Specificity of diagnostic nerve blocks: a prospective, randomized study of sciatica due to lumbosacral spine disease

Sciatica and the sacroiliac joint: a forgotten concept

The definition of sciatica is restricted to the pattern and localization of pain, although much emphasis is given to root compression as causative factor. Other sources of similar pain patterns are generally neglected. Despite absence of obligatory neurological signs in radicular syndromes, a number of patients are subjected to extensive, but redundant screenings. In this report, three patients are presented with presumed radicular pain syndromes, whose symptoms finally could be linked to the sacroiliac (SI) joint either via CT and MRI scans or via pain relief by intra-articular injection with local anaesthetics. Possible mechanisms of SI joint-related pain and difficulties in diagnostic specificity of signs and symptoms are discussed.

Neck and low back pain: neuroimaging

Spine imaging accounts for a major share of expenses related to neck and back pain. Improving image quality translates into better morphologic evaluation of the spine. Unfortunately, the morphologic abnormalities on spine imaging are common and nonspecific, obscuring the relevance to patient symptomatology. Furthermore, distinction between degenerative and age-related changes is not clear. The key is clinical correlation of imaging findings. This article presents a concise and illustrated discussion of spinal neuroimaging related to neck and back pain, with emphasis on degenerative disease.

WITHDRAWN: Injection therapy for subacute and chronic benign low-back pain

BACKGROUND

Injection with anaesthetics and/or steroids is one of the treatment modalities used in patients with chronic low back pain which needs evaluation with respect to the effectiveness on short and long term pain relief.

OBJECTIVES

To evaluate the effectiveness of injection therapy in patients with low back pain lasting longer than one month. We distinguished between three injection sites: facet joint, epidural or local injections.

SEARCH STRATEGY

We searched the Medline and Embase databases up to 1996 and other search methods as advocated by the Back Review Group search strategy. Abstracts and unpublished studies were not included.

SELECTION CRITERIA

Randomized controlled trials of injection therapy for pain relief (although additional treatments were allowed) in patients with benign low back pain lasting longer than one month and not originating from cancer.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trials for methodological quality. Subgroup analyses were made between trials with different control groups (placebo and active injections), with different injection site (facet joint, epidural and local injection), and timing of outcome measurement (short and long term). Within the resulting 12 subcategories of studies (2*3*2), the overall relative risks and corresponding 95% confidence intervals were estimated, using a random effects model (DerSimonian and Laird). In the case of trials in which control groups were active injections, we refrained from pooling the results.

MAIN RESULTS

Twenty-one randomized trials were included in this review. All studies involved patients with low back pain lasting longer than one month. Only 11 studies compared injection therapy with placebo injections (explanatory trials). The methodologic quality of many studies was low: only 8 studies had a methodologic score of 50 or more points. There were only three well designed explanatory clinical trials: one on injections into the facet joints with a short-term RR of 0.89 (95% CI: 0.65-1.21) and a long-term RR of 0.90 (95% CI: 0.69-1.17); one on epidural injections with a short-term RR of 0.94 (95% CI: 0.76-1.15) and a long-term RR of 1.00 (95% CI: 0.71-1.41); and one on local injections with a long-term RR of 0.79 (95% CI: 0.65-0.96). Within the 6 subcategories of explanatory studies the pooled RRs with 95% confidence intervals were: facet joint, short-term: RR=0.89 (0.65-1.21); facet joint, long-term: RR=0.90 (0.69-1.17); epidural, short-term: RR=0.93 (0.79-1.09); epidural, long-term: RR=0.92 (0.76-1.11); local, short-term: RR=0.80 (0.40-1.59); local, long-term: RR=0.79 (0.65-0.96).

AUTHORS' CONCLUSIONS

Convincing evidence is lacking on the effects of injection therapies for low back pain. There is a need for more, well designed explanatory trials in this field.

Interventional approaches to pain management

This article reviews the evidence for several common interventional techniques for the treatment of chronic pain, including: intraspinal delivery of analgesics, reversible blockade with local anesthetics, augmentation with spinal cord stimulation, and ablation with radiofrequency energy or neurolytic agents. The role of these techniques is defined within the framework of a multidisciplinary approach to the neurobehavioral syndrome of chronic pain. Challenges to the study of the analgesic efficacy of procedural interventions are explored, as are the practical issues raised by their clinical implementation, with the aim of helping nonspecialist physicians identify the patients most likely to benefit from these approaches.

The value of nerve root infiltration for leg pain when used with a nerve stimulator

Randomized comparative study of the efficacy of nerve root infiltration (NRI) guided by neurostimulator to find the value of nerve stimulators in nerve root infiltration was undertaken. The response to nerve root infiltration using local anaesthetics and steroid is unpredictable, partly because the exact nerve root giving rise to pain may not be truly infiltrated. The nerve stimulator is advocated to identify the nerve root of concern prior to infiltration. The current study assessed the results of NRI with and without the nerve stimulator. Ninety-six patients with leg pain awaiting selective nerve root infiltration using long acting local aesthetic, were prospectively randomized into two groups, in the first one, the nerve root block was carried out without nerve stimulator (n = 39) and in the second group the block was carried out with the guidance of a nerve root stimulator (n = 57). Seventy-seven of the patients who had lateral canal stenosis (a total 81) responded to NRI; within this group nerve stimulator was used for 50 patients. Nerve root infiltration was used to relieve post-discetomy leg pain (ten), post-disc prolapse (four) and in one patient post-nucleotomy leg pain. Overall 89% of the patients were responders of NRI. Responders of around 65% had the NRI performed with the aid of stimulator. The response rate to pain was 96% when NRI was guided by a neurostimulator and 79% when no neurostimulator was used. When responded there was no significant statistical difference using the Oswestry disability score between both groups. After excluding disc bulge in patients who respond partially to NRI, it is worthwhile repeating the injection. There was a significant difference in response rate when NRI was done under guidance of a nerve stimulator, the stimulator is safe to use and increases the specificity of the block.

Do diagnostic segmental nerve root blocks in chronic low back pain patients with radiation to the leg lack distinct sensory effects? A preliminary study

BACKGROUND

The present preliminary study documents the effects of a selective nerve root block (SNB) with short or long acting local anaesthetic compared with baseline measurements in patients with chronic low back pain radiating to the leg with maximum pain in one dermatome (L4).

METHODS

Ten consecutive patients underwent 20 controlled SNBs at L4 with ropivacaine 0.25% and lidocaine 1% in a prospective, randomized, double blind, crossover fashion. Baseline measurements included sensory function (assessed by pinprick on both unaffected and painful leg) and pain (Verbal Numeric Rating Scale; VNRS, 0-10). A change in size of areas with altered sensory function >10% and a VNRS change of 2 points were considered clinically significant. P-values<0.05 were considered statistically significant.

RESULTS

Asymptomatic hypoaesthesia, variable in extent and non-dermatomal in distribution, was present in seven patients at baseline. It appeared to be more extensive and distal with longer duration of pre-existing pain. SNB produced no consistent changes in extent and distribution of hypoaesthetic areas. Change in VNRS did not correlate with the extent of pre-block or post-block hypoaesthesia. No differences in effects were found between lidocaine and ropivacaine.

CONCLUSIONS

Pre-block assessment of sensory function is essential to assess the net effect of SNBs. In this small study group, SNBs failed to demonstrate uniform or distinct effects on sensory function.

Selective Nerve Root Injections Can Predict Surgical Outcome For Lumbar and Cervical Radiculopathy

OBJECTIVE

Diagnostic selective nerve root injection (SNI) results were analyzed in 101 patients who underwent lumbar or cervical decompression for radiculopathy and compared to surgical outcome 1 year postoperatively. A comparison of surgical outcomes was also examined between magnetic resonance imaging (MRI) and SNI results.

RESULTS

Of the 101 patients, 91 (90%) had positive and 10 had negative SNI results at the level operated. Ninety-one percent of the patients with a positive SNI had good surgical outcomes, whereas 60% of the patients with a negative SNI had good outcomes. Of the patients with a positive MRI result, 87% had good surgical outcomes, whereas a similar percentage of the patients with a negative MRI (85%) had good surgical outcomes. When findings between SNI and MRI differed (n = 20), surgery at a level consistent with the SNI was more strongly associated with a good surgical outcome. Of the patients with a poor surgical outcome, surgery was most often performed at a level inconsistent with the SNI finding.

CONCLUSIONS

Our study found that a diagnostic SNI can safely and accurately discern the presence or absence of cervical or lumbar radiculopathy. The diagnostic SNI can persuade surgeons from operating on an initially suspicious, but incorrect, level of radiculopathy. In cases where MRI findings are equivocal, multilevel, and/or do not agree with the patient's symptoms, the result of a negative diagnostic SNI (ie, lack of presence of radiculopathy) becomes superior in predicting the absence of an offending lesion.

Sacroiliac Joint Pain: A Comprehensive Review of Anatomy, Diagnosis, and Treatment

Sacroiliac (SI) joint pain is a challenging condition affecting 15% to 25% of patients with axial low back pain, for which there is no standard long-term treatment. Recent studies have demonstrated that historical and physical examination findings and radiological imaging are insufficient to diagnose SI joint pain. The most commonly used method to diagnose the SI joint as a pain generator is with small-volume local anesthetic blocks, although the validity of this practice remains unproven. In the present review I provide a comprehensive review of the anatomy, function, and mechanisms of injury of the SI joint, along with a systematic assessment of its diagnosis and treatment.

Radiofrequency denervation of lumbar facet joints in the treatment of chronic low back pain: a randomized, double-blind, sham lesion-controlled trial

OBJECTIVES

Radiofrequency facet joint denervation procedures have been common practice for 2 decades in treatment of chronic low back pain. We designed this multicenter, randomized, double-blind, sham treatment controlled trial to determine the efficacy of radiofrequency facet joint denervation, as it is routinely performed.

METHODS

Inclusion criteria were low back pain, duration more than 6 months, and >or=50% Visual Analog Scale (VAS) reduction on diagnostic block. Exclusion criteria were prior radiofrequency treatment, radicular syndrome, coagulopathies, specific allergies, cancer, and pregnancy. A total of 81 out of 462 patients were randomized to undergo radiofrequency facet joint denervation or sham treatment. The first evaluation was carried out 3 months after treatment. Primary outcome was determined with a combined outcome measure comprising VAS, physical activities, and analgesic intake, from a twice-weekly recorded diary. Secondary outcome measures were the separate diary parameters, global perceived effect (complete relief, >50% relief, no effect, pain increase), and SF-36 Quality of Life Questionnaire.

RESULTS

There were no dropouts before the first evaluation. The combined outcome measure showed no differences between radio- frequency facet joint denervation (n=40; success 27.5%) and sham (n=41; success 29.3%) (P=0.86). The VAS in both groups improved (P<0.001). Global perceived effect improved after radiofrequency facet joint denervation (P<0.05). The other secondary outcome parameters showed no significant differences. Relevant costs were evaluated.

DISCUSSION

The combined outcome measure and VAS showed no difference between radiofrequency and sham, though in both groups, significant VAS improvement occurred. The global perceived effect was in favor of radiofrequency. In selected patients, radiofrequency facet joint denervation appears to be more effective than sham treatment.

Classification in nonspecific low back pain: what methods do primary care clinicians currently use?

STUDY DESIGN

Postal survey.

OBJECTIVES

To describe the signs and symptoms that clinicians think represent nonspecific low back pain (NSLBP) subgroups, and to report the labels that clinicians give to those subgroups.

SUMMARY OF BACKGROUND DATA

The cause of most low back pain (LBP) cannot be diagnosed. Consequently, approximately 80% of primary care LBP presentations are most accurately labeled as NSLBP. Most Australian primary care clinicians think that NSLBP is heterogeneous and treat patients differently based on that heterogeneity. This research sought to identify the subgroups clinicians believe are recognizable within that heterogeneity.

METHODS

Analysis of survey data from 651 primary care clinicians from 6 professional disciplines: physiotherapy, manipulative physiotherapy, chiropractic, osteopathy, general medicine, and musculoskeletal medicine.

RESULTS

There was little consensus among participating clinicians regarding the signs and symptoms that identify NSLBP subgroups. Most clinicians give labels to NSLBP subgroups that imply putative pathoanatomy, however, the evidence that these labels are valid is scant and controversial.

CONCLUSIONS

A lack of consensus among participating clinicians regarding NSLBP subgroups and a lack of evidence for the validity of NSLBP subgrouping are a compelling argument for further research into this clinical practice.

Spasticité : intérêt du testing par anesthésie locorégionale et blocs thérapeutiques

Peripheral nerve blockade is one of the therapeutic possibilities to treat spasticity of various muscles. Percutaneous nerve stimulation allows accurate location of nerves and neurolysis can be performed using intraneural injection of 65% ethanol or 5 to 12% phenol. Spastic contraction of various muscle groups is a common source of pain and disability which prevents from having efficient rehabilitation. Test-blocks as well as neurolytic blocks are possible in most of motor nerves of the upper and lower limbs and main indications are spastic sequelae of stroke and spinal trauma but also of multiple sclerosis, cerebral palsy and chronic coma. The use of percutaneous nerve stimulation allows accurate location and four nerves are more frequently treated: pectoral nerve loop, median, obturator and tibial nerves. In patients with spasticity of the adductor thigh muscles, nerve blocks are performed via a combined approach using fluoroscopy and nerve stimulation to identify the obturator nerve. No complications occurred and minor side effects are transient painful phenomena during injection. These approaches proved to be accurate, fast, simple, highly successful and reproducible. Percutaneous neurolytic procedures should be done as early as possible, as soon as spasticity becomes painful and disabling in patients with neurological sequelae of stroke, head trauma or any lesion of the motor neuron.

Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance neurography and interventional magnetic resonance imaging with outcome study of resulting treatment

Object. Because lumbar magnetic resonance (MR) imaging fails to identify a treatable cause of chronic sciatica in nearly 1 million patients annually, the authors conducted MR neurography and interventional MR imaging in 239 consecutive patients with sciatica in whom standard diagnosis and treatment failed to effect improvement.

Methods. After performing MR neurography and interventional MR imaging, the final rediagnoses included the following: piriformis syndrome (67.8%), distal foraminal nerve root entrapment (6%), ischial tunnel syndrome (4.7%), discogenic pain with referred leg pain (3.4%), pudendal nerve entrapment with referred pain (3%), distal sciatic entrapment (2.1%), sciatic tumor (1.7%), lumbosacral plexus entrapment (1.3%), unappreciated lateral disc herniation (1.3%), nerve root injury due to spinal surgery (1.3%), inadequate spinal nerve root decompression (0.8%), lumbar stenosis (0.8%), sacroiliac joint inflammation (0.8%), lumbosacral plexus tumor (0.4%), sacral fracture (0.4%), and no diagnosis (4.2%).

Open MR—guided Marcaine injection into the piriformis muscle produced the following results: no response (15.7%), relief of greater than 8 months (14.9%), relief lasting 2 to 4 months with continuing relief after second injection (7.5%), relief for 2 to 4 months with subsequent recurrence (36.6%), and relief for 1 to 14 days with full recurrence (25.4%). Piriformis surgery (62 operations; 3-cm incision, transgluteal approach, 55% outpatient; 40% with local or epidural anesthesia) resulted in excellent outcome in 58.5%, good outcome in 22.6%, limited benefit in 13.2%, no benefit in 3.8%, and worsened symptoms in 1.9%.

Conclusions. This Class A quality evaluation of MR neurography's diagnostic efficacy revealed that piriformis muscle asymmetry and sciatic nerve hyperintensity at the sciatic notch exhibited a 93% specificity and 64% sensitivity in distinguishing patients with piriformis syndrome from those without who had similar symptoms (p < 0.01).

Evaluation of the nerve beyond the proximal foramen provided eight additional diagnostic categories affecting 96% of these patients. More than 80% of the population good or excellent functional outcome was achieved.

Scrotal pain as the presenting symptom of lumbar disc herniation: a report of 2 cases

STUDY DESIGN

Case description.

OBJECTIVE

To describe a treatable cause of scrotal pain associated with lumbar disc herniation

SUMMARY OF BACKGROUND DATA

Scrotal pain due to intraspinal compression of a sacral nerve root caused by lumbar disc herniation is probably very rare, as the literature contains only sporadic single case descriptions.

METHODS

Two patients with isolated scrotal pain were analyzed. In both patients, a lumbar disc herniation was found. Lumbar discectomy was performed in both patients.

RESULTS

Complete and persisting relief of the scrotal pain was obtained after lumbar discectomy.

CONCLUSIONS

Despite the absence of other symptoms or signs suggestive of nerve root involvement, lumbar disc herniation with intraspinal compression of a sacral nerve root seemed the most probable cause of the scrotal pain.

Pulsed radiofrequency neurotomy: advances in pain medicine

In the past three decades, radiofrequency neurotomy (RFN) has been established as a safe and effective treatment for facet and sacroiliac arthropathy. However, early reports of deafferentation pain syndromes and motor deficit with the application of radiofrequency lesions to other neural structures effectively halted further development of this technology for other applications until recent years. Pulsed radiofrequency neurotomy (PRFN) represents the most recent advance in radiofrequency technology in clinical practice. PRFN allows for application of radiofrequency current at markedly lower tissue temperatures, thereby minimizing the risk of adverse events. The initial clinical data on PRFN demonstrate response rates similar to conventional high temperature RFN lesions for facet and sacroiliac arthropathy and a host of other chronic pain disorders.

[Diagnostics and minimally invasive therapy for chronic low back pain]

Chronic low back pain is one of the most frequent causes for seeking medical help in Germany. Many factors play a causal role in its pathogenesis. This is where the dilemma resides in narrowing down the diagnosis and deciding on subsequent therapeutic intervention. There is overall agreement on the concept of when it is expedient to initiate further diagnostic measures. With the exception of clear pathomorphological findings and the presence of cardinal symptoms or warning signs, so-called "red flags", primary back pain should not be subjected to any specific diagnostic tests and therapy during the first 3 months. We present well-established techniques for blockade, discography, and minimally invasive treatment options such as cryotherapy, procedures for thermal ablation, and intradiscal electrotherapy. Vertebroplasty, currently a frequently applied method, is also included in the discussion of minimally invasive treatment for chronic low back pain.

Selective nerve root blocks

Selective nerve root blocks are valuable diagnostic and therapeutic procedures in patients with radicular symptoms. Understanding the anatomy, benefits, and risks, as well as precise needle placement, are important factors in performing successful nerve root blocks. The techniques we describe come from our training and ongoing experience. There are other acceptable methods as well.

Image-guided spinal injection for diagnosis and therapy

Over the past decade, major advances have been made in our ability to identify a putative cause of patients' spinal pain using image-guided injection techniques. These techniques might also provide a means of temporarily relieving patients' pain and facilitating increased mobility. This article aims to review the rationale for and the techniques of the more commonly used spinal injection techniques.

Hip spine syndrome: management of coexisting radiculopathy and arthritis of the lower extremity

BACKGROUND CONTEXT

Significant lumbar spinal stenosis and lower extremity arthritis may coexist in the elderly. This combination of lumbar stenosis with radiculopathy and lower extremity arthritis may lead to diagnostic uncertainty.

PURPOSE

To describe the findings of hip spine syndrome, a constellation of symptoms with extensive overlap of radiculopathy and lower extremity arthritis.

CONCLUSIONS

Evaluation of the patient with lower extremity pain in consideration for total joint arthroplasty should include functional inquiry of the spinal nerves. Diagnostic tests and injections may allow an informative weighting of the patient's symptoms, leading to a better understanding of the patient's pain syndrome. There is a group of patients who have a total hip arthroplasty and then develop or may continue to have pain of groin and buttock, secondary to sciatica of lumbar spinal stenosis. For the patient undergoing total hip arthroplasty with asymptomatic spinal stenosis, there may be increased neurological risk at surgery, related to the stenosis. The patient with both conditions may require surgical decompression of the lumbar stenosis as well as joint arthroplasty of the arthritic joint.

Single needle approach for multiple medial branch blocks: a new technique

BACKGROUND AND OBJECTIVES

Medial branch blocks are an important tool for the diagnosis of facet joint arthropathy. The most commonly used technique involves multiple needle placements, one for each nerve blocked. This multiple needle technique may require a large amount of local anesthetic for anesthetizing the skin, thereby increasing the rate of false-positive blocks.

TECHNIQUE

Diagnostic lumbar medial branch blocks are usually performed using multiple needles, one for each branch. The authors describe a different technique using a single needle for all levels. Initially, the needle is directed toward the medial branch located at the level of the affected facet joint in the antero-posterior view. After anesthetizing this nerve with local anesthetic, the same needle is withdrawn to the skin with the tip still in the subcutaneous tissue and repositioned to block the medial branch above, and thereafter below, while continuing to use only the antero-posterior view, thereby using only one entry site.

CONCLUSIONS

When performed correctly, the single needle technique provides accuracy similar to the more conventional multiple needle approach during the performance of diagnostic facet joint nerve blocks. Because only one skin entry point is needed, however, this technique may afford several advantages over the multiple needle approach. These may include less patient discomfort, less time required and less radiation exposure since only one C-arm position is used, a smaller volume of local anesthetic, and possibly a lower incidence of false-positive blocks.

Radiofrequency lesioning of dorsal root ganglia for chronic lumbosacral radicular pain: a randomised, double-blind, controlled trial

BACKGROUND

Results of observational studies have shown pain reduction with percutaneous radiofrequency lesioning of dorsal root ganglia for lumbosacral radicular pain, but there are few randomised controlled trials. We aimed to assess the efficacy of radiofrequency lesioning of dorsal root ganglia for lumbosacral radicular pain.

METHODS

We screened 1001 patients, who were mostly referred by their family doctor, in four hospitals for a double-blind randomised trial. 83 patients met inclusion criteria and thus were randomly assigned to receive a radiofrequency lesion or control treatment of the involved dorsal root ganglion. Control treatment was done in the same way as radiofrequency lesioning, but without radiofrequency current. Preoperatively and during 3-month follow-up, patients reported visual analogue leg-pain and back-pain scores, physical impairment, and use of analgesics in a diary. Primary outcome was success or failure of treatment, defined by a multidimensional decision rule, which included median outcome variables from the diary. Post-hoc analysis for possible covariate interference with outcome variables was done. Primary outcome data were analysed on an intention-to-treat basis.

FINDINGS

45 patients were assigned radiofrequency lesioning and 38 control treatment. Three patients dropped out before 3 months. After 3 months, seven (16%) of 44 patients treated with radiofrequency lesioning and nine (25%) of 36 in the control group had successful treatment (difference -9.1% [95% CI -33.0 to 12.0], p=0.43). No differences between groups in side-effects were seen.

INTERPRETATION

Lumbosacral radiofrequency lesioning of dorsal root ganglia failed to show advantage over control treatment with local anaesthetics. Thus, its use as routine treatment in lumbosacral radicular pain should not be advocated.

Spinal cord stimulation for chronic pain of spinal origin: a valuable long-term solution

STUDY DESIGN

A literature review was conducted.

OBJECTIVE

To review the indications and efficacy of spinal cord stimulation, particularly in reference to chronic pain of spinal origin.

SUMMARY OF BACKGROUND DATA

The first spinal cord stimulation was implanted by Shealy in 1967 via a subarachnoid route. Early systems were plagued with a high rate of complications and technical problems. With the evolving technology, especially the advent of multichannel programmable systems and more precise epidural placement, the ability of spinal cord stimulation to treat various pain syndromes improved. This article reviews the literature on spinal cord stimulation from 1967 to the present.

METHODS

The literature is reviewed, with a particular focus on recent studies investigating the efficacy of spinal cord stimulation for low back pain.

RESULTS

Most studies are limited by the same flaws, namely, retrospective study design. At this writing, the few published randomized prospective studies have suggested that spinal cord stimulation may be superior to repeat surgery. Complication rates have declined to approximately 8%, and reoperation is necessary in approximately 4% of patients. When current percutaneous techniques are used, a lead migration rate lower than 3% may be achieved. For certain topographies, laminotomy leads may be superior, particularly with regard to low back pain.

CONCLUSIONS

The ultimate efficacy of spinal cord stimulation remains to be determined, primarily because of limitations associated with the published literature. However, on the basis of the current evidence, it may represent a valuable treatment option, particularly for patients with chronic pain of predominantly neuropathic origin and topographical distribution involving the extremities. The potential treatment of other pain topographies and etiologies by spinal cord stimulation continues to be studied.

General principles of diagnostic testing as related to painful lumbar spine disorders: a critical appraisal of current diagnostic techniques

STUDY DESIGN

The literature on diagnostic tests available to the spine clinician for the evaluation of chronic low back pain was reviewed.

OBJECTIVES

To review critically the available information and data on invasive diagnostic tests used for evaluation of chronic low back pain.

SUMMARY OF BACKGROUND INFORMATION

Numerous published studies have described the technique and clinical results of diagnostic blocks for chronic low back pain. There are various methodologies, but most lack of an adequate "gold standard" with which to compare the results of the diagnostic test.

METHODS

The available published studies of diagnostic tests commonly used in the evaluation of chronic low back pain were reviewed, with a focus on invasive techniques. The techniques were evaluated on the basis of the data available to support the conclusions that could be drawn for each of these techniques. The principles of diagnostic testing, including specificity and sensitivity, were reviewed and applied in the context of the data available for each of these invasive tests.

RESULTS

The essential features the clinician seeks in a diagnostic test are accuracy, safety, and reproducibility. It is essential to have a gold standard with which to compare the accuracy of a given diagnostic test. There is no completely reliable gold standard with which to compare a diagnostic test (or injection) when the absence of pain is the end point. The clinical setting in which the test is used directly affects the test results. The prevalence of the disease therefore affects the meaningfulness of the test results. Imaging studies have their greatest value in the exclusion of other conditions. These studies alone were not adequate for predicting the patients who would respond to controlled diagnostic blocks of the facet joint. Facet joint diagnostic blockade probably is most accurately performed by median nerve branch block. The greatest specificity for a positive response to a facet denervation procedure is achieved when the diagnosis is established via highly controlled anesthetic blocks. Over the past few decades, the sacroiliac joint has received varying degrees of interest as an important pain generator of low back pain. Despite testimonials to the contrary, no diagnostic physical examination has correlated with sufficient specificity to diagnose this condition reliably from a clinical standpoint. Lumbar discography has been one of the single most controversial subjects in the management of degenerative, painful lumbar spine conditions. The specificity and sensitivity are high for the diagnosis of disc degeneration. The question that revolves around discography concerns the accuracy of this test for the diagnosis of discogenic pain. An integral part of the problem is the lack of an adequate gold standard. In a comparison of nerve root blockade, sciatic nerve block, posterior ramus block, and subcutaneous injection in a cohort of patients with sciatica, the sensitivity of nerve root block was very high, with only a moderate level of specificity. In the case of diagnostic selective nerve blocks used for evaluation of complex or protean nerve compression, surgical confirmation and clinical results should be a reliable gold standard. Conflicting results have been presented depending on the target lesion and method of study.

CONCLUSIONS

There are inherent limitations in the accuracy of all diagnostic tests. The tests used to diagnose the source of a patient's chronic low back pain require accurate determination of the abolition or reproduction of the patient's painful symptoms.

Indications for and benefits of lumbar facet joint block: analysis of 230 consecutive patients

Object

The authors evaluated the effectiveness of using a facet joint block with local anesthetic agents and or steroid medication for the treatment of low-back pain in a medium-sized series of patients.

Methods

Over a period of 4 years, the authors performed 715 facet joint injections in 230 patients with variable-length histories of low-back pain. The main parameter for the success or failure of this treatment was the relief of the pain. For the first injection—mainly a diagnostic procedure—the authors used a local anesthetic (1 ml bupivacaine 1%). In cases of good response, betamethasone was injected in a second session to achieve a longer-lasting effect.

Long-lasting relief of the low-back pain and/or leg pain was reported by 43 patients (18.7%) during a mean follow-up period of 10 months. Thirty-five patients (15.2%) noticed a general improvement in their pain. Twenty-seven patients (11.7%) reported relief of low-back pain but not leg pain. Nine patients (3.9%) suffered no back pain but still leg pain. One hundred sixteen patients (50.4%), however, experienced no improvement of pain at all. In two cases the procedure had to be interrupted because of severe pain. There were no cases of infection or hematoma.

Conclusions

Lumbar facet joint block is a minimally invasive procedure to differentiate between facet joint pain and other causes of lower-back pain. The procedure seems to be useful for distinguishing between facet joint pain from postoperative pain due to inappropriate neural decompression after lumbar surgery. It can be also recommended as a possible midterm intervention for chronic low-back pain.

Diagnostic selective nerve root blocks: indications and usefulness

Diagnostic SNRIs are a useful tool in the diagnosis of radicular pain in atypical presentations. Diagnostic SNRI is indicated in the following circumstances: (1) for atypical extremity pain; (2) when imaging studies and clinical presentation do not correlate; (3) when electromyography and MRI are not corroborative or are equivocal; (4) for anomalous innervations, such [figure: see text] as conjoint nerve roots or furcal nerves [71]; (5) for failed back surgery syndrome with atypical extremity pain; and (6) for transitional vertebrae. Patients should have demonstrated a failure to improve with less invasive treatment. In these patients, a diagnostic SNRI may localize the pain to a specific spinal nerve. It must be emphasized that the diagnostic SNRI only determines if pain is emanating from a specific nerve root or spinal nerve. A diagnostic SNRI does not determine what has caused the nerve root or spinal nerve pain, nor does it provide prognostic information. The etiology of the nerve root pain, mechanism of injury, underlying anatomy, duration of symptoms, comorbidities, patient desire, physician skill, and a host of other factors determine the appropriate treatment and prognosis.

A review of mechanisms of response to pain therapy: why voodoo works

A person's response to pain treatment may be due to factors other than the direct effect of analgesics. Amelioration of pain is often associated with modalities that appear to make no scientific sense. This review outlines the mechanisms of pain amelioration other than that by medication. These mechanisms help to explain why pain relief may follow the administration of allopathic modalities. Pain is modulated, enhanced, or diminished by both cerebral and peripheral mechanisms. Cerebral factors include the placebo response, psychological phenomena, and conscious cognitive activation. In addition to evoking endogenous opioids, these central mechanisms activate antinociceptive pathways beginning in the limbic forebrain and relayed in the periaqueductal gray matter to primary afferent nociceptive sites in the spinal cord dorsal horn (and medullary nucleus caudalis). Obvious peripheral factors that may diminish pain perception are those that decrease afferent stimuli. Paradoxically, stimulation of afferent neurons may also ameliorate pain by activating spinal or supraspinal inhibitory mechanisms. Finally, improvement in pain or other symptoms is often falsely attributed to a therapy when remission occurs because the underlying illness has run its normal course.

Nerve lesions and the generation of pain

This review addresses the issue of how axotomy of peripheral nerve fibers leads to pain and hyperalgesia. The point of axotomy (the nerve injury site), the dorsal root ganglia, and the dorsal horn of the spinal cord are candidate sites for generation of the pain signal that is likely to be critical for maintaining the neuropathic pain state. This review considers neuropathic pain from a "systems" perspective, tracing concepts of neuropathic pain from the work of Henry Head to the present. Surprisingly, the nerve injury site and the dorsal root ganglion belonging to a transected spinal nerve do not give rise to spontaneous activity in putative C-fiber nociceptors. The intact nociceptor belonging to adjacent uninjured spinal nerves, however, does acquire abnormal spontaneous activity and a chemical sensitivity to catechols. It is suggested that partially denervated tissues in the nerve, skin, and other locations may release substances that, in turn, sensitize the intact nociceptors. These abnormalities in the intact nociceptor, which arise in the context of Wallerian degeneration, probably play a role in creating or maintaining the abnormal pain state. These considerations probably also apply to the understanding of pain arising in other neuropathies. The findings relative to the "intact" nociceptor provide a rationale by which to understand how therapies distal to the nerve injury site may diminish pain.

Radiofrequency facet joint denervation in the treatment of low back pain: a placebo-controlled clinical trial to assess efficacy

STUDY DESIGN

A prospective double-blind randomized controlled trial was performed.

OBJECTIVE

To assess the efficacy of percutaneous radiofrequency articular facet denervation for low back pain.

SUMMARY OF BACKGROUND DATA

Uncontrolled observational studies in patients with low back pain have reported some benefits from the use of facet joint radiofrequency denervation. Because the efficacy of percutaneous radiofrequency had not been clearly shown in previous studies, a randomized controlled trial was conducted to assess the efficacy of the technique for improving functional disabilities and reduce pain.

METHODS

For this study, 70 patients with low back pain lasting of more than 3 months duration and a good response after intraarticular facet injections under fluoroscopy were assigned randomly to receive percutaneous radiofrequency articular facet denervation under fluoroscopic guidance or the same procedure without effective denervation (sham therapy). The primary outcomes were functional disabilities, as assessed by the Oswestry and Roland-Morris scales, and pain indicated on a visual analog scale. Secondary outcomes included spinal mobility and strength.

RESULTS

At 4 weeks, the Roland-Morris score had improved by a mean of 8.4% in the neurotomy group and 2.2% in the placebo group, showing a treatment effect of 6.2% (P = 0.05). At 4 weeks, no significant treatment effect was reflected in the Oswestry score (0.6% change) or the visual analog pain score (4.2% change). At 12 weeks, neither functional disability, as assessed by the Roland-Morris scale (2.6% change) and Oswestry scale (1.9% change), nor the pain level, as assessed by the visual analog scale (-7.6% change), showed any treatment effect.

CONCLUSIONS

Although radiofrequency facet joint denervation may provide some short-term improvement in functional disability among patients with chronic low back pain, the efficacy of this treatment has not been established.

Long-lasting analgesic effect of radiofrequency treatment of the lumbosacral dorsal root ganglion

OBJECT

The authors conducted a study to establish the benefit of radiofrequency (RF) treatment of the lumbosacral dorsal root ganglion (DRG) as a therapy to reduce symptomatic pain in patients with chronic spinal pain radiating to the leg.

METHODS

Two hundred seventy-nine patients were evaluated after undergoing their first RF treatment of the DRG. A four-point pain perception scale was used. Short-term effect was documented after 2 months. The influence of surgical history on outcome was examined by using chi-square analysis. The mean duration of analgesic effect was calculated by applying a probit survival analysis. Two months after undergoing RF treatment, 59% of patients reported satisfactory pain reduction. No serious adverse effects were noted. Surgical history was shown to have no significant effect on outcome. The long-term half-life time of pain reduction was 44.5 months.

CONCLUSIONS

The use of RF in the treatment of DRG appears to be a useful and safe therapy in patients with chronic spinal pain that radiates to the leg. The initial success rate is approximately 60%. It seems to lead to a time-limited effect on the target structure, and the mean duration of pain reduction is approximately 3.7 years. The mechanism of action remains unclear.

Injection therapy for subacute and chronic benign low back pain

STUDY DESIGN

The Medline and Embase databases containing randomized controlled trials of injection therapy published to 1998 were systematically reviewed.

OBJECTIVES

To evaluate the effectiveness of injection therapy with anesthetics, steroids, or both in patients with low back pain persisting longer than 1 month.

METHODS

Two reviewers independently assessed the trials for the quality of their methods. The primary outcome measure was pain relief. Subgroup analyses were performed between trials with different control groups (placebo and active injections), with different injection sites (facet-joint, epidural, and local injections), and with timing of outcome measurement (short- and long-term). Within the resulting 12 (2 x 3 x 2) subcategories of studies, the overall relative risks and corresponding 95% confidence intervals were estimated, using the random effects model of DerSimonian and Laird. In the case of trials using active injections as a control, the results were not pooled.

RESULTS

This review included 21 randomized trials. All the studies involved patients with low back pain persisting longer than 1 month. Only 11 studies compared injection therapy with placebo injections (explanatory trials). The methodologic quality of many studies was low: Only eight studies had a methodologic score of 50 points or more. There were only three well-designed explanatory clinical trials: one on injections into the facet joints with a short-term relative risk of 0.89 (95% confidence interval = 0.65-1.21) and a long-term relative risk of 0.90 (95% confidence interval = 0.69-1.17), one on epidural injections with a short-term relative risk of of 0.94 (95% confidence interval = 0.76-1.15) and a long-term relative risk of 1.00 (95% confidence interval = 0.71-1.41), and one on local injections with a long-term relative risk of 0.79 (95% confidence interval = 0.65-0.96). Within the six subcategories of explanatory studies, the pooled relative risks were as follows: facet joint, short-term: relative risk = 0.89 (95% confidence interval = 0.65-1.21); facet joint, long-term: relative risk = 0.90 (95% confidence interval = 0.69-1.17); epidural, short-term: relative risk = 0.93 (95% confidence interval = 0.79-1.09); epidural, long-term: relative risk = 0.92 (95% confidence interval = 0.76-1.11); local, short-term: relative risk = 0.80 (95% confidence interval = 0.40-1.59); and local, long-term: relative risk = 0.79 (95% confidence interval = 0.65-0.96).

CONCLUSIONS

Convincing evidence is lacking regarding the effects of injection therapy on low back pain. Additional well-designed explanatory trials in this field are needed.

2000 Volvo Award winner in clinical studies: Lumbar high-intensity zone and discography in subjects without low back problems

STUDY DESIGN

A prospective observational study of patients with low back pain and those without was performed.

OBJECTIVE

To investigate the prevalence and significance of a high-intensity zone in a group of patients asymptomatic for low back pain, but who had known risk factors for lumbar disc degeneration. This asymptomatic group was compared with a symptomatic group of patients with respect to the presence of anular high-intensity zone and the pain response with discography.

SUMMARY OF BACKGROUND DATA

Some authors have estimated the prevalence of a high-intensity zone in a group of symptomatic patients to be 86%. They have reported a strong correlation between a high-intensity zone and positive discography in patients with low back pain. Other investigators have reported evidence either supporting or discounting these findings.

METHODS

Patients with low back pain and those without underwent physical examination, psychometric testing, plain radiograph, magnetic resonance imaging, and discography. The presence of a high-intensity zone, anular disruption, and positive discographic pain then were compared between the two groups. There were strict inclusion criteria for both groups. A total of 109 discs in 42 patients were evaluated in the symptomatic group and compared with 143 discs in 54 patients in the asymptomatic group. The presence of a high-intensity zone was determined by a standardized criteria on T2-weighted magnetic resonance images. Psychometric testing also was administered to each patient before discography. Standard discography was performed on all the patients, and the pain response was recorded using a visual analog scale according to the Walsh et al criteria.

RESULTS

The prevalence of a high-intensity zone in the patient populations was 59% in the symptomatic group and 24% in the asymptomatic group. In the symptomatic group, 33 (30.2%) of 109 discs were found to have a high-intensity zone. In the asymptomatic group, 13 of 143 discs were found to have a high-intensity zone. In the symptomatic group, 72.7% of the discs with a high-intensity zone were positive on discography, whereas 38.2% of the discs without a high-intensity zone were positive. In the asymptomatic group, 69.2% of the discs with a high-intensity zone were positive on discography, whereas 10% of the discs without a high-intensity zone were positive. In the patients with normal psychometric testing, 50% of the discs with a high-intensity zone were positive on discography, as compared with 100% positive discography results in patients with abnormal psychometric testing or chronic pain.

CONCLUSIONS

The presence of a high-intensity zone does not reliably indicate the presence of symptomatic internal disc disruption. Although higher in symptomatic patients, the prevalence of a high-intensity zone in asymptomatic individuals with degenerative disc disease (25%) is too high for meaningful clinical use. When injected during discography, the same percentage of asymptomatic and symptomatic discs with a high-intensity zone were shown to be painful.

Provocative discography in patients after limited lumbar discectomy: A controlled, randomized study of pain response in symptomatic and asymptomatic subjects

STUDY DESIGN

This was a prospective observational study of patients with low back pain and those without after laminotomy and discectomy.

OBJECTIVES

To determine, using a strict experimental design, the relative pain intensity response to provocative discography in symptomatic and asymptomatic subjects after lumbar discectomy for intervertebral disc herniation.

BACKGROUND

Provocative discography frequently is used to evaluate persistent or recurrent low back pain syndromes in patients who have undergone posterior discectomy. The validity of interpreting painful injections during this procedure has not been critically assessed. The prevalence of significantly painful disc injections in a group with good outcomes after surgery is not known. Knowing the rates of significantly painful injections in asymptomatic patients after lumbar discectomy may clarify the meaning of painful injections in symptomatic patients.

METHODS

From a cohort of 240 patients who had undergone single-level limited discectomy for sciatica, 20 asymptomatic volunteers were recruited for experimental three-level lumbar discography. Inclusion criteria required nearly perfect scores on standardized back pain rating instruments, no other spinal pathology, and normal psychometric screening. A control group of 27 symptomatic patients, after single-level discectomy with intractable low back pain syndrome, and without other spinal pathology, underwent discography. Seven patients in the control group had normal psychometric tests. Experienced raters who were blinded to control versus experimental status of the subjects scored the magnetic resonance imaging, discogram, psychometric tests, and discography videotapes of the subjects' pain behavior.

RESULTS

There were 8 of 20 (40%) positive injections of discs that had previous surgery in the asymptomatic group and 17 of 27 (63%) positive injections in the symptomatic group. Specifically with regard to the symptomatic group, there were 3 of 7 (43%) positive injections (all concordant) in patients with normal psychometric scores, as compared with 14 of 20 (70%) positive injections (12 concordant) in patients with abnormal psychometric scores. Injections of discs that had previous surgery resulted in a mean pain score of 2.1 of 5 in the asymptomatic group, 2.1 in the symptomatic group with normal psychometric scores, and 3.4 in the symptomatic group with abnormal psychometric scores. Of the discs not treated with surgery, 2 were positive in the asymptomatic group (10%), 3 in 2 symptomatic subjects with normal psychological testing (29), and 18 in 13 symptomatic subjects with abnormal psychometric testing (76%).

CONCLUSIONS

A high percentage of asymptomatic patients with normal psychometric testing who previously have undergone lumbar discectomy will have significant pain on injection of their discs that had previous surgery (40%). This is not significantly different from the experience of symptomatic patients with normal psychometric testing undergoing discography on discs that had previous surgery. Patients with abnormal psychological profiles have significantly higher rates of positive disc injections than either asymptomatic volunteers or symptomatic subjects with normal psychological screening.

False-positive findings on lumbar discography. Reliability of subjective concordance assessment during provocative disc injection

STUDY DESIGN

Experimental disc injections in subjects with no history of low back symptoms.

OBJECTIVE

To determine in an experimental model the reliability of patients' subjective interpretation of pain concordancy during provocative disc injection.

BACKGROUND

Discography in the evaluation of low back pain relies on a patient's subjective assessment of pain magnitude and quality during disc injection. Reproduction of significant pain on disc injection, which is similar to patients' usual pain, is believed to prove that the disc injected is the source of the patient's low back pain. In the current study, this hypothesis was tested in a controlled setting on patients with known nonspinal pain in a common referral area of discogenic pain.

METHODS

Patients with no history of low back pain were recruited to participate in a study of discography. Patients scheduled to undergo posterior iliac crest bone graft harvesting for nonthoracolumbar procedures were evaluated with lumbar radiography, magnetic resonance imaging, and psychometric testing. Two to 4 months after bone graft harvesting, patients underwent lumbar discography by strict blinded protocol. Patients were asked to compare the sensations elicited at discography to their usual back/buttock pain since bone graft harvesting. Pain was rated as 0-5 on a pain thermometer and concordancy was rated as none, dissimilar, similar, or exact.

RESULTS

Eight subjects completed the study, and 24 discs were injected. Of the 14 disc injections causing some pain response, 5 were believed to be "different" (nonconcordant) pains (35.7%); 7 were "similar" (50.0%), and 2 were "exact" pain reproductions (14.3%). The presence of anular disruption predicted concordant pain reproduction (P < 0.05). Of 10 discs with anular tears, injection of 5 elicited pain that was similar to or an exact reproduction of pain at the iliac crest bone graft harvest sites. By the usual criteria for positive discography, 4 of the 8 patients (50%) would have been classified as positive. In these patients, the pain on a single disc injection was very painful, and the pain quality was noted to be exact or similar to the usual discomfort. All subjects had a negative control disc.

CONCLUSIONS

The findings of this study demonstrate that patients with no history of low back pain who had undergone posterior iliac bone graft harvesting for nonlumbar procedures often experienced a concordant painful sensation on lumbar discography with their usual gluteal area pain. Thus, the ability of a patient to separate spinal from nonspinal sources of pain on discography is questioned, and a response of concordant pain on discography may be less meaningful than often assumed.

Uninjured C-fiber nociceptors develop spontaneous activity and alpha-adrenergic sensitivity following L6 spinal nerve ligation in monkey

We investigated whether uninjured cutaneous C-fiber nociceptors in primates develop abnormal responses after partial denervation of the skin. Partial denervation was induced by tightly ligating spinal nerve L6 that innervates the dorsum of the foot. Using an in vitro skin-nerve preparation, we recorded from uninjured single afferent nerve fibers in the superficial peroneal nerve. Recordings were made from 32 C-fiber nociceptors 2-3 wk after ligation and from 29 C-fiber nociceptors in control animals. Phenylephrine, a selective alpha1-adrenergic agonist, and UK14304 (UK), a selective alpha2-adrenergic agonist, were applied to the receptive field for 5 min in increasing concentrations from 0.1 to 100 microM. Nociceptors from in vitro control experiments were not significantly different from nociceptors recorded by us previously in in vivo experiments. In comparison to in vitro control animals, the afferents found in lesioned animals had 1) a significantly higher incidence of spontaneous activity, 2) a significantly higher incidence of response to phenylephrine, and 3) a higher incidence of response to UK. In lesioned animals, the peak response to phenylephrine was significantly greater than to UK, and the mechanical threshold of phenylephrine-sensitive afferents was significantly lower than for phenylephrine-insensitive afferents. Staining with protein gene product 9.5 revealed an approximately 55% reduction in the number of unmyelinated terminals in the epidermis of the lesioned limb compared with the contralateral limb. Thus uninjured cutaneous C-fiber nociceptors that innervate skin partially denervated by ligation of a spinal nerve acquire two abnormal properties: spontaneous activity and alpha-adrenergic sensitivity. These abnormalities in nociceptor function may contribute to neuropathic pain.

Controversy. The use of selective nerve root blocks: diagnostic, therapeutic, or placebo?

An increasing number of therapeutic spinal injections are performed each year despite little validation in randomized controlled trials. Additional injections are performed for diagnostic purposes of localizing symptomatic nerve roots, again without detailed evaluation of accuracy, specificity, or sensitivity. Drs. Slosar and White argue that selective nerve root blocks are extremely useful; Dr Wetzel believes that selective nerve root blocks have no role in selecting patients for surgery.

Long-term effects of nerve blocks in chronic pain

Regional blockade techniques have been of crucial importance for decades in chronic pain therapy, but in recent years some developments have made a new definition of the status of invasive procedures necessary. The realization of chronic pain as a multifactorial process led to the establishment of an interdisciplinary approach to pain therapy, leaving blockades as only one step in a multimodal therapy. The mainstay of local anaesthetic blocks now is diagnostic and prognostic, but correct interpretation of the results is limited by different factors, and controlled studies on the diagnostic value of local anaesthetic blockade are lacking. In cancer pain, invasive procedures are necessary in only a few cases. Some neuroablative techniques can offer long-term pain reduction. In non-cancer pain, neurodestructive procedures should be reserved for some special indications (e.g. lumbar sympathetic neurolytic blocks in ischaemic diseases). In a great number of chronic pain conditions the sympathetic nervous system is involved or even has a central status. In the acute stage of these diseases sympathetic blockades can be the therapy of choice. There is no disease in which different invasive procedures are performed so frequently and so uncritically as in chronic low back pain. Up to now, however, all controlled studies of invasive procedures only demonstrated short-term effects and failed to prove long-term efficacy. Therefore any invasive technique should only be performed in well-selected patients over a defined period and with a limited number of blockades.

How to recognize and treat specific low back pain?

A wide variety of mechanical and non-mechanical disorders are associated with the clinical symptom of low back pain. Mechanical disorders are the cause of the vast majority of low back pain. Despite this frequency, the specific cause of mechanical low back pain can not be elucidated in spite of extensive diagnostic evaluation in a majority of individuals. Specific causes of low back pain are associated with less frequently occurring systemic illnesses including rheumatic, infectious, neoplastic, gynaecological and vascular disorders. The diagnostic process is more successful in identifying systemic disorders as the specific cause of low back pain. Non-surgical management is effective therapy with most patients with mechanical disorders of any form. Systemic illnesses require interventions directed specifically at healing the affected organ system.

Spinal pain mechanisms

Pain is an extremely complex process that involves the interaction of an array of neurotransmitters and neuromodulators at all levels of the neuraxis. Identification of the receptors and processes that are involved in the transmission of pain at a spinal level has led to the use of new agents and new techniques in pain management. These include use of preemptive analgesia and use of techniques such as intrathecal drug administration and epidural spinal cord stimulation. This review presents some of the findings from basic research that have led to these developments, particularly those that relate to the changes that occur following inflammation and nerve injury.