SPINAL DISORDERS

Disc Disease and Degenerative Disease of the Spine

Epidemiology of low back and log pain: Low back pain with or without radicularleg pain affects up to 85% of individuals at some point in their lives. In a given year it has been estimated that between 10%-15% of the population have back and/or leg pain. Sciatica is thought to affect about 2% of the population and about 12% of people with back pain. Age is an important factor in determining the likelihood of back symptoms with peak incidence in the 35- 55 age range. There is no difference in the incidence of back symptoms between men and women. However there are significant differences in the incidence of back symptoms according to race (white> black > other), education (elementary or none > high school > college) and region of the country (West >South and Midwest > Northeast). In the United States, back pain is the leading cause of activity limitation for peopleyounger than 45 years. It is the second most common cause of physician visits, the fifth most common reason for hospitalization and the third ranked reason for a surgical procedure. One percent of the U.S. population is permanently disabled with back painand at any given time another 1% is temporarily disabled. Each year there are an estimated 400,000+ compensable back "injuries" in the U.S.

A number of occupational risk factors have been studied. The relationship betweenoccupation and back symptoms is complex and affected by a variety of confoundingfactors, e.g. reporting bias influenced by the insurance and Worker's Compensation systems. Several studies have shown an increased risk of low back pain and disc prolapse (HNP) for occupations associated with heavy physical work. Exposure to vibration may increase the frequency of low back pain as seen in truck drivers, machinery operators and individuals who drive automobiles extensively. Psychological work factors are also known to affect the frequency of back symptoms. Monotony, work dissatisfaction, and poor relationships with coworkers are all associated with higher rates of back pain and work incapacity.

Individual risk factors have also been carefully studied. The effect of age has already been mentioned. Although gender. differences are not observed in the frequency of low back symptoms, males undergo surgery for disc herniation about 1.5-3 times as often as females. Spinal deformity, such as scoliosis and kyphosis, and leg length differences do not have a predictable predisposition to low back pain. There is also no strong association between body habitus and low back pain or sciatica. Some studies have demonstrated an association between tallness and low back symptoms. Surprisinglya similar finding for obesity has not been uniformly observed. An association between smoking and HNP and low back pain has been noted by several investigators. Numerous other individual risk factors have been examined although clear-cut relationships have not been forthcoming.

Spinal Disorders

Cervical and Thoracic Disorders: Most large epidemiological surveys lump cervical and thoracic pain with lumbosacraI symptoms, making it difficult to ascertain the relative incidence of these complaints. In one study, neck problems accounted for 7% of work absences related to "back" pain; thoracic problems accounted for only 0.2%. There may be a slightly greater frequency of cervical disc herniation observed in men as compared to women. The C5-6 and C6-7 discs are the most commonly affected. Increased risk for neck pain has been found to be associated with frequent lifting, cigarette smoking and frequent diving from a board, Driving, operating vibrating machinery,frequent head turning and several other plausible risk factors have not proven to be statistically significant.

Thoracic spine pain is less common than pain localized to the cervical or lumbar regions. Symptomatic thoracic disc herniation is every more infrequent. Because complaints referable to Lite thoracic region are relatively uncommon especially in the context of 'back strain' or 'lumbago', and because certain disorders, such as metastatic tumors, may have a predilection for this region, the clinician should he suspicious of non-degenerative causes in looking for the etiology of thoracic pain (see section on spinal tumors).

Historical background: Although the treatment of spinal disorders was discussed in the Edwin Smith papyrus and the writings of Hippocrates, surgery for these ailments was not generally undertaken until the latter part of the nineteenth century. The first successful laminectomy was probably performed by Paul of Aegina in the 7th century A.D., but this feat was not repeated until 1829 by Alban Smith of Danville, Kentucky. Elective spinal surgery required the development of anesthesia, aseptic techniques, improved instruments and, with the discovery of X-rays in 1895, improved diagnostic methods.

Walter Dandy developed air myelography in 1918 at the Johns Hopkins Hospital. The difficulties in properly performing this procedure limited its widespread use in the spine, although pneumoencephalography became an important procedure for intracranialimaging. Sicard introduced iodinated contrast myelography in 1920, allowing the relatively accurate diagnosis of intraspinal pathology. Subsequent evolution in contrast agents from lipid soluble to water soluble to non-ionic water soluble agents has greatly enhanced the accuracy and safety of this diagnostic procedure, which remains as the "gold standard" inintraspinal imaging. Computed tomography (CT) was first used to image the brain in1972. Several years elapsed before high-quality spinal images were routine. The development of magnetic resonance imaging (MRI) soon followed with the first head scan being produced on May 18,1979 in Nottingham, England. Spinal imaging became available within two years and is rapidly becoming the imaging modality of choice for most spinal disorders.

The syndrome of sciatica has been recognized since ancient times but the association of sciatic pain with lumbar disc herniation was not made until the twentieth century. Several descriptions of traumatic disc herniations existed in the pathological literature of the late 1800's and in the surgical literature of the early 1900's, but disc herniation was not linked with the genesis of sciatic pain. In 1929, Walter Dandy published two cases of sciatic pain associated with herniated disc fragments which responded to surgical discectomy. Unfortunately, the importance of this paper went largely unrecognized. During those years pathological specimens from what would now be called discectomy procedures were frequently interpreted as "chondromas". In 1934. Mixter and Barr published a paper describing their observations regarding the role of lumbar disc herniation as a common etiology of sciatic pain This revolutionized medical thinking at the time, ushering in a greater interest in the lumbar disc as a source of back and leg pain and in the surgical treatment of such disorders. Surgery for back and leg pain in association with nerve root compression has become one of the most commonly performed operative procedures.

This enthusiastic and generally successful treatment of sciatica secondary to lumbar disc herniation resulted in a preoccupation with the. disc as a source of back pain by physician and the public alike. It is worth remembering, however, that disc herniation accounts for a small percentage of radiating leg pains and an even smaller proportion of back pain. Incidental herniations are not rare and may be observed in up to 25%-30% ofmyelograms or MRIs. Bulging discs, in which there is a diffuse bulging of the annulus into the spinal canal, are oven more common and are less likely to produce sciatica.

The current management of patients with degenerative spine disease and low back pain involves physicians and allied health personnel from numerous disciplines including family practice, internal medicine, neurosurgery, physical medicine arid rehabilitation, orthopedics, neurology; psychiatry, anesthesiology, physical therapy, social work, orthotics and chiropractic. The number of proposed interventions for this group of patients is mind-boggling. Many widely prescribed treatments have no evidence for efficacy. Other efficacious treatments, which may benefit subsets of patients, are indiscriminately applied. Clearly, the optimal management of these conditions requires a broad-based understanding of the pathophysiology of these disorders, astute clinical skills, and an unbiased appreciation of effective therapeutic interventions.

Disc pathophysiology: The intervertebral disc consists of three parts: the annulus fibrous, the nucleus pulposus, and the cartilaginous endplates. The annulus, which forms the peripheral aspect of the disc, consists of collagenous fibers arranged in concentric layers. The fibers are oriented at a 30 degree angle to the horizontal and are embedded in an amorphous ground substance of proteoglycans and water. The nucleus also consists of these same components, although the amount of collagen is considerably less and the amount of proteoglycans is greater than the annulus. The annular fibers attach to the end plates and have dense attachment via Sharpeys fibersto the periphery of thevertebrae above and below. The cartilaginous end plates consist of hyaline cartilage andprovide an avenue for diffusion of nutrients from the bone of the vertebral bodies into thedisc.

Pathological evidence of degenerative changes within the disc is apparentbeginning in the third decade. Fissures develop in the annulus and progressand enlarge throughout life. These fissures may extend in a radial direction completely through theannulus. Concurrent changes within the nucleus include a loss of water content,and necrosis of nuclear fibers and fibrosis. These pathologicalevents significantly alterthe biomechanical properties of the disc and therefore the spinal motion segment as awhole (the motion segment consists of two adjacent vertebral bodies and the associatedligaments and disc).These changes may then predispose to disc herniation or bulging,facet arthropathy andosteophyte formation as well as ligamentous laxity and segmentalinstability".

The mechanisms producing a disc herniation are not well understood. Attempts to produceherniated discs in cadaver spines by application of various loads have notbeen generally successful. Most acute loading conditions produce endplate fracturesrather than posterolateral disc herniations. These finding suggest that most disc herniations are not the result of a single, acute traumatic event.

Numerous structures in the region of the disc are innervated by nociceptive afferent nerves.These include the anterior and posterior longitudinal ligaments, the periosteum, vascular adventitia, the dura, and the posterior aspects of the annulus. The development of

back pain in association with disc herniation may be the result of stimulation of thesenerve endings. The nerve root is invested with its own nociceptor system, the nervi

nervorum. It is presumed that the radicular pain associated with HNP is the result of

stimulating these fibers. The neurological manifestationsof nerve root compression

(reflex inhibition, paresthesias, sensory loss and motor weakness) likely result from either

direct compression bythe disc fragment or from stretchingthe root between the herniation

and the fibrous attachments of the root at the foramen. It isunclear whether disc

herniation per se is a painful condition. The finding of incidental HNP on up to 30% of

myelograms or MRIs would tend to support the view that the disc herniation itself is not the

source of pain. On the other hand, some patients with radicular pain and HNP do give a

prior history of low back pain which then evolved into a typical sciatic distribution. This

may present pain arising from the disruption of the disc without root impingement.

The degenerative processes occurring in the disc also impacts on the osseouselements. There is good evidence that disc degeneration leads to facet degeneration withthe occasional subsequent development of facet hypertrophy, acquired spinal stenosis, ligament hypertrophy, synovialchanges, segmental instability and the clinical syndromes associated with these changes.

CLINICAL EVALUATION

Low Back Disorders: The clinical assessment of patients with degenerative spine disease must be heavily weighted toward the history. Pain is frequently the chief complaint and must be well-characterized. A complete description of the pain is critical including its location, quality, severity, onset and duration., Factors which aggravate or relieve the pain must be elicited as well as any associated symptoms. Some impressions regarding the impact that the pain is having on the patient in terms of work and leisure activities, sleep, mood and interpersonal interactions should are obtained. If the patient perceives the symptoms as the result of injury, the circumstances surrounding this event roust be documented. It is well known that extraneous factors, such as Workmen's Compensation, litigation and disability issues have a major impact on the response to treatment; therefore, they must be accounted for. The patient must be questioned regarding neurological symptoms, such as weakness or gait difficulties, clumsiness or bowel or bladder complaints. The patient should be questioned about numbness, tingling or other sensory changes. The distribution and character of these changes should be understood.

The temporal course of the patient's symptoms is important as is a description of previous diagnostic and therapeutic attempts and the results. The past medical historyshould be elicited, both to evaluate for predisposing or associated conditions, as well as to determine the patient's fitness for various therapies (e.g. surgery). Because psychosocial factors are so influential in this patient population, a social history should also be obtained.

The physical assessment emphasizes the musculoskeletal, neurological andperipheral vascular examinations.

Lumbar radiculopathy: Pain which radiates from the hip or low lumbar region intothe leg is commonly presumed to be the result of lumbar nerve root irritation and/or compression. The most common cause of lumbar nerve root compression is disc herniation. Other observed causes include compression by a hypertrophic facet joint, ligamentum flavum hypertrophy in association with stenosis of the lateral spinal canal, and intraspinal synovial cysts. Less frequently, spinal roots may be compressed by tumors or other masses.

When the pain radiates down the posterior thigh and posterolateral calf approximating the distribution of the. sciatic nerve, it may be properly referred to as "sciatica", although this term predates the modern understanding that most sciatic pain is of radicular origin. Posterior thigh pain which does not extend below the knee may frequently be seen in patients without nerve root compression. This sort of referred pain

can occur with sacroiliac joint inflammation, myofascial pain syndromes, facet syndromes and a number of other conditions. Pain which radiates into the anterior thigh may result from upper lumbar (L1, 2 ,3 and occasionally L4) root involvement. Other diagnoses such as meralgia paresthetica, femoral mononeuropathy (especially in diabetics), muscular strains and hip disease should be considered.

Patients with true radiculopathy will often note an exacerbation of pain with cough, sneezeor Valsalva's. Also pain of radicular origin is frequently relieved by flexion of the knee (e. g. lying supine with the knee resting over a pillow).

Physical findings in patients with lumbar radiculopathy may include motor loss,dermatomal sensory findings or reflex changes alone with nerve root tension signs i.e., positive straight leg raising (SLR) test. The femoral stretch test may be positive in patients with upper lumbar radiculopathy (see Table 1).

Lumbar spinal stenosis: Lumbar spinal stenosis frequently presents as neurogenic spinal claudication. In this syndrome, patients describe pain involving the buttocks, thighs and legs which is brought on by ambulation and decreased by rest. These symptoms must be differentiated from true vascular claudication caused by occlusive arterial disease of the distal aorta or more peripheral arteries. Neurogenic claudication arises from ischemia of the cauda equina brought on by increased metabolic demand in the setting of tight stenosis of the spinal canal. Differential points between these two syndromes include the presence of normal peripheral pulses, and normal skin color and temperature in neurogenic patients. Patients with neurogenic symptoms also often describe relief of symptoms with the adoption of a flexed posture (e.g. will have greater exercise tolerance on a bicycle or when walking behind a shopping cart). Patients with lumbar stenosis may also describe low back pain and radicular symptoms in combination with or instead of, classic claudication.

The neurological examination in patients with spinal stenosis is frequently normal. Occasionally, walking the patient to bring out the symptoms of claudication will yield positive findings on sensory or reflex testing. Straight leg raise is typically negative. Pain is occasionally elicited with lumbar extension.

TABLE 1

RootPain PatternMotor SymptomsSensory SymptomsReflex Change

L2Anterior thighIliopsoasInguinalNone

L3Anterior thighIliopsoas;QuadricepsAnterior-lateralThighKnee Jerk

L4Lateral thighQuadricepsAnterior-lateralCalfKnee jerk

L5Posterior lateral thigh; lateral calfDorsiflexors; extensor hallucis longusLateral calf; dorsum foot; great toeNone

S1Posterior thigh; lateral calf; lateral footGastrocLateral footAnkle jerk

Cervical and thoracic disorders: Degenerative conditions of the cervical spine are less frequent than those of the lumbar spine. Cervical disc herniation and cervical spinal stenosis are the most commonly seen conditions. Thoracic disc herniationsaccount for less than 1% of disc herniations in the spine.

Thoracic disc disease: Thoracic disc hernintion.is commonly an incidental finding on MR scans. Symptomatic thoracic disc herniation produces pain, sensory loss or weakness (myelopathy). Pain may be radicular -- following the course of an intercostal nerve -- or it may be spinal. Sensory findings in this context are usually consistent with an incomplete ventral or lateral cord lesion (e:g. a Brown Sequard pattern ). A sensory level is usually not present except with severe myelopathy. Motor findings are those of a spastic paraparesis (weakness, hyperreflexia, clonus, hypertonus, Babinskis).

Cervical radiculopathy: Root compression in the cervical spine produces characteristic symptoms analogous to those in the lumbar region (Table 2). The numbering of cervical roots is such that a given root exits above its like-numberedvertebral body. Thus a C6 root will exit the C5-6 foramen and will be compressed by a herniation of the C5-6 disc. Although disc herniation is the most common cause of cervical radicular symptoms, foraminal stenosis as a result of osteophytes may produce an identical syndrome. Cervical radiculopathy is frequently first noted upon awakening without an identifiable precipitation event. The question of a cardiac source of pain is often raised when the radiculopathy is left-sided. Neck pain and pain with neck movements are important differentiating factors.

The pain of cervical radiculopathy is often brought on with axial neck compression associated with lateral flexion to the symptomatic side (Spurlings sign) or by downward traction of the involved arm with lateral neck flexion to the opposite side. Conversely, many patients report relief of symptoms by abducting their shoulder and placing their hand on their head.

Cervical myelopathy: Symptoms resulting from compression of the cervical spinal cord are most commonly caused by disc herniations or spinal stenosis. The latter may occur as a result of a congenitally narrow cervical spinal canal but is usually associated with spondylotic changes (osteophytes, disc bulged, facet and ligament hypertrophy). Infrequently spinal canal narrowing is produced by ossification of the posterior longitudinal ligament (OPLL). The radiographic changes consistent with spondylosis are common after age 40 and demonstrate increasing incidence with increasing age.

The measurement of spinal canal diameter on lateral radiographs taken at 3 feet tube-to-plate distance can be used to predict probable spinal cord impingement. The average A-P diameter in the mid and lower cervical spine in 17mm-18mm. Measurement less than 11mm are consistent with significant spinal cord impingement. The spinal cord may be compressed even when larger spinal cord diameters are noted because soft tissue, such as disc or ligamentum, may encroach on the spinal canal.

Varying patterns of clinical signs and symptoms may be noted. Their relative frequencies are seen in Table 3.

TABLE 2 Findings in Cervical Radiculopathy

Disc LevelC4-5C5-6C6-7C7-T1

Percent Cervical Discs20%70%

RootC5C6C7C8

ReflexPectoralBiceps; BrachioradialisTricepsFinger Jerk

Motor SymptomsDeltoid (Biceps)Biceps;BrachioradialisTriceps;Wrist ExtensorsHand Intrinsics

Sensory SymptomsShoulderRadial Forearm; Thumb, IndexDorsal Forearms; Middle FingerUlnar Hand, Forearm

Cervical myelopathy is frequently of insidious onset and is usually progressive. Acute worsening is occasionally seen as are periods of static symptoms lasting months or even years. Patients commonly describe symptoms of numbness or weakness of the hands, citing difficulty manipulating small objects. Proximal lower extremity weakness is often noted as is stiffness (spasticity). Patients may be aware of clumsiness of their gait and a tendency to fall. Overt sphincter disturbance is uncommon but urinary urgency is often reported. Amyotrophic lateral sclerosis (ALS) is an important differential consideration in some cases.

Table 3: Findings in Cervical Myelopathy

FINDINGSPERCENT

Pure Myelopathy59%

Myelopathy + Radiculopathy41%

Hyperreflexia87%

Babinski54%

Sensory Level41%

Posterior Column39%

Dermatomal Arm33%

Arm Weakness31%

Paraparesis18%

Hemiparesis18%

Quadriparesis10%

Brown-Sequard10%

Muscle Atrophy10%

Fasciculations10%

Radiological Evaluation: The radiologic evaluation of degenerative disease of thespine must be individualized. Extensive and expensive study is generally not indicated in patients who are not surgical candidates. The types of evaluation that may be performed include plain radiographs, dynamic radiograms (e.g. flexion-extension films), CT scanning (with or without intrathecal contrast), myelography, an MR scanning. Radio nuclide bone scanning is occasionally helpful. Other ancillary tests such as discography are rarely performed and their value may be questioned. Plain radiographs: The role of plain films in the evaluation of degenerative spine disease is somewhat limited. Nonetheless they are a useful screening tool to rule out bony destruction as seen with neoplasm or infection, and to visualize deformities, fractures or subluxation. Hyper mobility on flexion-extension films may be associated with pain or neurological symptoms. Vertebral movement of more than 4mm to 5mm in the lumbar region or more than 3mm in the cervical region should be considered abnormal.

CT scan: CT is often useful in the evaluation of a variety of disorders. It provides excellent visualization of bony detail. Disc material can often be differentiated from the thecal sac on plain CT of the lumbar spine. This test is less expensive than MR scanning or myelography, but is less likely to be diagnostic in most cases. In cases of far lateral disc herniation, CT is superior to myelography. A major disadvantage of CT scanning is visualization in only the axial plane. In spinal degenerative disease, CT has the advantages of excellent bony detail. It is noninvasive, and can be done as an outpatient procedure. It has a faster scanning time as compared to MR scanning. It is less expensive than MR scanning. It visualizes paraspinal soft tissue. It is often adequate formaking a diagnosis.

Table 4

Advantages to CT in-Spinal Degenerative Disease

Excellent bony detail

Noninvasive, outpatient procedure

Faster scanning time .vs MR

Inexpensive

Visualizes paraspinal soft tissue

Often adequate for diagnosis

Myelography: Myelography is currently performed in conjunction with CT scanning. This study remains as the gold standard for evaluation of most degenerative conditions of the spine. It is, however, are invasive test but it can be done on an outpatient basis. Some morbidity is to be expected (most commonly "post myelogram headache" seen in roughly 10%). Myelography may provide a more "dynamic" sense of the pathology in that films can be obtained after changes in position (e.g. a myelographi (block in cervical stenosis may allow passage of contrast with changes in neck position). Root impingement, especially in the cervical spine, is probably more clearly demonstrated on myelography than on MR scanning.

MR scan: Magnetic resonance imaging will be the first imaging study obtained for the evaluation of most patients presenting with hack or neck pain or radiculopathy. MR scanning will be diagnostic in most instances as it provides excellent anatomic resolution and allows visualization in multiple planes. Contrast enhancement with gadolinium is very helpful in distinguishing scar from recurrent disc in the previously-operated patient.Disadvantages to MR scanning are the relatively long scanning times which may not he tolerated by patients in severe pain or who are claustrophobic, the expense, the high level of operator skill required to produce consistently excellent image and the inability to scan patientswith certain implants (cardiac pacemakers, ferromagnetic aneurysm clips etc.) Bony detail is also not as well demonstrated on MR as with CT.

TREATMENT

Lumbar Disc Herniation: Most (80%+) patients with acute lumbar radiculopathywill improve without surgery, therefore a trial of nonoperative therapy is appropriate with the primary goal of palliating painful symptoms until resolution occurs.

Generally if symptoms are severe, a few (2-3) days of bed rest are appropriate. Longer regimens are not clearly more beneficial. Analgesics are usually required. Non-steroidal anti-inflammatory drugs (NSAIDS) may be prescribed for this purpose. Occasionally narcotic (codeine, oxycodone) or propoxyphene are necessary for adequate pain control. So-called muscle relaxants are probably of limited value, although their sedating effect may help patients comply with bed rest.

A number of therapeutic modalities have been proposed for the treatment of back pain and radiculopathy, most with tenuous evidence of efficacy. These include physical therapy, spinal manipulation, acupuncture, TENS and traction.

The duration of non-operative treatment must be individualized, but generally, a period of 4-6 weeks is considered appropriate before surgery is contemplated. Clearly the presence of a neurological deficit alters these considerations. The development of a cauda equine syndrome (urinary retention, perineal numbness, bilateral motor deficits, sphincter paresis) is an indication for emergent surgery.

Table 5 Indications for surgery in lumbar herniated nucleus pulposus (HNP) Failure of nonsurgical management

Cauda equina syndrome

Acute or progressive motor deficit

Severe pain not responding to analgesics (rare):

Lumbar spinal stenosis: Patients with neurogenic claudication secondary to spinal stenosis should be given a trial of nonoperative management because symptom severity may wax and wane, and patients may achieve a tolerable level of symptoms without surgery. NSAIDS, rest and physiotherapy are all appropriate early in the management of these patients. Surgical decompression is reserved for those individuals with refractory symptoms. Serious neurological deficits are very unusual in this disorder.

Operative treatment consists of relieving spinal canal and individual nerve root compression by means of bony removal. Hypertrophic facets and ligamentum flavum are removed along with any impinging disc material. This is most. frequently accomplished via a laminectomy although various modifications have been described, consisting of removal of lesser amounts of bone (laminotomies) Spinal segment instability is both a preoperative and a postoperative consideration and may be an indication for concomitant spinal fusion in a subset of these cases.

Thoracic disc herniation: Operation in thoracic disc herniation is most often indicated for neurological deficits (myelopathy). The approach is either through a thoracotomy which allows a very ventral trajectory to the disc approaching the problem .away from the neural elements; or through a paramedian approach which does not enter .the chest cavity. This latter approach is more useful when the disc fragment is laterally situated in the canal. Both of these approaches are considerably more difficult than the surgery for lumbar disc herniation and are associated with greater risks of morbidity.

Cervical disc herniation: As in lumbar radiculopathy, most patients with arm painfrom a cervical disc will recover spontaneously. Initial treatment should consist of rest (avoidance of activities which exacerbate symptoms), NSAIDS, cervical traction (home cervical traction 7-10 pounds for 15-20 min TID), and when pain has improved, physical therapy. Narcotic analgesics and muscle relaxants, may be necessary when symptoms are severe. Upper extremity motor weakness, if moderate or severe, is an indication to abandon nonoperative therapy and consider surgery. Patients who present with signs and symptoms of spinal cord compression should be considered for early surgery.

There are two main surgical approaches to deal with cervical disc herniation; either an anterior operation or a posterior approach. Each technique has its advantages and indications. The posterior approach is well suited to lateral disc herniations, especially if there are concurrent lesions at more than one level. The anterior interbody approach is best for central disc herniations with spinal cord compression, but it is also a very effective means for treating radiculopathy secondary to a disc herniation.

Cervical stenosis: Surgery is generally indicated for treatment of progressive myelopathy resulting from spinal canal stenosis. Several different operative approaches

are available for different circumstances. The nature of the compression must be carefully evaluated preoperatively. When the cord is compressed ventrally, consideration should be given to an anterior approach. Stenosis is usually most marked adjacent to the disc spaces because of ventral oseophytes (bars) so that decompression at the disc space may be sufficient. In some cases, greater bone removal is required usually in the form of a trough corpectomy where a slot of bone is removed spanning the necessary number of spinal segments. In this situation, the spine is fused usually with a strut graft and sometimes with internal fixation such as a cervical plate. In some cases, especially with a congenitally-narrow spinal canal, a posterior decompression is the appropriate operation, and is achieved by multilevel laminectomy or by laminoplasty in which the laminar arches are cut but then reattached in a way to provide a roomier spinal canal while maintaining the posterior elements.

The result from cervical decompression for myelopathy are sometimes disappointing. Patients occasionally progress in spite of an apparently adequate decompressive operation. The cause for this is unclear although contributing factors might be some degree of minor instability or selection of the wrong surgical approach. It is estimated that 70%-80% of patients are improved by surgery, although there may be a falloff in good results as patients are followed over time. Spasticity, if pronounced preoperatively, may continue to be a problem postoperatively. Baclofen may be indicated in these cases to try to reduce the increased muscle tone.