Essentials of Orthopedic Surgery, third edition / 07-The Spine

296 S.W. Wiesel et al.

Neck Pain Predominant

After 6 weeks of conservative therapy with no symptomatic relief, plain roentgenograms with lateral flexion–extension films are carefully examined for abnormalities. One group of patients will have objective evidence of instability. In the lower cervical spine (C3 through C7), instability is identified by horizontal translation of one vertebra on another of more than 3.5 mm, or of an angulatory difference of adjacent vertebrae of more than 11 degrees. The majority of patients with instability will respond well to further nonoperative measures, including a thorough explanation of the problem and some type of bracing. In some cases, these measures fail and a surgical fusion of the involved spinal segments will be necessary.

Another group of patients complaining mainly of neck pain will be found to have degenerative disease on their plain X-ray films. The roentgenographic signs include loss of height of the intervertebral disk space, osteophyte formation, secondary encroachment of the intervertebral foramina, and osteoarthritic changes in the apophyseal joint. The difficulty is not in identifying these abnormalities on the roentgenogram but in determining their significance.

Degeneration in the cervical spine can be a normal part of the aging process. In a study of matched pairs of asymptomatic and symptomatic patients, it was concluded that large numbers of asymptomatic patients show roentgenographic evidence of advanced degenerative disease. The most significant roentgenographic finding relevant to symptomatology was found to be narrowing of the intervertebral disk space, particularly between C5–C6 and C6–C7. There was no difference between the two groups insofar as changes at the apophyseal joints, intervertebral foramina, or posterior articular process.

These patients should be treated symptomatically with antiinflammatory medication, support, and trigger-point injections as required. In the quiescent stages, they should be placed on isometric exercises. Finally, they should be reexamined periodically because some will develop significant pressure on the neurologic elements (myelopathy).

The majority of patients with neck pain have normal roentgenograms. The diagnosis for this group is neck strain. At this point, with no objective findings, other pathology must be considered. These patients should undergo a bone scan and medical evaluation. The bone scan is an excellent tool, often identifying early spinal tumors or infections not seen on routine roentgenographic examinations. A thorough medical search may also reveal problems missed in the early stages of neck pain evaluation. If these diagnostic studies are positive, the patient is treated appropriately. If the foregoing workup is negative, the patient should have a thorough psychosocial evaluation; this is predicated on the belief that a patient’s disability is related not only to his pathologic anatomy, but also to his perception of

pain and his stability in relationship to his sociologic environment. Drug habituation, alcoholism, depression, and other psychiatric problems are frequently seen in association with neck pain. If the evaluation reveals this type of pathology, proper measures should be instituted to overcome the disability.

Should the outcome of the psychosocial evaluation prove to be normal, the patient can be considered to have chronic neck pain. One must be aware that other outside factors such as compensation and/or litigation can influence a patient’s perception of his subjective pain. Patients with chronic neck pain need encouragement, patience, and education from their physicians. They need to be detoxified from narcotic drugs and placed on an exercise regimen. Many will respond to antidepressant drugs such as amitriptyline (Elavil). All these patients need periodic reevaluation to avoid missing any new or underlying pathology.

Arm Pain Predominant (Brachialgia)

Patients who have pain radiating into their arm may be experiencing their symptoms secondary to mechanical pressure and inflammation of the involved nerve roots. This mechanical pressure may arise from a ruptured disk or from bone secondary to degenerative changes. Other pathologic causes of arm pain should be carefully considered. Extrinsic pressure on the vascular structures or on the peripheral nerves are most likely imitators of brachialgia. Pathology in the chest and shoulder should also be ruled out.

A careful physical examination should be conducted. If there is any question about these findings, appropriate roentgenograms and an EMG should be obtained. If any of these are positive for peripheral pressure on the nerves or other pathology, the appropriate therapy should be administered.

Should all these studies prove negative and the EMG is consistent, the patient is considered to have brachialgia. One must carefully reevaluate the patient who has a neurologic deficit or a positive EMG; those who have either should undergo an MRI. If the MRI is positive and is consistent with the physical findings, surgical decompression should be considered at this juncture.

It has been repeatedly documented that for surgery to be effective, unequivocal evidence of nerve root compression must be found at surgery. One must have a strong confirmation of mechanical root compression from the neurologic examination and a confirming study before proceeding with any surgery. The indications for surgery are the subjective complaint of arm pain and a neurologic deficit or positive EMG. An MRI must confirm the pathology. If the patient does not have these, there is inadequate clinical evidence to proceed with surgery. For patients who have met these criteria for cervical decompression, the results will usually be satisfactory: 95% of them can expect good or excellent outcomes.

298 S.W. Wiesel et al.

Conservative Treatment Modalities

Most patients with neck pain will achieve relief from a conscientious program of conservative care. As the algorithm indicates, all patients with either chronic or acute neck pain (except those with severe myelopathy) deserve an initial period of conservative therapy. There are a multitude of treatment modalities available, but many of them are based on empiricism and tradition. The purpose of this section is to discuss the rationale behind the use of some of the more common nonoperative therapeutic measures.

Immobilization

The cornerstone of conservative therapy is immobilization of the cervical spine. The goal of immobilization is to rest the neck so that healing of torn and/or attenuated soft tissues in acute cervical injuries can take place. In the chronic situation, the purpose of immobilization is to reduce any inflammation.

Immobilization can best be achieved by the use of a soft cervical collar that holds the head in a neutral or slightly flexed position. It is very important that the collar is fitted properly. If the neck is held in hyperextension, the patient is usually quite uncomfortable and does not derive any benefit from its use. In acute neck injuries, the collar should be worn on a full-time basis, night and day, until the acute pain subsides. This result may sometimes take as long as 4 to 6 weeks, and the patient should be aware of this time course from the outset of treatment so that the physician will not feel pressured to discontinue immobilization before the proper time.

Drug Therapy

There are different groups of medications that have proved helpful in the treatment of neck pain: antiinflammatory drugs, analgesics, and muscle relaxants. They are used as an important adjunct to adequate immobilization.

Antiinflammatory drugs are used because it is believed that inflammation in the soft tissues is a major contributor to pain production in the cervical spine, which is especially true for those patients with symptoms secondary to a herniated disk. The arm pain that these people experience is caused not only by the mechanical pressure from the ruptured disk but also by the inflammation in and around the involved nerve roots. Usually, if one can get rid of the inflammation, the patient’s pain will markedly decrease.

There is a spectrum of antiinflammatory agents available, but none has been proven superior. The author’s usual treatment plan is to begin the patient on adequate doses and, if the response is not satisfactory after 2

weeks, switch to another. Most patients will get significant relief from one of the agents presently available. It should be stressed that antiinflammatory medications are utilized in conjunction with immobilization; they do not replace adequate rest.

Analgesic medication is also very important during the acute phase of neck pain. The goal is to keep the patient comfortable. Most patients will respond to the equivalent of 30 to 60 mg codeine every 4 to 6 hours. If stronger medication is required, the patient should be monitored very closely. In some cases, narcotics are abused by the patient and addiction will become a problem to some degree. The treating physician must maintain control of the patient’s drug use at all times.

Injuries to the cervical spine frequently result in painful muscle spasm. A vicious cycle is established whereby pain leads to muscle spasm, which leads to ischemia and a further increase in pain. Once the cycle is established, it tends to be self-perpetuating. An effective muscle relaxant frequently breaks this painful cycle and allows more comfort and an increased range of motion in the cervical spine. Methocarbamol or carisoprodol in adequate doses are the drugs recommended. They are safe and quite effective.

Traction

Cervical traction has been used for many years. Today, opinions regarding its effectiveness range from that of it being a valuable clinical therapy to the conclusion that it is ineffective or potentially harmful or both.

There is no uniform idea as to how traction actually works, and there are a number of methods of actually applying the traction. The three major ways of administering traction are mechanical, manual, and home traction. Many believe that manual traction is preferred due to the interaction between the therapist and patient and the potential specificity of individually varying the traction.

In certain situations, cervical traction is contraindicated. Malignancy, cord compression, infectious disease, osteoporosis. and rheumatoid arthritis are the major disorders for which cervical traction should not be employed. It is also thought that when there is a herniated disk present, either in the midline or laterally, traction should not be considered.

The author believes that cervical traction is useful when a collar has proved ineffective in those patients with a cervical strain or a hyperextension injury. The major benefit is considered to be continued rest, and a home traction device is preferred. When used in this situation, only minimal amounts of weight (4–6 lb) should be used, and the direction of pull should be in slight flexion. As already mentioned, there are other ways of applying traction, but to date there is no valid scientific evidence available that traction in and of itself is effective.

300 S.W. Wiesel et al.

Trigger-Point Injection

Many patients will complain of a very localized tender spot in the paravertebral area. In some of these cases, the discomfort can be relieved by infiltration of the trigger point with a combination of Xylocaine and a steroid preparation or Xylocaine alone. There have been no true randomized clinical trials to study the efficacy of trigger-point injections, but empirical evidence indicates they seem to work on some patients. It is interesting to note that although the pharmacologic effects of these drugs may wear off in 2 to 3 hours, the relief may last indefinitely.

Before actually injecting a patient, a history of allergy to the drugs to be used should be obtained. The more localized the trigger point, the more effective the injection tends to be. An area of diffuse tenderness does not respond very well to this approach.

Manipulation

Manipulation of the cervical spine should be approached very carefully. In the United States, this is mainly performed by chiropractors, although other healthcare professionals are involved. The goal of manipulation is to correct any malalignment of the spinal structures, which is assumed to be the etiology of the patient’s pain. There is no real scientific evidence that manipulation of the cervical spine is effective in the treatment of acute or chronic neck problems.

Exercises

After a patient’s acute symptoms have cleared and there is no significant pain or spasm, an exercise regimen is reasonable. The exercises should be directed at strengthening the paravertebral musculature and not at increasing the range of motion. Motion will return with the disappearance of pain. The exercises are isometric in nature. They are performed once a day with increasing repetitions. It should be appreciated that at present there are no scientific studies demonstrating that isometric exercises or any other type of cervical exercises will reduce the frequency of recurrent neck pain episodes. Empirically, they do appear to have a positive psychologic effect and give the patient an active part in his treatment program.

Lumbar Spine

Low back pain occurs much more commonly than neck pain. The lifetime incidence of low back pain is estimated to be 65%. Every physician will either be personally affected (family, friends) or professionally challenged by this problem.

History

A general medical review, especially in the older patient, is imperative. Metabolic, infectious, and malignant disorders may initially present to the physician as low back pain.

The location of the pain is one of the most important historical points. The majority of patients just have back pain with or without referral into the buttocks or posterior thigh. Referred pain is defined as pain in structures that have the same mesodermal origin. These patients have a localized injury, and the referral of pain into the buttocks or thigh does not signify any compression on the neural elements. This type of pain is described as dull, deep, and/or boring.

Another group of patients complains of pain that originates in their back, but travels below the knee into the foot. It is described as sharp and lancinating. It may be accompanied by numbness and tingling. This pain is termed radicular pain or a radiculopathy. A radiculopathy is defined as a mechanical compression of an inflamed nerve root in which the pain travels along the anatomic course of the nerve. The compression can be secondary to either soft tissue (disk) or bone. The most common nerve roots affected are L5 and S1, levels that account for pain traveling below the knee. Finally, one should inquire about changes in bowel or bladder habits. Occasionally, a large midline disk herniation may compress several roots of the cauda equina (Fig. 7-4); this is termed cauda equina compression (CEC) syndrome. Urinary retention or incontinence of bowel or bladder are, along with severe pain, the major symptoms.

Physical Examination

The physical examination is directed at finding the location of the pain.

All patients with low back pain can have some nonspecific findings, which vary in degree depending on the severity of the condition; these include a list to one side, tenderness to palpation and percussion, and a decreased range of motion of the lumbar spine. These findings can be present in both radiculopathy and referred pain patients. Their presence denotes that there is a problem but does not identify the etiology or level of the problem. The neurologic examination may yield objective evidence of nerve root compression if present (Table 7-3). A thorough neurologic evaluation of the lower extremities should be conducted on each patient, particularly to check the reflexes and motor findings. Sensory changes may or may not be present, but because of overlap in the dermatomes of spinal nerves, it is difficult to identify specific root involvement.

In patients with radiculopathies, there are several maneuvers that tighten the sciatic nerve and, in so doing, further compress an inflamed lumbar root against a herniated disk or bony spur. These maneuvers are generally termed tension signs or a straight leg-raising test (SLRT). The conven-

304 S.W. Wiesel et al.

Several lumbosacral imaging modalities are currently available including plain films, myelography, CT, and MRI.

To evaluate the true clinical value of any diagnostic study, one must know its sensitivity (false negatives) and specificity (false positives). The specificity, or false-positive rate, is usually measured in a population of symptomatic patients who have undergone surgery; however, often there is a much higher rate of false positives when an asymptomatic group is studied. The accuracy of any single test increases when it is combined with a second or third diagnostic study: the challenge for the physician is to select diagnostic tests on the basis of their performance characteristics so that the correct diagnosis is obtained with the least cost and morbidity. The studies most frequently utilized in the diagnostic assessment of low back pain are described next and critically analyzed with this in mind.

Plain Radiographs

The diagnosis of disk herniation can usually be made on the basis of a history and physical examination. Plain radiographs of the lumbosacral spine must be obtained in the appropriate setting to rule out other pathologic conditions such as infection or tumor. Plain radiographs are valuable for seeking the diagnosis of spinal stenosis, spondylolisthesis, gross segmental instability, or fracture.

The radiograph must be of excellent quality and taken with attention to detail. In general, three views are all that are required to assess the lumbosacral spine: an AP view, a lateral view, and a coned-down lateral view of the lower two interspaces. On occasion, two oblique views are also taken to identify subtle spondylolysis or pars interarticularis defects. However, oblique views provide limited information and should not be routinely included.

Although plain films are useful for surveying the bony elements of the spine and paraspinal soft tissues, the contents of the spinal canal, including cord, dura, ligaments, and encroaching disk are not visualized. In addition, bony lesions may not be apparent until 50% of the cancellous bone has been destroyed.

Finally, degenerative changes such as disk space narrowing, traction osteophytes, vacuum disk phenomenon, and end-plate sclerosis are quite prevalent in older individuals. Unfortunately, these radiographic findings have been shown to correlate poorly with clinical symptoms.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is the diagnostic modality of choice when trying to evaluate the different tissues in the spine (Fig. 7-6); it is especially good for observing disk pathology. MRI with gadolinium-dieth- ylenetriaminopentaacetic acid (DTPA) contrast enhancement is superb for demonstrating intraspinal tumors and for distinguishing recurrent disk

FIGURE 7-6. (A) Magnetic resonance imaging (MRI) scan of a herniated disk, sagittal view. T1-weighted image (left) demonstrates a herniated disk (arrow) at the L5–S1 level. The T2-weighted image (right) shows loss of the normal white signal within the nucleus pulposus (arrow), a sign of degenerative disk disease. (From Boden SD, Davis DO, Dina TS, et al. Abnormal lumbar spine MRI scans in asymptomatic subjects: a prospective investigation. J Bone Joint Surg 1990;72A:403–408. Reprinted by permission.) (B) MRI scan of a herniated disk, axial view. T1-weighted image at the L5–S1 disk space demonstrates a large, central herniated disk with lateral displacement of both S1 nerve roots and posterior displacement of the cauda equine. (From Boden S, Wiesel SW, Laws E et al. The Aging Spine. Philadelphia: Saunders, 1991. Reprinted by permission.)

herniation from scar tissue. As with other diagnostic imaging modalities discussed, MRI also has been shown to have a significant clinical falsepositive rate in asymptomatic individuals. In one prospective and blinded study, 22% of the asymptomatic subjects under age 60 and 57% of those over age 60 had significantly abnormal scans. In addition, the prevalence of disk degeneration on the T12-weighted MRI scans was found to approach 98% in subjects over the age of 60.

Myelography

Myelography is employed for evaluating neural compression when an MRI cannot be used. Dye is injected into the dural sac and mixes with the spinal fluid. The outline of the contents of the spinal canal can be visualized on X-ray; any extradural mass such as a herniated disk appears as a filling defect in the dye column (Fig. 7-7) whereas an intrathecal mass appears as an outward protrusion.

The myelogram is an invasive procedure and should not be taken lightly. Complications include severe headache, nausea, vomiting, and, although rare, even seizures. Before the utilization of the water-soluble dye metri-