++
LBP is a symptom, not a disease. The incidence of LBP disability
has tended to increase over the years, but the overall prevalence
has remained remarkably steady. In spite of the wide variety of disorders
that may present with LBP, in the large majority of cases no definitive
diagnosis is ever given. Fortunately, most cases (80%–90%)
resolve within 6 weeks with or without treatment. Table 28-2 lists
the most common causes of chronic LBP by diagnosis.
+++
Infections of
the Lumbosacral Spine
++
Infectious causes of LBP include vertebral osteomyelitis, epidural
abscess, and discitis. Vertebral osteomyelitis accounts for between
2% and 4% of all cases of osteomyelitis, with
males being affected more than females, and the elderly more than
young people. In descending order, the most common sources of infection
are the genitourinary system, skin, respiratory tract, and spine surgery.
Risk factors include intravenous drug abuse, immune suppression,
and rectosigmoid disease. Although vertebral osteomyelitis may sometimes
begin abruptly, more often the presentation is insidious. Back pain
typically is described as sharp, persistent, and exacerbated with movement.
Fever may be minimal or absent. On physical examination, there is
usually marked tenderness over the affected vertebra, guarding,
and paraspinal muscle spasm. Treatment involves antibiotics and
immobilization.
++
Because of its poor blood supply, most cases of discitis either
are iatrogenic or occur secondary to direct spread from an infected
vertebra. Classically, patients report the onset of intense, spasmodic
pain appearing 1 to 2 weeks after spine instrumentation. Fever is
usually absent. In patients without previous surgery, the diagnosis
may takes months or even years to make. Pain from discitis may be
referred into the groin, flanks, hips, abdomen, or lower extremities.
It usually is exacerbated by movement and relieved by rest. In one
study, 3 of 13 patients with discitis had neurologic deficits at
diagnosis. Physical examination of the spine reveals localized tenderness and
restricted range of motion. Treatment is supportive, with antibiotics
and pain medication being the mainstays of therapy. Although the
treatment course is usually prolonged, surgical debridement is rarely
necessary. Some studies have shown discitis to be associated with
an increased incidence of chronic LBP.
++
Epidural abscesses account for approximately 1 in 10,000 hospital
admissions. Predisposing factors include intravenous drug abuse,
cirrhosis, and alcoholism, with men being affected at a greater
rate than women. Although severe back pain that follows a spinal
procedure should arouse suspicion, spinal instrumentation is usually
not the cause of an epidural abscess. In a review of 39 cases of
spinal epidural abscess over 27 years at Massachusetts General Hospital,
only one was secondary to epidural placement.
++
The four cardinal signs of an epidural abscess are back pain,
tenderness, leukocytosis, and fever. Interestingly, back pain is
not universal. If left untreated, symptoms progress over a period
of days or even months. Generally, the order of progression proceeds
from localized back pain to radicular pain, weakness, incontinence,
and paralysis. An epidural abscess is a surgical emergency. In one
study, whereas patients diagnosed within 36 hours of the onset of
symptoms had minimal residual weakness, no recovery was observed
in patients paralyzed longer than 48 hours. Other infections that
can result in back pain include herpes zoster, Lyme disease, and
infectious sacroiliitis.
+++
Vertebral Fractures
and Spondylolysis
++
As the life expectancy of the U.S. population has continued to
increase, so too has the incidence of spinal fractures. There are
two main reasons for this: increasing disability with age, and a higher
incidence of osteoporosis. In clinical practice, only 30% of
vertebral fractures come to the attention of physicians, primarily
because lack of severe back pain in many patients does not trigger
obtaining radiologic studies. However, the prevalence of radiographically
demonstrated vertebral deformities rises from 5% of individuals
between the ages of 50–54, to 50% in women over 80
years. The most common locations for vertebral fractures are at
the thoracolumbar junction, the mid-thoracic spine (T7–8),
and the lumbar vertebral column. The prevalence of spinal fractures
is highest in white women, owing the their increased incidence of
osteoporosis. Aside from the increased propensity for vertebral
fractures, some experts believe osteoporosis in and of itself can
cause spinal pain. Aside from the increased propensity for vertebral
fractures, some experts believe osteoporosis in and of itself can
cause spinal pain.
++
The patient with a vertebral fracture typically presents with
acute pain overlying the fracture site. For sacral fractures, pain
may radiate into the buttocks or leg. The precise incidence of neurologic deficit
depends on the extent, type and location of injury, but is usually
cited as being greater than 30%. One way of distinguishing
patients with spinal fractures from those with other types of fractures
is the fact that more than half of all patients with severe vertebral
fractures go on to develop chronic pain. Physical examination of
the patient with a vertebral fracture(s) usually reveals marked
tenderness on palpation. In patients with lumbar fractures who develop
radiculopathy, straight leg raising tests may be positive.
++
Exercise programs for elderly patients suffering from spinal
fractures have been shown to increase bone density, decrease the
use of analgesics, and improve quality of life. Since patients with
vertebral fractures are at increased risk to develop hip and other
fractures, walking programs, fall-prevention courses and even Tai
Chi may be beneficial. In most patients with isolated spinal fractures,
non-steroidal anti-inflammatory drugs and/or short-acting
opiods are sufficient for pain relief. In those with constant pain,
sustained release opioids may be necessary. For patients whose main
symptoms are consistent with radiculopathy, an epidural steroid
injection(s) or trial with neuropathic pain medications may be a
worthwhile endeavor. Two treatments that have been shown to both
reduce subsequent fractures and provide analgesia for fracture patients
are bisphosphonates and salmon calcitonin. In patients with focal
pain and limited spinal fractures who do not respond to conservative
measures, vertebroplasty, which involves the injection of an actylic polymer
into a partially collapsed vertebra, or kyphoplasty should be considered.
Finally, surgical intervention may be necessary in patients with
unrelenting pain, spinal instability, or worsening neurologic deficit.
Physical examination reveals marked tenderness on palpation. In
most patients, analgesics and bed rest are sufficient treatment.
In those who do not respond to conservative measures, vertebroplasty
or surgery may be indicated.
++
One interesting type of vertebral fracture is spondylolysis,
also known as pars interarticularis. For the white adult population,
the incidence of spondylolysis has been reported to range between
3% and 6%. There is general agreement that most
pars defects occur during childhood, with the large majority of
cases being asymptomatic. Risk factors for pars fractures include
spondylolisthesis, involvement in sports, and genetics. In active
adolescents, spondylolysis can be a significant cause of LBP.
++
Patients with pars interarticularis usually present with focal
LBP, although radiation into the buttock or thigh can occur. This
pain may be increased during activities that require extension or rotation
of the spine. On physical examination, many patients are noted to
have a hyperlordotic posture with tight hamstrings. Diagnosis can
be confirmed with plain radiographs, CT, or MRI.
++
The treatment of patients with symptomatic spondylolysis includes
analgesics, bracing, cessation of sports, hamstring stretching,
and strengthening of the abdominal muscles. In patients who require
further pain management, pars injections may be helpful. In some
cases, surgery may be necessary.
+++
Metastatic Spinal
Tumors
++
Bone is the third most common location of tumor metastases after
the lungs and liver. In patients with metastatic cancer, tumor invades
bone in 60% to 84% of cases, with the vertebral
column and pelvis being the most frequently affected sites. In one
study, 39% of all skeletal metastases were to the spine.
The pain associated with spinal metastases develops slowly over
weeks or months, gradually becoming more intense. Frequently, it
can be localized to the involved vertebral bodies. Patients typically
characterize it as a dull but constant pain. Aggravating factors
may include weight bearing, activity, and nighttime, when the patient
is trying to sleep. Besides back pain, other signs of spinal metastases
include fever, chills, weight loss, and generalized fatigue. Pain
treatment includes nonsteroidal anti-inflammatory drugs (NSAIDs),
neuropathic pain medications, opioids, orthotics, and activity modification.
In patients with neurologic deficits, surgical decompression may
be necessary. As an adjunct to conventional modalities, chemotherapy,
hormone treatment, corticosteroids, bisphosphonates, salmon calcitonin,
radioisotopes, and radiotherapy can be helpful.
++
Technically, the term spinal stenosis can refer to central canal
narrowing, lateral recess stenosis, or foraminal narrowing. The
typical presentation of someone with spinal stenosis is an elderly person
with axial low back and leg pain brought on by walking, especially
down stairs or hills. Frequently, this pain is bilateral and radiates
into the ankles. In contrast to patients with vascular claudication,
whose symptoms take longer to resolve, those with spinal stenosis
find that cessation of walking usually brings immediate relief.
Because lumbar extension narrows the spinal canal, patients are
often seen bending forward to obtain relief. Numbness and weakness
may be present, with sensory complaints usually following a stocking-like
distribution.
++
In contrast to patients with central spinal stenosis, those with
lateral recess stenosis or foraminal narrowing tend to have dermatomal
symptoms that relate to the irritation of an exiting nerve root(s).
Symptoms may be sensory, motor, or both. Sensory complaints are
more common than motor dysfunction because of the more peripheral
location of sensory fibers in the cauda equina.
++
The most common causes of spinal stenosis are broad-based disk
bulges, facet or ligamentum flavum hypertrophy, and osteophytes.
In addition, foraminal narrowing can occur secondary to spondylolisthesis
or loss of disk height. The diagnosis of spinal stenosis is usually
made by MRI or CT scan.
++
Most patients with spinal stenosis have only mild to moderate
limitation of function and can be treated conservatively. Some noninvasive
therapies include lifestyle modification, exercise programs, and
pharmacologic treatment with NSAIDs, neuropathic medications, and
opioids. In a review of published studies evaluating bed rest for
acute LBP and sciatica, Hagen and colleagues found that compared
with advice to stay active, bed rest at best has no effect, and
at worst may have harmful effects. For the acute exacerbation of
radicular symptoms, translaminar epidural corticosteroid injections
often provide good pain relief. In patients with foraminal narrowing,
the transforaminal approach enables the clinician to deposit corticosteroids
directly into the area of pathology. For patients with severe symptoms
that are unresponsive to conservative treatment, surgical decompression
may be required (Table 28-3).
++
++
A herniated disc, defined as the herniation of the nucleus pulposus
(HNP) through the annulus fibrosis, is the most common cause of
LBP, accounting for more than one third of cases. Statistically,
herniated discs are more likely to occur in the morning, when the
disk height is greatest and the compressive forces are increased.
In more than 95% of cases, either the L4-5 or L5-S1 disc
is affected. There also may be a genetic predisposition for disc
herniation. The most common age for disc rupture is during the third
and fourth decades of life.
++
Although the classic picture of an HNP is LBP accompanied by
radicular symptoms, in reality less than half of all patients with
disc herniations develop true sciatica. Sometimes, radicular pain develops
years after an HNP. Clinically, patients may complain of a sharp,
lancinating pain radiating down the leg in a dermatomal distribution.
Maneuvers associated with an elevation of intrathecal pressure,
such as coughing, sneezing, or prolonged sitting, usually aggravate
this pain. On physical examination, sensory loss, muscle weakness,
or diminished reflexes in the distribution of the affected nerve
root may be present. The straight-leg raising test, although highly
sensitive, is relatively nonspecific. Conversely, the crossed straight-leg
raising test is very specific but poorly sensitive. In severe cases,
bowel, bladder, or sexual disturbances may be present. The diagnosis
of HNP is generally made by CT, MRI, or myelography. Electromyographic
(EMG) findings can be helpful in patients with nerve root impingement.
++
In most cases, nonoperative treatment is sufficient for pain
arising from a herniated disc. Conservative measures that may provide
symptomatic relief include controlled exercise therapy, NSAIDs,
and, in patients with radicular symptoms, neuropathic medications.
Although spinal manipulation and traction may be beneficial in patients
with acute axial LBP, there is scant evidence for their routine
use in patients with radicular pain. In patients with the acute
onset or exacerbation of sciatica, epidural corticosteroid injections
can provide pain relief.
++
Over the past few years, numerous percutaneous techniques have
been developed to excise portions of herniated discs without performing
an open surgical procedure. Chemonucleolysis by injection of chymopapain
into the nucleus pulposus was first described more than 30 years
ago, and remains popular in Europe. In clinical studies, this technique
has been consistently found to provide better relief than conservative
treatment, but less certain results than discectomy. Newer, percutaneous
techniques include laser discectomy, arthroscopic microdiscectomy,
endoscopic discectomy and nucleoplasty. However, none of these treatments
directly removes the portion of nuclear material that has extruded
through an annular defect. This may explain their inferior results
when compared with conventional surgery. In patients who do not
respond to conservative treatments, lumbar discectomy can provide
relief in approximately 75% of cases (Table 28-4).
++
+++
Sacroiliac Joint
Pain
++
The sacroiliac joint is a large (average surface area is 17.5
cm2 in adults), auricular-shaped, diarthrodial
joint connecting the sacral spine to the iliac bones. The function
of the sacroiliac joint is to dissipate the load of the upper trunk
as it is transmitted to the lower extremities. As a cause of chronic
LBP, sacroiliac joint dysfunction is estimated to affect between
15% and 30% of patients. Typically, patients describe
a history of pain after falling, lifting and turning, or bracing
themselves with their legs during a motor vehicle accident. Mechanistically,
the typical injury pattern has been described as “an axial
load coupled with abrupt rotation.” Patients may describe
an aching, usually unilateral, low back or buttock pain that radiates
into the groin or thigh area. Prolonged sitting, standing, or bending
exacerbates pain. One disorder that is associated with a high incidence
of sacroiliac joint pathology is ankylosing spondylitis. Pregnancy,
because of the increased axial load, exaggerated lordotic posture,
and hormonal-induced ligamentous flexibility, may also precipitate
sacroiliac joint pain. Although infection and tumor can cause sacroiliac
joint pain, these etiologies are rare.
++
On physical examination, the most common finding in patients
with sacroiliac joint pain is tenderness overlying the joints. Patients
with sacroiliac joint arthropathy have also been described as having
a higher incidence of leg length discrepancy, pelvic obliquity,
and scoliosis. Numerous physical tests have been described as tools
to aid in the diagnosis of sacroiliac joint pain, with two of the
most common being Patrick’s test and Gaenslen’s
test. However, a study by Dreyfuss and colleagues found that there
are no historical or physical examination features that can reliably
be used to diagnosis sacroiliac joint pathology. Radiologic studies,
such as CT and bone scans, have similarly been shown to be unreliable.
As such, the only way to make a definitive diagnosis of sacroiliac
joint pain is with diagnostic joint injections, which should be
performed with radiologic guidance.
++
Treatment of sacroiliac joint pain can be a formative task for
pain physicians. Pharmacotherapy with medications such as NSAIDs
and tricyclic antidepressants can provide relief in some patients,
although the benefits are limited. In patients with leg length discrepancies,
shoe inserts can result in relief of symptoms by equalizing the
pressure across the pelvis. Spinal manipulation has been used for
years to provide relief to patients with sacroiliac joint pain,
although research is limited. EMG studies have demonstrated muscular
abnormalities in patients with sacroiliac joint dysfunction, which
have formed the basis for exercise treatment. Two studies have provided
preliminary evidence that prolotherapy can be helpful in patients
with degenerative joint disease, although none specifically addressed
sacroiliac joint pain. For acute pain, noninvasive modalities such
as transcutaneous electrical nerve stimulation (TENS), heat and
ice packs have been advocated. Perhaps the mainstay of treatment
for sacroiliac pain is sacroiliac joint injections with corticosteroids
and local anesthetic, which should always be accompanied by physical
therapy. Personally, the authors have found that radiofrequency
denervation of the L4 and L5 dorsal rami, and lateral branches of
S1 to S3, which innervate the sacroiliac joint, can provide long-term
relief in patients who respond to diagnostic nerve blocks.
++
Pain originating from the intervertebral discs is estimated to
affect approximately 39% of patients with chronic LBP.
The rationale behind discogenic pain is that as internal disc disruption
destroys annular lamellae, the remaining lamellae can no longer
bear the load that occurs during normal activities. As the stress
on the disc increases, the mechanical threshold required to produce
nociception is surpassed. The disc may then become chemically sensitized.
++
Patients with discogenic pain generally complain of the gradual
onset of aching LBP that can extend into the buttock, hip, groin,
or even a lower limb. This pain is frequently characterized as being
exacerbated by prolonged sitting or bending forward, although a
study by Schwarzer and colleagues found no clinical features that
could reliably distinguish patients with diskogenic pain from those
with other sources of LBP. Physical examination reveals an absence
of focal neurologic deficits. As sole therapy, the pain relief that
accompanies sacroiliac joint corticosteroid injection tends to be
short-lived. In patients who respond to diagnostic blocks with local
anesthetic, radiofequency denervation of the L4 and L5 dorsal rami
and S1–3 lateral branches which innervate the sacroiliac
joint, has been shown to provide long-term pain relief. A post-diskography
CT scan can provide additional information regarding anatomic abnormalities.
++
Treatment of diskogenic pain usually begins with conservative
therapy, including NSAIDs, weight loss, and physical therapy. In
patients with one- or two-level disc disease, intradiskal electrothermal
therapy (IDET) has been shown in uncontrolled studies to provide
moderate pain relief. Although MRI and CT scans can indicate degenerative
disc disease, the diagnois of discogenic pain is best made by provocative
discography. False-positive discography is most likely to occur
in patients with abnormal psychometric testing, multiple somatic
complaints, and previous back surgery. In addition to enhancing
sensitivity, obtaining a post-discography CT scan can provide additional
information regarding anatomic abnormalities. In patients who have
failed or who are not candidates for invasive therapy, opioids may
be of benefit.
++
First described by Goldthwait in 1911, pain arising from the
lumbar zygapophysial (LZ; facet) joints is frequently quoted to
affect 15% to 40% of LBP sufferers, although estimates
range from as low as 8% to as high as 94%. The
LZ joints are paired, true synovial joints that connect adjacent
vertebrae posterolaterally. The function of the LZ joints is to
limit rotation and assist the intervertebral disk in resisting compressive
forces during lordotic postures, so that maximal stress on the LZ
joints occurs during lumbar extension and rotation. The load borne
by these joints varies between 3% and 25% of the
axial load, increasing during disc space narrowing and facet arthritis.
During prolonged standing in a lordotic posture, 16% of
the axial load is assumed by the facet joints. In patients with
lumbar spondylosis, 70% of the compressive load can be
transmitted to the joints. Some of the etiologies for facet arthropathy
include microtrauma, capsular tears, synovial inflammation and impingement,
chondromalacia, microhemorrhage, and meniscoid entrapment. When
facet pain is caused by osteoarthritis, morning stiffness may be
present. Some studies have found the incidence of facet joint disorders
to be more common in women than in men.
++
Patients with lumbar facet disease typically present with the
gradual onset of deep, achy LBP that may be referred into the groin,
hip, buttock, or thigh. On physical examination, pain may be aggravated
by maneuvers that increase the load borne by the LZ joints, such
as hyperextension and rotation of the spine. On palpation of the
back, tenderness in the paraspinous region(s) can often be elicited.
CT or MRI scan may reveal hypertrophy of the facet joints. However,
numerous studies have demonstrated that the only way to definitively
identify the LZ joints as pain generators is to perform diagnostic
local anesthetic injections under fluoroscopic guidance into either
the facet joints themselves or the medial branches that innervate
them. For each facet joint, innervation is derived from the medial
branch of the primary dorsal ramus at the level of the joint and
one level above it. In those patients who obtain significant pain
relief from diagnostic nerve blocks, radiofrequency denervation
has been demonstrated to provide long-term relief. Some authors have
advocated confirmatory blocks before radiofrequency neurotomy.
++
Myofascial pain is a common cause of LBP, with one study finding
its prevalence to be almost 20%, second only to herniated
discs. In addition, some studies have found LBP to be associated with
elevated levels of paraspinal muscle tension. Myofascial LBP often
presents as a deep, achy pain that is aggravated by activity and
position changes. It may be localized to the low back, or radiate
into the buttock, sacrum, thigh, abdominal wall, or even calf, depending
on the affected muscle(s). Pain-induced weakness or paresthesias,
or both, may be present but are nondermatomal in distribution. On
physical examination, a tender, taut band of muscle may be noted (trigger
point) that when palpated results in a characteristic referral pattern.
Deep, traverse “snapping” palpation or needle
insertion often elicits the characteristic local twitch response.
++
The treatment of myofascial LBP is conservative. Some of the
therapies used for myofascial pain include ischemic compression
massage, the so-called spray-and-stretch technique, iontophoresis, and
physical therapy. A large, randomized controlled trial compared
osteopathic manipulation with conventional noninvasive therapy in
patients with axial LBP of less than 6 months’ duration. The
osteopathic treatment group required less pain medication than the
conventional treatment group, but had similar outcomes. When trigger
points are identified, trigger point injections using local anesthetic
can be helpful. A recent, randomized, double-blind study in patients
with chronic LBP found injections with botulinum toxin A to be an
effective treatment. When myofascial pain is associated with other
pathology of the lumbar spine as is often the case, these problems
need to be treated as well.
++
The piriformis is a flat, pyramidal muscle extending from the
anterior sacrum, greater sciatic foramen, and sacrotuberous ligament
to the greater trochanter of the femur. The major function of the piriformis
is to abduct and externally rotate the femur. The possibility that
sciatic symptoms may stem from the piriformis muscle dates back
to 1928, when Yeoman examined the relationship of the sacroiliac
joint, sciatic nerve, and piriformis muscle. Although six anatomic
variations between the sciatic nerve and piriformis muscle have
been described, in the large majority of cases the sciatic nerve
passes anterior to the muscle. Any process that causes the piriformis
to spasm or contract inappropriately, or less frequently, results
in muscle hypertrophy and sciatic nerve impingement, can lead to
piriformis syndrome.
++
The typical presentation of piriformis syndrome is buttock pain
or sciatica, or both, exacerbated by activities that necessitate
hip adduction and internal rotation, such as cross-country skiing
or prolonged sitting. Pain that accompanies bowel movements may
be present and, for women, dyspareunia. Physical examination may
reveal tenderness in the buttock extending from the lateral border
of the sciatic foramen to the greater trochanter. Both pelvic and
rectal examinations may reproduce the pain pattern. Pain is also
elicited during resistance to hip flexion, adduction, and internal
rotation (Freiberg’s sign). The neurologic examination
is usually nonfocal, with most patients having a negative straight-leg
raising test. Although CT, MRI, and electrodiagnostic studies may
be helpful, by themselves these tests are insufficient to make the
diagnosis.
++
For most patients with piriformis syndrome, conservative treatment
is sufficient. This includes physical therapy and correction of
leg length discrepancies, pelvic obliquity, abnormalities in gait or
posture mechanics, and associated back or leg problems. Medications
such as NSAIDs and muscle relaxants can sometimes be helpful. Other
treatments that have been advocated include transrectal massage,
vapocoolant spray coupled with soft-tissue stretching maneuvers,
and TENS therapy. When conservative treatment fails, injection of
the piriformis with local anesthetic and corticosteroids can relieve
muscle spasm and pain. This treatment should be done using either
a nerve stimulator to locate the sciatic nerve or fluoroscopy with
contrast. In instances in which relief is short-term, piriformis
injections can be repeated with botulinum toxin. In rare instances, surgical
sectioning of the piriformis muscle may be necessary.
++
One disorder that is easily mistaken for piriformis syndrome
is ischiogluteal bursitis. Patients with ischiogluteal bursitis
usually complain of severe pain in the center of the buttock, which
is worse with sitting or walking. This pain may radiate into the
thigh, but rarely extends below the knee. Tests involving motion
at the hip joint, such as straight-leg raising and Patrick’s
tests, are often positive. Pressure applied on the lateral rectal
wall during a digital rectal examination can elicit excruciating
pain. Conservative treatment includes NSAIDs and soft pillows or
so-called doughnuts for sitting. For patients with severe pain,
bursa injections performed with corticosteroids and local anesthetic
are indicated.
+++
Failed Back
Surgery Syndrome
++
The definition of failed back surgery syndrome (FBSS) is the
persistence or development of low back or leg pain following surgery
on the lumbosacral spine. Two statistics highlight the magnitude
of so-called failed back syndrome as a pain problem in the United
States. First, approximately 300,000 lumbosacral spine procedures
are performed each year in the United States as a treatment for
chronic LBP. Secondly, depending on the definition of failure, the
incidence of FBSS can be as high as 60%.
++
The reasons why patients continue to have pain following spine
surgery can be broadly categorized as follows: (1) poor patient
selection (e.g., patients with a somatoform disorder or who are malingering);
(2) surgery was not indicated in the first place or the patient
underwent the wrong procedure (e.g., a patient with discogenic pain
who underwent a laminectomy); (3) clear indication for surgery,
but the procedure did not correct the original problem; (4) complication
from surgery (e.g., discitis, pseudomeningocele, or a pars defect);
(5) recurrent disc herniation; (6) secondary instability or degenerative
changes occurring as a consequence of surgery (e.g., discogenic
pain or sacroiliac joint pain developing at the level immediate
below a spinal fusion, spondylolisthesis following laminectomy,
or pain that develops over the site of a donor graft); (7) persistent
or established neural injury (e.g., arachnoiditis or epidural scarring);
and (8) an intercurrent diagnosis, such as cancer.
++
The workup of patients with FBSS begins with a detailed history
and physical examination. Of particular importance is determining
whether the patient’s pain is of the same character and
quality as before the surgery, or represents a new symptom that
has arisen. For instance, a new pain complaint might indicate a
surgical complication. Equally crucial is determining whether or
not, and for how long, the patient experienced a pain-free interval.
The three most common scenarios are as follows:
++
- 1. No relief or the worsening of pain shortly after surgery.
This category includes a retained disc fragment, failure to remove
the offending disc, and certain iatrogenic infections.
- 2. Initial relief followed shortly thereafter by pain, numbness,
or weakness. Examples of this group of disorders are arachnoiditis,
epidural fibrosis, and battered-root syndrome with perineural scarring.
- 3. Excellent relief after the surgery followed by development
of pain months or years later. This group includes a recurrent disc
at the same or different level, pseudoarthrosis, and lumbar instability.
++
Overall, the most frequent causes of pain in patients with FBSS
syndrome are recurrent disc herniation, spinal stenosis, epidural
scarring, and arachnoiditis (Table 28-5). Table 28-5 lists the most frequent
diagnoses conferred at one pain management center in patients with
failed back surgery syndrome.
++
++
After obtaining a detailed history, the physician should arrive
at a reasonable differential diagnosis. At this point, diagnostic
studies are usually necessary. If a recurrent herniated disc or
spinal stenosis is suspected, an MRI scan is indicated. Because
scar tissue is relatively vascular, a gadolinium-enhanced MRI or
CT scan is usually necessary to detect epidural fibrosis. This diagnosis can
be confirmed with epidural mapping by the injection of contrast
media through the caudal canal. In patients with epidural fibrosis,
a filling defect is present. When arachnoiditis is suspected, myelography
is the diagnostic imaging study of choice. Additional accuracy can
be obtained when a myelogram is followed by CT. For osteomyelitis,
bone scanning is the preferred test.
++
The treatment of FBSS is aimed at the underlying cause. Depending
on the diagnosis, nerve blocks, including epidural corticosteroid
injections, sacroiliac joint blocks, and facet blocks, can sometimes
be of benefit. In patients with radicular symptoms, neuropathic
pain medications may provide relief. Some clinicians report good
results with epidural lysis of adhesions (i.e. Racz procedure) in
FBSS patients with epidural fibrosis, although in our experience
the analgesia conferred by this procedure tends to be short-lived.
Causes of FBSS that may amenable to surgery include a recurrent
disk herniation, postlaminectomy instability, recurrent spinal stenosis,
nonunion, and a host of surgical complications. However, in a study
by North and colleagues that followed 102 patients who underwent
repeat back surgery, only 34% had a successful outcome.
In patients who do not respond to nerve blocks, repeat surgery,
or other medications, opioids are indicated. Finally, spinal cord
stimulation may be of benefit for patients with FBSS who have intractable
pain, especially those for whom leg pain is the predominant complaint.
++
In addition to the usual causes of LBP, the astute clinician
must also consider the unusual. Because of their effects on the
musculoskeletal system, a host of different metabolic and endocrine
disorders can result in LBP, including hyperthyroidism, hyperparathyroidism,
and Cushing’s disease. For similar reasons, virtually any
rheumatologic disorder can present as LBP. Visceral pain emanating
from internal organs can be referred to the back secondary to convergence
in the spinal cord. These sources of visceral pain include genitourinary
organs, the kidneys, gallbladder, bowel, and liver. Vascular disease
can manifest as LBP, which if not detected, can be catastrophic.
Not only is the spine the site of metastatic tumors, but primary
tumors may originate there as well. In some patients, hematologic
disorders such as mastocytosis and hemoglobinopathies can lead to
low back pain, as can diseases such as sarcoidosis, Paget’s
disease and infectious endocarditis. Finally, psychiatric and functional
disorders can manifest as chronic back pain, which can be extremely
difficult to treat.