NECK COMPLAINTS/CERVICAL SPONDYLOSIS

Introduction:

Neck pain is a common complaint and is almost always a benign condition. Over 10% of the adult population recalls at least 3 episodes of neck pain within a 3-year period. 

One good way to approach the subject is to consider source of pain based on anatomic principles: what are the pain sensitive structures of the neck? To answer the question one must have an understanding of the basic anatomy of the neck/cervical spine and then consider what common or uncommon processes can disturb normal function thereby causing pain and other disabilities such as weakness or numbness.

Anatomy:

The cervical spine neck is composed of 7 blocks of bones  (vertebral bodies) layered one on top of another with discs which act as kind of shock absorbers between the bodies. Behind the bodies lies a canal surrounded by bone, and in this canal lies the spinal cord which extends from the base of the skull to the level of the lowest rib. The  spinal canal is lined by a parchment like envelope called the dura which forms a long tube running from the head to the tail bone. The spinal cord lies in bed of water (cerebrospinal fluid) within the dura and has enough space around it to allow for some upward and downward movement when the neck is flexed or extended. Small joints called facet joints or apophyseal joints allow for movement of the neck in all directions. The vertebral arteries which supply blood to the back of the brain travel on the side of the vertebral column in their own own canals on each side.

At multiple levels nerves emerge from the spinal cord on each side and course towards the neck and upper limbs to provide motor signals which cause the muscles to contract, or sensory feedback from the structures of the arms and neck. Each combined motor and sensory  component originates from two sub-rootlets which are attached to the cord itself:  one is attached to the back part of the cord (dorsal root) and subserves the function of sensation; it has a small bump or nodule on it which contains the bodies of the sensory nerves (dorsal root ganglia), and the other nerve rootlet is more anterior (ventral root) and contains motor nerves. The two components merge to form the mixed cervical roots. The autonomic (automatic) nervous system is supplied by grey and white rami (branches) which leave the root close to the junction of the dorsal and ventral components..

The cervical vertebrae are separated one from another by disks. The outer part, or rim of the disk, is tough and stringy (annulus fibrosus), and surrounds the inner part of the disc which is softer and more amorphous (nucleus pulposus). At the level of the disk, on each side is a small hole (root foramen), which allows the nerve roots to pass from their attachment to the cord to the structures of the arm and neck.

The boney elements of the neck are held in place by ligaments which extend longitudinally in front of and behind the vertebral bodies. The back of the canal is made up of plates of bone (laminae), and again, a ligament  holds them in place and courses down the posterior aspect of the central canal (ligamentum flava).  The whole structure is surrounded by muscles.

The nerve roots are numbered from 1 to 8 and the prefix "cervical" or "C" allows us to identify exactly what structure we are referring to. Each motor nerve root supplies specific muscles in the arm (myotome) and when the neurologist examines the muscles, based the pattern of weakness that he finds, he can deduce which motor nerve root is faulty. Equally, each sensory nerve root supplies a specific area of the skin (dermatome) and from the distribution of sensory loss the level of dysfunction can be pinpointed. The diagnosis can be a little tricky because of overlap of segmental innervation.

Pain Sensitive Structures:

Now that the basic anatomy is understood we camn apply that knowledge to identifying the pain sensitive structures which are: the surrounding muscles, sensory components of the cervical roots, apophyseal joints, dura, bone, ligaments, and the external rims of the discs.

Any mechanical distortion, pressure, tumor, or infection that affects these pain sensitive structures will signal its presence by causing pain.

“A Pain in the Neck”

The usual cause of neck pain is neck muscle spasm. The muscles at the back of the neck become tight and tense, and tender to pressure. This might happen after an injury – so called “whiplash,” It might occur because the nerve roots are irritated or compressed which triggers reflex muscle spasm, or the spasm can result just from psychological stress. In young people the cause is likely stress, in older folks it is almost always from disk degeneration and secondary bone spurring and pinched nerve roots (cervical spondylosis).

The pain is usually felt at the back of the neck, sometimes on the sides, it may be dull and acheing or sharp, and is worse with neck movement. It radiates from the back of the neck to the back of the head and even further forwards when it causes a headache sometimes called “muscle contraction headache” or “tension-type headache.” The headache is variously described as a feeling of pressure, tightness, or bursting anywhere over the head or even around the eyes.

The pain can be temporarily relieved by heat applied to the back of the neck or by gentle massage. The physician prescribes muscle relaxant drugs to help the muscle unwind, but often simple over the counter analgesics are sufficient. If, in a young patient when there is no obvious organic cause, some form of psychotherapy or muscle relaxation techniques may be effective.

Root pain

If the sensory part of the nerve root is disturbed, pain will be felt in the distribution of that root. The pain radiates down the arm (brachalgia), may be dull and acheing or sharp and shooting and classically is aggravated or relieved by changing neck posture. It can be extremely severe and warrant fairly powerful analgesic medication. At the other end of the spectrum, sensory root symptoms may consist of only numbness or tingling.

The usual cause of root pain is pressure on the nerve root by a ruptured disk or arthritis of the apophyseal joints which abut the nerve root foramina.

Occasionally shingles, a virus infection by Herpes Zoster, affects the cervical nerve roots. The virus grows in the dorsal root ganglia, causes severe root pain, to be followed in a few days by a skin rash in the dermatome involved. The rash is blistery and is a restricted form of chicken pox.

Cervical Spondylosis

Cervical spondylosis is a degenerative arthritic like condition of the cervical spine. Disks degenerate, the disk spaces between the vertebrae become narrowed, and the adjacent bones react by growing arthritic  spurs.  This kind of arthritis is akin to osteoarthritis, not to systemic forms of inflammatory arthritis. An acute disk rupture will put pressure on the adjacent nerve root or, if the herniation is very large, it can even compress the spinal cord. An acute disk herniation is sometimes called a “soft” disk, whereas the boney spurring and ligamentous swelling or hypertrophy is  referred to as “hard” disk.

Cervical spondylosis is common. It is estimated to be prevalent in about 50% of people at age 50, and 75% of people over 65.

The sign of asymptomatic spondylosis is restriction of neck movement. One should normally be able to twist ones neck so that the chin approximates the point of the shoulder. Of people older than age 50, 40% have some limitation of neck movement.

Spondylosis may be the cause of:

Local pain in the neck

Root dysfunction (radiculopathy) 

Cord dysfunction (myelopathy).

Each will be discussed. 

Radiculopathy:

Dysfunction of the nerve root leads to radicular pain as described above, weakness in the muscles of that particular the myotome, and loss of the appropriate tendon reflex. Tendon reflexes are elicited by the neurologist who taps on a tendon with a reflex hammer at the wrist and in front of and behind the elbow.  Sensory loss for pin prick or light touch is in the distribution of the dermatome, that is the area of skin supplied by the particular nerve root involved. The table details the main myotomal distributions of the nerve roots and the figure demonstrates the dermatomes of the arm.

Myelopathy:

Cord compression can occur both from anterior or posterior structures. Anteriorly an acute disc rupture may compress the cord from in front, or reactive bony spurring and ridging of the vertebral bodies distorts the anatomy so that the anterior margins of the spinal canal look for all the world like a wash board with transverse ridges at the levels of the discs. The ligamentum flava lines the back of the canal and can become thickened so that the cord is pincered between the anterior osteophytes in front and the ligament behind. The risk of cord compression is related not only to the severity of the pathology as described above but also to the baseline diameter of the spinal canal. Some people are born with wide canals and some have narrow canals. If the canal starts off being narrow, spurs are more likely to impinge on the cord.  On an x-ray image the canal diameter from in front to behind (antero-posterior) can be measured. Anything less than 12-13mm qualifies for a diagnosis of canal narrowing or spinal stenosis. Less room = more risk.

The spinal cord is the cable that sends electrical messages from the brain to the body and relays messages from the body to the brain. The signs and symptoms of myelopathy may therefore be primarily motor, sensory or mixed. The motor and sensory descending and ascending pathways are called tracts and the different parts of the body are represented discretely in the tracts (somatotopic representation).

The cord contains many ascending and descending tracts. The clinician can test descending motor pathways by evaluating strength, and ascending pathways for pain, temperature, touch by stimulating with pin, a warm or cold object, or a wisp of cotton respectively. Position sense is tested by asessing the ability to tell the position of a toe  with the eyes closed when it is passively flexed or extended. If the cord is compressed or distorted in any way the resultant dysfunction in any particular tract is random, no matter the direction of the compressing force.

Motor signs and symptoms include increased tone and stiffness of the lower limbs, together with weakness. The weakness has a specific distribution: it affects primarily hip flexion, toe and foot extension, and knee flexion. Other movements are less or not at all affected. Because of toe or foot weakness the patient may scrape the tips of the shoes on the ground when walking and the tips of the shoes wear out.

The sensory modalities that lend themselves to easy testing are pin prick, light touch, vibration sense (as provided by a tuning fork), and position sense. The distribution of pin prick sensory loss in myelopathy is variable depending on which part of the tract is dysfunctional, so that any particular level of loss on, say, the trunk does not necessarily denote pathology at that particular level, but could reflect partial tract dysfunction at a higher level. Consequently, when examining the patient the only way to define the precise level of dysfunction in the cord is to demonstrate root dysfunction which accurately pinpoints the level.

In cervical spondylosis the tendon reflexes in the arms may or may not be present, and in the lower limbs there will generally be an enhancement of the reflexes at the knees and ankles. The response to scraping the sole of the foot is important:  extension of the toes - an extensor plantar response or Babinski reflex indicates a problem with the pyramidal tract, one of the main motor descending pathways..

When the cord is compressed, bladder function may be compromised. With cervical cord dysfunction there is frequency of urination, urgency to pass, and even incontinence associated with the urgency. This represents a small spastic irritable bladder.

Investigation:

The mode of choice for study of the cervical spine is magnetic resonance scanning (MRI).  The MRI demonstrates bone, disc, and cord effectively.

If MRI is not available, CT (computed tomography) scanning will suffice, particularly if combined with injection of an iodinated dye into the spinal canal (myelography), but with xrays, the patient is exposed to radiation. The CT does demonstrate the bony change more effectively than MRI.

Regular x-ray images will demonstrate the state of the bones and disk spaces and allow for measuring of the central canal diameter. X-rays made with the neck flexed or extended are used to explore stability of the spine and abnormal movement of one vertebra on another is called subluxation.

Electrophysiological studies are sometimes requested. These are used to measure the velocity of electrical conduction along the nerves of the arm. This test is designed to pick up on a pinched nerve or nerve root. Pinching causes slowing of conduction.. The Electromyogram (EMG) is performed by needling muscles of the arm with an electrode that picks up electrical activity in the muscle. Damage to the nerve or nerve root results in a specific pattern of abnormality in the muscle and this, depending on its distribution, can help to localize which nerve roots are dysfunctional. EMG and nerve conduction studies are particularly useful to diagnose peripheral entrapment complicating cervical spondylotic radiculopathy. This combination is sometimes called “double crush.”

Indications for imaging:

 If only nerve root dysfunction is diagnosed, it is not essential to image at once but if there is no resolution within a month or so, imaging is indicated. Some physicians image early.

The finding of cord signs or symptoms prompts early imaging, not only to confirm the diagnosis of cervical spondylosis, but also to exclude other potential causes of cord compression.

If myelopathy is present but the MRI does not show cord compression, flexion/extension films of the cervical spine are made to exclude subluxation which might intermittently compress the cord.

“Red Flags”: 

Imaging in patients with myelopathy is indicated urgently in the presence of fever or a history of cancer. If the diagnosis turns out not to be cervical spondylosis,but some other cause of cord compression  the appropriate treatment pathway will be followed.

Treatment:

Only a minority of patients with cervical spondylosis will be offered surgery, and despite the fact that spondylosis is so common, there is not much literature by way of controlled trials to support the notion of surgery as as viable treatment option unless there is severe anatomical cord pinching with supporting signs. In general, therefore the management will be conservative

Treatment of neck pain and radiculopathy:

The best treatment for benign neck problems with neck pain and radiculopathy is rest and symptomatic medication.

 Patients aggravate their necks at night while sleeping and will often complain of a stiff neck on awakening in the morning. They settle rapidly in a hot shower. Correction of sleeping posture is often successful in alleviating pain.Th That means that the neck should be supported at night in bed. Two hard, cheap, feather pillows (or synthetic if the patient is allergic to feathers), not down, usually help . Some patients respond to a buckwheat husk pillow which serves the same function. If there is no improvement, the patient should sleep in a soft cervical collar. Proprietary commercial neck pillows with hollows designed to accommodate the head only occasionally help. Local heat helps, as does gentle massage.

Cervical traction was frequently prescribed in the past; its effectiveness has been questioned, but occasionally a patient responds to over the door traction with a water bag weight filled to weigh about 10 pounds.

Chiropractic manipulation, although sometimes of symptomatic value, is mentioned only to point out that it carries a significant risk of complications. The main vertebral artery is occasionally injured by chiropractic manipulation, resulting in a stroke.

Analgesics should be used as necessary. If the pain is very severe stronger medication is necessary.

Muscle relaxant medication may be prescribed. In the list of choices are diazepam, cyclobenzaprine, and methocarbamol. All carry the potential risk of sedation.

Patients with chronic pain often respond to antidepressants, which alter central pain pathways.

In acute “soft disk” herniation a burst of oral corticosteroid is often helpful.

In the absence of cord compression and with resistant neck or root pain, a visit to the pain clinic is worth considering. An injection of corticosteroid locally often tides the patient over. Corticosteroid may be injected around the dura (epidural injection), or around the facet joints which themselves are a significant source of pain.

Treatment of myelopathy:

Acute disc herniation with severe cord compression and clinical signs of myelopathy is best treated surgically.

For the chronic patient with mild myelopathic symptoms and signs, immobilization in a soft cervical collar should be the first therapeutic intervention.  The collar prevents flexion and extension of the neck. Imaging studies have shown that with flexion the cord is driven forwards and may bowstring on projecting bone spurs or osteophytes. The collar should be worn all day and all night for about 3-4 weeks and the patient should then be reassessed.  Many patients respond to sleeping in a collar long term. In the interim, an MRI will have been done and the precise state of the cord defined. About 80-90% of patients improve with conservative therapy

The role of surgery:

There are very few prospective controlled trials of surgery for spondylotic myelopathy. Retrospectively there is some evidence that patients with surgery do better, but retrospective studies are not considered the “gold standard.”

The only extant trial of surgery for mild to moderate spondylotic myelopathy was conducted in the Czech Republic and the conclusion was that patients did the same with and without surgery.

Each patient referred for a surgical opinion should be evaluated individually and the surgeon will come to a judgement about the need for surgery and the type of operation offered. Surgery may be diskectomy (removing the disk), laminectomy (decompression from the rear by removing the lamina which unroofs the vertebral canal), or a fusion procedure where two vertebrae are joined together. Fusion  can be achieved either by operating from behind or from the front of the neck. Surgery should be considered for patients with spondylotic myelopathy or subluxation which does not respond to conservative treatment.

Prognosis:

The natural history of neck pain and muscle contraction headache has never been studied. In general the course of spondylotic radiculopathy is one of intermittency. Relapses and remisions occur unpredictably. Patients with myelopathy are encouraged to sleep in the collar, “for ever”.

Whiplash Injury:

The Quebec Task force on Whiplash Associated Disorders defined whiplash as:

An acceleration-deceleration, mechanism of energy transfer to the neck. It may result from rear-end or side impact motor vehicle collisions but can also occur during diving or other mishaps. The impact may result in bony or soft tissue injuries (whiplash injury), which in turn may lead to a variety of clinical manifestations (whiplash-associated disorders).

Rear end collisions are responsible for 85% of whiplash injuries; the incidence varies from country to country but ranges in the region of 13 to 106/100,00 inhabitants.

The pathology ranges from a trivial muscle/nerve stretch to ligament or disk rupture, tearing of the vertebral end plates, fractures, and injury to the facet joints.

If neurological signs of root or cord dysfunction are present, the injury is considered to be severe. If there is no neurological deficit the damage is accordingly mild. Headache comes on in about 6 hours in 2/3 of the patients but can be delayed for 72 hours. Muscle contraction headache is present in about 80% at 1 month. Other complaints include dizziness, numbness/tingling, cognitive and psychological complaints. Pain is related to the severity of the injury and can persist for years. Cognitive complaints are likely psychological in origin. Dizzyness or a mild feeling of imbalance is secondary to neck muscle spasm, and true spinning sensations (rotary vertigo) are likely ear related.

The influence of pending litigation on symptoms remains controversial, but it is worth considering the case of Lithuania where no insurance existed. Here almost all reported patients with whiplash became aymptomatic spontaneously. The inference is that the expectation of disability and compensation may be a significant factor in persistent whiplash symptoms. Conversely settlement of litigation does not always cure the patient so the issue is far from resolution

A reasonable approach would be to separate out those patients with whiplash who have neurological signs on examination and support the notion of a significant injury in that cohort.  Whiplash is essentially a benign condition and treatment should be as described for mild cervical spondylosis. Persistence beyond 6 weeks after the injury indicates further study and treatment.

SUGGESTED FURTHER READING

Ronthal M. Neck Complaints. Boston, Butterworth-Heinemann, 2000

Mixter WJ, Barr JS. Rupture of the intervertebral disk with involvement of the spinal canal. N Engl J Med 1934; 211: 210

Pallis CA, Jones AM, Spillane JD. Cervical spondylosis. Brain1954; 77: 274

Swezey RC. Chronic neck pain. Rheum Dis Clin North Am 1996; 22: 411

Wilkinson M (ed). Cervical spondylosis: Its early diagnosis and treatment (2^nd ed) Phlidelhia: Saunders 1971

Adams CBT, Logue V. Studies in cervical spondylotic myelopathy II. Movement and contour of the spine in relation to the neural complications of cervical spondylosis. Brai 1971; 94: 557

Gooding MR. Pathogenesis of myelopathy in cervical spondylosis. Lancet 1974; 2: 1180

Nurick S. The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis. Brain 1972; 95: 101.

Ronthal M, Rachlin JR. Cervical spondylosis. In: JohnsonRT, Griffin JW (eds). Current Therapy in Neurological Disease (5^th ed). St Louis: Moseby. 1997: 76-79.

Rowland LP Surgical treatment of cervical spondylotic myelopathy: Time for a controlled trial. Neurology 1992; 42:5

Kadanka L. Approach to spondylotic cervical myelopathy: Conservative vs surgical results in a 3 year follow up study. Spine 2002;27: 22

Kadanka L. Predictive factors for mild forms of spondylotic cervical myelopathy treated conservatively or surgically. Eur J Neurol 2005; 12: 16

Spitzer WO, Skovron ML, Salmi LR et al. Scientific monograph of the Quebec Task Forceon Whiplash-Associated Disorders: redefining “whiplash” and its management. Spine 1995; 20: 8S

Alexander MP. In the pursuit of proof of brain damage after whiplash injury. Neurology 1998; 51: 336

Vertebral column from the front. The red object is the vertebral artery

Vertebral column from the side

Spondylotic ridging in front, but no cord compression

Spurs compressing the exiting cervical nerve roots

Severe cervical spondylosis with cord compression in front by spurs and at the back by the Ligamentum Flavum

Myotomes: 

A simplified anatomical schema that the clinician uses to localize which cervical root is dysfunctional based on the pattern of weakness