kaye - cervical disc disease

8/13/2019 Kaye - Cervical Disc Disease

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Cervical spine disorders predominantly cause

neck pain and/or arm symptoms. Cervical disc

prolapse and cervical spondylosis are the two

common cervical spine disorders. Degenerative

changes in the vertebral column are the basic un-

derlying pathological processes in both these

conditions. Although the two conditions may be

distinct clinical entities, the shared common

pathogenetic mechanism results in a spectrum of

clinical presentation depending upon whether

the degenerative disease has resulted primarily

in disc rupture or cervical spondylosis. As in the

lumbar region the critical clinical feature de-

pends on whether there is nerve root entrapment

causing arm pain and/or focal signs of neural

compression in the upper limb. Cervical cord

compression due to disc prolapse or cervical

spondylosis is discussed in Chapter 15.

Cervical disc prolapse

In the 1934 report of their experiences with rup-

tured intervertebral discs, Mixter and Barr

described four cases with cervical disc disease.Prolapse of an intervertebral disc is less common

in the cervical region than in the lumbar area.

The disc herniation occurs most frequently at

the C6/7 level and slightly less commonly at the

C5/6 level. Disc herniation above these levels

and at the C7/T1 level is much less common. The

predominant frequency of disc prolapse at C6/7

and C5/6 is due to the force exerted at these

levels which act as a fulcrum for the mobile

spine and head.

Anatomy and pathology

The structure of the cervical disc is essentially the

same as in the lumbar region and consists of an

internal nucleus pulposus surrounded by the ex-

ternal fibrous lamina, the annulus fibrosus. The

role of trauma in the degenerative process and

disc herniation is not clear. It is probable that

repetitive excessive stresses do exacerbate the

normal ageing process and cause disc degenera-

tion. Although it is frequently possible to identify

some minor episode of trauma prior to the onset

of an acute disc prolapse, a readily identifiable

episode of more major trauma as the precipitat-

ing event is much less frequent.

The cervical disc prolapse is usually in the

posterolateral direction, because the strong

posterior longitudinal ligament prevents direct

posterior herniation. The posterolateral disc

herniation will cause compression of the adja-

cent nerve root as it enters and passes through

the intervertebral neural foramen. Unlike the

lumbar region, the nerves pass directly laterally

from the cervical cord to their neural foramen,so that the herniation compresses the nerve at

that level (Fig. 14.1). The arrangement of the

cervical nerve roots and the relationship to

the vertebral bodies differ from the lumbar

region the C1 nerve root leaves the spinal

canal between the skull (the foramen magnum)

and the atlas, and the C8 root, for which there is

no corresponding numbered vertebra, passes

through the C7/T1 foramen. Consequently, a

C5/6 disc prolapse will cause compression ofthe C6 nerve root, a C6/7 prolapse causes com-

pression of the C7 nerve root and the C7/T1 disc

CHAPTER 14

14Cervical disc disease andcervical spondylosis

197


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198 CHAPTER 14

prolapse causes compression of the C8 nerve

root.

Occasionally a cervical disc may herniate

directly posteriorly, causing compression of the

adjacent cervical spinal cord (Chapter 15) which

is a neurosurgical emergency.

Clinical presentation

The characteristic presenting features of a patient

with an acute cervical disc herniation consist of

neck and arm pain and the neurological manifes-

tations of cervical nerve root compression.

Although the pain usually begins in the cervi-

cal region it characteristically radiates into the

periscapular area and shoulder and down the

arm (brachial neuralgia). The neck pain com-

monly regresses while the radiating arm pain be-comes more severe. It is usually described as a

deep, boring or aching pain and the patient is

usually severely distressed and debilitated by the

discomfort. The distribution of the pain is wide-

spread and conforms to sclerotomes (segmental

distribution to muscle and bone) rather than to

dermatomes. The patient frequently complains

of sensory disturbance, particularly numbness or

tingling in the distribution of the dermatome af-

fected. The location of the sensory disturbance ismore useful than the pain as an indication of root

level: thumb (and sometimes index finger) in C6

lesions, middle finger (and sometimes index fin-

ger) in C7 lesions, and little and ring fingers in C8

lesions. The patient may notice weakness of the

arm, particularly if the C7 root is affected, as this

causes weakness of elbow extension and themovement has only very little supply by other

nerve roots (C8). A severe C5 root lesion may

cause weakness of shoulder abduction and the

patient may complain of difficulty in elevating

the arm.

Examination features

Cervical spine movements will be restricted and

the head is often held rigidly to one side, usually

moderately flexed, and tilted towards the side of

the pain in some patients but occasionally away

from it in others. Lateral tilt relaxes the roots on

the side of the concavity but diminishes the inter-

vertebral foraminae, and flexion slightly sepa-

rates the posterior part of the intervertebral space

and lessens the tension in the prolapse. If the disc

herniation is long standing there may be wasting

in the appropriate muscle group, particularly the

triceps in a C7 root lesion. The patient is then ex-

amined for weakness in each of the muscle

groups (Tables 14.1 and 14.2). Weakness of elbow

extension and finger extension is most common-

ly caused by a C6/7 prolapse with compression

of the C7 nerve root. Less commonly, disc hernia-

tion with compression of the C5 root will cause

weakness of shoulder abduction, compression of

the C6 root will cause mild weakness of elbow

flexion, and compression of C8 may cause weak-

ness of the long flexor muscles, triceps, finger ex-

tensors and intrinsic muscles.The deep tendon reflexes provide objective ev-

idence of nerve root compression in the following

distribution.

Biceps reflex C5

Brachioradialis (supinator) reflex C6

Triceps reflex C7

Sensation should be tested in the arm and hand

and the sensory loss will be characteristic for the

nerve root involved (Fig. 14.2) although there

may be some overlap.A full neurological examination must be per-

formed and particular care taken to assess the

Fig. 14.1 Posterolateral cervical disc prolapse causing

compression of the adjacent nerve root.


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presence in the lower limbs of long tract signs,

such as increased tone, a pyramidal pattern of

weakness, hyperreflexia or an upgoing plantar

response. If there is a cervical disc herniation

these features will indicate that it is compressing

the spinal cord.

Summary of clinical features

Clinical localization of disc prolapse is possible in

CERVICAL DISC DISEASE AND CERVICAL SPONDYLOSIS 199

Table 14.1 Segmental innervation of upper limb musculature.

C3, 4 Trapezius; levator scapulae

C5 Rhomboids; deltoids; supraspinatus; infraspinatus; teres minor; biceps

C6 Serratus anterior; latissimus dorsi; subscapularis; teres major; pectoralis major (clavicular head);

biceps; coracobrachialis; brachialis; brachioradialis; supinator; extensor carpi radialis longus

C7 Serratus anterior; latissimus dorsi; pectoralis major (sternal head); pectoralis minor; triceps;

pronator teres; flexor carpi radialis; flexor digitorum superficialis; extensor carpi radialis longus;

extensor carpi radialis brevis; extensor digitorum; extensor digiti minimi

C8 Pectoralis major (sternal head); pectoralis minor; triceps; flexor digitorum superficialis; flexor

digitorum profundus; flexor pollicis longus; pronator quadratus; flexor carpi ulnaris; extensor carpi

ulnaris; abductor pollicis longus; extensor pollicis longus; extensor pollicis brevis; extensor indicis;

abductor pollicis brevis; flexor pollicis brevis; opponens pollicis

T1 Flexor digitorum profundus; intrinsic muscles of the hand (except abductor pollicis brevis; flexorpollicis brevis; opponens pollicis); hypothenar muscles

Table 14.2 Segmental innervation of upper limb

joint movements.

Shoulder Abductors and lateral C5

rotators

Adductors and medial C6, 7, 8rotators

Elbow Flexors C5, 6

Extensors C7, 8

Forearm Supinators C6

Pronators C7, 8

Wrist Flexors and extensors C6, 7

Digits Long flexors and extensors C7, 8

Hand Intrinsic muscles C8, T1

C6

T2

T1

C7

T1

C5

C4

C6

T2

C7

C4

C5

C8C8

C6

C3

Fig. 14.2 Upper limb dermatome distribution.


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200 CHAPTER 14

most patients with brachial neuralgia due to cer-

vical disc prolapse. The following features are

typical (but not invariable) for disc herniation:

C6/C7 prolapsed intervertebral disc (C7 nerve root) Weakness of elbow extension

Absent triceps jerk

Numbness or tingling in the middle or index

finger.

C5/6 prolapsed intervertebral disc (C6 nerve root)

Depressed supinator reflex

Numbness or tingling in the thumb or index

finger

Occasionally mild weakness of elbow flexion.

C7/T1 prolapsed intervertebral disc (C8 nerve root)

Weakness may involve long flexor muscles,

triceps, finger extensors and intrinsic muscles

Diminished sensation in ring and little finger

and on the medial border of the hand and forearm

Triceps jerk may be depressed.

Differential diagnosis

The clinical features of an acute cervical disc pro-

lapse, with severe neck and arm pain and com-

monly diminished sensation in the dermatome of

the affected cervical root, are so characteristic

that in the vast majority of cases the diagnosis is

self-evident. The most common cause of radiat-

ing arm pain, other than acute prolapse, is

spondylosis but, as has been indicated, disc pro-

lapse and spondylosis are aspects of one continu-

ing degenerative process and, in the cervical

region, the distinction between them becomesblurred. Other unlikely but possible differential

diagnoses include:

cervical nerve root compression by a spinal

tumour (e.g. meningioma, neurofibroma)

(Chapter 15)

thoracic outlet syndrome (Chapter 17)

Pancoasts tumour infiltrating the roots of the

brachial plexus

peripheral nerve entrapments, such as carpal

tunnel syndrome, median nerve entrapment inthe cubital fossa and tardy ulnar palsy (Chapter

17).

Management

Most patients with arm pain due to an acute soft

cervical disc herniation achieve good pain relief

with conservative treatment. This should includebed rest, a cervical collar, simple analgesic

medication, non-steroidal anti-inflammatory

medication and muscle relaxants. Manipulation

of the neck is potentially hazardous and is

contraindicated.

The following are indications for further inves-

tigation and surgery.

1 Pain:

(a) continuing severe arm pain for more than

10 days without benefit from conservative

therapy

(b) chronic or relapsing arm pain.

2 Significant weakness in the upper limb that

does not resolve with conservative therapy.

3 Evidence of a central disc prolapse causing

cord compression this should be investigated

urgently.

Radiological investigations

High-quality MRI is now the investigation of

choice and has almost completely replaced both

myelography and CT (Fig. 14.3). The cervical

myelogram using water-based non-ionic iodine

contrast material was a most useful investigation

for determining the presence and site of the disc

herniation (Fig. 14.4). CT scanning by itself is fre-

quently not helpful, but if performed following

intrathecal iodine contrast it will demonstrate a

disc herniation, and smaller volumes of intra-

thecal contrast are necessary than with myelo-graphy (Fig. 14.5).

Operative procedure

The two most commonly performed operations

for cervical disc prolapse are:

1 Cervical foraminotomy with excision of the

disc prolapse.

2 Anterior cervical discectomy, with subsequent

fusion.

Cervical foraminotomy. This involves fenestration


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recurrent disc herniation, but this is very uncom-mon. In general, the results of the procedure are

very satisfactory, with excellent relief of arm pain

and, provided the nerve has not been irreparably

damaged by long-standing disc herniation, re-

turn of full strength to the arm.

Anterior cervical discectomy. This involves an ante-

rior approach to remove the cervical disc and the

prolapse. Some surgeons perform formal fusion

at the level using bone taken from the iliac crest,bovine bone, artificial bone, or an intervertebral

cage, usually filled with bone chips. The fusion

CERVICAL DISC DISEASE AND CERVICAL SPONDYLOSIS 201

(a)

(c)

(b)

Fig. 14.3 MRI of cervical disc prolapse. (a) Cervical

axial T1-weighted image (arrow shows disc prolapse).

(b,c) Sagittal MRI showing disc prolapse compressing

the spinal theca and distorting the cervical cord.

of the bone posteriorly, to provide direct access tothe cervical nerve root and disc prolapse. Asmall

amount of bone from the lateral margins of the

adjacent lamina and articular facets is removed to

identify the nerve root in the foramen. Further

bone can then be removed from around the nerve

root to enlarge the neural canal. The nerve root is

gently retracted and the disc herniation excised.

The major advantages of the technique are that

the nerve is directly decompressed both by re-

moval of the disc herniation and by enlargementof the foramen, and cervical fusion is not neces-

sary. The major disadvantage is the possibility of


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202 CHAPTER 14

may be supplemented by a metal (usually titani-

um) plate screwed onto the anterior vertebral

surface, bridging the disc space. Some surgeons

do not perform a formal fusion, as spontaneous

fibrous or bony fusion will occur across the disc

space provided all the disc has been excised. The

major disadvantage is that the fusion will result

in additional stress at the adjacent cervical levels,

thereby rendering them more prone to degenera-

tive disease.

An anterior approach with disc excision is

mandatory for a central disc protrusion.

Postoperative care

Whatever approach is used, the patient is encour-

aged to mobilize the day after surgery. A soft cer-

vical collar may be useful in the first week after a

foraminotomy to minimize the neck pain. A firm

collar is usually worn for the first 46 weeks after

anterior discectomy, or until there is evidence of

fusion.

The prognosis for pain relief following the op-eration is excellent provided the diagnosis has

been accurate and the nerve decompressed.

Cervical spondylosis

Cervical spondylosis is a degenerative arthritic

process involving the cervical spine and affecting

the intervertebral disc and zygapophyseal joints.

Radiological findings of cervical spondylosis are

present in 75% of people over 50 years of age who

have no significant symptoms referable to the

cervical spine.

Pathological changes

The degenerative process resulting in cervical

spondylosis and its progression occur in most

cases largely as a result of the inevitable stresses

and traumas that occur to the cervical spine as a

result of the normal activities of daily living. It is

probable that the process is aggravated by repet-

itive or chronic trauma, as may occur in some oc-cupations, and as a result of an episode of severe

trauma.

The process principally involves the interver-

tebral discs and zygapophyseal joints. Reduced

water content and fragmentation of the nuclear

portion of the cervical discs are natural ageing

processes. As the disc degenerates there is

greater stress on the articular cartilages of the

vertebral end-plates and osteophytic spurs de-

velop around the margins of the disintegratingend-plates, projecting posteriorly into the spinal

canal and anteriorly into the prevertebral space.

Fig. 14.4 Cervical myelogram showing a postero-

lateral cervical disc protrusion with compression

of the cervical nerve root.

Fig. 14.5 CT myelogram showing a posterolateral

cervical disc protrusion.

kaye - cervical disc disease

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