神経系身体機能障害の紹介

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Physical

Dysfunction

the

Nervous

System*

of

DavidButler'"

Introduction

Physical

dysfunction

of

tis$ues

such

as

muscle,

.ioint,

skin, anc{

fascia

is

a

familiar

concept

to

physiot,herapists.

No

one would

deny

that

these

tissues

must

be

_physically

heaEthy

for

optimal

functioning.

Multi-tissue

considerations are an

es-sential

part

of modern

manual

therapy2).

Another

tissue,

whose

physical

health

rnust

be

considered

is

the

nervous system.

This

tissue

and

i'ts

physical

abilities

are often

forgotten

in

manual

therapy,

where

the

preference

has

been

to

fecus

on

joint

and iriuscle.

Jn

recent

years

however,

there

has

been

greater

interest

in

physical

dysfunction

in

the

nervous system and

the

use of

tests

such

as

the

S]ump

test

and

the

Upper

Limb

Tension

Test

have

become

more

cornmon4).

To

play

soccer or

baseball,

talge

up

yoga

or

Tai

Chi

or

_perform

baUet

optimally

requires

a

physical-ly

healthy

nervous system which

moves

and

stretches

during

the

inovements.

The

main

role

of

t/he

nervous

systefn

is

communication

through

elec-trochemical

conduction,

However,

this

communica-tion

must occur

in

a

nervous

system

which

is

con-tinually

moving and stretching.

This

issue,

of a mobi]e and stretchy nervous

system

should

be

a consideration

for

any

profes-sion

involved

with

human

movement.

We

shoutd

also contemplate

the

clinical

consequences when '

IajMXkldiuafi21ag:,

o.]6G,ft "*

_University

of

South

Austrttlia

Kev

words:

Nerve,

Biomechanics,

Neuregenic

pain

the

nervous

system

cannot

adapt

to

movement.

For

example,

there

may

be

scarring

around

periph-eral nerve, an

irijured

disc

may

be

_physically

im-pinging

on

the

meninges or nerve root, or

the

nerv-ous

system

may

be

sensitive

to

any movement

due

to

changes

in

the

sensitivity of some of

its

s}rn-apses.

The

Nervous

System

as

a

Continuum

The

nervous system

is

best

seen as an organ,

meaning

that

when something

happens

in

one

_part,

it

has

repercu$sions

for

the

whole.

To

fully

appre-ciate

_physical

dysfunction

in

the

nervous

system,

it

needs

to

be

seen as a continuum,

The

continuurn

operates

at

three

Levels-mechanicaL

electrical and

chemical.

Changes

in

any

of

these

will

have

impli-cations elsewhere

in

the

system.

Unfortunatety,

traditional

teaching

has

always

divided

up

the

nervous system,

for

instance

into

peripheral,

cen-tral

and

autonomic components and

this

has

im-paired

"continuum

_thinking".

_For

example,

if

a

pa-tient

compiains

of

pain

and

paraesthesia

on

the

lat-eral aspect of

t.he

foot,

it

is

usual

for

clinicians

to

consider

the

tissues

of

the

foot

and

the

L5-Sl

nerve

root as sources.

However,

the

potential

role of

neural

tissue

such

as

the

sural nerve,

the

central

nervous

system

and

the

autonomie

nervous system are

often

forgotten

or

belittled.

These

neural

tissues

can

be

tested

in

many ways.

One

convenient

technically

and

diagnostically

valid

usual-Japanese Physical Therapy Association

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Iy.

be

done

without sophisticated imaging

tech-niques

and

nervc

eonduction

tests

and

includes

tests

which

_physically

load

the

nervous systern,

such as

neurodynamic

tests.

The

term

neurodynamic

test

has

replaeed

tension

teste).

The

term

neurodynamic$ also allows

_greater

recognition of

the

_{physiological}

consequences

of

placing

loading

on neural

tissues.

In

the

_past

there

has

been

too

much

emphasis

on

the

mechanical

fea-tures

alone.

The

operating

definition

of a iieurodyRamic

test

is:

'

A

physical

test

tvhereb.v

a

section

of

the

nervous system's tzzn.rr.e

of

movement

elasticity

and

mecha-nosensitivily

t's

tested

by

combinations

of

limb

meve-ments.

Neuroanatomicag

Design

for

Movement

To

fully

appreciate

t'he

importance

of

_physical

heaEth

of

the

nervous

system,

a

revievv

of

neuro-anatomy

forcussing

on

design

fonnoveinent

is

pre-sented.

1.

Exarnples

of

neuroanatomical

design

for

move-mentb

The

connective

tissues

involved

in

the

nervou$

system,

in

_particular

the

dura

mater, epineurium

and

_perineurium

are extremely strong.

The

gen

arrangement

is

in

the

longitudinal

axis

and

each of

tbe

tissues

contains some

elastin

fibres.

During

flexion

and extension of

the

trunk,

the

posterior

dura

must

stretch

more

than

the

or

dura,

hence

there

is

twice

the

elastic content

in

the

posterior

dura.

eThe _axons

iR

the

_peripheral

_and

central

nervous

systems are

folded

and

twisted.

With

loading,

the

axons

straighten

out and untwisL

This

occurs

in

the

peripheral

and

central nervous

tems

and

is

obviously

a

design

feature

which

allows

unhindered

cemmunication

in

all

_postures

and movements.

-

The

_connective

tissue

_{components of}

the

nervous

systern are well

innervated.

The

dura

mater

is

Association

An

Introduction

to

Physicai

Dysfunction

of

the

Nerveus

System

tt

tt

241

innervated

by

the

sinuvertebral

nerve

and

the

connective

tissue

sheath of

the

_peripheral

ous

system

is

self

innervated

via

the

nervi

nervorum.

This

innervation

is

responsive

to

chemical

and

_physical

stimulL

.

The

_{nervous system weighs}

_about

3

_percent

_of

bodyweight

yet

it

may

take

20

percent

of

the

oxygen

output

of

the

hearL

To

enable a

_good

blood

supply

to

the

nervous

system

in

any

desired

posture,

the

vasa

nervorum

is

designed

with coils, reserve

channels

and

folded

feeder

vessels.

This

anatomical

design

is

necessary

because

of

tbe

forces

on

the

nervous system.

Some

examples

of

forces

_placed

during

daily

activities

follow.

2.

Forces

_placed

on

the

nervous

system

eThe _{spinal canal}

is

between

6

_and

9

_centimetres

longer

in

flexion

than

extension.

The

neural

tissues

contained

in

the

canal

must

continually

adapt

to

the

length

change, without

any

ence

to

conduction.

During

elbow

flexion

it

is

obvious

that

the

rnechanical

demands

on

the

median

and

radial

nerves

are

different

to

that

on

the

ulnar.

.

The

_surrounding

tissues

(neural

_container)

_of

the

median nerye

are

approximaLely

20%

longer

in

a

position

such as

the

Upper

Limb

Tension

TestiO}.

The

tissues

around

the

sciatict'tibial nerve are

proximately

17%

longer

in

SLRi).

Clearly,

the

nervous system needs anatomical

features

_to

allow such movement.

The

nervous system adapts

to

_this

_by

straining

and

thus

increasing

the

pressure

within

its

tissues

and

by

g]iding

in

reiation

to

surrounding

tissues.

Strain

and

movement

of nerves can

be

remarkable.

For

example,

during

eLevation of

the

arm,

the

median nerve may slide

2cm

in

relation

to

sur-rounding

tissues

in

the

armS).

During

cervjcal

flex-ion,

the

brainstem

elongates

one

and

half

Japanese Physical Therapy Association

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242

'

±

'eiijEJts?Xf\'f

I{elationship

between

Me

¢

inanics

aRd

Physiology

ln

a

crude

sense,

the

nervous system could

be

looked

at as a very

large

and

long

ligament

which

contains

nerve

fibres.

However

there

are

Beuro-physioLogical

processes

which are affected

by

and

may even rely on movement.

For

exampLe. venous

blood

flow

in

a

nerve

wil]

stop

at.

8

_percent

nerve

elongation.

The

axopLasm

of neurones carries

neurotransmitters which

rely

on

continual

rnove-rnent and continual oxygen suppiy

to

keep

the

axoplasm

flowing.

The

number and sensitivity of

stretch

activated

ion

channeis

in

the

axolemma

is

such

that

a

certain,

yet

limited

amount

of

move-ment will

bc

permitted

before

symptoms

occur.

The

connective

tissue

sheath of

_peripheral

nerve

and

the

_gliding

tissues

around and

in

thE,'

nerve are

surelv

healthier

with

movement.

"

All

of

these

physiological

processes

are

likely

to

be

aitered

during

injury

or

_pain

states.

Pathobiogogical

Proeesses

Related

to

Physieal

Dysfunetion

in

the

Nervous

System

Various

injuries

ancl

diseases

could

lead

to

altered nervous system mechanics which

in

turn

lead

to

the

clinical

finding

of

_physical

dysfunction

in

the

nervous

system.

Some

examples are a

disc

impinging

on nerve

root,

blood

in

the

spinal

canal

post

surgery,

diabetes,

scar

development

within

a

nerve,

instability

of surrounding

tissues,

and

changes

in

central

nervous system regulation

whieh

may

amplify

impulses

from

the

peripheral

tissues,

including

the

periphera}

nervous

system.

Injuries

or

diseases

may

lead

to

pain

in

the

nerv-ous system.

Pain

and other symptoms

may

be

re-lated

to

changes

in

the

connective

tissues

ef nerve

or

maladaptive

processing

in

the

Iong

fibres.

Maladaptive

processing

involves

changes

in

the

number

and

sensitivity

and

ion

channels

in

the

axolernma

of

neurones6).

eg

25

igce

4

e

Testing

the

Physical

Health

of

the

Nervous

System

via

Neurodynamic

Tests

There

are

three

ways

in

which

a

physiotherapist

can

test

Lhe

_physical

health

of

_the

nervous

system,

if

taught

appropriately:

-

_palpation

of nerves e _neurodynamjc

tests

etests

_of

_the

_physical

_health

_of

_target

_tissues

_of

the

nervous

system,

eg, muscle

and

skin,

1.

PalpaLion

of

peripheral

nerve

Many

peripheral

nerves can

be

carefuily

_palpated

and

the

responses

assessed.

Pathological

changes

in

the

connective

tissues

wi]1

be

usually

mecha-nosensitive

and

any

neuronal

changes

in

peripheral

nerve

(ectopic

impulse

generating

sites) wM usually

be

mechanosensitivc.

2.

Neurodynamic

tests

Just

as

a

muscle

can

be

tested

to

assess

whether

it

has

_good

health

and strength and works

in

pat-tern

with other muscles and a

joint

can

be

tested

to

see

that

it

has

the

required

accessory

and

physio-logical

movements,

the

nervous

system

can

also

be

tested.

There

are

base

neurodynamic

tests

which cover wide areas of

the

body.

These

are

the

SLR,

Knee

Bend

test,

Passive

Neck

Flexion,

Slump

test,

and

Upper

Limb

Tension

Tests

focussing

on

the

radial, median and

ulnar

nerves,

From

these

base

tests,

more refined

tesLs

can

be

perlormed

using

different

sequences of

testing

and

different

staTting

posi-tions.

With

the

appropriate

combination

of

move-ments

the

physical

health

of

miner nerves

such

as

the

sural

or

the

radial

sensory

nerve

can

be

evaluated.

More

refined

testing

would

be

necessary

when

the

clinician

had

a strong

hypothesis

that

physical

dysfunction

of

the

nervous system was

predominant

in

the

_patients

_pain

state.

Therefore

clinicians require clinical reasoning skills

to

utilise

the

tests

safely and effectively4j.

It

is

also obvious

in-Japanese Physical Therapy Association

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volved

during

moveinent.

Introduction

to

Physical

Dysfunction

of

the

Nervous

Systern

3.

Key

issues

in

testing

There

are

many

issues

in

testing4]S]7).

Two

key

issucs

relate

Lo

structura]

differentiation

and

pe-ripheral and central sensitivity.

Structurai

differentiation

is

a

testing

process

which

is

used

to

infer

that

a

patient

has

a

_physical

dysfunction

in

their

nervous sy$tern.

It

involves

the

movement

of

a

distal

part

of a

limb

or

the

body

to

see whether

this

ehanges an already evoked

pain.

For

exampie

in

SLR,

if

the

addition

of

ankle

ciorsiflexion

alters spinal

pain,

t.hen

there

is

li]sely

to

be

some

_physical

dysfunction

in

the

nervous

system.

Another

example

is

when cervical

flexion

aEters

low

back

pain.

The

inference

of

_physical

dysfunction

in

the

nervous system

is

increased

if

there

are

other

features

in

the

pattern

suggestive of

nervous

system

involvernenL

for

examplc,

symp-toms

in

an

innervation

field,

er

the

presence

of

paraesthesia4).

Closely

linked

to

structural

differentiation

is

the

examination

of sensitivity.

When

a neurodynamic

test

(or

any

_physical

test)

is

_performed,

the

mechanosensitivy

could

be

from

any

damaged

tissue

lprimafrv

hmperaigesia)

or

it

may

be

due

to

changes

in

central nervous system sensitivity.

This

means

that

the

structures

examined may

be

quite

normal

or

minirnally

damageci

but

changes

in

the

central nervous system

are

amplifying

input

even

non-noxlous

input.

This

is

called seconda7Iv

hJ)peralgesia7).

Treatment

and

Neurodynagnic

Tests

Neurodynamic

tests

can

be

used

[n

treatment.

Guidelines

are

in

reierences4}

5)7).

The

aim

is

, as

far

as

possible,

to

give

the

_patient

back

what

they

once

had.

Therefore

te

return

the

nervous system

to

its

ability

to

gLide

and

stretch

without

any undue mechanosensitivity.

This

can

be

achieved

with careful active Find

passive

movement of neural

243

tissues

and

the

tissues

which

surround

the

nervous

system.

The

clinician's

knowledge

of

neure-dynamics

and nervous system

mechanosensi-tivity

should also

be

_passecl

on

to

the

_patient.

The

ideal

approach

is

for

the

patient

to

understand

his

condition and

treatment

rationale

'in

combination

with

the

appropriate movement

therapy.

Conclusiom

Physical

health

of

the

iiervous systein

is

a

nece$-sary

_part

of

health.

Physiotherapists

should

con-sider

the

mechanical abilities and sensitivity of all

tissues.

To

date,

the

nervous system

has

been

for-gotten

in

manual

therapy.

This

_paper

encourages a

closer

look

at

the

rnechanics

and

sensitivity

of

neural

tissues.

References

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Beith

ID,

Robins

EJ,

Richards

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assessment of

the

adaptive mechanisms within and surrounding

the

periphera[

nervous systeui, cluring changes

in

nerve

bed

le"gth

resu]ting

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Churchill

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Zoech

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