Autonomic Dysfunction in Spinal Cord Injury

TAKEHIKO YUKISHITA＊1), KEIKO LEE＊2), HIROYUKI KOBAYASHI＊1) 2)

＊1)Department of Hospital Administration, Juntendo University Graduate School of Medicine, Tokyo, Japan, ＊2)Center for

Advanced Kampo Medicine and Clinical Research, Juntendo University Graduate School of Medicine, Tokyo, Japan

Autonomic dysfunction following spinal cord injury, which includes autonomic dysreflexia, orthostatic

hypotension, body temperature dysregulation, bladder dysfunction, and bowel dysfunction, strongly influences the

quality of life in spinal cord injury patients. Although understanding the autonomic dysfunction in spinal cord

injury patients will improve their health and quality of life, few medical professionals are familiar with the

dysfunction and its management. Given the sharp rise in the number of elderly patients with spinal cord injury in

recent years, we consider that health professionals should be able to provide proper information on the

management of autonomic dysfunctions to patients with spinal cord injury and their caregivers. This paper

describes an overview of the autonomic dysfunction commonly found in people with spinal cord injury.

Key words: spinal cord injury, autonomic dysfunction, autonomic dysreflexia, orthostatic hypotension,

body temperature dysregulation

Introduction

Impaired autonomic functions following spinal

cord injury strongly influence the patientsʼ quality

of life. Although understanding the autonomic

dysfunction in persons with spinal cord injury is

crucial to improving the health and quality of life in

these individuals, few medical professionals are

familiar with the dysfunction. This paper briefly

summarizes the main points of spinal cord injury

and autonomic nervous system, and then provides

an overview of the autonomic dysfunction com-

monly found in individuals with spinal cord injury.

Spinal cord injury

Spinal cord injury, which involves damage to the

nerves within the spinal canal, often causes

permanent changes in sensory, motor and auto-

nomic functions below the site of the injury.

Physical trauma, such as motor vehicle accidents,

catastrophic falls and sports injuries, fractures or

dislocates the vertebrae. The fractured or dislo-

cated vertebrae irreversibly damage the corre-

sponding level of the spinal cord, impeding neural

communication between the brain and the body.

The level of the injury and the severity of the

damage to the nervous tissue determine how body

functions remain intact or become disabled.

Recent advances in regenerative medicine

research offer hope to spinal cord injury patients,

their family, and health professionals. In particular,

regenerative medicine using induced pluripotent

stem (iPS) cells is anticipated to repair spinal cord

injuries in the near future 1). Given that the

development of regenerative therapy for spinal

cord injury still requires time, appropriate treat-

ments, rehabilitation, and daily management can

370

Corresponding author: Takehiko Yukishita

Department of Hospital Administration, Juntendo University Graduate School of Medicine

2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan

TEL: +81-3-3813-3111 (ext. 3206) E-mail: tyukishi@juntendo.ac.jp

〔Received May 9, 2016〕

Copyright © 2016 The Juntendo Medical Society. This is an open access article distributed under the terms of Creative Commons Attribution Li-

cense (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original source is properly credited.

doi: 10.14789/jmj.62.370

Current TopicsOrgan Diseases and

Autonomic Nervous System

Juntendo Medical Journal2016. 62(5), 370-376

https://creativecommons.org/licenses/by/4.0/

contribute significantly to improving the quality of

life in spinal cord injury patients.

Epidemiology of spinal cord injury in Japan

Even though Japan does not have a national data-

base of spinal cord injury, there are an estimated

5,000 new spinal cord injury patients each year, and

the total is probably more than 100,000 patients. A

survey carried out from 1990 to 1992 concluded that

the annual incidence of traumatic spinal cord injury

was 40.2/1,000,000 2).

However, a recent study showed a higher inci-

dence of spinal cord injury especially in the elderly

population 3)(Figure-1). The epidemiological survey

conducted in Tokushima Prefecture in 2011 and

2012 revealed that the annual incidence of trau-

matic spinal cord injury in elderly people (>65

years old) was 215.7/1,000,000 in 2011 and 230.4/

1,000,000 in 2012, whereas the incidence in individ-

uals aged from 16 to 64 was 106.4/1,000,000 in 2011

and 90.8/1,000,000 3).

Although other surveys indicate that there could

be some regional differences in Japan 4)-6), medical

personnel should expect to witness a marked

increase in elderly patients with spinal cord injury

in the ensuing years.

Autonomic nervous system

The autonomic nervous system regulates various

physiologic processes, such as the heart rate,

digestion, respiratory rate, and urination without

conscious control. The autonomic nervous system

plays an essential role in maintaining homeostasis,

i.e., the dynamic equilibrium of the biological sys-

tems to maintain relative constancy of the internal

environment in spite of external environmental

changes.

The autonomic nervous system is divided into two

major divisions; the sympathetic nervous system

and the parasympathetic nervous system. The two

systems act like an accelerator and a brake on a car.

The sympathetic nervous system is activated in

response to stress and danger and increases the

metabolic activity and rate by releasing epinephr-

ine (Figure-2A). On the other hand, the parasym-

pathetic nervous system is activated during rest,

sleep, and digestion and restores blood pressure and

the resting heartbeat (Figure-2B). These two

systems have opposite effects on the body organs,

which serves to balance each other in order to

maintain homeostasis.

Autonomic dysfunction in spinal cord injury

Autonomic dysfunctions are common consequen-

ces of spinal cord injury. Spinal cord injury disrupts

the descending spinal voluntary motor and involun-

tary autonomic pathways, resulting in dysfunctions

of the cardiovascular system, sudomotor system,

bladder, bowel and sexual organs.

The levels and the severity of injury to these

pathways produce a variety of autonomic dysfunc-

tions depending on the altered supraspinal control

of the sympathetic and parasympathetic nervous

systems 7).

Common autonomic dysfunction in spinal cord

injury includes the following:

• Autonomic dysreflexia

• Orthostatic hypotension

• Body temperature dysregulation

• Bladder dysfunction

• Bowel dysfunction

Autonomic dysreflexia

People with spinal cord injury above T5-T6

occasionally suffer from an acute syndrome of

massive and uncontrollable sympathetic discharge,

which is known as autonomic dysreflexia. Prompt

and correct medical intervention is required

Juntendo Medical Journal 62(5), 2016

371

■ 2011■ 2012

Age（years）16－30 31－45 46－60 61－75 76＋

（/millions/year）

0

50

100

150

200

250

300

350

Incidence

Figure-1 Annual incidence of traumatic spinal cord injuryin Tokushima Prefecture in 2011 and 2012

(Katoh S, et al: Spinal cord, 2014; 52: 264-267 3))

because it may lead to a potentially life-threatening

hypertension 8), which must be recognized imme-

diately; however, few health professionals are

familiar with this condition.

Symptoms of the autonomic dysreflexia include

the following:

• High blood pressure (>20 mmHg above base-

line)

• Pounding headache

• Flushed face

• Sweating above the level of spinal injury

• Nasal stuffiness

• Nausea

• Slow pulse (lower than 60 beats per minute)

• Goose flesh below the level of spinal injury

Autonomic dysreflexia can occur as a result of

peripheral or visceral stimulation below the level of

the injury. The stimulation induces a widespread

activation of the sympathetic nervous system,

causing a rise in blood pressure 9). Normally, nerve

receptors in the heart and blood vessels detect this

rise in blood pressure. Then, the brain sends a

message to the heart, allowing the heartbeat to slow

down and the blood vessels to dilate. However, the

spinal cord lesion blocks the descending inhibitory

signals to below the level of the injury, failing to

lower the blood pressure 8)-10). (Figure-3)

Table-1 shows possible causes of autonomic

dysreflexia in spinal cord injury 8).

If autonomic dysreflexia is suspected, treatment

should be initiated immediately. Table-2 summa-

rizes the treatment of autonomic dysreflexia 8).

Since bladder dilatation and bowel distention are

common causes of autonomic dysreflexia, medical

professionals should investigate these conditions

initially.

Medications are generally used only if the offend-

ing stimulus cannot be identified and removed, or

when the symptoms persist even after removal of

Yukishita, et al: Autonomic dysfunction in spinal cord injury

372

Dilates pupils

Inhibits salivation

Relaxes bronchi

Accelerates heartbeat

Inhibits peristalsisand secretion

Inhibits bladder contraction

Stimulates orgasm

Stimulates glucoseproduction and release

Secretion of adrenalineand noradrenaline

A

T1

T12

Figure-2A: Sympathetic nervous system, B: Parasympathetic nervous system

(©Alila Medical Media)

Constricts pupils

Stimulates flowof saliva

Constricts bronchi

Slows heartbeat

Stimulates peristalsisand secretion

Contracts bladder

Pelvic splanchnic nerves

Stimulates bilerelease

B

Nerve X（Vagus）

Nerve IX

Nerve III

Nerve III

Nerve VIINerve VII

Stimulus（Full bladder）

Inhibitory signalsblocked at SCI

Hypertension BradycardiaVasodilatoradove SCI

Widespreadvasoconstriction

Increasedblood pressure

Baroreceptorresponse

Figure-3 Pathophysiology of autonomic dysreflexia inspinal cord injury (SCI)

the suspected cause. Oral nifedipine administration

is a suitable antihypertensive medication for this

situation.

Prevention of autonomic dysreflexia is the best

approach not only for patients with spinal cord

injury, but also for health professionals 8). Therefore,

patients with spinal cord injury should be educated

on bladder and bowel management techniques. A

brochure on autonomic dysreflexia written in

Japanese published by Beppu National Rehabilita-

tion Center For Persons With Severe Disabilities

will help the patients (http://www.rehab.go.jp/bep

pu/book/pdf/livinghome_no25.pdf).

Orthostatic hypotension

Another blood pressure disturbance caused by

the autonomic dysfunction is orthostatic hypoten-

sion. Orthostatic hypotension is a sudden and

significant fall in blood pressure when a person

assumes a standing position. The Consensus

Committee of the American Autonomic Society and

the American Academy of Neurology defines

orthostatic hypotension as a reduction of systolic

blood pressure of >20 mmHg or a decrease in

diastolic blood pressure of >10 mmHg within

3 minutes of standing 11). Symptoms of orthostatic

hypotension include dizziness, lightheadedness,

blurred vision, nausea, paleness, and temporary loss

of consciousness.

Spinal cord injury patients with prolonged bed

rest often experience orthostatic hypotension even

while sitting on a wheelchair for a few minutes. A

lesion of the baroreflex loop because of spinal cord

injury fails to activate the sympathetic nervous

system, narrowing the blood vessels to adjust the

blood pressure 12).

The loss of lower extremity muscle pump

function due to a spinal cord injury can also cause

orthostatic hypotension 12) 13). Excessive venous

pooling in the lower extremities occurring from the

lack of the skeletal muscle pumping decreases

venous return to the upper body.

Initial treatment of orthostatic hypotension is to

have the patient lie down in a bed or to lean against

the back of a wheelchair. Abdominal binders or

compression garments can be helpful for patients

with severe orthostatic hypotension 14). Gradually

increasing the frequency of a sitting posture should

improve the blood pressure adjustment. Hence,

health professionals should encourage the patients

Juntendo Medical Journal 62(5), 2016

373

Intervention

1 Sit the patient upright

2 Loosen any tight clothing or constrictive devices

3 Monitor the blood pressure every 2 to 5 minites duringthe episode

4 If no indwelling catheter is present, perform an inter-mittent catheterization

5 In an indwelling catheter is present, heck it for obstruc-tions and irrigate the catheter

6 If symptoms are still present and systolie blood pressureis 150 mmHg or greater, treat the blood pressurepharmacologically

7 If symptoms are still present and systolie blood pressureis less than 150 mmHg, manually disimpact the bowel

8 If symptoms persist, search for other precipitants (seeTable-1)

9 Consider admission or referral if symptoms persist or noprecipitant is found

Table-2 Treatment steps for autonomic dysreflexia inspinal cord injury

Category Noxious stimulus

Bladder InfectionDistension

Urinary tract Urethral distensionInstrumentationCalculus

Gastrointestinal DistensionInstrumentationInfection or inflammationUlcerationReflux

Anorectal DistensionInstrumentationHemorrhoidsAnal fissure

Dermatologic Pressure soreIngrown ossification

Skeletal Heterotopic ossificationFractureJoint dislocation

Reproductive Labour and deliveryMenstruationTesticular torsionEjaculationIntercourse

Hematologic Deep vein thrombosisPulmonary embolism

Central nervous system Syringomyelia

Medications Nasal decongestantsSympathomimeticsMisoprostol

Table-1 Possible causes of autonomic dysreflexia in spinalcord injury

to stay active and to avoid lying down on a bed for a

long time.

Body temperature dysregulation

In recent years, heat stroke has become a social

concern in Japan. According to the Fire and Disas-

ter Management Agency, more than 55,000 people

with heat stroke were transported to emergency

hospitals from May 2015 to September 2015 (http:

//www.fdma.go. jp/neuter/topics/houdou/h27/10/

271016_houdou_1. pdf). Although elderly persons

have increased risk for developing heat stroke,

patients with spinal cord injury also carry a high

risk for hyperthermia because of body temperature

dysregulation.

Most people with complete spinal cord injuries do

not sweat below the level of the injury. Further-

more, many quadriplegics cannot even sweat above

the level of the injury. With the loss of the ability to

sweat, patients with high spinal cord injury are

unable to lower their body temperature in a hot

environment 15). Therefore, when patients with high

spinal cord injury stay in temperature over 25℃

with high humidity even for a short period of time,

the body core temperature begins to rise immedi-

ately, and quickly develop hyperthermia. The

symptoms of hyperthermia include nausea, head-

ache, nasal congestion, tiredness, low blood pres-

sure and reduced concentration.

One of the best treatments for spinal cord injury

patients with hyperthermia is to wrap a cold wet

towel around the neck. Health professionals should

advise people with spinal cord injury to avoid hot

environments and to turn on an air conditioner or

an electric fan without any hesitation.

It should be noted that people with spinal cord

injury are more prone to developing hyperthermia

during exercise than people without spinal cord

injury 16). Since Tokyo was elected as the host city

for the 2020 Olympic and Paralympic games, the

number of people with spinal cord injury who

exercise regularly have increased. Medical person-

nel should provide education on how to exercise and

prepare for competitions in the heat.

Bladder dysfunction

Spinal cord injury at any level almost always

affects bladder functions, because the nerves

controlling the bladder originate in the sacral spinal

cord (S2-S4). The kidneys and ureters still work

properly even after the spinal cord injury and keep

producing urine and carrying the urine to the

bladder.

Normally, when the stored urine expands the

bladder wall, the stretch receptors send a message

through parasympathetic sensory nerves and the

spinal cord to the brain. Then, the brain sending a

message back down the spinal cord and parasympa-

thetic motor neurons to the bladder allows the

detrusor muscle in the bladder wall to contract and

the sphincter muscle to relax for voiding. (Fig-

ure-4) As a result, urine passes down the urethra to

exit the body.

Injury to the spinal cord interrupting the neural

communication between the bladder and the brain

impairs the normal bladder functions which involve

the autonomic action of coordinating the relaxation

of the sphincter muscle and contracting the

detrusor muscle, leading to a difficulty in proper

urination.

Following a spinal cord injury, the bladder is

usually affected in one of two ways: spastic (reflex)

bladder and flaccid bladder. Spastic (reflex)

bladder occurs when the stretch receptors are

triggered from filling the bladder with urine. Since

Yukishita, et al: Autonomic dysfunction in spinal cord injury

374

Stretch receptorSensory

Motor

Cerebral cortex

Pons

Detrusor muscle

Internal sphincter

External sphincter

Pelvic nerveparasympathetic fibers

Urethra

Somatic motor fiberof pudendal nerve

Figure-4 Neural control of micturition(©Alila Medical Media)

spinal cord injury blocks ascending messages to the

brain, a micturition reflex is triggered at the sacral

spinal cord to empty the bladder. Spastic bladder

usually occurs when the injury is above the T12

level. Flaccid bladder occurs when the signals from

the stretch receptor fail to contract the detrusor

muscles even when the bladder is full. This can

cause the bladder to become over-stretched.

Prolonged fullness of the bladder forces the urine to

flow back into the kidneys through the ureters,

which is called“vesicoureteral reflux.”

In both types of impairment, bladder manage-

ment to prevent urinary tract infection is impor-

tant 17). As residual urine in the bladder mostly

causes urinary tract infection, bladder management

begins with complete emptying of the bladder.

Intermittent catheterization (ICP) is the preferred

method for spinal cord injury patients to completely

empty the bladder 17) 18).

Bowel dysfunction

Spinal cord injury often disrupts the bowel

function, resulting in complications ranging from

constipation to bowel accidents. Bowel dysfunction

following spinal cord injury is increasingly recog-

nized as a major life-style problem, reducing the

quality of life for spinal cord injury patients 19).

When the rectum walls are expanded with stools,

stretch receptors in the rectal walls send messages

to the brain through the spinal cord, causing an

urge to defecate. The urge to defecate informs the

person to go to the bathroom, and triggers the

opening of the anal sphincter to push out the stool

(Figure-5).

Bowel dysfunction mostly depends on the level of

the injury, and just like bladder dysfunction, it can

be categorized into two patterns: upper motor

neuron bowel and lower motor neuron bowel 20).

The upper motor neuron bowel resulting from a

spinal cord lesion above the sacral level damages

the urge to defecate. The anal sphincter will remain

tight even when the rectum becomes full, and will

open on a reflex basis. The lower motor neuron

bowel, which results from a lesion to the sacral

spinal cord and nerve roots, causes the loss of

defecation reflex and the anal sphincter muscle

remains open. As a result of these bowel dysfunc-

tions, defecation may occur at any time and places

in complete disregard of the patientsʼ wishes.

Bowel management is necessary for patients with

spinal cord injury to stay healthy and to minimize

Juntendo Medical Journal 62(5), 2016

375

Brainstem

Cerebral lesions － Stroke, M.S., Acquired brain injury,Parkinson’s disease, Cerabral palsy

Transverse colon

Smallintestine

Ascendingcolon

Anus Internal anal sphincter（smooth muscle）

External anal sphincter（skeletal muscle）

Rectum

Sigmoidcolon

Descendingcolon

Appendix

Caecum

S1S2S3S4S5

Upper motorneuron

Spinal cordlesions － Trauma,Spina bifida, M.S.

Spinal cord

Hypothalamus

Anterior viewof sacrum

1st

Spinal cord

Coccyx

foramensacralAnterior

Sacral nerves

2nd3rd4th

5thLower motorneurons

Reflex defecationcentre（S2－S4）

Peripheral nerve damage － Diabetes

Figure-5 Neural control of bowel function(©Blamb)

the risk of bowel accidents in social life. Bowel

management emphasizes emptying the bowel on a

regular schedule. The method and scheduling of

bowel movements depend on the level of the injury

and the lifestyle of the patient. The following man-

ual written in Japanese published by the National

Rehabilitation Center For Persons With Disabilities

provides practical information for spinal cord injury

patients with bowel dysfunction (http://www.rehab.

go.jp/whoclbc/japanese/pdf/J29.pdf).

Conclusion

Proper management of autonomic dysfunctions in

spinal cord injury patients will improve their health

and quality of life. Given the sharp rise in the

number of elderly patients with spinal cord injury

in recent years, health professionals should be

informed and prepared to provide proper informa-

tion on the management of autonomic dysfunctions

to spinal cord injury patients and their caregivers.

Acknowledgements

I wish to express my sincere appreciation to the

late Dr. Teruaki Hayashi for taking care of numer-

ous patients with spinal cord injury, including

myself, at Kanagawa Rehabilitation Hospital.

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