Chronic Pain

Question 1

Why is multidisciplinary teamwork necessary for managing chronic pain? What are the components of such a multidisciplinary team? How are patients usually referred to a pain clinic?

Answer 1

○ Chronic pain is a complex disorder and patients suffering from chronic pain usually have biologic disease that coexists with cognitive, affective, behavioral, and social factors.
○ Hence, management of such a disease process requires the expertise of health care providers from a range of medical specialties.
○ The team at most centers consists of a physician, often an anesthesiologist, a psychologist, and a physical therapist working together. ○ Patients are usually referred to a chronic pain clinic by their primary care physicians for a problem with chronic pain that has not responded to conventional medical therapy.
○ In the pain clinic, the physician coordinates the diagnosis and medical treatment, the psychologist incorporates patient education and cognitive behavioral therapy, and the physical therapist plans an appropriate exercise regimen for the patient aimed at improving function.
○ Thus the team members interact to manage the chronic pain problem using a multimodal approach.

Question 2

How should the initial evaluation of a patient be carried out in the pain clinic? How is a treatment plan established for a patient evaluated in a chronic pain clinic?

Answer 2

○ On his or her arrival to a chronic pain clinic, the patient should be evaluated by a physician with expertise in pain medicine.
○ During the initial evaluation, the potential psychological, medical, and social contributions to the patient’s pain should be evaluated.
○ While it would be ideal for a psychologist and a physical therapist to also evaluate each new patient and then this multidisciplinary team meet to discuss the various aspects of the patient’s history, as well as a probable diagnosis, this is seldom possible in today’s constrained health care environment.
○ Nonetheless, the physician who conducts the initial evaluation must devise a treatment plan for each patient that takes into consideration all aspects of the patient’s care and arranges for appropriate referral to other members of the team when needed.

Question 3

Name some treatment modalities for the management of chronic pai

Answer 3

3. Treatment modalities available in most chronic pain clinics include oral pharmacotherapy, diagnostic and therapeutic nerve blocks, the neuraxial
   administration of opioids, neurostimulation techniques, biofeedback, and physical therapy.

Question 4

List some of the psychological components of the chronic pain disease process.
What is the potential value of the Minnesota Multiphasic Personality Inventory when evaluating patients with chronic pain?

Answer 4

○ Chronic pain as a disease process may include psychiatric and psychological manifestations, some of which include depression, insomnia, and avoidance of social and vocational obligations.
○ Dependence on analgesics and visits to multiple physicians are common among patients with chronic pain.
○ The Minnesota Multiphasic Personality Inventory is a useful test for the detection of many of these common comorbidities that often coexist in those suffering with chronic pain.

Question 5

What is meant by the term low back pain? What is the usual pattern of recovery for patients presenting with low back pain?

Answer 5

○ Low back pain (LBP) is the most common reason why people seek medical attention and is also known as lumbosacral pain.
○ This refers to pain in either the lumbar or the sacral spinal region.
○ Anatomically, the region is defined as the area of the back between the tip of the twelfth thoracic spinal process up till the sacrococcygeal joint.
○ Most people presenting with low back pain recover with no treatment.
○ A majority recover by 6 weeks (60% to 70%) or mostly by 12 weeks (90%). ○ The recovery after 12 weeks, however, is slow and uncertain.

Question 6

How does the typical patient with low back pain present to a pain physician?

Answer 6

○ Patients presenting with low back pain usually have pain either localized to the back region (acute or chronic lumbosacral pain) or distributed in the area of nerve (acute or chronic radicular pain).
○ Acute radicular pain is typically caused by a herniated nucleus pulposus in younger patients.
○ Signs of radiculopathy include numbness, weakness, or loss of deep tendon reflexes in the area of the affected nerve.
○ In the elderly, foraminal narrowing may affect the spinal nerve leading to acute radicular pain.
○ Patients presenting with chronic radicular pain require a detailed search for a reversible cause of nerve root impingement.
○ MRI or electrodiagnostic testing could give some clues to the cause of pain in patients who have had prior surgery.
○ Acute lumbosacral pain with no radicular symptoms in most cases may be
myofascial in origin and require no further radiologic investigation.
○ Chronic lumbosacral pain may arise from many parts of the vertebral unit; most commonly implicated are the sacroiliac joint, lumbar facets, and the intervertebral disks.
○ Diagnostic nerve blocks involving injection of local anesthetic at these anatomic sites leading to temporary pain relief can aid in localizing the origin of pain.
○ Diagnosis and treatment of the patient with low back pain rely on the location of pain (primarily radicular or lumbosacral) and the duration of symptoms (acute or chronic).

Question 7

What are the pathophysiologic mechanisms which commonly contribute to low
back pain?

Answer 7

○ The following pathophysiologic mechanisms result from degenerative changes in the spinal functional unit due to aging and injury, and can give rise to lumbosacral and/or lumbar radicular pain:
▪ Synovitis in the facet joints leading to capsular laxity and subluxation;
facet-related pain is predominantly localized over the lumbosacral junction.
▪ Degeneration in the intervertebral disks leading to loss of hydration of the nucleus pulposus. Further compromise with tears within the annulus fibrosis
is termed internal disk disruption; discogenic pain is predominantly localized
over the lumbosacral junction.
▪ Internal disruption of the disk may also lead to herniated nucleated pulposus, which is an extension of nuclear material beyond the disk margin. These disk herniations often extend posterolaterally to involve the spinal nerve inciting an intense inflammatory reaction and producing acute radicular pain (“sciatica”

Question 8

How can chronic low back pain arising from the lumbar facet joints be distinguished from lumbar radiculopathy?

Answer 8

○ Pain arising from the lumbar facet joint is predominantly localized near the lumbosacral junction, while lumbar radicular pain is localized within the leg.
○ The pain arising from facet joints is usually diagnosed by the injection of
a small volume of local anesthetic into the joint under fluoroscopic guidance.
○ Substantial pain relief suggests that pain originates from inflammation of that particular joint. However, a substantial number of patients will report pain reduction even when a nonactive agent such as normal saline is injected.
○ This placebo response can complicate certain diagnosis using diagnostic injections.

Question 9

What are some warning signs on the initial history and physical when evaluating a patient with low back pain that may indicate significant physical comorbidity that
should be promptly investigated?

Answer 9

○ When first evaluating a patient with back pain, the physician should be aware of certain conditions that may indicate significant physical comorbidity,prompting further investigation.
○ In the patient’s history, these include new onset or worsening pain after trauma, infection, or previous malignancy.
○ Patients who report worsening neurologic deficits, or bladder or bowel dysfunction, warrant early radiologic imaging to rule out neural compression

Question 10

How should a physician approach medical therapy for the most common
presentations of low back pain?

Answer 10

○ Medical therapy for the most common presentations of low back pain is based on how a patient presents to the pain physician and on the duration of pain symptoms.
○ Acute radicular pain: Therapy is usually started with a 7-day course of simple analgesics alone or in combination with an opioid analgesic and a muscle relaxant for associated muscle spasm.
○ Chronic radicular pain: Therapy usually begins with a trial of antidepressants or anticonvulsants since opioids are less effective for
neuropathic pain.
○ Patients who are poor responders to combination medical therapy
are offered a trial of spinal cord stimulation.
○ Acute lumbosacral pain is usually managed with a short course of a simple analgesic alone or in combination with an opioid and a muscle relaxant as needed.
○ Pharmacotherapy is usually followed by physical therapy for patients with persistent pain.
○ First-line management for patients with chronic lumbosacral pain involves diagnostic medial branch nerve blocks to rule out facet joint pain. If positive, radiofrequency treatment may prove beneficial.
○ For patients with continued pain, a formal physical and behavioral
therapy program is usually recommended

Question 11

What are the socioeconomic considerations of low back pain and its treatment?

Answer 11

○ Low back pain and its treatment place a huge socioeconomic burden on society.
○ Only 40% to 45% of the patients who are disabled for 6 months will ever return to work.
○ The return to work rate for patients absent for 2 years is close to zero.
○ The risk factors for developing chronic low back pain include age, gender,
socioeconomic status, body mass index, tobacco use, general health status,
strenuous physical activities, job dissatisfaction, depression, and anatomic
variations.

Question 12

What is neuropathic pain? What are some of the typical signs and symptoms of neuropathic pain?

Answer 12

○ Neuropathic pain is persistent following injury to the nervous system.
○ The three most common types of neuropathic pain include postherpetic neuralgia, diabetic peripheral neuropathy, and complex regional pain syndrome.
○ Patients with neuropathic pain often report:
▪ Spontaneous pain—that is, it occurs without any stimulus.
▪ Hyperalgesia—an exaggerated painful response to a mildly noxious stimulus.
▪ Allodynia—a painful response to a normally nonnoxious stimulus. (

Question 13

What is postherpetic neuralgia?

Answer 13

○ Postherpetic neuralgia refers to pain that persists for extended periods of time (more than 3 to 6 months) after an acute infection of herpes zoster.
○ Postherpetic neuralgia usually occurs in elderly or immune compromised patients due to a secondary infection of varicella zoster virus (called shingles) leading to damage to small unmyelinated nerve fibers.
○ The pain is characterized by episodic lancinating pain accompanied by severe allodynia in the affected dermatome.
○ In recent years the availability of a vaccine has reduced the incidence of
postherpetic neuralgia.

Question 14

What treatment modalities have been used for the treatment of postherpetic
neuralgia?

Answer 14

○ Postherpetic neuralgia has been treated with occasional success with sympathetic nerve blocks in patients who have sought early treatment, but sympathetic blocks are ineffective in those with established postherpetic neuralgia.
○ Treatment ofestablished postherpetic neuralgia is challenging.
○ Tricyclic antidepressants and anticonvulsants remain the mainstay of treatment.
○ Topical lidocaine is useful to reduce the painful allodynia.

Question 15

What are some of the side effects of tricyclic antidepressants that may limit their usefulness in elderly patients with postherpetic neuralgia?

Answer 15

○ Side effects of tricyclic antidepressants include orthostatic hypotension, sedation, urinary retention, and an increase in appetite.
○ Tricyclic antidepressants may also cause worsening of preexisting heart block.
○ These side effects may limit the usefulness of tricyclic antidepressant medication therapy in elderly patients suffering from postherpetic neuralgia.

Question 16

What is diabetic peripheral neuropathy? How does it present?

Answer 16

○ Diabetic peripheral neuropathy, the most common cause of neuropathic pain, occurs as a result of damage to small unmyelinated nerve fibers.
○ The symptoms are numbness associated with paresthesias, dysesthesias, and pain commonly described as burning or deeply aching.
○ Symptoms can progress slowly over many years, and may affect the hands as well as the lower extremities.
○ Diabetic patients with poor glucose control are at the greatest risk for developing diabetic peripheral neuropathy.

Question 17

What is complex regional pain syndrome? What differentiates type I and type II complex regional pain syndromes?

Answer 17

○ Complex regional pain syndrome (CRPS) refers to signs and symptoms that emerge in certain patients after injury to peripheral nerves, typically after trauma to an extremity.
○ After the initial trauma, and during healing, persistent neuropathic pain
associated with sympathetic nerve dysfunction develops and is characterized by swelling, edema, erythema and temperature changes.
○ The term CRPS type I, also called reflex sympathetic dystrophy, is used when pain occurs without an identifiable injury to a major nerve (e.g., ankle sprain).
○ CRPS, type II, also called causalgia, presents with the same signs and symptoms but following an identifiable nerve injury (e.g., a pelvic fracture with a partial sciatic nerve transection).

Question 18

What are the clinical manifestations of complex regional pain syndrome?

Answer 18

○ Clinical manifestations of complex regional pain syndrome include chronic, severe burning pain, hyperalgesia, bone demineralization, joint stiffness, and atrophic changes.
○ Patients typically have localized sympathetic nervous system dysfunction,
which is manifest as warm, erythematous, dry, and swollen skin early in the disease process, followed by vasoconstriction, with cool, pale, and edematous skin later in the course.
○ Patients usually characterize the pain in these syndromes as aching,
intense, and/or agonizing.
○ The pain appears to be enhanced by mechanical stimulation, movement, and the application of heat or cold.

Question 19

How is the diagnosis of complex regional pain syndrome of the upper or lower extremity made?

Answer 19

○ The diagnosis of complex regional pain syndrome is based on the appearance of the typical signs and symptoms after injury and the absence of any other underlying condition.
○ Some practitioners have suggested that the diagnosis can be made by
performing sympathetic nerve blocks in the affected extremity and evaluating the patient for relief of the pain.
○ For the upper extremity a stellate ganglion block may be performed, while for the lower extremities lumbar sympathetic blocks are usually performed.
○ However, there is a significant placebo response to diagnostic blocks, and the true role of sympathetic blocks in the diagnosis and management of CRPS remains in question.

Question 20

What is the treatment for complex regional pain syndrome? How does the time delay to diagnosis and treatment affect treatment outcome?

Answer 20

○ The management of CRPS requires a multimodal approach
○ The primary goal of managing patients diagnosed with CRPS is maintenance and restoration of function through aggressive physical therapy, which is possible only with adequate pain
reduction.
○ Sympathetic nerve blocks often aid in short-term pain reduction and
hence facilitation of physical therapy.
○ Tricyclic antidepressants and anticonvulsants usually form the first line of analgesic therapy.
○ Spinal cord stimulation is now used more commonly and may provide a more effective long-term means to produce pain reduction, hence facilitating long-term physical therapy aimed toward functional restoration of the affected extremity.
○ A delay in the diagnosis and treatment of complex regional pain syndrome may result in poorer outcome.

Question 21

What pharmacologic agents are commonly used for intravenous regional
sympathetic nerve blockade? How is this technique believed to work?

Answer 21

○ Intravenous regional sympathetic nerve blockade has been used for the treatment of complex regional pain syndromes.
○ Pharmacologic agents that have been used for intravenous regional sympathetic nerve blockade include guanethidine and bretylium.
○ Guanethidine is taken up by presynaptic sympathetic nerve terminals
where it is concentrated in norepinephrine neurotransmitter vesicles and replaces norepinephrine, thereby blocking norepinephrine release.
○ Bretylium blocks norepinephrine release from nerve terminals. These agents are believed to exert their analgesic effects in sympathetically maintained states by blocking norepinephrine release from sympathetic nerve terminals.
○ Neither agent is now commonly used: guanethidine is not available for clinical use in the United States and bretylium is associated with profound hypotension.
○ More commonly, intravenous regional blocks are conducted with local anesthetic alone, typically 0.5% lidocaine; careful attention must be paid to avoid toxic levels of local anesthetic.
○ The relative effectiveness of intravenous regional blockade versus
sympathetic ganglion blocks is unknown.

Question 22

What are the various ways in which cancer can cause pain? What is the primary treatment for cancer pain?

Answer 22

○ Pain is the most common presenting symptom of undiagnosed malignancy.
○ Cancer pain may be due to direct invasion of the malignancy or treatment. ○ Local tumor infiltration or metastases to bone or nerves are especially painful.
○ Patients may also experience pain as a side effect of chemotherapy, irradiation, or surgical treatment.
○ Examples include phantom limb pain, peripheral neuropathy, and
radiation fibrosis.
○ Approximately 40% of patients with cancer experience chronic pain.
○ The primary focus of pain reduction in patients with cancer is direct
treatment of the malignancy, with successful treatment often leading to
complete pain resolution.

Question 23

What are some oral analgesics used to treat persistent cancer pain? What is the World Health Organization stepwise approach to managing cancer-related pain?

Answer 23

○ The mainstay of treatment of chronic pain for cancer patients is opioid therapy.
○ Other analgesics which are commonly used are tricyclic antidepressants,
anticonvulsants, and corticosteroids.
○ Tricyclic antidepressants may have additional benefits of treating depression (common among cancer patients), potentiating the effect of opioids, facilitating nocturnal sleep, and improving mood.
○ Anticonvulsant medications may be useful in neuropathic pain.
○ Corticosteroids play a role in decreasing the sensation of pain, improving mood, and increasing appetite, all of which are ongoing problems in patients with chronic cancer pain.
○ The World Health Organization’s analgesic approach has been adopted
worldwide to promote the aggressive treatment of cancer-related pain by
tailoring analgesic use to the severity of pain.
○ It comprises a simple three-step analgesic ladder starting with nonopioids and moving toward more potent opioid analgesics as necessary to control pain

Question 24

When oral intake by patients is limited, what are some alternative routes of
analgesic drug delivery used to manage persistent cancer pain?

Answer 24

○ Intravenous, neuraxial, transdermal, and transmucosal routes of administration are alternative routes of analgesic drug delivery for the cancer patient with chronic pain in whom the oral administration of medicines is not possible.
○ Implantable intrathecal drug delivery systems using intrathecal opioids, local anesthetics, clonidine, and other agents are now often used in managing intractable cancer pain.

Question 25

What are some neurosurgical procedures for the treatment of chronic pain that maybe useful in cancer patients in whom less invasive procedures have been unsuccessful in providing pain control?

Answer 25

○ Patients with chronic pain secondary to cancer who have not had success with pain control with less invasive procedures may benefit from some neurosurgical procedures for the treatment of the pain.
○ Neurosurgical procedures that may be useful in these cancer patients include a cordotomy or dorsal rhizotomy.
○ A cordotomy is the open or percutaneous interruption of the spinothalamic tract.
○ A dorsal rhizotomy is the interruption of the sensory nerve root.

Question 26

Which is the most common uniformly efficacious neurolytic block for visceral
malignancy? What are the limitations of such a block?

Answer 26

○ One of the most common nerve blocks that successfully treats abdominal visceral malignancy is the neurolytic celiac plexus block.
○ The neurolytic celiac plexus block (NCPB) may be useful to treat pain associated with cancer of the pancreas or upper abdominal viscera.
○ One limitation of this block is the inability to treat pain from the left colon and pelvic viscera as the sensory and autonomic nervous system fibers only from the abdominal viscera are carried by the celiac plexus.
○ NCPB has a long-lasting benefit for 70% to 90% of patients with abdominal visceral malignancies.

Question 27

What are some of the pharmacologic agents used for pain management?

Answer 27

○ Pharmacologic agents used for pain management include nonsteroidal
antiinflammatory agents, antidepressants, anticonvulsants, muscle relaxants, and opioids.
○ Opioid analgesics are the most common agents used in the management of cancer-related pain, but their long-term benefit in managing patients with
noncancer pain remains unclear.
○ The antidepressants and anticonvulsants are the most common agents used for the long-term treatment of chronic neuropathic pain.

Question 28

What are simple analgesics and how can they be useful in chronic pain
management? How are cyclooxygenase-2 selective drugs useful for chronic pain
management and how do they differ from nonselective drugs?

Answer 28

○ The term simple analgesic has been traditionally reserved for acetaminophen and the nonsteroidal antiinflammatory drugs (NSAIDs).
○ They are the most common agents used to treat mild to moderate pain.
○ Even though poorly supported by evidence for use in chronic illnesses such as low back pain, the use of NSAIDS remains fairly common.
○ They may be useful in conjunction with opioids for the treatment of chronic pain in patients with pain that involves an inflammatory
process or in patients with bone pain such as arthritis.
○ They also constitute the first step of the WHO analgesic ladder and are used to treat mild to moderate cancer-related pain.
○ Enzyme selective NSAIDs (i.e., the COX-2-selective inhibitors) have a
lower risk of GI bleeding as compared to nonenzyme selective drugs, even though they are comparable in their analgesic efficacy.

Question 29

How do antidepressants exert their actions? List some antidepressants commonly
used for pain management and their side effects

Answer 29

○ Antidepressants are thought to exert their effect by normalizing sleep patterns, decreasing anxiety, and decreasing the patient’s perception of the pain.
○ Antidepressants may enhance neurotransmitters acting on descending efferent inhibitory pain pathways, thus producing analgesia that is independent of their antidepressant effects.
○ Antidepressants commonly used for th emanagement of chronic
pain include tricyclic antidepressants and newer selective norepinephrine reuptake inhibitors (SNRIs).
○ Examples of tricyclic antidepressants include the secondary amine agents (nortriptyline and desimipramine) and tertiary amine agents (amitriptyline and imipramine), which are more poorly tolerated. Side effects of tricyclic antidepressants include dry mouth and urinary retention, and potentially worsening of preexisting heart block.
○ The newer SNRIs (venlafaxine, duloxetine) are effective in treatment of
neuropathic pain, such as painful diabetic peripheral neuropathy.
○ Though SNRIs have a similar analgesic efficacy as tricyclic antidepressants, they are better tolerated because of a favorable side effect profile.

Question 30

Which anticonvulsants are commonly used for pain management? What are the most common side effects associated with each agent? What are the first-line treatments for neuropathic pain?

Answer 30

○ The anticonvulsant drugs gabapentin and pregabalin are effective for pain
management.
○ These drugs are commonly used as they are fairly well tolerated with mild to moderate side effects like somnolence, drowsiness, and peripheral edema. ○ They are also commonly used to treat all types of neuropathic pain.
○ The choice of neuropathic agent should be guided by the severity of the pain and the side effect tolerability by each patien

Question 31

What potential problems are encountered by physicians when prescribing opioids?

Answer 31

○ Use of long-term opioid therapy for the treatment of chronic noncancer pain remains controversial.
○ The most common problems encountered by physicians when
prescribing opioids are aberrant drug-related behavior (e.g., losing prescriptions, unauthorized escalation of drug dose) and opioid tolerance (need for increasing drug dose to produce the same effect).
○ Overt addiction (i.e., preoccupation with use of the opioid despite negative consequences like job loss) is uncommon.

Question 32

What basic principles guide the use of opioids in terminally ill patients as compared with those with nonmalignant chronic pain?

Answer 32

○ Opioid analgesic prescribing for nonmalignant chronic pain is adapted from cancer pain management.
○ This practice involves using a long-acting opioid for continuous analgesia while a short-acting analgesic is used to cover intermittent spikes in pain intensity, or breakthrough pain. However, the long-term use of opioids has come under increasing scrutiny for managing noncancer pain, thus
adopting more stringent guidelines is wise.
○ Most practitioners agree that opioids should be used only when other, more conservative measures have failed.
○ Patients should receive these medications from a single prescriber and they should only be continued when they lead to less pain and improvement in function.
○ Many practitioners have adopted routine use of random urine drug testing to help ensure that patients remain compliant with chronic opioid therapy and that they are not using other prescription or illicit drugs.

Question 33

What are the current guidelines for the stepwise pharmacologic management of
neuropathic pain?

Answer 33

○ Evidence-based guidelines for the pharmacologic management of neuropathic pain recommend a stepwise pharmacologic approach.
○ Following initial assessment and diagnosis, realistic goals should be discussed with the patient.
○ Therapy is usually begun with a tricyclic antidepressant, SNRI, or anticonvulsant as the first-line drug, followed by opioids or tramadol, alone or in combination (second-linedrugs).
○ Serial follow-ups are conducted to evaluate response to therapy and
alternative first- or second-line drugs are commenced based on the response.
○ Certain antiepileptics, antidepressants, and NMDA receptor antagonists can be used as a third line of drugs for a selective group of patients who respond poorly to the previous therapy.

Question 34

What is meant by the term interventional pain therapy? Name some of the
commonly performed interventional procedures used to treat pain

Answer 34

The term interventional pain therapy encompasses a variety of treatments
used for specific pain syndromes and these range from diagnostic nerve blocks
to therapeutic injections of steroids and sympathetic nerve blocks. Some of
the commonly performed procedures in the pain clinic include:
epidural steroid injections, facet joint nerve blocks, and radiofrequency
ablation. (

Question 35

How is an epidural steroid injection useful as an interventional therapeutic
procedure? What side effects should patients be informed about?

Answer 35

35. The injection of steroid into the epidural space is aimed at the inflammatory
    response that is associated with acute disk herniation. Epidural steroids are most
    useful for treating acute radicular pain, where a steroid injection if given within
    6 weeks can accelerate the resolution of leg pain. Patients should be informed about
    pain at the injection site and transient worsening of any radicular pain if present on
    presentation. Infection, bleeding, and neural injury are all uncommon and
    discussions about these rare complications should be based on individual patient
    concerns.

Question 36

What are the different techniques used to inject steroids into the epidural space?
What is the rationale for using one technique over another?

Answer 36

Epidural injection of steroids can be done using either the interlaminar or
transforaminal approach. The transforaminal approach may be more effective as
it allows the concentrated steroid solution to be injected directly adjacent to
the spinal nerve close to the site of the inflammation, yet there is little
scientific evidence to guide the choice between these two approaches. (

Question 37

When should a physician suspect the facet joint as a cause of low back pain?
How can a facet joint block be useful as a diagnostic tool?

Answer 37

One of the many causes of low back pain is pain arising from the facet joints.
Facet-related pain should be suspected in patients who have persistent pain over in
the lumbosacral area, and have typical patterns of referred pain with maximal
tenderness directly over the facet joints. Facet joint blocks are commonly used as a
diagnostic tool and involve intraarticular injections of a mixture of local
anesthetic and corticosteroids. Intermediate pain relief lasting weeks to months
is common and supports the diagnosis of facet-related pain

Question 38

What is the role of radiofrequency ablation in the long-term management of
persistent facet-related pain?

Answer 38

8. Radiofrequency denervation of the lumbar facet joints can provide longer
   duration of pain relief than intraarticular injections in some patients with facet-
   related pain. About 50% of patients will respond with a 50% reduction of pain
   lasting for up to 12 months. Radiofrequency denervation involves the delivery of
   energy adjacent to the sensory nerve in the facet joint. The procedure can be
   repeated with similar efficacy after repeat treatment

Question 39

What is the current role of lumbar diskography in the management of lumbosacral
pain?

Answer 39

The use of lumbar diskography is based on the hypothesis that the intervertebral
disk is the source of ongoing pain in about 30% to 40% of the patients presenting
with lumbosacral pain. Provocative diskography is currently used to select patients
for surgical fusion but has largely remained a controversial test because of the
subjective nature of the test and the lack of convincing evidence that use of
diskography improves surgical outcome. Diskography has also been used to select
patients for intradiscal electrothermal therapy (IDET), a treatment that uses thermal
energy to treat discogenic pain. Evidence for use of IDET is mixed; in some reports,
30% to 50% of patients showed long-term pain reduction and improvement in
standing and sitting tolerance. The use of both diagnostic diskography and IDET has
declined in recent years. (706)

Question 40

What is minimally invasive disk decompression? How does it work and what is a
limitation of this procedure?

Answer 40

Percutaneous plasma disk decompression (PDD) is a minimally invasive
procedure used to treat chronic radicular pain due to a focal disk bulge identified
on imaging studies, usually MRI. PDD reduces pain and improves long-term
functional status in highly selected patients—those with ongoing leg pain and
small disk protrusions. The procedure uses radiofrequency energy to remove a
portion of nucleus pulposus, which eases the pressure of the disk and hence
decompresses any pressure on the spinal nerve causing pain. A major limitation of
this technique is that it is only useful for patients with herniations smaller than
3 mm, and this comprises less than 5% of patients with low back pain. (707)

Question 41

How are sympathetic nerve blocks useful as a diagnostic tool in chronic pain
management? What is the current evidence of their role in managing chronic pain
syndromes?

Answer 41

41. Certain pain syndromes such as CRPS and microvascular insufficiency causing
    ischemic extremity pain are believed to be maintained by hyperactivity of the
    sympathetic nervous system and are termed sympathetically maintained pain
    syndromes. Blockade of the sympathetic nerve fibers produces pain relief in these
    disease states and these nerve blocks are hence often used to diagnose CRPS and
    related syndromes. There is a paucity of evidence supporting the use of repeated
    sympathetic blocks to provide long-term pain relief or improvement in function;
    however, these nerve blocks are still used to provide short-term pain relief and
    facilitate physical therapy

Question 42

What is the anatomical location of stellate ganglion? How is a stellate ganglion
block useful in the management of chronic pain?

Answer 42

The stellate ganglion is formed by the fusion of the inferior cervical and the
first thoracic sympathetic ganglia. There is significant anatomic variation in the
cervical and thoracic sympathetic chain and in many individuals the superior
thoracic and inferior cervical ganglia are separate structures. On the medial side
of the ganglion is the lateral border of the longus colli muscle. Posteriorly are the
neck of the first rib and the transverse process of the seventh cervical vertebra.
Anteriorly lay the first part of the subclavian artery and the origin of the
vertebral artery behind the dome of the lung. Anatomically, the sympathetic
supply of the head, neck, and the arms passes through the stellate ganglion on
each side. Hence a stellate ganglion block is performed to diagnose and treat
sympathetically maintained pain of the head, neck, and the upper extremity.

Question 43

How is a stellate ganglion block performed? Describe a safer alternative to the
conventionally performed stellate ganglion block.

Answer 43

The most common approach to the stellate ganglion is the anterior paratracheal
approach guided by surface anatomy of the C6 vertebra. When performing the
block without radiographic assistance, the operator palpates the anterior tubercle of
the transverse process of the C6 vertebra then retracts the overlying carotid
artery and jugular vein laterally. A needle is advanced until seated on the anterior
tubercle of C6, where about 10 mL of local anesthetic is injected incrementally.
The local anesthetic spreads along the prevertebral fascia in the caudal direction
to bathe the stellate ganglion. Another approach that has been used is approaching
the ganglion at the level of C7; however, this carries a substantial risk of
pneumothorax because the dome of the lung lies in close approximation to the
needle injection site. When performed under radiographic assistance, the needle is
placed just inferior to the uncinate process of the C6 or C7 vertebra near the
junction of the transverse process and the vertebral body

Question 44

List the common conditions for which stellate ganglion block is used in treatment.

Answer 44

4. A stellate ganglion block is used to diagnose and treat painful syndromes
   involving the upper extremity, most commonly CRPS. There is some evidence that it
   may also be useful for treating neuropathic pain arising from ischemia, herpes
   zoster, early postoperative neuralgia, and postradiation neuritis. Stellate ganglion
   block has also been used in the treatment of some disease states associated with
   vascular compromise, including intractable angina pectoris, Raynaud disease,
   frostbite, vasospasm, and occlusive or embolic phenomena. Stellate ganglion
   block has shown usefulness in controlling hyperhidrosis of the upper
   extremity

Question 45

What are the signs of a successful stellate ganglion block?

Answer 45

Successful stellate ganglion block is signaled by the appearance of Horner
syndrome, a constellation of signs and symptoms which includes miosis (pupillary constriction), ptosis (drooping of the upper eyelid), and enophthalmos (sunken
eyeball). Other signs of a successful block include nasal congestion, anhidrosis (lack
of sweating), and venodilation in the involved extremity. There will also be an
increase in local temperature by at least a degree Celsius in the affected extremity.
Thus there are several signs the clinician should look for to confirm success of a
stellate ganglion block.

Question 46

What are the complications of stellate ganglion block?

Answer 46

Stellate ganglion block is associated with the following minor and major
complications. Minor complications include a recurrent laryngeal nerve block
causing hoarseness, phrenic nerve blockade leading to unilateral diaphragmatic
paresis, and somatic blockade of the upper extremity (brachial plexus block)
characterized by sensory and motor loss on the ipsilateral side. Major
complications include intravascular injection of local anesthetic causing immediate
seizures, and epidural or intrathecal injection of the local injection causing a
neuraxial block. The complication of a neuraxial block can be a high epidural or
spinal with loss of consciousness and apnea, for which immediate resuscitation
would be required

Question 47

What is the anatomic location of the celiac plexus and what are the structures that
lie immediately adjacent to the celiac plexus?

Answer 47

The celiac plexus is comprised of a diffuse network of nerve fibers that lie over the
anterior surface of the aorta at the T12-L1 vertebral level surrounding the origin of
the celiac artery from the aorta. Presynaptic nerve fibers travel from the sympathetic
chain toward the ganglion over the anterolateral aspect of the inferior thoracic
vertebra as the greater, lesser, and least splanchnic nerves. Postsynaptic fibers
innervate all the abdominal viscera, including the gastrointestinal tract between the
gastroesophageal junction and the splenic flexure of the colon. Sympathetic fibers
to the descending and sigmoid colon, the rectum, and the pelvis do not travel
through the celiac plexus

Question 48

What are the most common techniques by which a celiac plexus block can be
performed?

Answer 48

48. A neurolytic celiac plexus block (NCPB) can be performed using either a transcrural
    or a retrocrural approach. The transcrural technique consists of placing the
    neurolytic agent directly on the celiac ganglion anterolateral to the aorta. This
    approach reduces the chance of nerve root involvement. The retrocrural approach
    involves positioning the needles posterior to the diaphragmatic crura in close
    apposition to the T12 vertebral body. The percutaneous posterior approach is
    performed using surface anatomic landmarks to position needles in the vicinity of
    the celiac plexus. NCPB is then achieved with the injection of 20 to 30 mL of either
    alcohol (50% to 100%) or phenol (10% to 12%). The position of the needle can be
    verified by computed tomography (CT), fluoroscopy, or ultrasound (using an
    endoscopic ultrasound-guided transgastric approach). No single technique has
    proven superior to the othe

Question 49

What is the clinical indication for a celiac plexus block?

Answer 49

. A neurolytic celiac plexus block is used to control pain arising from intraabdominal
structures, including the pancreas, liver, gallbladder, omentum, mesentery, and the
gastrointestinal tract from the stomach to the transverse colon. Most often the
source of the pain is malignancy, particularly pancreatic cancer. The pain relief for
these patients can be dramatic, and has long-lasting benefit for 70% to 90% of
patients. The use of the NCPB for nonmalignant pain, such as those with chronic
pancreatitis, is debatable

Question 50

How does a celiac plexus block differ from a splanchnic nerve block?

Answer 50

During NCPB, a transcrural approach places the neurolytic agent directly on the
celiac ganglion, anterolateral to the aorta, while a retrocrural approach places
the solution posterior to the diaphragmatic crura in close apposition to the T12
vertebral body. A splanchnic nerve block is a minor modification to the classic
retrocrural celiac plexus block; the only difference being that for a splanchnic nerve
block, the needles are placed in the midportion of T12 rather than in the
cephalad portion of L1 as is done for a celiac plexus block.

Question 51

. What are the complications associated with celiac plexus block?

Answer 51

51. The normal and expected physiologic effects of producing a sympathetic block
    to the abdominal viscera are diarrhea from unopposed parasympathetic stimulation
    of the bowel and orthostatic hypotension from splanchnic vasodilation.
    There are other potential complications of a neurolytic celiac plexus block.
    Intravascular injection of 30 mL of 100% ethanol results in a blood ethanol level
    high enough to produce intoxication. Intravascular injection of 30 mL of 10%
    phenol will cause clinical manifestations similar to local anesthetic toxicity,
    including seizures, cardiac arrhythmias, and even cardiovascular collapse.
    Perhaps the most feared complication of NCPB is paraplegia. Segmental spread at
    the level of T12 or L1 may cause spasm or even necrosis of the artery of
    Adamkiewicz, which compromises the blood supply of the anterior two thirds of
    the spinal cord in the low thoracic region. Best available estimates of the
    incidence of paraplegia place the risk at less than 1:1000. (711)

Question 52

52. Describe the applied anatomy of the lumbar sympathetic chain

Answer 52

2. The lumbar sympathetic chain consists of four to five paired ganglia that lie over the
   anterolateral surfaces of the L2-L4 vertebra. Their cell bodies lie in the anterolateral
   region of the spinal cord from T11 to L2, where the preganglionic fibers exit the
   spinal canal with the corresponding spinal root, join the sympathetic chain, and
   then synapse with the appropriate ganglion. Postganglionic fibers exit the
   ganglion to form a diffuse network of perivascular fibers surrounding the vessels in
   the lower extremities; postganglionic fibers also travel within the nerves of the
   lumbosacral plexus.

Question 53

What are some of the clinical uses of a lumbar sympathetic block? List the
complications that may be encountered while performing a lumbar sympathetic
block

Answer 53

Spinal cord stimulation is based on the hypothesis that a nonnoxious stimulus
interferes with the perception of pain. This input of a nonpainful stimulus directly
activates the ascending fibers within the dorsal columns of the spinal cord that
transmit nonpainful stimuli and this principle is used to treat chronic back pain.
A typical spinal cord stimulator system is comprised of a pacemaker-like
implanted pulse generator connected to an electrode positioned over the dorsal
columns of the spinal cord in the posterior epidural space. (712)

Question 54

What fundamental physiologic principle forms the basis of spinal cord stimulation?

Answer 54

. Spinal cord stimulation is based on the hypothesis that a nonnoxious stimulus
interferes with the perception of pain. This input of a nonpainful stimulus directly
activates the ascending fibers within the dorsal columns of the spinal cord that
transmit nonpainful stimuli and this principle is used to treat chronic back pain.
A typical spinal cord stimulator system is comprised of a pacemaker-like
implanted pulse generator connected to an electrode positioned over the dorsal
columns of the spinal cord in the posterior epidural space. (

Question 55

What is the current role of spinal cord stimulation in managing chronic pain
syndromes?

Answer 55

Current evidence supports the use of spinal cord stimulation (SCS) to treat pain,
in particular for patients presenting with chronic lumbosacral pain or radicular
pain after prior lumbar surgery. The evidence for the use of SCS for lumbosacral
pain has been inconclusive, but with the advent of new dual lead systems and
electrode arrays providing a broader area of stimulation, SCS may become more
useful for treating pain in these patients. Management of chronic radicular pain
using SCS is the best studied indication with the highest overall rate of
successful long-term pain reduction. SCS has proven to be less expensive and more
successful than repeat surgery in the management of persistent pain after prior
lumbar surgery. (7

Question 56

What are the complications of spinal cord stimulation?

Answer 56

The most common complication associated with SCS is lead displacement with the
need for reoperation to reposition the lead(s). In modern case series, less than
5% of patients experienced wound infection or dehiscence. (712)