The Gazette 1989

453 / 482

GAZETTE DECEMBER 1 9 89
Whiplash
Whiplash injury of the spine and supporting structures is arguably
the most common injury experienced by victims of motor accidents
in the Republic today. Public perception of whiplash is of a minor
injury, often exaggerated by the patient. Unfortunately, lawyers can
be of a similiar opinion, and this article should improve their
understanding of this debilitating injury.
The force of impact on the spine the sensory nerves causes pain or
and skull varies in proportion to the
speed of collision. Studies show a
rear end impact at 10 mph pro-
duces a force of nine times gravity
(9g) in the area of the lower spine,
and causes a whiplash effect of
acceleration and deceleration or
hyperextension (backward) and
hyperflexion (forward) movement
of the spine. By leverage the impact
force at the lower spine is amplified
almost threefold at the upper spine
and skull, and thus the skull con-
tents suffer a force of twenty three
times gravity (23g) even at this low
speed of 10 mph. Thus, speeds of
30 mph can bring forces up to
seventy times gravity (70g) to bear
• on the skull contents.
" . . . speeds of 30 mph
can bring forces up to
seventy times gravity
(70g) to bear on the
skull contents."
Although the range of movement
between any t wo adjacent verte-
brae is very restricted (probably
blocked by the intervertebral discs),
the spine has a relatively wide
range of movement due to the sum
of all the vertebral movements.
Hyperextension and hyperflexion
greatly exceed the normal move-
ment range of the spinal joints, and
they react as any other joint, e.g.
ankle, subjected to sprain. Trau-
matic arthrosis w i t h oedema
(swelling) of their synovial lining
and supporting ligaments is pro-
duced. This swelling may cause
pressure on the nerves which exit
from the spinal cord through the
intervertebral foramina.
The three main nerve types
which emanate from the spinal
cord through the intervertebral
foramina are: (i) sensory, (ii) motor
and (iii) sympathetic. Pressure on
paraesthesiae (numbness) over the
dermatome (the portion of skin
subserved by the particular nerve).
Motor nerve impingement may pro-
duce power loss, as when one's
knee suddenly gives way. Injury to
the sympathetic nervous system is
By
Cahal J, Mu l d o o n,
,
F.D.S.R.C.S
suspected when blurring of vision
and hearing upsets occur.
" . . . the syndrome of
pain and muscle spasm
is self-perpetuating."
The paraspinal muscles are
arranged in mirror images of each
other on either side of the spine,
and work together by propriocept-
ion to maintain a normal posture
throughout all movements. Some
of these muscles are torn and
injured by the whiplash mechan-
ism, and are painful in use. This
pain and the pressure on the sens-
ory nerves due to joint swelling will
produce a reflex arc involving the
motor nerves, and cause muscle
spasm. Pain and spasm prompt
inappropriate movements of com-
plementary muscles e.g. spasm of
one trapezius muscle activates the
contralateral trapezius muscle of
the neck and upper back, and so
the syndrome of pain and muscle
spasm is self-perpetuating.
" . . . pain and
discomfort interfere
with sleep, and this
compounds tiredness
and irritability."
At the upper end of the spine, the
skull and brain suffer approximately
three times as much force as the
lumbar area. Injury to the frontal
cortex, temporal lobes and tissues
around the limbic system of the
brain results. These areas govern
mood, feelings and behaviour in the
normal subject, and their injury is
followed by poor memory, de-
creased concentration and irrita-
bility. The pain and discomfort
interfere wi th sleep, and this com-
pounds tiredness and irritability.
The muscles of the throat and the
temporomandibular joint can also be
strained by whiplash, and pain on
swallowing and chewing is then seen.
Headache is a prominent part of
this syndrome, and may arise in
two ways. Firstly, sudden decelera-
tion/acceleration of the brain within
its fixed compartment of the skull
causes a contra coup effect, with
cortical oedema and micro haem
orrhages of the brain stem.
Secondly, reflex spasm of the
muscles in the back of the skull and
upper neck produces a tension
headache at the back of the skull.
"The patient . . . is
unable to sit
comfortably or adopt a
normal posture on
standing."
Cahal J. Muldoon.
4 3 1