Double-blind evaluation of chemonucleolysis for herniated lumbar discs. Late results

Surgical versus non-surgical treatment for sciatica: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To investigate the effectiveness and safety of surgery compared with non-surgical treatment for sciatica.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the World Health Organisation International Clinical Trials Registry Platform from database inception to June 2022.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials comparing any surgical treatment with non-surgical treatment, epidural steroid injections, or placebo or sham surgery, in people with sciatica of any duration due to lumbar disc herniation (diagnosed by radiological imaging).

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data. Leg pain and disability were the primary outcomes. Adverse events, back pain, quality of life, and satisfaction with treatment were the secondary outcomes. Pain and disability scores were converted to a scale of 0 (no pain or disability) to 100 (worst pain or disability). Data were pooled using a random effects model. Risk of bias was assessed with the Cochrane Collaboration's tool and certainty of evidence with the grading of recommendations assessment, development, and evaluation (GRADE) framework. Follow-up times were into immediate term (≤six weeks), short term (>six weeks and ≤three months), medium term (>three and <12 months), and long term (at 12 months).

RESULTS

24 trials were included, half of these investigated the effectiveness of discectomy compared with non-surgical treatment or epidural steroid injections (1711 participants). Very low to low certainty evidence showed that discectomy, compared with non-surgical treatment, reduced leg pain: the effect size was moderate at immediate term (mean difference -12.1 (95% confidence interval -23.6 to -0.5)) and short term (-11.7 (-18.6 to -4.7)), and small at medium term (-6.5 (-11.0 to -2.1)). Negligible effects were noted at long term (-2.3 (-4.5 to -0.2)). For disability, small, negligible, or no effects were found. A similar effect on leg pain was found when comparing discectomy with epidural steroid injections. For disability, a moderate effect was found at short term, but no effect was observed at medium and long term. The risk of any adverse events was similar between discectomy and non-surgical treatment (risk ratio 1.34 (95% confidence interval 0.91 to 1.98)).

CONCLUSION

Very low to low certainty evidence suggests that discectomy was superior to non-surgical treatment or epidural steroid injections in reducing leg pain and disability in people with sciatica with a surgical indication, but the benefits declined over time. Discectomy might be an option for people with sciatica who feel that the rapid relief offered by discectomy outweighs the risks and costs associated with surgery.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021269997.

Nonsurgical medical treatment in the management of pain due to lumbar disc prolapse: A network meta-analysis

BACKGROUND

Evaluate the comparative effectiveness of treatment strategies for patients with pain due to lumbar disc prolapse (LDP).

METHODS

PubMed, EMBASE, and the Cochrane Database were searched through September 2017. Randomized controlled trials on LDP reporting on pain intensity and/or global pain effects which compared included treatments head-to-head, against placebo, and/or against conventional care were included. Study data were independently double-extracted and data on patient traits and outcomes were collected. Risk of bias was assessed using the Cochrane risk of bias tool. Separate Bayesian network meta-analyses were undertaken to synthesize direct and indirect, short-term and long-term outcomes, summarized as odds ratios (OR) or weighted mean differences (WMD) with 95% credible intervals (CI) as well as surface under the cumulative ranking curve (SUCRA) values.

RESULTS

58 studies in global effects and 74 studies in pain intensity analysis were included. Thirty-eight (65.5%) of these studies reported a possible elevated risk of bias. Autonomic drugs and transforminal epidural steroid injections (TESIs) had the highest SUCRA scores at short-term follow up (86.7 and 83.5 respectively), while Cytokines/Immunomodulators and TESI had the highest SUCRA values at long-term-follow-up in the global effect's analysis (86.6 and 80.9 respectively). Caudal steroid injections and TESIs had the highest SUCRA scores at short-term follow up (79.4 and 75.9 respectively), while at long-term follow-up biological agents and manipulation had the highest SUCRA scores (86.4 and 68.5 respectively) for pain intensity. Some treatments had few studies and/or no associated placebo-controlled trials. Studies often did not report on co-interventions, systematically differed, and reported an overall elevated risk of bias.

CONCLUSION

No treatment stands out as superior when compared on multiple outcomes and time periods but TESIs show promise as an effective short-term treatment. High quality studies are needed to confirm many nodes of this network meta-analysis.

Nonsurgical interventional therapies for low back pain: a review of the evidence for an American Pain Society clinical practice guideline

STUDY DESIGN

Systematic review.

OBJECTIVE

To systematically assess benefits and harms of nonsurgical interventional therapies for low back and radicular pain.

SUMMARY OF BACKGROUND DATA

Although use of certain interventional therapies is common or increasing, there is also uncertainty or controversy about their efficacy.

METHODS

Electronic database searches on Ovid MEDLINE and the Cochrane databases were conducted through July 2008 to identify randomized controlled trials and systematic reviews of local injections, botulinum toxin injection, prolotherapy, epidural steroid injection, facet joint injection, therapeutic medial branch block, sacroiliac joint injection, intradiscal steroid injection, chemonucleolysis, radiofrequency denervation, intradiscal electrothermal therapy, percutaneous intradiscal radiofrequency thermocoagulation, Coblation nucleoplasty, and spinal cord stimulation. All relevant studies were methodologically assessed by 2 independent reviewers using criteria developed by the Cochrane Back Review Group (for trials) and by Oxman (for systematic reviews). A qualitative synthesis of results was performed using methods adapted from the US Preventive Services Task Force.

RESULTS

For sciatica or prolapsed lumbar disc with radiculopathy, we found good evidence that chemonucleolysis is moderately superior to placebo injection but inferior to surgery, and fair evidence that epidural steroid injection is moderately effective for short-term (but not long-term) symptom relief. We found fair evidence that spinal cord stimulation is moderately effective for failed back surgery syndrome with persistent radiculopathy, though device-related complications are common. We found good or fair evidence that prolotherapy, facet joint injection, intradiscal steroid injection, and percutaneous intradiscal radiofrequency thermocoagulation are not effective. Insufficient evidence exists to reliably evaluate other interventional therapies.

CONCLUSION

Few nonsurgical interventional therapies for low back pain have been shown to be effective in randomized, placebo-controlled trials.

Surgical interventions for lumbar disc prolapse

BACKGROUND

Disc prolapse accounts for five percent of low-back disorders but is one of the most common reasons for surgery.

OBJECTIVES

The objective of this review was to assess the effects of surgical interventions for the treatment of lumbar disc prolapse.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Spine and abstracts of the main spine society meetings within the last five years. We also checked the reference lists of each retrieved articles and corresponded with experts. All data found up to 1 January 2007 are included.

SELECTION CRITERIA

Randomized trials (RCT) and quasi-randomized trials (QRCT) of the surgical management of lumbar disc prolapse.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial quality and extracted data from published papers. Additional information was sought from the authors if necessary.

MAIN RESULTS

Forty RCTs and two QRCTs were identified, including 17 new trials since the first edition of this review in 1999. Many of the early trials were of some form of chemonucleolysis, whereas the majority of the later studies either compared different techniques of discectomy or the use of some form of membrane to reduce epidural scarring. Despite the critical importance of knowing whether surgery is beneficial for disc prolapse, only four trials have directly compared discectomy with conservative management and these give suggestive rather than conclusive results. However, other trials show that discectomy produces better clinical outcomes than chemonucleolysis and that in turn is better than placebo. Microdiscectomy gives broadly comparable results to standard discectomy. Recent trials of an inter-position gel covering the dura (five trials) and of fat (four trials) show that they can reduce scar formation, though there is limited evidence about the effect on clinical outcomes. There is insufficient evidence on other percutaneous discectomy techniques to draw firm conclusions. Three small RCTs of laser discectomy do not provide conclusive evidence on its efficacy, There are no published RCTs of coblation therapy or trans-foraminal endoscopic discectomy.

AUTHORS' CONCLUSIONS

Surgical discectomy for carefully selected patients with sciatica due to lumbar disc prolapse provides faster relief from the acute attack than conservative management, although any positive or negative effects on the lifetime natural history of the underlying disc disease are still unclear. Microdiscectomy gives broadly comparable results to open discectomy. The evidence on other minimally invasive techniques remains unclear (with the exception of chemonucleolysis using chymopapain, which is no longer widely available).

Chemonucleolysis in lumbar disc herniation: a meta-analysis

PURPOSE

To carry out a systematic review and meta-analysis of the efficacy of chemonucleolysis in the treatment of lumbar disc herniation.

METHODS

Clinical trials were selected from 3 electronic databases (The Cochrane Controlled Trials Register, MEDLINE, and EMBASE). Data were analyzed with the software STATA, using the meta command.

RESULTS

Twenty-two clinical trials were eligible. For chemonucleolysis versus placebo, the summary risk ratio estimate for pain relief as outcome was 1.51 (95% CI: 1.27-1.80). The summary estimate was 1.07 (95% CI: 0.95-1.20) for the comparison between chymopapain and collagenase. Regarding chemonucleolysis with chymopapain versus surgery, the fixed-effect summary estimate of effect for pain relief was 0.93 (95% CI: 0.88-0.98) with surgery as the reference group. In this case, heterogeneity was statistically significant.

CONCLUSIONS

Chemonucleolysis with chymopapain was superior to placebo and was as effective as collagenase in the treatment of lumbar disc prolapse. Results for studies comparing chemonucleolysis with surgery were heterogeneous, making it difficult to interpret the summary measure of effect.

Surgical interventions for lumbar disc prolapse

BACKGROUND

Disc prolapse accounts for five percent of low-back disorders but is one of the most common reasons for surgery.

OBJECTIVES

The objective of this review was to assess the effects of surgical interventions for the treatment of lumbar disc prolapse.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Spine and abstracts of the main spine society meetings within the last five years. We also checked the reference lists of each retrieved articles and corresponded with experts. All data found up to 1 June 2006 are included.

SELECTION CRITERIA

Randomized trials (RCT) and quasi-randomized trials (QRCT) of the surgical management of lumbar disc prolapse.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial quality and extracted data from published papers. Additional information was sought from the authors if necessary.

MAIN RESULTS

Thirty-nine RCTs and two QRCTs were identified, including 16 new trials since the first edition of this review in 1999. Many of the early trials were of some form of chemonucleolysis, whereas the majority of the later studies either compared different techniques of discectomy or the use of some form of membrane to reduce epidural scarring. Despite the critical importance of knowing whether surgery is beneficial for disc prolapse, only three trials have directly compared discectomy with conservative management and these give suggestive rather than conclusive results. However, other trials show that discectomy produces better clinical outcomes than chemonucleolysis and that in turn is better than placebo. Microdiscectomy gives broadly comparable results to standard discectomy. Recent trials of an inter-position gel covering the dura (five trials) and of fat (four trials) show that they can reduce scar formation, though there is limited evidence about the effect on clinical outcomes. There is insufficient evidence on other percutaneous discectomy techniques to draw firm conclusions. Three small RCTs of laser discectomy do not provide conclusive evidence on its efficacy, There are no published RCTs of coblation therapy or trans-foraminal endoscopic discectomy.

AUTHORS' CONCLUSIONS

Surgical discectomy for carefully selected patients with sciatica due to lumbar disc prolapse provides faster relief from the acute attack than conservative management, although any positive or negative effects on the lifetime natural history of the underlying disc disease are still unclear. Microdiscectomy gives broadly comparable results to open discectomy. The evidence on other minimally invasive techniques remains unclear (with the exception of chemonucleolysis using chymopapain, which is no longer widely available).

[Nucleolysis in the herniated disk]

Back pain associated with a herniated disk has become an important and increasing general health problem in Germany and other industrialized countries. After all methods of conservative treatment have been exhausted, nucleolysis may be a minimally invasive alternative to surgery. In nucleolysis, chondrolytic substances or other substances, which reduce the pressure within the disk by other means, are injected into the nucleus pulposus under CT guidance. Among various substances, which have been employed for nucleolysis, an ozone-oxygen mixture appears to be very promising. The water-binding capacity of ozone results in a reduction of pain for several months. Moreover, it has an anti-inflammatory effect and results in an increase of perfusion. Ozone is converted into pure oxygen in the body and has a low allergic potential. Recent minimally invasive therapeutic methods such as percutaneous nucleotomy or laser treatment do not result in superior results compared with nucleolysis.

Randomized Trials of Neurosurgical Interventions: A Systematic Appraisal

OBJECTIVE

To systematically appraise the study design and quality of reporting of randomized controlled trials (RCTs) on neurosurgical procedures and to identify potential defects and biases.

METHODS

Randomized controlled trials with at least five patients comparing any neurosurgical procedure against another procedure, nonsurgical treatment, or no treatment were retrieved from MEDLINE, EMBASE, and the Cochrane Library. We analyzed study design, quality of reporting, and trial results.

RESULTS

The median sample size in the 108 eligible reports was 68 patients. Ninety-nine trials (91.7%) reported inclusion and exclusion criteria, 55 (50.9%) mentioned the randomization mode, and 87 (80.6%) adequately described withdrawals, but only 31 (28.7%) described allocation concealment, only 23 (21.3%) gave power calculations, and only 20 (18.5%) were adequately powered. Significant efficacy or trend for efficacy was claimed in 46 reports (42.6%), and no difference between the compared procedures was found in 60 trials (55.6%). Trials with a larger sample size were more likely to report withdrawals (P = 0.02) and power calculations (P = 0.006). Only 14 trials (13.6%) were double-blind, and this was less frequent in longer trials (P = 0.02). Among quality criteria, only the reporting of randomization mode improved significantly over time (P = 0.015).

CONCLUSION

Several aspects of the design and reporting of randomized controlled trials on neurosurgical procedures can be improved. Larger, adequately powered, and accurately reported trials are needed.

The Cochrane review of surgery for lumbar disc prolapse and degenerative lumbar spondylosis

STUDY DESIGN

A Cochrane review of randomized controlled trials.

OBJECTIVES

To collate the scientific evidence on surgical management for lumbar-disc prolapse and degenerative lumbar spondylosis.

SUMMARY OF BACKGROUND DATA

Surgical investigations and interventions account for as much as one third of the health care costs for spinal disorders, but the scientific evidence for most procedures still is unclear.

METHODS

A highly sensitive search strategy identified all published randomized controlled trials. Cochrane methodology was used for meta-analysis of the results.

RESULTS

Twenty-six randomized controlled trials of surgery for lumbar disc prolapse and 14 trials of surgery for degenerative lumbar spondylosis were identified. Methodologic weaknesses were found in many of the trials. Only one trial directly compared discectomy and conservative management. Meta-analyses showed that surgical discectomy produces better clinical outcomes than chemonucleolysis, which is better than placebo. Three trials showed no difference in clinical outcomes between microdiscectomy and standard discectomy, but in three other studies, both produced better results than percutaneous discectomy. Three trials showed that inserting an interposition membrane after discectomy does not significantly reduce scar formation or alter clinical outcomes. Five heterogeneous trials on spinal stenosis and degenerative spondylolisthesis permit very limited conclusions. There were nine trials of instrumented versus noninstrumented fusion: Meta-analysis showed that instrumentation may facilitate fusion but does not improve clinical outcomes.

CONCLUSIONS

There is now strong evidence on the relative effectiveness of surgical discectomy versus chemonucleolysis versus placebo. There is considerable evidence on the clinical effectiveness of discectomy for carefully selected patients with sciatica caused by lumbar disc prolapse that fails to resolve with conservative management. There is no scientific evidence on the effectiveness of any form of surgical decompression or fusion for degenerative lumbar spondylosis compared with natural history, placebo, or conservative management. The Cochrane reviews will be updated continuously as other trials become available.

Intraoperative chymopapain in lumbar laminotomy for disc disease: a less invasive technique

The use of chymopapain in the treatment of lumbar disc herniation has been widely studied since Smith first described its use in humans in 1963. The authors describe the use of chymopapain intraoperatively in open lumbar microdiscectomy in 63 patients. When combined with the results of a previous study performed at the same institution, the authors found that this technique significantly reduces the rate of recurrent disc herniation when compared with traditional laminotomy with discectomy. This procedure maximizes the benefits of each approach taken separately, allowing for decompression of the nerve root from a free fragment or sequestered disc and preventing recurrence through dissolution of the nucleus pulposus. Overall, outcome was good or excellent immediately postoperatively in 73% of the 63 patients and in 64% at last follow-up evaluation. Additionally, this procedure is safe with no complications noted in the immediate perioperative period or at follow-up evaluation.

Randomized controlled trials in industrial low back pain relating to return to work. Part 2. Discogenic low back pain

The purpose of this review was to determine the efficacy of treatments for discogenic low back pain (LBP) by examining all randomized controlled trials (RCTs) of discogenic LBP published in the English language literature between 1975 and 1993 with "return to work" (RTW) as the end point. From more than 4,000 LBP citations, nearly 600 articles were initially reviewed; 35 studies met our selection criteria. Twenty-two studies were discussed in Part 1 (Acute Interventions) or will be discussed in Part 3 (Chronic Interventions). In this review, of 13 RCTs assessing interventions for LBP with sciatica, 9 were appropriate for their focus on, and radiologic confirmation of, discogenic LBP. The treatments assessed included chemonucleolysis, surgical discectomy, and epidural steroid injection. A 26-point system to assess the quality of methodologic rigor was used for each article. Our literature survey found a need for additional studies comparing surgery, conservative care, epidural steroids, traction, and other approaches to determine their individual effects for RTW after discogenic disease.

Effect of pronation and supination orthosis on Morton's neuroma and lower extremity function

Twenty-three adult patients with Morton's neuroma of one foot were randomized to receive in-shoe orthoses made from a hard, compressed, felt material that would either pronate or supinate both feet. The response of the neuroma pain was measured using subjective visual analogue scales, an objective examination, and the MACTAR patient-specific measure of maximal function. The development of any other lower limb symptoms was also recorded. The pain associated with Morton's neuroma was not significantly altered by changing the position of the foot with the compressed felt orthosis. Forcibly pronating the foot did not produce a significant incidence of lower limb symptoms in the short term.

Chemonucleolysis versus discectomy: a randomized multicenter trial

A randomized clinical trial was carried out to compare the results of open discectomy with those of chemonucleolysis in 151 patients suffering from a disc herniation at L4-5 or L5-S1. All patients fulfilled strict entry criteria; 78 patients underwent open discectomy and 73 were subjected to chemonucleolysis. An increase in radicular pain immediately after treatment was encountered in 16 patients (22%) in the chemonucleolysis group, as compared to none in the discectomy group. The efficacy of discectomy appeared to be definitely superior to that of chemonucleolysis. Within a follow-up period of 1 year, 18 patients (25%) required open discectomy following failed chemonucleolysis; two patients (3%) in the discectomy group needed a second operation. Open discectomy following previous chemonucleolysis was successful in only 44% of cases. Comparison of the final results of the two modes of treatment 12 months after the last intervention (including second treatment) did not reveal any significant differences. The duration of the preoperative symptoms, the level of disc herniation, and the leakage of contrast medium out of the disc appeared to be of no relevance to the final outcome. The complication rates in both treatment groups were low.

Chemonucleolysis with chymopapain: results in 150 patients

Chemonucleolysis with chymopapain has been advocated for the treatment of lumbar disc disease. When polled by a mail questionnaire, 150 consecutive patients who had undergone chemonucleolysis reported an overall success rate of only 40% and a failure rate of 60%. However, 57% of the patients were active or had only mild restriction of daily activities. Of those patients employed prior to injection, only 63% had returned to work. Those with workmen's compensation benefits fared considerably worse than those covered by third-party insurance (17% vs. 51% success). These results cast doubt on the long-term benefits of chymopapain in the treatment of lumbar disc disease.

Percutaneous nucleotomy. An alternative to spinal surgery

As an alternative to the well-established surgical procedures for the treatment of disk herniation, percutaneous nucleotomy has proved to be very satisfactory. In several cases this approach has brought complete relief to the patient without sacrifice of bone and without causing soft tissue damage as would have been inevitable with the usual surgical methods. Percutaneous nucleotomy is also a true alternative to chemical nucleolysis when leakage of contrast agent into the spinal canal has already been observed during diskography. Furthermore, this method avoids disagreeable complications encountered in chemical nucleotomy, for example, anaphylactic shock or the escape of the nucleolytic agent into the spinal canal. The method basically consists of removing the nucleus pulposus (or a major part of it) by means of a forceps that is introduced to the site through a cannula. In this manner a reduction of volume of the disk is achieved. The procedure can easily be carried out under local anesthesia. This method should be avoided in the case of prolapse within the spinal canal and especially when displacement beyond the level of the disk has occurred. In the period between 1979 and 1985 we carried out percutaneous nucleotomies in 51 patients with herniation mostly combined with a narrow spinal canal or spondylolisthesis. The clinical results from 32 of 51 patients can be assessed as very good, good, or satisfactory. We consider the proportion of patients showing good clinical results to be high, bearing in mind that the indication was not just disk herniation alone but, in most cases, combined with other lumbar pathologies as well.

Chemonucleolysis: a note of caution

Following the approval in 1982 by the Federal Food and Drug Administration of chymopapain for public use by the medical profession in the treatment of ruptured lumbar intervertebral disk disease, chemonucleolysis has become widespread in the United States; a considerable experience has been obtained in the past 3 years, allowing for an appropriate examination of the original claims for the procedure. Chemonucleolysis is not as efficacious as surgery for simple ruptured lumbar intervertebral disk disease. Whereas the complication rates of chemonucleolysis are probably no greater than that for surgery, the incidence of unpreventable anaphylaxis and other untoward reactions makes it certainly no more safe. There is no biological basis for the belief that chemonucleolysis will result in a shorter convalescence than surgery, and it appears that chemonucleolysis has significantly increased the cost of invasive treatment of patients with ruptured lumbar intervertebral disk disease.

Mechanism of action of intradiscal chymopapain in the treatment of sciatica: a clinical, biochemical, and radiological study

Seventeen patients with intractable sciatica due to prolapse of a lumbar disc, treated by intradiscal injection of chymopapain (chemonucleolysis) were studied. Analysis of serial 24 hour urine collections showed a significant increase in urinary glycosaminoglycan after chemonucleolysis. This was not detected in four patients undergoing routine discography. Enzymic analysis of urinary glycosaminoglycan after chemonucleolysis suggested that the increase in levels was largely due to an increase in the amounts of chondroitin sulphate present, probably resulting from proteoglycan breakdown in the intervertebral disc. Eight of the patients treated by chemonucleolysis underwent serial computed tomography (CT). One month after the injection the only change seen was a loss of definition of the disc prolapse, which could be interpreted as a loss of turgidity in the disc as a result of proteoglycan breakdown by chymopapain. By six months the CT of those patients whose symptoms had improved showed that the degree of disc prolapse was usually less marked and the disc margin more clearly defined, suggesting that by this stage anatomical remodelling had occurred.

Post-chymopapain (chemonucleolysis)--clinical and computed tomography correlation: preliminary results

Chymopapain was first used for treatment of lumbar disc herniation in 1964 and has been used extensively in Canada and Europe for the last decade, but was recently released for general use in the United States. The enzyme is thought to cause decrease in intradiscal pressure and in disc volume; however, little in vivo evidence exists to support this concept. High resolution computed tomography (CT) scans were performed for diagnosis and at a variable period following chemonucleolysis on 17 randomly selected patients. The results of the study were: disc space narrowing occurred almost invariably; retraction of the prolapsed or extruded disc occurred in many patients; clinical improvement was closely related to retraction of the prolapsed or extruded disc; the best clinical results were obtained in patients who were injected at a single level with a clearly demonstrable disc prolapse or herniation.

Multiple cerebral hemorrhages following chymopapain chemonucleolysis. Case report

A case of multiple cerebral hemorrhages following chymopapain chemonucleolysis is reported. The authors believe the probable etiology was intrathecal extravasation of chymopapain after injection of the drug into a lumbar disc space.

Chymopapain

Chymopapain is a proteolytic enzyme injected intradiscally for the treatment of herniated lumbar discs. The average success rate is 73 percent for elimination of backache and sciatica. Side effects occur in three percent of patients, the most serious being anaphylaxis in about one percent. A majority of patients experience severe back pain or spasms during the first 24-48 hours after treatment. This treatment modality consumes fewer hospital days and produces a quicker return to work than does surgery. It does not affect subsequent surgical procedures adversely. Chymopapain chemonucleolysis is safe and effective when administered by experienced physicians and when adequate precautions are taken. It can be considered the last step before surgery in the conservative management of herniated lumbar discs.

Etiological theories and treatments for chronic back pain. I. Somatic models and interventions

This is the first part of an extended review of the etiology and treatment of chronic back pain (CBP). This paper will address the pathophysiology of CBP, the somatic conceptualizations that have been developed, and the treatment modalities that have been employed to alleviate the symptoms. The adequacy of the different models and treatments will be critically examined. The second paper in this set will examine psychological models and interventions. Common problems to both somatic and psychological approaches will be discussed at the close of the second paper.

Animal studies and clinical trials of chymodiactin® (chymopapain)

The comparative toxicology studies using chymopapain (Discase®) versus the refined form of chymopapain (Chymodiactin®) are summarized, along with the double-blind clinical studies leading to the release of Chymodiactin®.

Increased glycosaminoglycan excretion after chymopapain injection of intervertebral discs

The urinary excretion of glycosaminoglycans during the 24 hours after intradiscal injection of chymopapain was found to be greater than during the 24 hours before injection when comparison was made either on the basis of a complete 24-hour urine collection or by the use of a glycosaminoglycan/creatinine ratio. Each individual in a group of 14 patients showed this increase after injection. In contrast, no significant increase over the pre-injection levels was detected in serum glycosaminoglycans during the post-injection time periods for which blood samples were available.

High resolution computed tomography in the diagnosis of laterally herniated lumbar discs

Fourteen patients presenting with lumbar radiculopathy had normal or nondiagnostic plain radiographs, myelograms and polytomes of lumbar spine. The high resolution computed axial tomography (HR CAT) demonstrated laterally herniated discs in all cases. The CAT findings correlated well with the clinical presentations and were proven at surgery to be the cause of lumbar nerve entrapment. The preoperative accurate localization of the lesion resulted in complete postoperative relief of lumbar radiculopathy and back pain in 12 cases with two cases, though relieved of the radiculopathy, had residual mild nondisabling low back pain. In cases presenting with sciatica and having nondiagnostic myelograms and other conventional radiological studies, HR CAT of spine is the only reliable radiological test that can be used to rule out laterally herniated lumbar discs.