Stephen J. Davis, Mark A. Ziemba,

MRCP, MD2

FRACR

Cervical Spine MR Findings’

showed

characteristic

separa-

tion of the disk from the vertebral end plate, lesions still evident as late as 9 months

stration delayed nostic These

after

injury.

The

demon-

of this type of lesion resolution may have

and prog-

its

and surgical implications. lesions, anterior longitudinal

ligament tears,

injuries, and

occult

anterior anterior

had

acute

cervical

hernia-

tions causing cord impingement. Radiographically occult injuries are well demonstrated with MR imaging, and findings correspond to previously

ical

described

surgical

pathologic

and

anatom-

conditions.

terms: Ligaments, injuries, 319.49 #{149}Ligaments, spinal, 319.49 #{149} Ligaments, MR studies, 319.1214 #{149} Spinal cord, compression, 341.49 Spinal cord, injuries, 341.49 #{149} Spinal cord, MR studies, 341.1214 #{149} Spine, injuries, 31.412 Spine, intervertebral disk, 3i6.423 #{149} Spine, MR studies, 31.1214 #{149} Trauma 1991;

extension, most

or of which

Californian

Orthopedic

MATERIALS

reviewed.

principal selection

surgical

underwent injury, and

have juries

to prevertebral

muscle,

inter-

vertebral disk, and anterior longitudinal ligament (ALL), lesions that have been difficult to confirm with imaging in humans (2,3) (Fig i). In the second mechanism, hyperextension injury results from direct anterior craniofacial trauma. Although trauma

may

result

in serious

dislocation,

the

hy-

radio-

graphic features are often subtle and fractures may be occult (4), making radiographic recognition difficult,

even in unstable injuries. Twenty-five percent of the Duke University series of 400 tension many graphic

cervical fracture

injuries were dislocations,

of these

showed

signs

minimal

(MR)

radio-

(5).

The purpose of this study determine whether magnetic imaging

can

be

was to resoused

to

define the nature and severity of hyperextension cervical injuries and relate the findings to reported pathologic and radiologic features. The relationship of clinical features to MR findings

was

attempt

to identify

assessed

in a preliminary

patients

Group,

likely

to

from and have management by the ability to demonstrate with MR imaging.

Valley

Presbyterian

Hospital,

Extension

imaging

details

tion are outlined

in the Table.

tients underwent at 3 months and jury.

the

Three

patwo

follow-up imaging: one at 9 months after

in-

Three imagers at three institutions were used to obtain the following images: a i.5-T imager (Signa; GE Medical Systems, Milwaukee) to obtain 5-mm-thick, sagittal, TI-weighted (500-600/20 [repetition time msec/echo

time

msecj,

one

signal

aver-

aged) and 5-mm-thick, sagittal and T2*weighted gradient-echo (75/i3, angle, six signals averaged) images; 0.35-T

imager

(MT/S;

Diasonics,

Calif) to obtain 5-mm-thick, weighted (1,000-1,500/40, averaged) and 5-mm-thick,

tems

North

axial, 200 ffi a

Milpitas,

sagittal, T280, two signals axial (1,500/30,

images; and Philips Medical

America,

Shelton,

a 1.5-T Sys-

Conn)

to

obtain

4-mm-thick, sagittal, Ti-weighted (600/20, two signals averaged); 5-mmthick, sagittal, cardiac-gated, T2-weighted (1,900-2,100/25,

and

100,

5-mm-thick,

signals derwent

dergoing

two

axial

averaged)

signals

two

All

patients

un-

before

Un-

images.

cervical radiography MR imaging.

The MR images

averaged);

(i,000-1,400/20,

were

evaluated

for the

following abnormalities in a systematic anatomic assessment conducted from anterior to posterior: (a) prevertebral injuries to the scalene, longus colli, sternocleidomastoid,

Van

was

No other All patients within 4 months of of the patient popula-

two signals averaged) imager (Gyroscan;

hyperexand

METHODS

mechanism of injury. criteria were applied.

are mild.

However, experimental and studies of this injury type demonstrated characteristic in-

AND

MR images and clinical reports of nine patients injured in rear-end motor-vehicle collisions and five patients with direct facial or anterior cranial trauma were retrospectively

Magnetic Resonance Center, Long Beach Memorial Hospital, Long &ach, 28, 1990; revision requested August 15; revision received February 25, 1991; acAddress reprint requests to S.J.D., Magnetic Resonance Imaging, Department of Gardiner Hospital, Verdun St. Nedlands, Western Australia 6009, Australia. University of Cahifornia, San Francisco, Veterans Administration Medical CenSouthern

MD, PhD

Jr.

Injuries:

sult in acceleration “whiplash,” injuries,

benefit altered lesions

180:245-251

I From the Memorial Calif. Received June cepted February 28. Radiology, Sir Charles 2 Current address: ter, Fresno, Calif. 3 Current address: Nuys, Calif. t: RSNA, 1991

G. Bradley,

hyperextension injuries are common and are associated with significant morbidity (i). They occur by means of two mechanisms. Rear-end motor-vehicle collisions re-

nance

Index

Radiology

William

#{149}

ERVICAL

perextension

vertebral

disk

C

such

annular

end-plate fractures usually occurred at multiple levels except when preexistent degenerative disk narrowing reduced spine mobility. Seven patients

MD

Hyperextension

Cervical hyperextension injuries are common and often show minimal radiographic abnormalities, even with severe or unstable lesions. Fourteen patients, nine with acceleration hyperextension “whiplash” injuries and five injured by direct frontal head trauma, underwent magnetic resonance (MR) imaging within 4 months of injury. Five of seven patients with anterior spinal column injuries

Louis M. Teresi, Bloze, MD3

#{149}

A. Elizabeth

#{149}

and

other

prevertebral

esophageal,

laryngeal,

sue

and

injuries;

and

prevertebral

muscles;

other

soft-tis-

hematomas

and other fluid collections; (b) anterior spinal column injuries, including ALL tears or “sprain” injuries; anterior intervertebral disk injuries, including horizontal separation of the disk from the vertebral end

Abbreviations: ligament, ment.

PLL

ALL =

=

posterior

anterior longitudinal longitudinal liga-

245

Radiographic

and MR Findings Radiographic

in 14 Patients

Findings

Time

MR Imaging

Between Injury and

Patient Age (yb’ Sex

Soft-Tissue injury

MR Imaging

Spondylosis

Findings

Anterior Prevertebral Abnormality

ALL

injury

Disk injury

Fracture

Multilevel Disk Herniation

Cord injury

Posterior injury

Disk Injury

Whiplash 33/F

4WF 2WF 42v’P 36/F 44/F 35/M

. . .

C5-6

. . .

C5-6 . ..

. . .

. . . . . .

Wide disk C5-6, C6-7 Wide

2mo 4mo 4wk 4 wk

C5-6,C6-7

...

74iM

4mo

. ..

. . .

2mo 2mo

. . .

disk

. . .

. . .

. . .

. . .

. . .

. . .

. . .

...

...

. ..

. . .

..

. . .

. . .

. . .

. . .

. .

. . .

. . .

...

.

.

...

6 wk

C6.7

C5-6 C5-6

. . .

. . .

C5-6, C6-7

. . .

C5-6

.

. . .

...

. . .

. . .

...

...

. ..

...

. . .

. . .

. . .

...

. . .

. . .

. . .

. . .

...

. ..

..

.

. . .

...

C5-6

C6-7

. . .

. . .

Yes, 2

C5-6

C5-6

. . .

Interspinous

Yes, 2

..

C-6 end plate . . .

. .

.

C5-6

ligament

26fF

...

.

2wk

..

...

...

Direct 43,?

Wide disk

C5-6, C6-7

4 wk, 3 mo 8 d, 9 mo 3d

C6-7

4M4 5WM

...

. . .

. . .

Wide disk C6-7

46/F

C4-5, C5-6

. . .

7d

. . .

. . .

Craniofacial

. . .

. ..

. ..

C5-6

Yes

. .

C4-5, C5-6

Yes

. . .

Yes

. . .

...

Trauma

C5-6, C6-7

. . .

. . .

C5.6,

. . .

Yes, 2

.

C6.7 . .

.

. . .

C6-7

. . .

Fluid,

musde

. . .

C6-7

. . .

C6-7

C-7, T-1

. . .

. . .

Yes

C5-6

. . .

Yes, 3 Yes, 2

C5-6 facet

Yes, 2

end plate 4U’M

Subtle

C4-5, C5-6, C6-7

soft-tissue widening

plate

and annular

anterior

terial

injury;

rior longitudinal

body;

trauma and

(c) posterior ligament

to the

vertebral

ar-

disk and poste(PLL)

injuries,

induding disk herniation, preexistent spondylosis, rupture or separation of the PLL from the vertebra, and epidural hematoma formation; (d) spinal cord injury; and (e) fluid collections adjacent to or fractures of the posterior vertebral arch and injuries

to the

and musdes Symptoms, graphic

posterior

cervical

(2). clinical

findings

signs,

were

ligaments

with

MR

The

anatomical

caused

by each

mechanisms

sites

of the

of injury

Column

Seven

of lesions two distinct are presented

partially

torn

anterior

as well as separated from vertebral body below (Fig other

level,

the

Yes

. . .

Yes,

. . .

although elongated and at two adjacent spaces,

which

was

consistent

healing Five

tear (Fig 3). patients had

from

with

increased

intensity

a sprain

separation

the vertebral

plate,

intradiskal

paralleling

the been

or

of the

end

pro-

signal

vertebral

images seen

injury, and in severe

Injury

3

patients

had

evidence

injury,

two

of an

from

the

imaging lowed

studies.

(Figs 4, in experi-

up

at 3 months,

hires had healed, tensity persisted rupture

in the

patient the

end

Disk in

rup-

plate,

indicating slower healing of the disk (Fig 4). High signal intensity at the interface of the disk and vertebral end plate was seen as late as 9 months after injury. These duced characteristic

disk

injuries shortening

patient

had

a frac-

levels.

ALL

ruptures,

ver-

less

mobile

(Fig

7).

Herniation

to

but high signal inat the site of disk vertebral

or three

presumably

fol-

ALL

No

tebral end-plate fractures, separations of disk from end plate, and disk herniations were all seen at multiple 1evels. The other patient’s injury occurred immediately adjacent to spondylotic segments, which were

at postmortem extension frac-

In one

types.

fractures of plates (Figs withboth

ture recognized on cervical radiographs obtained before MR imaging, although some patients had evidence of disk widening (Table). Among the seven anterior column injuries, six had evidence of multilevel injury (Figs 2-6) occurring at two

end

dislocations (7-9). It has been confirmed at diskography but not, our knowledge, seen noninvasively

(6)

There were three occult the anterior vertebral end 3, 6) occurring in patients injury

ligament

was intact, redundant

hire

column

Radiology

#{149}

2). At the

extension examination

acceleration hyperextension whiplash group (Figs 2, 3) and five from the direct craniofacial trauma group (Figs 4-7). Four patients had ALL injuries, two had horizontal avulsion of the vertebral end plates, and five had separation of the disk from the vertebral end plate. Two patients had ruptures of the ALL anterior to the disk, with tears at two disk levels in one patient (Figs 4a, 5a). At one level, the ligament ap-

246

C3-4

. . .

mental “acceleration extension” injuries, at anterior interbody fusion surgery performed up to 2 years after

Table.

anterior

at least

plate on T2-weighted 6). This lesion has

RESULTS

Anterior

. . .

to the disk, the anterior

ducing

and radio-

correlated

peared

disk

findings.

in the

Fluid

C3-4

tearing

vertebral

1d

proand

thickening of the torn anterior anulus (Figs 4, 5), with separation of the anulus from the end plate.

Of the

nine

patients

with

accelera-

tion hyperextension whiplash injuries, four had acute posterolateral cervical disk herniations large enough to indent or displace the cord (Figs 2, 3). All four patients developed radicular arm

symptoms

after

several

weeks,

with three showing a positive Spur!ing maneuver where lateral flexion of the cervical spine to the side of a posterolateral disk herniation produces radicular symptoms to that side. At clinical examination, six of these nine patients had immediate onset of neck pain, a clinical feature associated with a more severe injury, and all disk herJuly 1991

a.

b.

Figure 2. Six weeks after rear-end motor-vehicle-accident whiplash injury, an acute disk injury at C5-6 above the C6-7 spondylotic level is seen in sagittal (1,500/40 [aJ and 1,500/80 [bJ) images. The characteristic site of hyperextension disk injury is adjacent to the end plate with

high

signal

intensity

on the 1,500/40

image

(arrow

in a) and

a poorhy

defined

increase

in signal

intensity in the anterior half of the disk on the i,500/80 image (straight arrow in b). A large disk herniation is at the same level, with rupture of the PLL and inferior extrusion. A sprain or partially healed tear of the ALL is at C5-6 superiorly, and apparent ALL discontinuity anterior to the C-6 vertebra is at an unusual site for injury (arrowhead in a), possibly due to the adja-

cent disk degeneration. Figure include

1. Injuries due to cervical extension (a) tear of the ALL at the level of the end plate, (b) focal prevertebral fluid collection, (c) horizontal fracture of the vertebral end plate (d indicates normal anterior curve of prevertebral fascia anterior to C6-7 [21,22]), (e) separation of the disk from the vertebral end plate, (f) posterior disk herniation, (g) tear of the anulus with thickening and redundancy of the fibers, (h) cord injury due to transient posterior subluxation of C-4

on C-5 with resultant compression the posteroinferior C-4 vertebra of C-5. (Modified from reference

between and lamina 18.)

Low signal

intensity

in the posterior

mediate onset of symptoms. Three presented with the central cord syndrome, one with an anterior cord syndrome, and one with incomplete quadriparesis. All five had evidence of cord “edema,” with diffuse increase in cord signal intensity on T2weighted MR images but no evidence

were

onset

24 hours

seen

of neck

after

in this

pain,

injury,

group.

often

De-

up to

is a typical

fea-

ture of mild ligament injury and a clinical feature in most patients with acceleration hyperextension injury (iO). The three patients with delayed onset of neck pain had no evidence of injury at MR imaging. Three of the five patients with direct craniofacial trauma had disk herniations large enough to indent or displace the cord, occurring at two levels in one case, for a total of eight disk herniations of this size in seven patients in the entire study group. Two of the disk herniations had apparently ruptured through the I’LL (Figs 2, 6), a feature described as uncommon in one large series (ii). Disk herniations occurred above, below, or at the level of the anterior column

appears

elongated

at C4-5,

C5-6,

is oblique transverse in the anterosuperior

and

C6-7.

altered signal inend plate of C-6

tensity (arrowheads) associated with probable disruption of the ALL (arrow). Similar changes are suspected at the anterosuperior end plate

of C-5. No fracture was seen on plain radiographs. Bulges exist at C4-5 and C5-6, and an acute left paracentral disk herniation is at C6-7.

Note

opmentally

Volume

the

multilevel

small

180

injury

a devel-

1

hemorrhage

or other

curve

poor

prognostic sign (i2,i3) (Figs 4a, 5b). All five had clinical improvement, and resolution

was

complete

Paravertebral

in three.

Injuries

Two patients had evidence of prevertebral fluid collections i and 7 days after injury (Figs 6, 7). One of these had a focal muscular injury involving the longus colli muscle (Fig 6c). One patient had evidence of injury in the posterior interspinous ligaments (Fig

40

DISCUSSION Mechanism

prognostic feature in both mechanisms of injury. If the spondylosis severe enough to cause disk space

was

narrowing, the acute disk injury occurred at a normal disk adjacent to the level of spondylosis (Figs 2, 7). Injury

All five patients injured by means of direct frontal head trauma were first

canal.

#{149} Number

and

of cord

flexion injury with a forward

2b).

patients, all aged more than years, had evidence of preexisting degenerative disk disease, a poor

Cord

site of a recoil anterior to C-7,

of C5-6 is

niations

layed

Five

There

region

expected space

injury. Figure 3. Four weeks after a rear-end motor-vehicle-accident whiplash injury, acute disk herniation at C6-7, sprain of the ALL, and probable occult end-plate fracture are seen in a sagittal (500t20) image. The ALL

interspinous

most likely due to hemosiderin deposition at the (curved arrow in b). Note the normal prevertebral of the prevertebral fascia. 6 = C-6.

seen

with

myelopathy

with

im-

and

Manifestations Injury

Pathologic of Hyperextension

Hyperextension injuries are common (Fig i). Eight percent to 20% of motorvehicle

accidents

are

rear-end

coffisions

and often extension Whiplash,

result in acceleration or whiplash injuries

extension

injury

the neck the head

originally

without or neck

described

to the

soft

hyper(1,14). as

tissues

hyper-

of

application of force to (i5), has also been deRadiology

#{149} 247

a.

b.

a.

Figure 4. Hyperextension caused by direct facial trauma with anterior cord syndrome. (a) In a sagittal (1,900/25) image obtained at 4 weeks, rupture of the ALL at two levels (C5-6 and C6-7) is shown (arrowheads). The rupture occurs adjacent to the end plate. The low-signalintensity vertical bands in the anterior disk likely represent “retracted” outer annular fibers (straight arrows). Disk herniation is at the level of injury to the anterior column (C5-6) with

adjacent cord injury (curved arrows). Mild disk degeneration is present. (b) In a sagittal (1,900/ 25) image obtained at follow-up 3 months after injury, the ALL shows evidence of healing (arrows).

The

fined

as an “acceleration

sprain”

anterior

(2,3).

ception

anuhus

some

of the

and

authors

head ward

when after

tension ing

the

recoil

the body a rear-end

flexion

and

on

(3). An element

with pain of several

C-5

to

strik-

be followed

by

of rotation

makes the disks and ligaments ble to rupture (16). Most ( > 95%) of these injuries

mild, terval

the

by the occiput may

ALL

and

the

end

plate.

4

features

=

are

C-4.

often

subtle

and fractures may be occult, even in unstable injuries. In one series, 30% had only soft-tissue swelling, 65% had thin, transversely oriented fractures of the anteroinferior end plate (Fig 7), 15% had disk widening, and 15% had disk

of

accelerates forimpact. Hyperex-

centers

is limited

back,

disuse

(2). Hyperextension from inertia of the

generally

C-6 level,

per-

ongoing the

the

radiographic

public

decry

this term altogether of the neck results

from

extension

Because

of litigation

ability,

is separated

susceptiare

developing after an inhours or days and

vacuum phenomenon (4), a nonspecific phenomenon that is most commonly caused by degeneration (17). Focal widening of a disk space, an indicator of a potentially serious unstable injury (18), was seen in all four of our patients with ALL injury (Figs 4a, 5a). The spectrum of cervical hyperextension injury ranges from tears of muscu-

har fibers

to serious

lesions

such

as sepa-

symptoms then intensifying, similar to ligament injuries elsewhere (10). Moderate injuries produce immediate and severe symptoms and result in tears of muscle and the ALL, stretch and tear of

ration of the disk or damage to the posterior joints. Anterior precervical muscular tears involve the sternomastoids, scalenes, longus colli (Fig 7), or

the lower

stretched,

cervical

disk

anulus,

and

trac-

tion of sympathetic and cervical plexus nerves or roots. Severe injuries occur in 1 % and include enlargement of intervertebral disks, neurologic deficit including quadriplegia without bone damage, and cerebral contusion (10).

The second

mechanism

causing

cervi-

cal hyperextension injury is direct anterior facial or craniofacial trauma. Although these injuries may result in serious hyperextension dislocations, the 248

Radiology

#{149}

esophagus.

The

the

the ligament anulus

beneath

of the

ALL

ALL

may disk,

and

more

tear

PLL

away

causing

the prevertebral

are

severely,

and

from

the

hemorrhage

fascia.

More

severe force disrupts the ALL and may either separate the intervertebral disk from the vertebral end plate or cause horizontal rupture of the disk. Continued posterior displacement of the vertebra separates the I’LL from the vertebral body and fractures or dislocates the facets

or

other

posterior

elements.

The

b.

Figure

5.

Day 3 after

hyperextension

injury

caused by direct frontal head trauma (central cord syndrome). (a) MR image (1,900/25) shows disk bulges at C4-5 and C5-6 and nipture of the ALL just inferior to the C-6 infenor end plate (straight arrow) at the site characteristic of hyperextension injury. There is annular tearing at the anteroinferior margin of the C4-5 disk (curved arrow) producing thickening of the anterior annular fibers. (See also Fig 4b.) Note the multilevel injury and developmentally small canal. (b) T2-weighted image (1,900/100) shows cord injury characterized by ill-defined increased signal intensity in the cord posterior to C-4, C-5, and C-6 (between arrows). The clinical syndrome resolved in iO days, and

the cord-signal-intensity also resolved later. 4, 5, 6

cord

may

posterior

retroluxing

=

be

abnormality

had

at follow-up imaging 3 months C-4, C-5, C-6, respectively.

“pinched”

inferior

vertebral

between

margin

of

body

the

the and the July

lam1991

b. Figure 6. herniation i,900/100)

with cord injury images. The ALL

T-i (arrows

in b) are shown

sion

At day

extends

inferior (* in b) and

brah fluid the longus

adjacent

injury.

The

to the

of the

left

subjacent often

on midline sagittal but characteristic

(2). The disks

at C5-6 and

C5-6

and

signs

improved

leaving

compression, in the left

cervical

(18).

facets

almost

normal

spinal

ALL,

the largest

cervical

spine,

inferior

C-2

midpoint

of

thickest

over

with

vertebral

the

disks

body,

MR only

5 mm

seen in the spine.

from

side

scoliotic

cxfor on

may can be

or laterally

containing

fat and

the

and longus capitis muscles ALL and the prevertebral (Figs

6, 7). Anterior

ryngeal

and

continuous mediastinum,

Volume

to this,

retrotracheal

longus

a coffi

the

retrophaare

#{149} Number

1

in signal

diskectomy.

and

5

the posterior

arrow

pharyn-

retropharynanterior

fascia

on

sagittal

to the

it draws

images

(Figs

1, 2,

displacement of the prevertefat, even in the absence of measurprevertebral soft-tissue swelling,

a reliable hematoma

radiographic or edema

sign (23).

fragments

from

Avulsion

is

of subjacent anterior

of

injuries

and may

end

anterior be poorly

and

fractures

plate

abutting

spondylotic visualized

of the the

disk

bar fracon rou-

tine radiographs and may result in instability and neural damage due to accompanying

ligament

disruption

matomas without

(24).

may

and

he-

may occur both with ALL tears. The injury

be either

soft-tissue

Retropharyngeal

ble if the ALL is torn, a widened

and

to injury.

and is unsta-

the only disk

C4-5 disk

and

visual

disturbance

seen

features

indicate

a severe

space. Initial by muscular

instability spasm,

views

clue

or prever-

(c, in a) and

A large

in c). The

disk

extru-

are preverteDamage to

clinically

(ii).

multilevel

may be and flexion/

are adequate

only

when the range of motion is satisfactory (25,26). This subacute instability is radiographically visible only several weeks after the injury. Soft-tissue swelling in the retrotracheal or retropharyngeal space is a warning sign of possible cervical instability. Prevertebral widening, usually seen between C-i and C-4, is pronounced in the first 3 days and reduces to normal after 2 weeks in 50% of cases and after 3 weeks in 90% (21,27) (Figs 6, ing

the vertebra occur (Figs 4, 6), a significant radiographic finding when there is no other evidence of spondylomargin

due

7). The absence the

small

There injury.

extension

on radiographs.

but at the C-6 level

probably

tebral masked

fascia. They visible as the

fat stripe

of the PLL and

from C-4 to C-6. of hyperextension

the vertigo

(solid C-5.

=

intensity,

cord signal intensity in c) characteristic

explaining

fracture

fat is located in the region immediately

space tures

between the fascia (21) spaces

fascia

cartilaginous

from the skull base to the lying between the prever-

180

after

sis. These

flexed

ALL injuries give rise to hemorrhage edema in the prevertebral space,

space

completely

bral able

is

to side,

discontinuities

possibly occult

rupture

to show vertebral fractures) and parasagittal avulsion fractures of C-7 (arrowheads

7). Focal

visualized

the ligament

injury,

a possible

bral

move-

in cervical is essential

usually

images,

apparent

anteroand

increase

probable

away from the spine by a few millimeters (21,22), resulting in a normal focal forward curve of the normal preverte-

it blends

sheer

nerve

vertebra,

to the

where

It limits

Although

measure

and

adheres

between vertebrae and its integrity

stability.

and

the

the anulus.

ments tension, sagittal

vertebra,

the

longus

This geal

consist-

in the

at

diffuse

there is diffuse increased cohli muscle (open arrows

prevertebral

(2,7-

ligament

originates

C6-7 show

indicates

with

b, i,900/iOO, windowed oriented superior-end-plate

tebral

ing of the ALL and the anterior twothirds of the vertebrae (6), is the initial site of serious hyperextension injury.

The

(a, 620/20; transversely

geal and esophageal contain fat and are

or near

column,

C5-6 disk herniation

then

appearances

anterior

acute

The

9,19,20).

The

large

and

sympathetic

C6-7

subluxation

radiographic

C.

to the forehead,

are seen is intact,

vertebra

posterior

resolves,

trauma

produces

myehopathic

momentary normal

direct

from C5-6 with cord a focal hemorrhage

colhi musche

Fluid

ma

7 after

on early

of prevertebral radiographs

widen-

makes

tive hyperextension The two prevertebral

injury

disrup-

unlikely

(27).

abnormalities seen were in patients who underwent imaging within 1 week of injury. All the ac-

celeration

hyperextension

this

were

series

when prevertebral expected to have

imaged

disk

are

injuries

separation

of

in

4 weeks,

abnormalities been resolved.

Hyperextension a characteristic

injuries after

include the

inter-

vertebral disk from the vertebral end plate (3,7,8,19). This lesion was described experimentally in monkeys as a result of the acceleration hyperextension

mechanism

(7)

and

has

been

Radiology

seen

#{149} 249

at autopsy

in severe

injuries resulting Nab also found

eight

patients

years

of injury,

hyperextension

in death comparable

(9,20). Maclesions in

operated

on within

2

at both

diskography operation, in which the disk could easily separated from the adjacent

and be ver-

tebra at blunt dissection, indicating little or no reattachment of the disk to the vertebra from which it had been avulsed. Anterior fusion resulted in relief of symptoms in seven of eight of these patients (7), indicating the potential clinical significance of this lesion. Evidence of this injury was seen in five of seven patients with anterior column injuries patients)

(at more than one and at follow-up

ter injury. sions sity

In the short

showed in

the

fuse

region

the

intensity

le-

signal

anterior

less well

signal

these

high

of

with

high

term,

discrete

component

level in three 9 months afintenannular

defined, in the

dif-

a.

disk

itself (Figs 2, 6, 7). The changes were more linear and confined to the diskend-plate interface at follow-up (Fig 4). Although

most

soft-tissue

injuries

heal quickly and completely, repair of tearing through a disk may be slow and incomplete, and these lesions do not produce changes demonstrable on routine radiographic studies (7). In one case with follow-up imaging 3 months after injury,

ALL

ruptures

had

healed,

high signal intensity persisted injured disks (Fig 4). Follow-up graphs

7 years

higher

rate of spondylosis,

disk

injury

after

and

accelerated

acute

has

occurred

above

the C-7 vertebra where it usually signal

showed

a

to

usually

by

diskectomy

herniation

heroth-

with

of symptoms

root

is rare

examples in this at the level of

evidence ten have appearance

sis had

intensity

poorly

acute herniation occurred at an adjacent nondegenerated level (Fig 7). There is little reference to acute cervical disk herniation in the literature about pathologic hyperextension, probably because the herniation tends to develop after the acute phase, with radicular symptoms typically beginning after 1 month and, in the majority, spontaneously resolving after approximately 6 months.

states

that a rotational element to produce disk herniation (16), a feature that could be expected

is

necessary

most

250

cases.

Although

#{149} Radiology

the

herniations

in are

study

images

the

et al (30).

injuries syndrome

cord

particularly more than

developmental and anterior occur with

prognosis

the

in this

elopathy in which the upper more severely affected than

the anterior column injury (Figs 2, 4), above it (Fig 6), or below it (Fig 3). In patients in whom preexisting spondylonarrowing,

cases

McArdle

evidence

Roaf

to

imporis pro-

anomalies

tion

fascial

curve

(2)

(Fig

anterior

to

fascia inferiorly, may be of high

predispose

limbs are the lower

(Fig

7),

less

mobile.

of spondylosis

(22) or

stenosis (Fig 5b). Central cord syndromes frequently minimal or no radiographic

of bone displacement and ofa good prognosis. MR cord associated with a favorable is a diffuse

marginated

homogeneous

increase

of the cord without

MR

rhage or altered weighted images

and

in signal

on T2-weighted evidence

of hemor-

signal intensity on Ti(12,13) (Fig 5). All five

patients first seen with myelopathy showed these changes, with all five haying clinical improvement and three haying complete resolution. If hyperextension injuries occur in patients

elasticity

with

are

nonspondylotic

patients,

these patients hyperextension,

fracture

spondylosis,

reached to cord often

(22). Similarly,

the

sooner

limits

than

of

in

predisposing

injury without

with mild cervical

congenital

the high prevalence injury. Six of seven anterior column injuries injuries

exception

multilevel

spine In

at the

from

first

the

fracture

(Fig

joint

strain

of the

mandible

vertebral

with

these

ligament

flexion

ischemia,

mobile

seen

recoil

open,

injury

adjacent

posterior

poromandibular

the

presumably

patient,

abnormalities include

ducing

was

this

2-6),

in a patient with disk narrowing

degenerative

injuries

flung

(Figs

seen

whose

occurred level. Other ing

was

multilevel

only

in paor those

or segmentato cord injury

5).

often result (3i), a my-

occurs 40 years

as stenosis

such

defects

had

herni-

with

in disk

anterior

cases

disk

and fusion (28). Some exclude disk niation in the discussion of whiplash hyperextension injuries (29), while

resulted

gentle

PLL appeared ruptured (Figs 2, 6). Rupture of the PLL was also reported in two

This aged

as a cause

normal

degenera-

to anterior

(3). There were several small group, occurring

remain

in two

limbs. tients

irritation

the

Of interest of multiple-level patients with

traumatic

disk

Note

posed),

toms

that

of spondylosis.

suggesting

Hyperextension in the central

ers state

level

I’LL (11) (a feature of surgical tance if anterior decompression

ation is uncommon, it is most often seen in the cervical spine. One study reported several C3-4 disk herniations following whiplash, with cranial sympresponding

the

signal intensity extending into the outer annular fiand disk bulging at the same level. The disk injury

(arrowheads in a). This curve may represent the prevertebral lies 3-4 mm anterior to the vertebra. This prevertebral tissue on gradient-echo images in normal patients. A = anterior.

intensity

stated

tion (26). Although

injury at C3-4 is evidenced by increased bers (arrow in a). There was cord injury

(a) Sagittal (1,000/40) and (* in a) in the retropharyngeal in b) (36). An acute disk

while

in the radio-

whiplash

b.

Figure 7. Myehopathy 1 day after direct frontal head trauma. (b) axial (1,500/30) images show a prevertebral fluid collection space producing a rectangular lesion on axial images (arrowheads

as artery

and

tear-

2b),

tem-

or

even

the

mouth

stretch

vascular

or

is

prosym-

pathetic turbance.

chain injury causing visual disTraction injuries of the larynx, including dislocation, occur, as do lesions of the upper cervical nerve root in the cervical plexus (21).

The Role

of MR

Imaging

Radiologic investigation is directed toward the detection of injury, instability, and treatable causes of cord compression. Although bone injury is well assessed with conventional radiography and causes

computed of

tomography, cervical

instability

soft-tissue or

cord

pingement such as ligament injury disk herniation are best demonstrated

im-

or

July 1991

and differentiated from intrinsic cord damage with MR imaging (12). The value of MR imaging in patients with myelopathy or cervical radiculopathy established, and potential indications include progressive neurologic deficit, spinal

cord

injury

bone

injury,

signs

above

seen

injury.

in the

and

absence

MR

imaging

of is

role of sura role for with non-

in all patients

penetrating cord injuries, even if stable, and all patients with abnormal alignment on radiographs (32). The role of MR imaging in the absence

of neurologic

signs

is more

gating

with

patients

graphic

such

dif-

signs

that

feature.

clinical

of

instability or are associated with a poor prognosis may provide others. In the selection of patients for further investigation

who

have

more

than

mild

whiplash, features of these injuries associated with a worse prognosis must be recognized. These features include cmical ones such as the use of a cervical collar for more than i2 weeks, relapse necessitating better physical therapy, radiation of pain or paresthesias into the arm, the presence of neurologic signs,

and

significant

findings

(33).

investigation

prevertebral

and

or paravertebral

focal

narrowing

disks,

will

vere

injuries.

also

soft

or widening

help

to detect

tissues

ment

in

lesions

patients

fusion. of the

include

neurologic

who

The

responded

effect

demonstration was not studied,

180

#{149} Number

1

without

15.

with po-

particular

clinical

17.

imaging

MRCP, Bonnie Ziemba ster,

The assistance

Harris matic

22.

risk of insta#{149}

Tech Aspects

Road Safety

2.

Jeffreys

Soft

3.

5.

The

TE.

nature tissue

of coffisions.

1970; 43:1-13. injuries

In: Disorders

of the

cer-

of the cervical

27.

spine. London: Butterworth, 1980; 81-89. MacNab I. Acceleration extension injuries of the cervical spine. In: Rothman R, ed.

The spine. 4.

24.

2nd ed. Philadelphia:

i982; 647-660. Edeiken-Monroe

B, Wagner

Hyperextension

dislocation

28.

Saunders, LK, Harris

JH.

29.

of the cervical

spine. AJR 1986; 146:803-808. GehweilerJA, Clark WM, Schaaf RE, Powers B, Miller MD. Cervical spine trauma: the common combined conditions. Radiohogy 1979; 130:77-86. Denis F. Updated classification of thoracohumbar fractures. Orthop Trans 1982; 6:8-9. MacNab I. Acceleration injuries of the cervical spine. J Bonejoint Surg [Am] 1964;

30.

31.

MacNab

9.

10.

ii.

to 12.

13.

I.

The

“whiplash

Clin North

syndrome.”

Bohlman

HI-I.

Acute

Crit Rev

24:201-236.

Dagi TF. The exchusion of cervical spine injury (editorial). AmJ Emerg Med 1988; 6:312-313. Herkowitz HN, Rothman instability of the cervical 9:348-357.

Hohh M.

Soft tissue

Cervical

Spine

cervical

spine.

RH.

Subacute

spine.

Spine

neck injuries.

Research

Society,

In: The ed. The

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Lip-

pincott, 1989; 436-439. Penning L. Prevertebral hematoma in cervical spine injury: incidence and etiologic significance. AJR 1981; 136:553-561.

Tamura TJ. Cranial symptoms after cervical injury. J Bone Joint Surg [Br] 1989; 71: 283-287. Hirsch SA, Hirsch PJ, Hiramoto H, Weiss A. Whiphash syndrome: fact or fiction? Orthop Clin North Am 1988; 4:791-795. McArdhe CB, Crofford MJ, Mirfakhraee M. Surface coil MR of spinal trauma: preliminary experience. AJNR 1986; 7:885-893. Hardy AA. Cervical spinal injury without

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Goldberg

Paraplegia

1977; 14:296-305.

AL, Rothfus

WE,

of magnetic

SH, Walt I.

Deeb

ZL, et ah.

resonance of acute

on the

Radiol

cervicotho1988; 17:89-

injuries factors Surg

of the neck influencing [Am] 1974;

The prognosis

in

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injuries resulting from rear-end vehicle collisions. J Bonejoint Surg [Br] 1983; 65: 608-611. Miles KA, Mainaris C, Barnes MR. The incidence and prognostic significance of

radiological juries 1988;

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tissue

injury.

tients with cervical spondylosis. AJR 1986; 146:277-284. Clark WM, GehweilerJA, Laib R. Twelve significant signs of cervical spine trauma. Skeletal Radioh 1979; 3:201-205.

Norris

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Traufrom 1968;

Regenbogen VS. Rogers LF, Atlas SW, Kim KS. Cervical spinal cord injuries in pa-

34.

and disloJ Bone Joint

R. disc

soft

spine

1985;

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fractures

cations of the cervical spine. Surg [Am] 1979; 61:8:iii9-1i42. Kulkarni MV, Bondurant FJ, Rose SL, Narayana PA. 1.5 tesha magnetic resonance imaging of acute spinal trauma. RadioCraphics 1988; 8:i059-1082. Flanders AE, Schaefer DM, Doan HT, Mishkin MM, Gonzales CF, Northrup BE. Acute cervical spine trauma: correlation of

Imaging

diagnostic evaluation racic trauma. Skeletal 95Hohl M. Soft tissue automobile accidents: prognosis. J Bonejoint 56:1675-i682.

Am 1971; 2:389-403.

Taylor AR, Blackwood W. Paraplegia in hyperextension cervical injuries with normah radiographic appearances. J Bone Joint Surg [Br) i948; 30:245-248. Sellecki BR, Williams HBL. Injuries to the cervical spinal cord in man. Sydney: Australian Medical, 1970.

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The impact

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56:1655-1662. Paakkaha T.

boney 32.

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Radioh 1988; 17:

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but

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changes

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def-

KM. Neck sprains after car acciBr Med J 1989; 298:973-974. CayJR, Abbott KH. Common whiplash injuries of the neck. JAMA 1953; 152:1698-

in

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of neurologic

177:25-33.

324-329.

21.

or radiographic

1990;

Porter dents.

nulus

23. ACknowledgments: acknowledge the

Orthop

on manageof this ab-

16.

20.

injury

signs

features indicating a high bility or a poor prognosis.

those

normality but this subject seems worthwhile in view of slow healing and MacNab’s good results with anterior fusion in this lesion (7). Disk

Volume

patients

7.

corresponding to experimentally produced acceleration hyperextension whiplash injuries that have already been described. Disk injury characteristically separates the disk from the vertebral end plate, producing a lesion that has been previously demonstrated suranterior

assessed

Se-

Many lesions produced by hyperextension can be shown only with MR

gically

is being

6.

These

The

vicah spine.

CONCLUSIONS

imaging.

on management

of

more

14.

whip-

of MR

cvi-

dence of spondylosis or congenital anomaly are also features of a poor prognosis (34,35), and flexion and cxtension radiographic views obtained in the alert patient, particular attention being paid to localized swelling of the

severe

acceleration impact

at any

Radiographic

injuries.

with

risk

a more

with degree

icit. Radiology

of such

is useful in patients deficit, demonstrating

indicating

lash

Investi-

a high

minority

in hyperextension

or radio-

indicate

MR findings

impingement

tentially reversible causes. All patients with lesions in this group had immediate onset of neck symptoms, a clinical

study

one

a small

MR imaging neurologic

feature

be

cord

injuries, although this tendency has not been established. The demonstration of prevertebral abnormalities and tearing of the ALL is best appreciated within 2 weeks of injury, as fluid collections resolve and ligament tears heal more quickly than associated disk injuries.

ficult to establish. It would be necessary to identify imaging abnormalities related to persistent pain. The transverse disk avulsion injury identified in this may

causing

also occurs, and the injury often occurs at multiple levels. These MR changes are likely to be seen among severe whiplash injuries, representing

level

of radiographically of MR imaging

closely tied to the perceived gery. Some would advocate

is

of

an unexpected

the level The role

herniation

abnormalities

to the cervical 17:493-4%.

spine.

in soft tissue Skeletal

in-

Radioh

Davis WL, Harnsberger R, Smoker WRK, Watanabe AS. Retropharyngeal space: evaluation of normal anatomy and with CT and MR imaging. Radiology 174:59-64.

Radiology

diseases 1990;

251

#{149}