronary arteries

Cardiac

Arteries

Veinssympathetic

Bladder

Body Parasympathetic

Base, sphinctersSympathetic – alpha1

Bladder

Treatment

Sexual Function

ParasympatheticsS2-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


SCI subjects with a lesion level above T6

Also been reported in other conditionsCVA, MS


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


Parasympathetic above lesionFlushing of facePounding headacheStuffy noseBlurred visionSlow heart rate


Sympathetic below lesionElevated blood pressure JitterinessGoosebumpsPallor of the skinSweating (above lesion)


Systolic of 250-300 and diastolic of 200-220 have been reported9


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 stimulationFES to legs but not arms16


Complications include:Retinal hemorrhageSubarachnoid hemorrhage Intracerebral hemorrhageMISeizureDeath


Very important

Life threatening

Most serious complication of spinal cord injuries

Treatment

AcutelySit the patient upright

Prevents further increase in blood pressureRapid 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

ParasympatheticsAnatomyTransmittersFunction

Summary

SympatheticsAnatomyTransmitters

ExceptionsFunction

Summary

Autonomic DysreflexiaWhich patientsLevel of injuryTreatment

Summary

Questions

Summary

Thank you

The Autonomic Nervous System Keith Sequeira MD, FRCPC Assistant Professor UWO.

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