Primary Care;
Clinics in Office Practice
Volume 23 • Number 2 • June 1996
Copyright © 1996 W. B. Saunders Company
Orthopedics
LOW
BACK PAIN
H.Ulrich Bueff MD
William Van Der Reis MD
From
Mt. Zion Medical Center (HUB), and Department of Orthopaedic Surgery,
University of California, San Francisco, School of Medicine (HUB, WVDR), San
Francisco, California.
Address
reprint requests to
H. Ulrich Bueff, MD
UCSF Mt. Zion Medical Center
1600 Divisadero Street
San Francisco, CA 94115
Back
pain is a common complaint to the general practitioner and the most common
presentation to the orthopedic surgeon. Eighty percent of the adult population
experiences back pain at one time, and 1% of this group also complains of
sciatica. The annual incidence is approximately 15% to 20%. The socioeconomic
burden of this complaint is astounding. Costs of health care are estimated to
range from 20 to 50 billion dollars annually. This does not take into account
the costs of litigation and the burden on the time of orthopedists, general
practitioners, and physical therapists. The families and friends of the
patients often suffer the consequences of reduced income and depression.
Approximately 15% of the patients account for 80% to 90% of the total cost. One
percent of the US population chronically is disabled by back pain. The rate of
disability claims has increased 14 times the rate of population growth.
This
problem is not restricted to the United States. In the United Kingdom, 11% of
the population reported that their activities had been restricted by back pain
within the past 4 weeks. Two million consults to a medical practitioner are
made annually; 300,000 hospital visits by outpatients are made annually, and
approximately 100,000 inpatient hospital admissions are made annually. [6]
[8]
The
good news is that the pain usually is self-limiting. Fifty percent of the
patients recover in 2 weeks, and 90% recover by 6 weeks. In many circumstances,
an accurate diagnosis is never made, which may precipitate costly diagnostic
workup and prevent efficacious treatment.
Back
pain can be divided into acute and chronic pain. Acute low back pain refers to
patients who have a problem with their back that occurred within hours to 1
month. Chronic low back pain refers to conditions in which patients continue to
have a problem or fail to recover in the expected time frame, with problems
continuing 1 month or more. Fewer than 5% of patients with low back pain have
chronic low back pain. It is this group of patients that accounts for 85% of the
total expenditure on treatment of and compensation for low back pain. The focus
in treatment of these patients is nonsurgical in most cases and should include
the physical and psychological disabilities of the patient. Patients should be
referred to psychologists for evaluation as well.
Occupational
and psychological factors often play a critical role in the cause of low back
pain. In general, patients with chronic low back pain tend to be dissatisfied
with their present occupations and believe that their jobs are boring and
repetitious. These patients also have higher divorce rates, more problems with
headaches and gastrointestinal ulcers, and higher rates of alcoholism than the
general population. Once relieved of their work duties, it becomes more difficult
to return to work as time progresses.
The
future of medical care under managed care will ask the general practitioner to
take on a larger role in the care of this group of patients with acute and
chronic back pain. A small portion of these patients will necessitate surgical
intervention. The history and physical examination must be thoughtful and
consistent regardless of the initial presentation of the patient. In many
cases, a traditional diagnosis is never made; however, more often than not, the
patients recover. Workup of these patients need not include costly radiographic
and interventional diagnostic tests that not only increase the cost of care but
also often cloud the diagnostic picture. Initial evaluation, including history
and physical examination, should be aimed to rule out serious pathology and
pinpoint acute surgical issues.
The
majority of patients improve with conservative management. There has been no
scientific evidence to support the usefulness of corsets, bed rest,
transcutaneous nerve stimulation, or traction for the treatment of acute low
back pain. [3] [4]
ETIOLOGY AND PATHOPHYSIOLOGY
The
cause of pain is found in only 12% to 15% of patients with low back pain. The
bulk of patients present with pain in the lumbar spine secondary to a
derangement of mechanic origin. The spine may be divided into three columns.
The anterior column includes the anterior longitudinal ligament, anterior
portion of the vertebral body, and anterior portion of the intervertebral disc.
The middle column is composed of the posterior longitudinal ligament, posterior
body, and posterior intervertebral disc; the posterior column includes the
ligamentum flavum and the posterior elements (facet joints, pedicles,
transverse processes, laminae, and spinous processes). Surrounding these
elements are multiple ligaments (inter-transverse, interspinous, anterior
longitudinal, posterior longitudinal) and muscles. The spinal cord and nerve
roots are protected within these structures (Fig 1) (Figure Not Available) .
The
intervertebral disc is made of an inner nucleus pulposus and a tough,
cartilaginous outer annulus fibrosis. The fibers of the annulus are arranged
concentrically. The disc is designed to absorb vertical loading of the spine.
The facet joint, anterior longitudinal ligament, posterior longitudinal
ligament, and posterior ligaments are designed to prevent excessive rotation,
flexion, and extension. The anterior longitudinal ligament is much thicker than
the posterior longitudinal ligament. The posterior longitudinal ligament is
attenuated laterally at the level of the disc, predisposing herniations to
occur more frequently in this region. The bony components provide protection
for the spinal cord and nerve roots. In adults, the spinal cord terminates at
the L1-L2 level, and the nerve roots of the lumbosacral plexus make up the
cauda equina. In the lumber spine, the nerve roots leave the canal via the
neural foramen below its corresponding vertebral body. Any pathology within the
neural foramen may irritate the nerve root. In the canal, the nerve roots
separate from the cauda equina one disc level above its exit from the canal
(i.e., L3 separates at the L2-L3 disc and exits below the L3 body). Radicular
symptoms in the distribution of one nerve root may be caused by one of two
possible disc herniations: a central or lateral disc herniation. Chronic
overuse, acute injury, and systemic disease may contribute to disruption or
degeneration of these elements.
The
motion segment has been developed to help describe the functional spine. It is
composed of two adjacent vertebral bodies and the intervening disc. There are
three joints in this complex (the disc and the two facet joints). The motion
segment incorporates the bones, ligaments, nerves, vessels, and joint capsules.
All these elements are interrelated, and damage to one area can affect all
others. This makes pinpointing the source of pain even more difficult (Fig 2)
(Figure Not Available) .
History
The
history is the key to the evaluation of low back pain. In most cases, the
diagnosis can be made by a thorough history. The physical examination and
diagnostic tests are used for confirmation of the findings during the history.
The history must begin with the traditional questions regarding pain. Where is
the pain? Does the pain radiate down the legs? How long has the pain been
present (hours, days, weeks, months, years)? Acute onset of low back pain has a
better prognosis for recovery than chronic low back pain does. Injuries that
occur at work do not fare as well as those occurring outside the workplace.
Describe the pain (aching, burning, stabbing)? Is there night pain? Night pain
should be a concern and may indicate that there is an underlying malignancy or
infection.
How
much restriction of activity is there? How long can the patient sit, stand, or
walk? People with disc herniations usually have difficulty sitting for long
periods, and the pain is relieved by standing or lying down. Patients with
mechanic low back pain have exacerbation of their symptoms with physical
activity (lifting, twisting, bending) and have relief with rest. Patients with
spinal stenosis develop pain with ambulation and spinal extension. They have
more difficulty going down hills than going up hills. Furthermore, their pain
is relieved by sitting down. It is critical to evaluate these patients for
possible vascular claudication as well. Patients with vascular claudication
have difficulty going uphill; their onset of pain occurs at a reproducible
distance, and their pain is relieved by standing still. One good test to
differentiate these groups is stationary bicycling. Patients with vascular
claudication have difficulty with bicycling, but those with neurogenic
claudication usually do not. Morning stiffness may be indicative of a
rheumatologic arthropathy.
Is
there weakness or numbness? Muscle weakness, if progressive, must be evaluated
urgently, and any pathologic lesions should be decompressed. It is critical to
differentiate between low back pain and leg pain.
One
must determine whether the back pain or leg pain is worse and determine their
relative importance. The leg pain may be referred from the back; it may be
radicular in origin, or it may be from primary hip or knee pathology. Pain from
degenerative changes of the lumber spine rarely radiates below the knee,
whereas disc herniation may cause pain to radiate to the foot. Radicular pain
may direct evaluation to a specific nerve root level. L3 and L4 radicular pain
radiate to the inner thigh; L5 progresses down the lateral calf and dorsum of the
foot, and S1 symptoms radiate down the posterior calf, sole, and lateral foot.
Groin pain usually is related to hip pathology.
More
than in any other orthopedic evaluation, the psychological and social histories
must be taken. In patients with chronic problems, it may be wise to refer them
to a psychologist or psychiatrist before proceeding with any surgical
intervention. Waddell et al. [12] evaluated 103 patients with
industrial injury who had failed one operation and underwent a second spine
procedure. There was improvement in only 50%, and 20% deteriorated. Results of
spine surgery in workers' compensation cases clearly are worse than in patients
with nonindustrial problems. Several questions must be asked. Is there
litigation pending? How is the home life and work situation? What is the
patient's source of income? How long since the patient has last worked? Is
there a psychiatric history, or social history: smoking, drinking, or drugs?
Bowel
and bladder symptoms and perianal numbness may be indicative of a cauda equina
syndrome. This is a true emergency and needs emergent decompression. The
patient should be asked to draw the area of primary pain and areas of radiation
as well. Has the patient undergone previous surgery? If the patient never had pain
relief after the first procedure, it is possible the correct disease was not
addressed. If the patient had a significant time interval with good pain
relief, it is possible that there are now degenerative changes subsequent to
the previous surgery or that there is a new pathologic lesion. If the patient
had only short-term relief, the issue is more difficult. The source may be
postoperative scar formation that is not usually amenable to reoperation.
Physical
Examination
The
physical examination should start with a basic medical examination and then
focus on the orthopedic and neurologic examinations. The authors focus on the
orthopedic and neurologic aspects of the examination. The lumbar spine then
should be inspected and palpated. Areas of localized hair growth may indicate
that there is an underlying spinal dysraphism (most commonly spina bifida
occulta). The spine should be palpated with the patient in the prone position.
Tightness and spasm of the paraspinal muscles should be noted. One should palpate
the spinous processes, the posterior superior iliac spine, the iliac crest, the
greater trochanter, and the course of the sciatic nerve. Localized tenderness
of the lumbar spine may indicate that there is a lumbar sprain or strain.
Scoliotic deformities may be present. If so, the plumb line should be dropped
from T1 to the sacrum to evaluate whether they are compensated.
If
the patients complain of incontinence of stool, a rectal examination should be
performed to assess for sphincter tone. Rectal examination also can help in the
evaluation of coccygeal pain. Gait should be assessed. A broad-based gait may
be indicative of central or long tract disease. The patients should have their
height and weight measured. Patients may not be aware of a loss in height,
which points to compression fractures of the vertebral bodies. The patient
should be asked to toe walk and heel walk. This incorporates strength of the
anterior tibial and posterior musculature and coordination.
Range
of motion of the lumbar spine should be evaluated, forward flexion and
extension and right and left lateral bending. It is important to differentiate
bending at the hips from bending of the lumber spine. Patients normally have a
smooth contour of the back when bending forward. Patients who maintain their
lumbar lordosis with forward flexion have a stiff lumbar spine and are flexing
at the hips. Patients with excessive kyphosis may have compression fractures or
Scheuermann's kyphosis. Patients with scoliosis may have a visible rib hump
with forward bending, and subtle curves are easier to see when bending forward
than in the erect position. One can document the amount of bending with the
angle of forward inclination or with the distance from fingertips to the floor.
Patients should be able to bend equally to one side and the other. In general,
patients with disc disorders have pain with forward flexion, whereas patients
with spinal stenosis have pain with extension of the lumbar spine.
Hip
examination should be performed to differentiate primary hip pathology from low
back disorders. Range of motion of the hips, including flexion, extension,
internal rotation, external rotation, abduction, and abduction, should be
documented. Flexion contractures of the hip are assessed by maximally flexing the
opposite hip to flatten the spine and then measuring the angle between the
femoral shaft and the table.
The
patients then should have motor and sensory examinations of the lower
extremities Table 1. The straight leg raise test is
done in the seated and supine positions. This stretches the sciatic nerve and
the lower lumber nerve roots. In the seated position the calf should be brought
into full extension. If this reproduces the patient's radicular symptoms, the
test is positive. In the supine position, the leg is held in full extension and
flexed at the hip. If the patient's radicular symptoms are elicited at 30° to
60°, the test is positive. One also should perform the test on the
contralateral extremity. If this causes radicular symptoms down the symptomatic
leg, the crossed straight leg test is positive. The straight leg raise test is
sensitive but nonspecific, whereas the crossed straight leg test is specific
for a herniated disc but not as sensitive as the affected straight leg raise. [16]
TABLE 1 -- NEUROLOGIC EVALUATION
|
Nerve Root
Level |
Motor
Function |
Reflex |
Sensation |
|
L2 |
Hip
flexors (illopsoas) |
|
Anterior
thigh |
|
|
Knee
extensors (quadriceps) |
Patellar
tendon |
Medial
thigh and |
|
L3 |
|
|
knee |
|
L4 |
Ankle
dorsiflexors (anterior tibialis) |
Patellar
tendon |
Medial
calf |
|
L5 |
Toe
extensors (extensor hallucis longus) |
|
Lateral
calf, dorsum of the foot |
|
S1 |
Plantar
flexors (gastrocnemius and soleus) |
Achilles
tendon |
Lateral
foot and sole of the foot |
Light
touch should be evaluated through the entire leg, foot, and ankle. Strength of
the hip, thigh, calf, and foot musculature also must be documented. Hip flexors
and extensors are evaluated best in the supine position. Quadriceps,
hamstrings, gastrocnemius, soleus, anterior tibialis, and toe flexors and
extensors should be graded on a one-to-five scale. One indicates no movement,
two is a flicker of movement, three is movement against gravity, four is
movement against mild resistance, and five is full strength.
The
patient should be evaluated for the Waddell
signs:skin tenderness, stimulation, distraction, regional disturbances, and
overreaction to stimuli. [13]
Diagnostic
Tests
Imaging
Plain
radiographs are not necessary on all first visits. If the patients are older
than 50 and have a history of cancer, weight loss, fever, night pain, rest
pain, or trauma, they should have radiographs on the initial visit. The imaging
studies should be performed to confirm the finding based on the history and
physical examination. Initial films include anteroposterior and lateral views
of the lumbar spine, and true anteroposterior of the lumbosacral spine (45°
titled-up view) should be obtained. Oblique views can be obtained to visualize
the neural foramina, facets, and pars interarticularis. Standing views including
the iliac crests occasionally are obtained to evaluate deformity of the lumbar
spine and obliquity of the pelvis. Radiographs of the hips are obtained if
there is concern about hip pathology
One
study [15] found 35% of asymptomatic patients had abnormalities of
the lumbar spine on CT scan. The incidence was 19.5% in individuals younger
than 40 years of age and 50% in patients older than 40. The MR imaging also has
been shown to find abnormalities in patients who are asymptomatic. One study [2] evaluated 67 asymptomatic patients and found
abnormalities in one third. Twenty percent of the patients younger than 60
years old had disc herniations, and 50% of those older than 60 had
abnormalities (36% disc herniation and 21% spinal stenosis). Similarly Jensen
et al [9] showed 52% disc bulges and 27%
disc protrusions in asymptomatic volunteers. Radiographic findings alone do not
always correlate with clinical findings. In the absence of clinical findings, one
should not necessarily pursue further treatment. It also is true that if
clinical findings are clear, radiographic correlation not only is unnecessary
but also may confuse the diagnostic picture.
Myelography
has moderate sensitivity in the diagnoses of disc herniation and spinal
stenosis but with the advent of MR imaging has lost much of its usefulness.
Myelography now is used in conjunction with CT scanning in the evaluation of
spinal stenosis. CT scanning allows better visualization of stenotic defects
than myelography alone. CT scanning also subjects the patient to a lower dose
of radiation and is associated with fewer complications than myelography. CT
images also can be reformatted by computer to provide many different image
projections including three-dimensional reconstructions.
MR
imaging also can provide many projections and sections through the lumbar spine
in the evaluation of low back pathology. MR imaging is significantly superior
to CT scanning in the evaluation of soft-tissue pathology. MR imaging can show
changes within the disc and vertebral body based on alterations in the fluid
and fat content of each region respectively. Gadolinium enhancement with MR
imaging further enhances this imaging technique. These scans especially are
useful in evaluating postoperative lumbar spine patients with persistent pain.
The scan can aid in differentiation between scar tissue and herniated disc
material. Scar tissue has increased signal intensity compared with disc
material (Fig 3) (Figure Not Available) .
Discography
has two possible roles in the evaluation of low back pain. The disc pathology
may be visualized on the discogram, and the patient's symptoms of low back pain
may be reproduced by the test itself. Studies [14] have shown that
the discogram can reproduce the patient's pain response reliably. This
information can aid in the preoperative evaluation of patients with low back
pain.
Electrodiagnostic
studies help in certain instances. Patients in whom there is a question of
peripheral neuropathy (i.e., diabetes) stimulating nerve root pathology may
benefit from electromyogram evaluation. Electromyogram also is useful in
differentiating peroneal neuropathy from nerve root pathology and in evaluating
lesions of the upper motor neurons.
Differential Diagnosis
Mechanic
Lumbar
Strainor Sprain. Patients may present with acute or chronic low back strain. Acute strains usually follow a twisting
or lifting maneuver. Any movement is painful, and patients may walk in a
slightly flexed position. The patients do not have radicular symptoms, and pain
usually is relieved by lying down. The pain is usually severe and diffuse over
the low back and associated with paravertebral muscle spasm.
Physical
examination may be limited. One should attempt to rule out tension signs
(straight leg raise and femoral stretch tests) and evaluate for paravertebral
muscle spasm. Radiographs are not necessary if the patient is too
uncomfortable.
Treatment
includes short-term rest (2-3 days), anti-inflammatory medications, and instruction
on proper techniques for stretching, strengthening, and lifting. Pillows under
the knees, head, and neck usually help. Heat applied to the low back may help
relieve the muscle spasm. Light massage and ultrasound also may help relieve
the spasm. The patient should sleep on a firm bed to prevent sagging and
therefore an increase in lumbar lordosis. At work, a hard, straight-backed
chair is helpful. The patients should avoid lifting until symptoms have
subsided, and then lifting should be performed with a straight back, the legs
should do the work, and the arms can rest on the thighs. Once symptoms have
resolved completely, exercises should be done to stretch and strengthen muscles
and to improve range of motion.
Chronic
strains are more difficult to treat and are common presentations to the general
practitioner and the orthopedic surgeon. Presentation commonly is a mild
backache aggravated by twisting, bending, or lifting. This usually is improved
by rest. Patients more often have a moderate, nagging backache with an acute
flare-up. The pain often radiates to one or both thighs. Pain usually is
aggravated by activity. Physical findings include poor range of motion in the
lumbar spine and lumbar tenderness to palpation. Straight leg raising may
increase the lumbar discomfort, and paravertebral muscle spasm may be present.
If
severe, a short course of bed rest may help. Patients also should be given a
short course of anti-inflammatory medications and may benefit from a formal
course of physical therapy and back school. External supports (corsett or
lumbar support) can be helpful. Ligaments and muscles heal with scar formation,
and each subsequent injury to the back is cumulative. If all conservative
measures have failed, lumbar or lumbosacral fusion should be considered. Risks
of pseudoarthrosis and persistent pain must be discussed with the patient in
detail.
Mechanic Low
Back Pain
Patients
with chronic low back pain associated with physical activity, especially
lifting, make up a small percentage of the patients with low back pain.
Unfortunately, these patients do not have a good prognosis for improvement.
Before extensive evaluation, these patients should have psychological
evaluation. Symptoms are thought to be secondary to degenerative changes in the
lumbar spine. Discography may be used to localize the pathology to one or two
specific levels. Spinal fusion often is the final option if other conservative
measures have failed.
Spinal
Stenosis
Spinal
stenosis encompasses any narrowing of the spinal canal or neural foramen. The
different causes of spinal stenosis have been classified. This includes
congenital narrowing and acquired stenosis. Acquired stenosis can result from
degenerative, combined, iatrogenic, post-traumatic, or other less common causes
(i.e., Paget's disease) [1] (Fig.4) (Figure Not Available) .
Presentation
depends on the level and site of stenosis. Neural foraminal stenosis may result
in radicular symptoms. Central stenosis at multiple levels may result in
neurogenic claudication. Neurogenic claudication involves pain in the legs
brought on by walking and relieved by sitting. Vascular claudication must be
ruled out as a possible source for these symptoms (Fig 5) (Figure Not
Available) .
On
physical examination, findings also depend on the level of stenosis. In
general, lumbar spine extension exacerbates the pain. Plain radiographs are
helpful in the evaluation of spinal stenosis. Degenerative changes and neural
foraminal stenosis can be seen on these films. CT scanning and CT with myelography
also are helpful. As with almost all disorders of the low back, initial therapy
is conservative. Rest, anti-inflammatory medications, and back exercises may be
helpful. In this group of patients, epidural injections of steroids can be
efficacious. If conservative measures fail, decompression at the level of
stenosis can relieve the symptoms.
Spondylolisthesis
Spondylolisthesis
is the anterior displacement of one vertebral body on another. The posterior
portion of the arch, including the inferior facets, remains with the sacrum.
The rest of the vertebral body slips forward. If there is disruption of the
interarticular portion of the neural arch without forward displacement of the
vertebral body, it is termed spondylosis.
The displacement is graded based on the degree of forward displacement:
grade I: less than 25%; grade II: 25% to 50% grade III: 50% to 75%; grade IV:
greater than 75%. The traditional classification is as follows.
- Dysplastic: congenital dysplasia of the superior facet
of S1, leading to slip of L5 on S1 (Fig 6) (Figure Not Available) .
- Isthmic: congenital defect of the isthmic portion of
the neural arch. Usually occurs at the L5 level. The defect may be
unilateral or bilateral. With bilateral defects, forward slippage occurs
and may present anywhere from grade I to grade IV. The cause of this
defect has not been defined. It is likely that patients have a
predisposition for a defect in the pars and subsequent trauma causes the
disruption. Patients usually present in their late teens. Predisposing
activities include gymnastics. Clinical presentation has a wide range, and
the condition may be silent. Patients may have aching low back pain
secondary to the degenerative changes and increased stress on the
ligamentous structures. Root impingement may occur and result in
unilateral or bilateral sciatica. With spondyloptosis (100%
spondylolisthesis), cauda equina syndrome has been reported. On
examination, patients usually have tight hamstrings and the classic
heart-shaped low back. The radiographic examination of choice for
spondylolisthesis includes the lateral and the oblique radiographs of the
lumbar spine. Treatment is conservative if symptoms are minimal and there
is no neural impingement. Patients are given instructions on postural
exercises. Patients also may benefit from corsets. If symptoms persist or
if neural symptoms occur, fusion should be considered.
- Degenerative: usually occurs in the older patient
population (> 50 years old) secondary to degenerative changes in the
disc space and the facet joints. This occurs most commonly at the L4-L5
level and usually is not greater than grade I (Fig. 7) (Figure Not
Available) .
- Traumatic: occurs secondary to an acute injury with a
fracture of the posterior neural arch. Fractures may heal if treated with
immobilization in a brace for several months.
- Pathologic: localized or generalized bone disease may
cause the posterior arches to become incompetent (Fig. 8) (Figure Not
Available) .
Insufficiency
or Compression Fracture
In
the elderly population, insufficiency fractures of the sacrum and compression
fractures of the lumbar vertebral bodies are possible with minimal trauma.
Diagnosis is made with the history of acute onset of low back or pelvic pain
with often minimal trauma. On physical examination, there may be tenderness on
palpation of the lumbar spine or sacrum. Radiographic findings confirm the
diagnosis. Treatment is conservative and includes rest. Mobilization should be
attempted as soon as the acute pain has resolved to prevent deconditioning of
the patient. Follow-up radiographs should be obtained to assess for progression
or displacement.
Disc
Herniation
Patients
present with acute onset of low back pain radiating to the leg. This syndrome
was first described in 1934. [11] It is possible
that one traumatic event can cause rupture of the annulus fibrosus and
herniation of the nucleus pulposus, but in most cases, there is a sequential
process that occurs. Initially, the stresses on the annulus weaken the disc
itself. This weakening is part of the normal aging process and is confirmed by
the high incidence of disc herniations in asymptomatic elderly patients.
Because the blood supply to the disc space is poor, repair of disc disruption
is inadequate. When the annular complex becomes insufficient and stresses are
great enough, the nucleus pulposus and degenerated annulus herniates into the
canal. The areas of greatest weakness are lateral to the midline. When the
annular bulge occurs, the pain fibers in the outer annulus elicit a pain
response. This is usually a deep pain that is not well localized and may
radiate into the buttocks and thighs. There may be associated paravertebral
muscle spasm that exacerbates the pain. The bulge may progress to frank herniation,
at which time impingement of the cauda equina and nerve roots may occur. If the
herniation becomes separated from the main body of the disc, it is termed an extruded disc. The more lateral
herniations tend to involve one nerve root. As the herniations become more
central, more than one nerve root can be involved, and in large herniations,
the cauda equina becomes involved (Fig.9) (Figure Not Available) .
The
most common levels of involvement are L4-L5 and L5-S1. L3-L4 is involved less
commonly, and other levels are rare. If pain is diffuse and cannot be localized
to one level, disc herniation may be minimal, and confirmation is made only
with the MR imaging scan. One should proceed to the MR imaging in this case
only if symptoms have not improved with conservative treatment. The traditional
disc herniation occurs in the healthy, middle-aged adult. Patients may or may
not have a history of intermittent backache in the past. There may be an acute
injury to incite this episode, but these injuries often are minor. The pain
starts in the low back, and as it intensifies, it radiates into the lower
extremity. The back pain may subside as the patient develops numbness and
weakness in the lower extremity. If the patient attempts to walk on the leg,
the pain becomes much worse.
On
physical examination, the patients are in significant pain. There often is
paravertebral muscle spasm and decreased lumbar lordosis. The patients have
difficulty walking. Range of motion in the lumbar spine is reduced, and the
straight leg raise elicits their radicular symptoms. The patients may lose
specific reflexes based on the level of herniation (ankle jerk--S1; patellar
tendon reflex--L4). Motor weakness and dermatomal-decreased sensation are
helpful in pinpointing the level of the lesion. Compression of the S1 nerve
root usually is the result of L5-S1 disc herniation,
L5
compression from L4-L5 disc herniation, and L4 symptoms from L3-L4 herniation
(Fig 10) (Figure Not Available) .
Evaluation
with MR imaging or CT myelography is not indicated in most cases unless
conservative treatment has failed. If patients have bowel or bladder symptoms
or have a progressing neurologic deficit emergent, MR imaging is indicated.
Most
patients with disc herniation respond to conservative treatment. Bed rest for 1
to 2 days provides the most relief while preserving muscle tone and strength. [4]
Pain relief with conservative therapy is secondary to decreased edema
surrounding the nerve roots. With time, reabsorption of the disc material
occurs. In some cases, complete neurologic recovery never occurs.
There
are many interventional options for treatment, including injection of
chymopapain, percutaneous discectomy, microdiscectomy, and traditional open
discectomy. The gold standard is the microdiscectomy with excision of the
herniated disc. In younger patients without significant histories of back
problems, isolated discectomy is indicated. In older patients with a longer
history of back problems and evidence of degenerative disc disease, discectomy may
be combined with posterior fusion. If patients present with cauda equina
syndrome, early disc excision should be performed. Decompression should be
completed within 6 hours. Waiting longer than 72 hours still may allow for
neurologic recovery, but the risk of permanent deficit is greater. [10]
Disc
degeneration may cause a patient to present with aching low back pain. The
patients usually are older. The patients have narrowing of disc space on
radiography. Degeneration of the disc leads to increased stress on the
intervertebral joint and the facet joints. Osteoarthritic changes occur with
spur formation at the margins of the vertebral bodies and sclerotic changes in
the end plates. These patients may be compensated well because this is a slow
degenerative process and an acute strain may incite a pain response. The
patients should be treated conservatively initially as long as there is no
progressive neurologic deterioration or cauda equina syndrome. Patients may
respond to a short period of rest, anti-inflammatory medications, and postural
exercises. Initial management may be followed by an epidural steroid injection.
Once the acute inflammatory stage has passed, the arthritic changes and
narrowing of disc space stabilize the joint, and symptoms may subside. If all
conservative measures fail, posterior fusion with or without decompression may
be performed.
Ankylosing
spondylitis occurs in younger patients, usually men. Complaints usually begin
with pain at the sacroiliac joints. Paget's disease, osteomalacia,
hyperparathyroidism, and osteoporosis can cause low back pain, and treatment
usually is symptomatic.
Tumor
The
most common tumors of the spine are metastatic. The most common metastatic
tumors are prostate, breast, kidney, thyroid, and lung. The most common primary
tumor is multiple myeloma. Chordoma is a rare tumor usually in the low sacral
region. It arises from remnants of the notochord. It is a locally invasive
tumor and necessitates wide excision. Benign tumors are rare. Aneurysmal bone
cysts, hemangiomas, and osteoid osteomas are the most common. Hemangiomas have
vertical striations on the plain radiograph. Aneurysmal bone cysts usually are
in the posterior elements and form large masses with calcific deposits. Osteoid
osteomas are painful, and the pain is relieved by salicylates. They also
usually arise in the posterior elements and are visualized best on CT scan.
They show a rim of dense sclerotic bone with a hollow nidus.
Infection
Osteomyelitis
Back
pain with associated fever and elevation in white blood cell count and
erythrocyte sedimentation rate is not difficult to diagnose as possible
infection. This should stimulate emergent evaluation with plain films and
possible MR imaging scan. Unfortunately, most cases of infection of the spine have
a much more indolent presentation. Patients have mild low back pain that
worsens with activity. White blood cell count and sedimentation rate may be
within normal limits. Patients also may complain of weight loss. [7]
The
infection usually begins in the disc space or in the end plate and migrates to
the center of the vertebral body. Patients should be questioned for possible
sources of infection (i.e., previous urologic procedures). Radiographic
findings may show destruction of the vertebral margins and obliteration of the
disc space if severe. MR imaging can help localize an infection of disc space
or an abscess cavity. Blood cultures should be obtained if the patient spikes a
fever. Aspiration of the vertebral body before administration of antibiotics
should be attempted.
Treatment
should commence with immobilization and appropriate intravenous antibiotics. If
this fails and the patient develops increasing pain or neurologic deficits,
anterior surgical decompression and fusion are the treatments of choice [5]
(Fig 11) (Figure Not Available) .
It
is important to rule out tuberculosis as the possible source of infection.
Symptoms usually are indolent and include chronic low back pain, weight loss,
and night sweats. Elevated sedimentation rate usually is present. All patients
should have a tuberculin skin test with an anergy panel if infection is
suspected. Early in the process, there are few radiologic changes; later there
may be destruction of the vertebral body with preservation of the disc space.
Referred Pain
Pain
may originate from pelvic, abdominal, or retroperitoneal structures. Men may
have referred pain from a prostatic lesion. Women may have pain from ovarian or
fallopian tube disorders. Pain also may originate from primary hip disease.
Degenerative hip disease can cause groin pain that radiates down the inner
thigh. Trochanteric bursitis causes lateral pain, which can be shown on
palpation.
CONCLUSION
There
are multiple reasons for low back pain. A thorough history and physical
examination will guide the treating physician to the right diagnosis and will
help avoid unnecessary diagnostic tests. A timely initiation of therapeutic
modalities should shorten absence from work for most of the involved patients.
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