Transcript The Autonomic Nervous System

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