SPINAL DISORDERS
Disc Disease and Degenerative Disease of the Spine
Epidemiology of low back and log pain: Low back pain with or without radicular
leg 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 people
younger 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 pain
and 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 between
occupation and back symptoms is complex and affected by a variety of confounding
factors, 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. Surprisingly
a 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 nondegenerative 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 intracranial
imaging. 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" in
intraspinal 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% of
myelograms 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 mindboggling. 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 Sharpey’s fibers to the periphery of the
vertebrae above and below. The cartilaginous end plates consist of hyaline cartilage and
provide an avenue for diffusion of nutrients from the bone of the vertebral bodies into the
disc.
Pathological evidence of degenerative changes within the disc is apparent
beginning in the third decade. Fissures develop in the annulus and progress and enlarge
throughout life. These fissures may extend in a radial direction completely through the
annulus. Concurrent changes within the nucleus include a loss of water content,
and necrosis of nuclear fibers and fibrosis. These pathological events significantly alter
the biomechanical properties of the disc and therefore the spinal motion segment as a
whole (the motion segment consists of two adjacent vertebral bodies and the associated
ligaments and disc). These changes may then predispose to disc herniation or bulging,
facet arthropathy and osteophyte formation as well as ligamentous laxity and “segmental
instability".
The mechanisms producing a disc herniation are not well understood. Attempts to
produce herniated discs in cadaver spines by application of various loads have not
been generally successful. Most acute loading conditions produce endplate fractures
rather 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 these
nerve 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 manifestations of nerve root compression
(reflex inhibition, paresthesias, sensory loss and motor weakness) likely result from either
direct compression by the disc fragment or from stretching the root between the herniation
and the fibrous attachments of the root at the foramen. It is unclear 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 osseous
elements. There is good evidence that disc degeneration leads to facet degeneration with
the occasional subsequent development of facet hypertrophy, acquired spinal stenosis, ligament
hypertrophy, synovial changes, “segmental instability” and the clinical syndromes associated
with these changes.
CLINICAL EVALUATION
Low Back Disorders: T he 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 history
should 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 and
peripheral vascular examinations.
Lumbar radiculopathy: Pain which radiates from the hip or low lumbar region into
the 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, sneeze or
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
Root
Pain Pattern
L2
Anterior thigh
L3
Anterior thigh
L4
Lateral thigh
L5
Posterior lateral
thigh; lateral calf
Motor
Symptoms
Iliopsoas
Sensory
Symptoms
Inguinal
Reflex Change
Iliopsoas;
Quadriceps
Quadriceps
Anterior-lateral
Thigh
Anterior-lateral
Calf
Lateral calf;
dorsum foot;
great toe
Knee Jerk
Dorsiflexors;
extensor hallucis
longus
None
Knee jerk
None
S1
Posterior thigh;
lateral calf;
lateral foot
Gastroc
Lateral foot
Ankle 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 herniations
account 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-numbered
vertebral 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 (Spurling’s 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 Level
Percent Cervical
Discs
Root
C4-5
C5-6
20%
C6-7
70%
C7-T1
C5
C6
C7
C8
Reflex
Pectoral
Triceps
Finger Jerk
Motor Symptoms
Deltoid
(Biceps)
Shoulder
Biceps;
Brachioradialis
Biceps;
Brachioradialis
Radial Forearm;
Thumb, Index
Triceps;
Wrist Extensors
Dorsal Forearms;
Middle Finger
Hand Intrinsics
Sensory Symptoms
Ulnar 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
FINDINGS
Pure Myelopathy
Myelopathy + Radiculopathy
Hyperreflexia
Babinski
Sensory Level
Posterior Column
Dermatomal Arm
Arm Weakness
Paraparesis
Hemiparesis
Quadriparesis
Brown-Sequard
Muscle Atrophy
Fasciculations
PERCENT
59%
41%
87%
54%
41%
39%
33%
31%
18%
18%
10%
10%
10%
10%
Radiological Evaluation: The radiologic evaluation of degenerative disease of the
spine 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 for
making 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 patients
with 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 radiculopathy
will 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. Nonsteroidal 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 pain
from 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.
SPINAL TUMORS
A variety of tumors affect the spine, spinal cord, nerve roots, and associated
structures. From a clinical and anatomical standpoint, these lesions may be classified as spinal
(or vertebral), epidural, intradural extramedullary, and intradural intramedullary.
Although some tumors overlap these various compartments, thinking about spinal tumors in
this way is relevant both from the perspective of developing a differential diagnosis, and in
terms of planning further evaluation and treatment.
Spinal column and epidural tumors: Tumors involving the vertebral column and adjacent
epidural space include metastatic lesions from a variety of sources, primary
tumors of bone and cartilage, tumor, of lymphocytic origins (e.g. plasmacytoma, myeloma,
lymphoma), vascular elements (hemangioma), nerve sheath (e.g. schwannoma), and
other lesions such as chordoma, eosinophilic granuloma, meningioma, etc.
Metastatic tumors: The spine is the most common site for osseous metastasis. When one
considers that: approximately one million new cases of cancer are diagnosed annually,
approximately two-thirds of cancer patients eventually develop metastatic disease, and skeletal
metastasis ranks third after metastasis to the lung and liver, it is apparent that metastasis will be
the most common form of spinal neoplasm.
The most common solid tumors to secondarily involve the spine are: breast, prostate, and
renal carcinomas, which account for nearly 80% of vertebral metastases. Tumors of unknown
primary account for about 5%-10% of cases. Metastases of hematopoietic neoplasms account
for about 4%-10% of most series.
The incidence of spinal metastases appears to increase in a rostrocaudal direction
and probably is a function of the volume of cancellous bone within the vertebrae which
also increases rostrocaudally. When the level of involvement for symptomatic lesions is
considered, however, thoracic levels appear more common. Undoubtedly, this is because
the thoracic spinal canal, being smaller, is more readily compromised and cord compression is
more likely to ensue. Approximately one-third of vertebral metastases are asymptomatic.
The vertebral body is the most common site of involvement, although the pedicles,
transverse processes and posterior elements maybe involved. Solely epidural tumor
without bony involvement is occasionally noted. Multiple sites of involvement in the spine
are often seen. Non-contiguous multiple metastases are seen in at least 15% of patients.
Metastatic disease producers symptoms by several mechanisms. Bony destruction
with fracture or distortion of periosteum and ligaments produces localized pain. Collapse
produces deformity. Spinal instability may be associated with pain or deficits.
Neurological deficits and radicular pain occur because of direct compression by tumor or by
partially destroyed vertebral elements.
The most common symptom of vertebral metastasis is pain, which occurs as the
presenting complaint in up to 95% of patients. Pain may result from bony destruction
causing stimulation of nociceptors in periosteum and ligaments, or it may be the result of
neural compression (particularly the spinal roots), causing a radiating pain. Finally, patients my
occasionally experience generalized pain in the lower extremities below the lesion, perhaps as a
results of spinal cord compression (possibly due to spinothalamic tract involvement). The pain
of vertebral metastasis may be associated with movement and weight-bearing much like other
causes of spinal pain. However, pain during recumbence, particularly that which awakens the
patient from sleep, should raise the question of spinal tumor.
Motor weakness is the most common finding on neurological examination in
patients presenting with vertebral metastasis. The pattern of neurological deficit is, of
course, dependent on the level of spinal involvement. Lesions above T10 (spinal cord
level) will generally produce a spastic paraparesis (or in the cervical region, quadriparesis) with
the findings of weakness, hyperreflexia, and extensor plantar responses. Lesions at the level of
the conus medullaris and cauda equina will give rise to a flaccid paresis which, if longstanding,
is associated muscle atrophy and a flaccid bladder.
Lesions laterally located in the canal in the cervical region may initially affect the ipsilateral
arm and leg. Autonomic dysfunction may be seen with lesions in the upper thoracic or cervical
regions. Sphincter disturbances usually occur late in the course of neurological deterioration.
The exception is for lesions arising at the conus medullaris where bowel and bladder
disturbance may be apparent earlier.
Sensory loss is also frequently observed and with high grade lesions a "sensory
level" may be determined. With incomplete deficits, the sensory level may not correlate
with the vertebral level of involvement and may suggest a level of involvement more
caudal than it actually is. Partial lesions may also produce sensory loss primarily of
spinothalamic (ventral and lateral) or dorsal column (dorsal) modalities. Asymmetrical
involvement is frequently seen.
Diagnostic evaluation: Plain radiographs are generally the first modality used to
evaluate patients suspected of having a spinal tumor. They are, however, fairly insensitive
measures of neoplastic involvement and normal radiographs do not rule out a spinal
tumor.
Inability to visualize a pedicle on an AP film is a common radiographic sign of
metastatic disease. Vertebral collapse or lytic changes should be looked for as well as increases
in paraspinal soft tissue shadows. Osteoblastic changes are suggestive of specific primary
tumors: prostate and breast are commonly blastic. Bladder, thyroid, carcinoid tumors, or
testicular cancer may also have blastic metastases.
Radionuclide bone scans are sensitive but non-specific for metastatic bone
disease. Technetium scans may be positive weeks or even months before radiographic
changes are detectable. False negative scans may occur when the metastatic process is growing
rapidly without bony reaction. Examples of tumors associated with false negative scans include:
renal or lung carcinoma, multiple myeloma, lymphoma, leukemia, and Ewing’s sarcoma.
Computed tomography (CT) is both sensitive and relatively specific for metastasis with
bony destruction. Limitations included poor visualization of the contents of the spinal canal,
lack of multiplanar imaging and difficulty imaging large areas of the spine.
Combining CT with myelography will eliminate many of these problems. Myelography may be
disadvantageous for several reasons: it is invasive, neurological deterioration may
occur after a myelogram performed below a complete spinal block (presumably as a result of
CSF pressure differentials), and evaluation of patients with a complete block may require both a
lumbar and lateral C1-2 puncture.
Magnetic resonance imaging (MR scanning) has become the imaging modality of
choice for many clinical situations in which the differential diagnosis of spinal tumor has been
raised. MR provides considerable spatial resolution, allowing the localization of lesions to the
appropriate spinal compartment. Additionally, the nature of the lesion may be suggested by
signal characteristics on T1, T2 and proton density (PD) weighted images as well as by uptake
of gadolinium enhancement. Changes in bone marrow signal characteristics are frequently a
sensitive indicator of metastatic vertebral involvement. MR is particularly useful for the
diagnosis of intramedullary tumors and cysts.
Relative disadvantages to MR imaging in the diagnosis of spinal tumors include the longer
imaging times which may not be well tolerated by patients who are acutely ill or in severe pain.
Bony detail is less well seen on MR than CT. The quality of imaging on MR is also more
operator-dependent than some other modalities so that inexperienced personnel (e.g. at night)
may not generate studies of the usual quality. Occasionally small or cystic lesions in the
subarachnoid space will be missed on sagittal MR scans, so complete multiplaner imaging
should be done. These few concerns notwithstanding, MR scanning is generally the first
imaging study that should be done in a patient with signs and symptoms compatible with cord,
nerve root or cauda equina compression.
Laboratory evaluation: Few laboratory studies are specifically helpful in the
diagnostic evaluation of a patient suspected of having a spinal tumor. Routine laboratory
evaluation, including CBC, platelets, serum electrolytes and glucose, liver function tests
calcium, magnesium, albumin and urinalysis will be useful in evaluating a patient’s general
status. PT, PTT and possibly a bleeding time are appropriate if surgery or invasive
procedures are contemplated. In a patient suspected of having a plasma cell dyscrasia, urine for
Bence-Jones proteins and serum protein electrophoresis may be helpful in suggesting a
diagnosis. PSA testing may allow diagnosis of prostate carcinoma. Occult blood on urinalysis
should raise the question of renal cell Ca.
Lumbar puncture is rarely helpful although CSF protein levels may be elevated and,
in the setting of a complete block, the closing pressure drops rapidly. It should be
remembered, however, that lumbar puncture may precipitate neurological worsening.
Metastatic workup Common sense should be employed when performing a
search for the primary tumor (or other metastases) in patients with possible spinal
metastasis. Remember that up to 10% of spinal metastases have unknown primary
tumors even after autopsy study. If surgery appears to be indicated in any case, extensive
testing beforehand may add little. Assuming the patient's clinical condition allows, studies
to look for the most common primary sites is appropriate. Chest and spine radiographs, breast
examination and possibly mammography, rectal examination, stool guaiac and evaluation of the
appropriate laboratory studies (above) is a reasonable battery of tests. More extensive
evaluation can be undertaken in specific situations.
Treatment: Treatment of metastatic involvement of the spine must be
individualized with special attention to the issues of spinal stability, pain, neurological
deficit, and duration and rate of evolution of symptoms. It may be useful to subdivide
patients into three groups for treatment based on the severity of neurological findings:
Group 1: Signs/symptoms of new or progressive cord
Compression. These patients are at high risk for
rapid deterioration and require immediate evaluation.
Group 2: Radicular signs/symptoms or mild stable signs of
cord compression. These patients generally
should be admitted and evaluated within 24
hours.
Group 3: Pain in the absence of neurological signs or
symptoms. These patients may be evaluated
over several days usually as an outpatient.
Steroids: There is little doubt that corticosteroids are beneficial in the management of
patients with neoplastic spinal cord compression. Some controversy surrounds the
optimal dose in this context. Some clinicians advocate large doses (e.g. 100mg
Spinal Disorders
dexamethasone bolus followed by 25mg qid for several days for acute spinal cord
compression). Others cite steroid-related complications, such as infections,
hyperglycemia, intestinal perforation arid mental status changes as reasons to use more
moderate doses. Conclusive data are lacking. For short-term use in neurologicallycompromised patients (Group 1), the risks of high doses appear small, but definitive
treatment must be initiated expeditiously. Smaller doses (4mg-10mg dexamethasone qid) are
appropriate in Group 2 or 3 patients during evaluation.
Radiation Therapy (R;T): An extensive literature documents the beneficial effects of
radiation therapy for a large number of solid tumors causing cord compression.
Approximately 1/3-1/2 of treated patients improve and are able to walk at the completion of
therapy. Half of these patients maintain this ability at one year. Pain relief is noted in
about 50%. Response to therapy is related to radiation sensitivity of the tumor and initial
neurological grade. A typical treatment involves 200cGy per day to total of 3000eGy3500cGy, although treatment is individualized with respect to fractionation, fields and
dose.
Some tumors involving the spine are particularly radiation-sensitive or tend to be treated first
by radiation alone or radiation and chemotherapy after biopsy to confirm
diagnosis. Examples include: Ewing's sarcoma, primary lymphoma, and solitary
plasmacytoma.
Surgical Treatment- Surgical management of spine lesions has undergone
Considerable evolution in the last two decades. The two most significant areas of
development are: the proliferation and popularization of various approaches to the spine,
notably anterior and anterolateral approaches, and the advances in internal fixation
technology for reduction and stabilization of the spine. Additionally, improved imaging has
aided preoperative planning and has resulted in earlier diagnosis. Laminectomy is no
longer the primary procedure performed for neoplastic spinal cord compression.
Surgery is indicated for the treatment/evaluation of suspected spinal metastasis
in the following circumstances:
(1) To obtain a diagnosis (e.g. unknown primary)
(2) When there is associated spinal instability or deformity
secondary to neoplastic vertebral destruction
(3) When neurological deficits progress during or after a course of
irradiation
(4) When cord compression is the result of bone in the spinal canal
(5) In certain radio-resistant tumors (e.g. renal cell carcinoma)
(6) When rapid progression to severe neurological deficit has
occurred and patient can be operated on soon after onset (<.24
hours)
The surgical approach must be tailored to the specific problem. Metastatic cord
compression is usually ventral anti thus requires an anterior or anterolateral
decompression. This may require a thoracotomy or extraperitonal exposure.
Decompression generally must be followed by reconstruction/stabilization. This is most
often accomplished with rods or plates affixed to the spine by means of hooks, screws or
wires. A large variety of implants are currently available for instrumenting the spine, many
having originally been devised for the treatment of scoliosis or fracture. Most such
implants are made of titanium, which is quite strong and resistant to fatigue fracture.
Titanium is more expensive than stainless steel, but introduces fewer artifacts on CT and
MR scans.
PRIMARY BONE TUMORS
Aneurysmal bone cyst (ABC): This is not truly a neoplasm. It affects children and young
adults. Fifteen percent of ABCs are spinal and generally involve the laminar arch and posterior
elements (60%). They may be associated with osteoblastoma or other tumors. They may
involve adjacent vertebrae. The treatment of choice is surgical excision, as they may recur after
curettage.
Osteod Osteoma: This is a benign, bone forming tumor. Ten percent are spinal.
They have a predilection for the posterior spinal elements. By definition; they are less
than 1.5 cm in diameter (see osteoblastoma). Classically they present with localized pain
which is dramatically relieved by aspirin. The lack of an aspirin response (seen in
approximately two-thirds), does not rule out this lesion. A bone scan is the most sensitive study.
The lesion will be seen on CT often as a “target” of dense bone surrounded by a halo of
resorption. The. treatment is surgical excision.
Osteoblastoma: This is a benign, bone forming tumor (<1 % of all bone tumors).
Histologically, it is identical to osteoid osteoma but characterized by growth (>1.5 cm). More
than 40% involve the spine. A plain film demonstrates expansion of cortical bone. The
treatment is surgical excision if possible. Curettage and-bone grafting may yield
satisfactory results but recurrence can occur. The recurrence rate with initial total gross removal
is approximately 10%.
Hemangioma: These are benign vascular lesions generally involving the vertebral body. They
are found incidentally on approximately 10% of spinal MR scans and are
rarely symptomatic. A minority are associated with pain or neurological symptoms. Plain
radiographs typically demonstrate a classic "corduroy cloth" appearance with thickened
trabeculation of the involved body. The treatment must be individualized. It may include
radiation, surgery and embolization. The latter may be an adjunct to surgical excision or
radiation but is not presently useful as definitive therapy alone.
Giant cell tumors: They are often slow-growing but may be locally aggressive.
They most commonly involve the vertebral body. Recurrence is common with partial
resection. Radiation induced sarcomas may occur especially with higher doses. The
Treatment is complete excision where feasible. Radiation may be appropriate for nonresectable lesions.
Eosinophilic granuloma: This is usually a benign condition affecting children
usually before age ten. Vertebral lesions constitute 10%-15% of these tumors and most often
affect the vertebral body. Vertebral collapse producing a "vertebra planum" may occur.
Neurological compromise may result requiring decompression and stabilization. Multiple
lesions and poorer prognoses may be noted in Hand-Schuller-Christian disease and LettererSiwe disease. Treatment consists of biopsy, spinal decompression and stabilization, and
radiation therapy.
Benign cartilage tumor: (Osteochondromas and Enchondromas).
Osteochondromas are not true neoplasms. They consist of a cartilage-capped, bony
growth, first noted in childhood, arising adjacent to an epiphyseal plate. Although usually
solitary, a hereditary form, multiple osteochondromatosis, occurs as an autosomal dominant
disorder. Spinal involvement with these lesions is rare. Enchondromas, which are benign
intraosseous tumors of hyaline cartilage, generally occur in the hands and feet. Syndromes of
multiple enchondromatosis occur but rarely involve the spine. Malignant degeneration of these
lesions into chondrosarcoma is not infrequent in these latter syndromes.
Chondrosarcoma: This is a malignant tumor of cartilage, second in frequency to
osteosarcoma as a primary sarcoma of bone. It occurs more frequently in males. The
mean age of occurrence is approximately 40 years. It is most common in the pelvis,
femur, scapula and humerus. Fewer than 4% arise in the spine or sacrum. The treatment
of choice is complete en bloc excision (which is rarely feasible in the spine). Wide excision
is usually performed. Radiation and chemotherapy are of little benefit.
Chordoma: These are rare primary malignancies arising from notochordal
remnants. They occur in the axial skeleton (clivus 35%, sacrurn 50%, vertebral column
15%). They account for 1%-4% of malignant bone tumors. The male to female ratio is
2:1. They occur in all age groups with peaks after the fifth decade. Radiologically an
osteolytic soft tissue mass is usually seen with stippled calcification. The treatment is
complete surgical excision. Radiation therapy may have a limited role for palliation
because these lesions are not radiosensitive.
Osteosarcoma is the most common primary malignant tumor of bone. It
represents 20% of osseous tumors with an incidence of 2:1.,000,000. The peak incidence is in
the second decade (associated with the growth spurt). 1%-3% arise in the spine. Paget's disease
is a predisposing condition in older adults. The treatment is wide excision. Adjuvant
chemotherapy and local radiation therapy is usually given. The prognosis is very poor.
Other sarcomas and primary malignancies: Other types of sarcomas of the spine are
relatively uncommon. These include fibrosarcomas, rhabdomyosarcomas- and tumors arising
from other cells of origin. It has been estimated that <1000 cases per year are seen in the U.S.
The treatment is generally like that for sarcomas elsewhere, although en bloc excision is rarely
feasible.
Plasma cell tumors: This tumor is composed of malignant plasma cells. It
presents as solitary lesions in 3%. It is most commonly systemic (multiple myeloma). The
male to female; ratio is 3:1. - The age of patients is usually <50 years at presentation. The
spine is the initial site in 25% -50% of cases. Pain is the most common presentation. A
lytic lesion is seen on radiographs. The bone scan may be negative. The treatment is radiation
therapy as the primary modality. Surgery is done for stabilization of the spine. Chemotherapy
is given for progressive systemic disease.
INTRADURAL EXTRAMEDULLARY TUMORS
The differential diagnosis of masses in this compartment is considerably different from
extradural lesions. Intradural metastasis is uncommon, accounting for only 1%-5% of
spinal metastatic disease from systemic malignancies. Occasionally, cerebrospinal spread
of CNS neoplasms may result in solid metastases in the spinal compartment. This is perhaps
most commonly seen in medulloblastoma, but is also recognized in other tumors, including
primitive neuroectodermal tumors (PNET’s), malignant glial neoplasms (glioblastoma, highgrade ependymomas and oligodendrogliomas) and intracranial sarcomatous tumors.
The most common tumors in adults in the intradural extramedullary space are
meningiomas and benign nerve sheath tumors (schwannomas and neurofibromas).
Spinal ependymomas, which are often intramedullary in the spinal cord, may also arise
from the filum terminale and appear as extramedullary growths. The myxopapillary variant
of ependymoma is commonly seen in this location. Dermoid and epidermoid lesions may
be found in the lumbar or lumbosacraf level. Teratomas and lipomas often occur in association
with spinal disruption in the lumbosacral region.
Nerve sheath tumors, including schwannomas (neurilemmomas) and
neurofibromas are the most common intradural extramedullary lesions. They predominate
in the lumbar region. There is a slight male preponderance. Roughly 72% are intradural
extramedullary, 14% are solely extradural, 13% are "dumbbell" (involving both
compartments along an exiting nerve), and 1% are intramedullary. Neurofibromas, and to a
lesser extent spinal schwannomas, may be associated with von Recklinghausen's
neurofibromatosis (NF-1). In the context of NF-1,malignant degeneration of
neurofibromas to neurofibrosarcomas usually occurs. The treatment is surgical excision.
Recurrence is uncommon with complete resection
Meningiomas are the second most common intraspinal neoplasm. They are most
common in the 4th-6th decades. Women are affected 8-10 times more often than men.
These lesions generally involve thoracic levels and are often anterior or anterolateral in the
canal. They are usually well seen on MR scans and enhance brightly with gadolinium.
The treatment is surgical excision. Radiation or chemotherapy are not indicated for these
benign lesions.
Ependymomas are often considered as intramedullary lesions (see below), but most
commonly arise from the filum at the lumbar level. There is a male predominance with
presentation usually in the 3rd or 4th decades. Although generally benign in this location,
malignant behavior can be seen. The treatment is total excision when possible. Radiation
therapy is reserved for malignant or incompletely excised lesions.
Dermoids, epidermoids and teratomas are uncommon lesions generally seen in
the pediatric age group. They are congenital and are often associated with other
anomalies, such as dysraphism, dermal sinus tracts, and cutaneous lesions (such as
angiomas and hairy patches or lipomas). Although most common in the lumbosacral area,
they may occur throughout the spine. The treatment is surgical excision. Teratomas of
the sacrococcygeal region may undergo malignant change.