Per Wessberg

2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group.

Study Design. A randomized controlled multicenter study with a 2-year follow-up by an independent observer. Objectives. To determine whether fusion of the lower lumbar spine could reduce pain and diminish disability more effectively when compared with nonsurgical treatment in patients with severe chronic low back pain (CLBP). Summary of Background Data. The reported results after fusion surgery on patients with CLBP vary considerably, and the evidence of treatment efficacy is weak in the absence of randomized controlled studies. Patients and Methods. A total of 294 patients referred to 19 spinal centers from 1992 through 1998 were randomized blindly into four treatment groups. Patients aged 25–65 years with CLBP for at least 2 years and with radiologic evidence of disc degeneration at L4–L5, L5-S1, or both were eligible to participate in the study. The surgical group (n=222) included three different fusion techniques, not analyzed separately in this study. Patients in the nonsurgical group (n=72) were treated with different kinds of physical therapy. The surgical group comprised 49.5% men, and the mean age was 43 years. The corresponding figures for the nonsurgical group were 48.6% and 44 years. The patients had suffered from low back pain for a mean of 7.8 and 8.5 years and been on sick leave due to back pain for a mean of 3.2 and 2.9 years, respectively. The Visual Analogue Scale (VAS) was used to measure pain. The Oswestry Low Back Pain Questionnaire, the Million Score and the General Function Score (GFS) were used to measure disability. The Zung Depression Scale was used to measure depressive symptoms. The overall result was assessed by the patient and by an independent observer. Records from the Swedish Social Insurance were used to evaluate work disability. Patients who changed groups were included in the analyses of significance according to the intention-to-treat principle. Results. At the 2-year follow-up 289 of 294 (98%) patients, including 25 who had changed groups, were examined. Back pain was reduced in the surgical group by 33% (64 to 43), compared with 7% (63 to 58) in the nonsurgical group (P =0.0002). Pain improved most during the first 6 months and then gradually deteriorated. Disability according to Oswestry was reduced by 25% (47 to 36) compared with 6% (48 to 46) among nonsurgical patients (P =0.015), according to Million by 28% (64 to 46) compared with 8% (66 to 60) (P =0.004), and accordingtoGFS by 31% (49 to 34) compared with 4% (48 to 46) (P =0.005). The depressive symptoms, according to Zung, were reduced by 20% (39 to 31) in the surgical group compared with 7% (39 to 36) in the nonsurgical group (P =0.123). In the surgical group 63% (122/195) rated themselves as “much better” or “better” compared with 29% (18/62) in the nonsurgical group (P <0.0001). The “net back to work rate” was significantly in favor of surgical treatment, or 36% vs. 13% (P =0.002). The early complication rate in the surgical group was 17%. Conclusion. Lumbar fusion in a well-informed and selected group of patients with severe CLBP can diminish pain and decrease disability more efficiently than commonly used nonsurgical treatment.

Chronic low back pain and fusion: a comparison of three surgical techniques: a prospective multicenter randomized study from the Swedish lumbar spine study group.

Study Design. A multicenter randomized study with a 2-year follow-up period and an independent observer was conducted. Objective. To compare three commonly used surgical techniques to achieve lumbar fusion primarily in terms of their ability to reduce pain and decrease disability in patients with severe chronic low back pain. Summary of Background Data. Lumbar fusion can be used to reduce pain and decrease disability in patients with chronic low back pain, and different surgical techniques are available. The reported results after fusion surgery vary considerably, but most studies are retrospective and/or performed on heterogeneous patient groups. Spine surgeons commonly use the techniques presented in this report. However, in the absence of randomized trials it is difficult to know whether any one of them is better than the others for these patients. Methods. From 1992 through 1998, 294 patients referred to 19 spinal centers were blindly randomized into four treatment groups: three surgical groups (n = 222) and one nonsurgical group (n = 72). The sociodemographic and clinical characteristics did not differ among the groups. Eligibility included patients 25 to 65 years of age with therapy-resistant chronic low back pain that had persisted for at least 2 years and radiologic evidence of disc degeneration (spondylosis) at L4–L5, L5–S1, or both. Only patients randomized to one of three surgical groups were analyzed in the current study: Group 1 (posterolateral fusion; n = 73), Group 2 (posterolateral fusion combined with variable screw placement, an internal fixation device; n = 74), and Group 3 (posterolateral fusion combined with variable screw placement and interbody fusion; n = 75). The “circumferential fusion” in Group 3 was performed either as an anterior lumbar interbody fusion (n = 56) or as a biomechanically similar posterior lumbar interbody fusion (n = 19). The groups were composed of 51%, 58%, and 40% men respectively, and the respective mean ages were 44, 43, and 42 years. The patients had experienced low back pain for at least 2 years (mean, ≈8 years). They had been on sick leave for approximately 3 years. Pain was measured by a visual analog scale, and disability was assessed by the Oswestry Low Back Pain Questionnaire, the Million Visual Analogue Score, and the General Function Score. Depressive symptoms were measured by the Zung Depression Scale. The global overall rating of the result was assessed by the patient and an independent observer after 2 years. Hospitalization data including operation time, blood loss, blood transfusion, and days of hospitalization in connection with surgery were reported, along with complications and the fusion rate. Records from the Swedish Social Insurance Board providing information on sick leave and economic compensation for Swedish residents were used to evaluate the patients’ work status. Results. An independent observer examined 201 (91%) of 222 patients after 2 years, after 18 “group changers” and 3 dropouts had been excluded from the analyses. All surgical techniques were found to reduce pain and decrease disability substantially, but no significant differences were found among the groups. In all three groups, the patients rated the overall outcome similarly, as did the independent observer. The more demanding techniques in Groups 2 and 3 consumed significantly more resources in terms of operation time, blood transfusions, and days in hospital after surgery. The early complication rate was 6% in Group 1, 16% in Group 2, and 31% in Group 3. The fusion rate, as evaluated by plain radiograph, was 72% in Group 1, 87% in Group 2, and 91% in Group 3. Conclusions. All the fusion techniques used in the study could reduce pain and improve function in this selected group of patients with severe chronic low back pain. There was no obvious disadvantage in using the least demanding surgical technique of posterolateral fusion without internal fixation.

Muscular and kinematic behavior of the lumbar spine during flexion-extension

Reduction in lumbar muscular activity at full body flexion, known as flexion relaxation, has been studied in relation to overall trunk, lumbar spine, and hip flexion, but has not been evaluated in conjunction with motion on the segmental level. In this study, intervertebral motion in a lumbar motion segment, trunk flexion, and the electromyographic activity in the lumbar erector spinae muscles were simultaneously measured during dynamic flexion-extension in seven patients with chronic low back pain with symptoms suggesting segmental instability and in six asymptomatic controls. A linkage system, which attached directly to the spinous processes of a lumbar motion segment, was used to continuously measure the sagittal plane intervertebral motion, while a potentiometric goniometer measured trunk flexion; myoelectric activity was measured using surface electrodes. It was found that intervertebral motions, as well as trunk mobility, were significantly less in the patients, both in terms of range and pattern of motion. Flexion relaxation was demonstrated in the controls by a 78% decrease in myoelectric activity at full flexion, whereas in the patients, only a 13% reduction was found, with most of the patients experiencing no reduction at all. Flexion relaxation occurred only in subjects in whom intervertebral rotation had reached a stage of completion considerably before full trunk flexion was achieved. These findings suggest that persistent muscle activation, which restricts intervertebral motion, is a means by which the neuromuscular system provides stability to help protect diseased passive spinal structures from movements that may cause pain.

Regulation of breathing in the rat: Indications for a role of central adenosine mechanisms

Abstract The adenosine agonist N 6 -phenylisopropyladenosite e (PIA) was given intracerebroventricularly to halothane-anesthetized rats. Administration of 10 μg PIA caused a decrease in pulmonary ventilation due to effects on both respiratory frequency as well as tidal volume. The respiratory depression was accompanied by bradycardia and hypotension. The data indicate that central adenosine mechanisms might be involved in respiratory and circulatory regulation.

Adenosine mechanisms in the regulation of breathing in the rat

The central respiratory effects of various adenosine (A) analogues were studied in halothane-anesthetized rats. Intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) injections of the A analogues (2-Cla, L-PIA, CHA and NECA) reduced minute ventilation (VE) due to decreases in respiratory frequency (f) as well as tidal volume (VT). Dose-dependent effects were seen after i.c.v. L-PIA in both normal and vagotomized rats. Analysis of the A-induced changes using the occluded breath technique revealed an increase in expiratory time (TE) as well as a decrease in inspiratory drive. NECA, a relatively specific A2 agonist seemed to be somewhat more potent in eliciting respiratory depression than a relatively specific A1 agonist like L-PIA. Pretreatment with the methylxanthine theophylline completely antagonized the respiratory depression induced by L-PIA. It is concluded that central A receptors are involved in the central regulation of breathing and that A interacts with the respiratory control system mainly by decreasing inspiratory neural drive and prolonging expiratory time.

Comparison of Cobb angles in idiopathic scoliosis on standing radiographs and supine axially loaded MRI

Study Design. Prospective, patient controlled. Objective. To compare Cobb angles in idiopathic scoliosis between standing radiographs and a nonradiographic procedure. Summary of Background Data. Repeated radiographic examinations at young age may increase the risk for breast cancer in adulthood. MRI images the spine satisfactorily but is cumbersome in standing. A harness supplying axial load to a lying subject simulates the standing radiograph appearance of the lumbar spine. Methods. Thirty patients with idiopathic scoliosis greater than 20° performed a routine posteroanterior and lateral standing thoracolumbar spine radiograph and an MRI in supine position without and with axial loading. Results. Mean Cobb angle for the major curve was 31° on standing radiographs, 23° on nonloaded supine MRI, and 31° on supine loaded MRI. Axially loaded, compared with nonloaded, MRI increased the Cobb angle by 8°. The mean difference between standing radiograph and supine axially loaded MRI was 0°, with an intermethodologic variation(s) of 3.4°. Radiographic and MRI (axially loaded) Cobb angles correlated positively (r = 0.78). Conclusions. Axial loading on supine MRI produces coronal Cobb angles similar to standing radiographs. This is a way to acquire reliable Cobb angles without radiation in the monitoring of idiopathic scoliosis.

Preoperative Fibrinogen Plasma Concentration Is Associated With Perioperative Bleeding and Transfusion Requirements in Scoliosis Surgery

Study Design. Prospective observational study. Objective. To investigate the potential association between fibrinogen, bleeding, and transfusion requirements after scoliosis surgery. Summary of Background Data. Bleeding complications during and after orthopedic surgery are associated with increased morbidity and mortality. Early identification of patients with increased risk of excessive bleeding offers the possibility to initiate countermeasures. Fibrinogen is a key protein in the coagulation cascade, and thus a potential biomarker for bleeding risk. Methods. A total of 82 otherwise healthy patients (mean age: 15 ± 3 years, 85% girls) undergoing surgery for adolescent idiopathic scoliosis were included in the study. Patient variables (age, gender, operation time, and thrombosis prophylaxis), preoperative laboratory variables (hemoglobin, platelet count, activated partial thromboplastin time [aPTT], prothrombin time [PT], and fibrinogen), peroperative and postoperative bleeding volume, and transfusions were registered. Correlations between laboratory variables and bleeding volume were calculated with Pearson test. Patient variables and laboratory variables were compared with Student t test between patients with bleeding volume in the upper quartile (“bleeders”) and the remaining patients, and between patients with extensive transfusion (defined as >2 U of packed red cells) and no or limited transfusions (⩽2 U). Results. Mean fibrinogen concentration was 3.0 ± 0.7 g/L (range, 1.3– 4.9). Mean total perioperative bleeding volume was 1552 ± 1019 mL (range, 100–5800 mL). Total bleeding volume correlated significantly with preoperative fibrinogen concentration (r = −0.31, P = 0.005) but neither with platelet count, aPTT, nor PT (P = 0.61, 0.46, and 0.57, respectively). Bleeders had significantly lower preoperative fibrinogen plasma concentration (2.6 ± 0.6 vs. 3.1 ± 0.6 g/L, P = 0.002). Of total, 16% (13/82) of the patients were transfused with >2 U of packed red cells. Patients with extensive transfusions had significantly lower preoperative fibrinogen plasma concentration (2.5 ± 0.7 vs. 3.1 ± 0.6 g/L, P = 0.002), while preoperative platelet count, aPTT, and PT did not differ. Conclusion. The results indicate that preoperative fibrinogen concentration is a limiting factor for postoperative hemostasis during and after scoliosis surgery. Preoperative measurement of fibrinogen concentration provides more information about bleeding volume and transfusion requirements than standard screening tests.

Surgical results in hidden lumbar spinal stenosis detected by axial loaded computed tomography and magnetic resonance imaging: an outcome study.

Study Design. An outcome study of patients with neurogenic claudication and/or sciatica with hidden stenosis, detected only by axial loading of the lumbar spine (ACE) but not at the traditional unloaded examination (psoas relaxed position) during computed tomography (CT) myelography or magnetic resonance imaging (MRI), followed up after surgery. Objective. To estimate the clinical effect of decompression with or without fusion in patients with hidden stenosis in the lumbar spine. Summary of Background Data. A number of patients with neurogenic claudicatio with or without sciatica do not have corresponding imaging abnormalities. Axial loaded CT and MRI have disclosed hidden stenosis in certain cases. The surgical effect in patients with hidden stenosis has never been described. Methods and Materials. Axial loading of the lumbar spine during CT and MRI was performed in 250 patients with neurogenic claudication and sciatica. All fulfilled the inclusion criteria for ACE, i.e., suspected but not verified spinal stenosis in 1 to 3 levels. In 125 patients (50%), a significant narrowing of the spinal canal occurred. Out of these 125 patients, 101 had a clear stenosis besides the stenosis only detected at ACE. In 24 patients, a hidden stenosis was detected in 1 to 3 levels only at the ACE. These patients were observed for 1 to 6 years after decompression with or without fusion regarding subjective improvement of leg and back pains, walking capacity, satisfaction, and health related quality of life. Results. At follow-up, 76% of the patients had leg pain less than 25/100 on a VAS scale and 62% had back pain less than 25/100. Ninety-six percent were improved or much improved regarding leg and back pains The ability to walk increased significantly after surgery. Walking capacity to more than 500 m increased from 4% to 87%. Twenty-two patients were subjectively satisfied with the surgical results. The ODI score, the SF-36 and the EQ-5D score corresponded well to the above mentioned improvements at follow-up. Conclusion. According to this study, the results of surgery in hidden lumbar stenosis only detected by axial compression in extension during CT or MRI, are convincing and comparable with the results of surgical treatment for stenoses diagnosed by unloaded examinations.

Central respiratory and cardiovascular effects in the rat of some putative neurotransmitter amino acids

SummaryRespiratory performance was studied in halothane anesthetized rats after intracerebroventricular (i.c.v.) injection of β-alanine, taurine or glycine (0.01–1 mg). The amino acids induced a marked decrease in both respiratory frequency (f) and tidal volume (VT), which was immediate and longlasting. The respiratory depressant action of glycine could readily be reversed by strychnine, a glycine antagonist. Measurement of respiratory time intervals, inspiratory time (TI), expiratory time (TE) and total cycle duration (TTOT), after administration of the putative neurotransmitter amino acids revealed that the effects on f were due to prolongation of the duration of expiration. The duration of inspiration was principally unaltered, but mean inspiratory flow (VT/TI) and respiratory timing (TI/TTOT) decreased. In experiments employing the occluded breath technique, P0.1 was reduced in the same magnitude as the mean inspiratory flow (VT/TI). The results also showed a change in central (bulbopontine) setting for TE, while the setting to TI was unaltered. An inert amino acid, valine, which was administered i.c.v. in the same doses, had no effects on respiratory parameters.Apart from the effects on basal ventilation of β-alanine, taurine and glycine, the CO2 induced respiratory response was blunted. These three amino acids also depressed heart rate and mean arterial pressure.Although relatively high doses were used to induce the respiratory effects, it may be hypothetized that the putative neurotransmitters β-alanine, taurine and glycine may have a physiological role in the central regulation of breathing.

Validity of a Computer Touch-Screen Questionnaire System in Back Patients

Study Design. Validation study. Objective. A system for patient self-recording on a computer touch-screen was developed. The validity of this method compared with the use of regular paper-and-pen questionnaires was studied. Summary of Background Data. Systematic evaluation of health problems often involves the use of self-reporting questionnaires in order to collect data on different variables. Recording of such data for subsequent analysis requires several steps including filling out of paper forms and secretarial work. Missing values and misrecordings are frequent problems. Methods. Seventy-nine patients with back problems visiting our outpatient clinic for surgical evaluation were invited to take part in the study by answering a mailed questionnaire concerning background data, pain, function, quality of life, and depressive symptoms approximately 3 weeks before their visit. At the day of the visit they were asked to again answer the same questions with a replicate response option format displayed on a computer touch-screen. Results. The agreement concerning background history questions, measured by kappa values was generally good (0.71-1.0). For visual analogue scale recordings (0-100) of back and leg pain, the mean of the differences were 1.1 and 2.1, respectively, and the correlations (Pearson) 0.72 and 0.87. The Euro-Qol 5 Dimension Score, the General Function Score, the Zung Depression Scale and the physical dimensions of the Short Form-36 showed a high degree of agreement between paper and screen recordings with difference means close to 0 and reliabilities comparing well to published methodologic errors for paper form versions. There were, however, differences concerning the mental components of the SF-36 with somewhat higher ratings on screen recordings. Missing values were 0% for screen recordings and for paper forms, 2.3% on individual questions and 12% on composite scores. Conclusion. Computerized touch-screen questionnaires virtually eliminates missing values and show good validity and reliability compared to paper forms. The SF-36 tended to produce slightly higher values on touch-screen recordings in questions concerning mental health.