Outcome research in patients with chronic low back pain

Outcome research in chronic low-back pain is entering a new phase. In the past several years, several outcome measures have been evaluated for their psychometric properties, and databases for patients with low-back pain exist for some of them. A set of recommended and standardized outcome measures and questionnaires is now available for the different outcome domains. The use of computerized versions of these questionnaires will allow simplified data collection and analyses, which will not only help to formulate a more uniform design of research trials, but can be useful for clinicians interested in documenting multi-dimensional outcomes in their patient population.     

Corticospinal excitability in patients with chronic low back pain

OBJECTIVE: This study was designed to investigate corticospinal excitability of lumbar muscles using transcranial magnetic stimulation (TMS) in patients with chronic low back pain and correlate this with self-rated measures of disability and pain. METHODS: Twenty-four patients with chronic low back pain and 11 healthy control subjects were used in this study. TMS was delivered through an angled double-cone coil, with its cross-over on the vertex and a posterior-to-anterior current flow in the brain. Electromyographic (EMG) recordings were made from erector spinae (ES) muscles at the fourth lumbar level. Motor cortical excitability was assessed using motor threshold (MTh) for motor evoked potentials (MEPs) and threshold for silent period (SP) during facilitation of the back muscles. Latency, duration, and area of MEPs and SPs were also measured. RESULTS: The latency, duration, and size of MEPs and SPs did not differ between the left and right ES muscles in either the patients or the control subjects and also did not differ between the patients and the control subjects. However, there was a significantly higher MTh and threshold for the SP in the patients as compared with the control subjects; the full significance of this requires further investigation. Interestingly, there was a positive correlation between the self-rated measure of disability (the Oswestry Disability Index score) and both the MTh and the threshold for the SP in the patients. There was also a positive correlation between the self-rated index of back pain and the threshold for the SP in the patients. This finding of an association between clinical and neurophysiologic measures reinforces the need for further research to establish the clinical relevance of these rises in MTh and SP threshold. CONCLUSIONS: In summary, this study has revealed that corticospinal excitability, driving ES muscles close to the site of pain, is lowered in patients with chronic low back pain.     

Nerve root injuries in patients with chronic low back pain

In conclusion, the nerve roots and the DRG play an important role in the pain mechanisms of patients suffering from chronic low back pain. Signs of demyelination and increased sensitization for stimuli occurs after a direct nerve root trauma, and the plasticity for the DRG also may change the response to a given peripheral stimuli when repeated frequently over a long period of time. The regeneration mechanisms of spinal nerve roots and DRG regarding function are slow, and the final grade of recurrence depends on the degree of injury. The limited regeneration mechanisms for nerve injury and the fact that "established chronic pain centers" are hard to influence after a long pain history favor an aggressive strategy for pain management. Today, a number of treatment strategies exist for chronic low back pain patients (with or without a diagnosed nerve root injury). These strategies include physiotherapy, nonsteroid anti-inflammatory drugs (NSAIDs), steroids, analgesics of different types and administration routes, surgery, and other sorts of invasive treatments. Further knowledge about the nerve root, DRG, and the rest of the nervous system in these patients is necessary; for understanding how and when to treat patients with chronic low back pain, we need to understand more about what we are trying to treat.     

Predictive tests for non-return to work in patients with chronic low back pain

Return to work (RTW) is the primary goal in the rehabilitation of patients with chronic low back pain. In spite of expensive rehabilitative efforts, many patients do not RTW. To increase cost effectiveness, predictive tests for non-RTW are needed to select patients for rehabilitation. The reliability of these tests must be high, to prevent exclusion of patients who might improve. This study evaluates the reliability and predictive validity of four tests and the following psychosocial factors for non-RTW: nationality, off-work duration, unemployment and work load. It was designed as a prospective cohort study of 99 patients with chronic low back pain. Upon entry, physical work load, time off work, unemployment and nationality were recorded. The study investigated four tests with an anticipated prognostic value for non-RTW: the Numeric Pain Rating Scale (NRS, 9-10 of a maximum of 10), the Step Test and Pseudo Strength Test (precipitous cessation) and Behavioural Signs. After 12 months, the RTW rate was obtained from the physicians responsible for sick-listing by postal survey. The response rate regarding RTW was 91% at 1 year. The RTW rate at 1 year was 20%. All investigated tests significantly correlated with non-RTW. Regression analysis showed that the best prediction of non-RTW was obtained when at least two out of the four tests were positive (positive predictive value 0.97, sensitivity 0.45). Unemployment, time off work, nationality and physical work load were less predictive. The results show that the combination of the four prognostic tests allows a very reliable prognosis of non-RTW. The cost effectiveness of rehabilitation aiming at RTW will, therefore, be increased by excluding patients with two or more positive tests.     

Management of chronic disabling low back pain with 360 degrees fusion. Results from pain provocation test and concurrent posterior lumbar interbody fusion, posterolateral fusion, and pedicle screw instrumentation in patients with chronic disabling low back pain.

STUDY DESIGN: A follow-up study conducted by an independent observer was performed on the authors' first 29 consecutive patients treated with concurrent posterior lumbar interbody fusion, posterolateral fusion, and pedicle screw instrumentation, for whom at least 2 years had transpired since the operation. OBJECTIVE: To evaluate the results of concurrent instrumented posterior lumbar interbody fusion and posterolateral fusion used to manage chronic disabling low back pain. SUMMARY OF BACKGROUND DATA: Patients chosen for surgery all had a history of chronic disabling low back pain exceeding 2 years and a sick leave period in excess of 6 months (average, 3.4 years). METHODS: From 1989 to 1993, 29 consecutive patients were surgically treated with fusion. The level of fusion was chosen depending on radiologic changes and results from a intradiscal injection provocation test. Bone union was verified by computed tomography scan with 1-mm-thin slices and sagittal reformation, and by a "second look" in all but three patients. All patients were evaluated subsequently by an independent observer in November 1995, 4.7 years after surgery on the average. RESULTS: Bone fusion was obtained in 27 of the 29 patients (93%). There was a highly significant reduction in back and leg pain measurements. Of the 29 patients, the results were excellent in 9 patients (31%), good in 6 patients (21%), fair in 6 patients (21%), and poor in 8 patients (27%). A total of 18 patients (62%) had returned to work. CONCLUSION: The authors consider posterior lumbar interbody fusion with concurrent posterolateral fusion and pedicle screw instrumentation a possible method for managing chronic disabling low back pain.     

The association of pain with physical activities in chronic low back pain.

Most patients with chronic low back pain associate strenuous physical activities with increased pain. This association can cause avoidance of those activities believed to cause intolerable discomfort. This study explored the relationship of performance of physical activities with self-reported pain measures in 40 consecutive patients with disabling low back pain (mean duration 17 months) during a functional restoration rehabilitation program (mean treatment period 7 weeks). Evaluations were performed at initial presentation and at program completion. Measures included quantification of performance on eight physical tests assessing flexibility, lifting capacity and endurance. Before physical testing patients were asked to complete a pain analog scale, a quantified pain drawing, and a rating of the pain anticipated to result from the performance of each physical test. Results showed that pain measures did not generally correlate with measured physical performance. At completion of treatment, significant improvement in performance on all physical tests was found, but these were not associated with consistent changes in pain measures. These results demonstrate that subjects with chronic low back pain can increase their physical performance abilities within their same pain experiences. Medical recommendations for subjects' involvement in physical activities should not be based solely on the reported association of pain with those activities.     

Selective changes in multifidus dimensions in patients with chronic low back pain

Summary This study of 52 patients (27 men) with recent (18 months) or chronic (>18 months) low back and unilateral radicular pain symptoms was undertaken to investigate whether wasting of the paraspinal muscle components is generalised or selective. During the patients' routine computed tomographic lumbar spinal scans a standardised transaxial view was obtained along the upper end-plate of the L4 vertebra, and the cross-sectional areas of the paraspinal muscles and their components, multifidus and erector spinae, estimated. Irrespective of whether the symptoms were recent or chronic, multifidus dimensions were significantly greater on the side ipsilateral to the radicular pain symptoms. The results indicate selective changes of multifidus in these patients and possibly reflect an adaptive response by this muscle, such as to an increased role in stabilising the lumbar spine in the face of overall paraspinal muscle atrophy. Present address: Royal Hospital and Home, Putney, West Hill, London SW15 3SW, UK     

Significant differences of brain blood flow in patients with chronic low back pain and acute low back pain detected by brain SPECT

Background

The aim of this study was to examine and compare the areas of brain blood flow in patients with chronic low back pain (CLBP) without structural abnormality and acute low back pain (ALBP) with lumber disc herniation (LDH). Functional neuroimaging studies provide evidence of abnormalities in the regional cerebral blood flow during low back pain. Recent studies have shown that CLBP is associated with plastic, pathophysiological changes in the brain. However, there has been no report yet statistically or by neuro-images on the compared brain single photon-emission computed tomography (SPECT) findings between CLBP and ALBP patients.

Methods

The subjects comprised 14 patients, 7 CLBP and 7 ALBP patients. The CLBP group included the patients who had no or minor structural abnormality in the lumbar spine on magnetic resonance imaging (MRI) and met the criteria for a classification of “pain disorder” (chronic) according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision. The ALBP group included the patients who had symptoms within 3 months of onset and LDH revealed by MRI. All patients were assessed using brain SPECT. We then performed a two-tailed view analysis using the easy Z score imaging system, determined the mean Z scores, and performed vBSEE software (Fujifilm RI Pharma, Tokyo, Japan) for both CLBP and ALBP patients.

Results

The CLBP group showed significantly reduced blood flow in the bilateral prefrontal cortex of the frontal lobe and increased blood flow in the bilateral posterior lobe of the cerebellum.

Conclusions

SPECT images and statistical analyses revealed the brain blood flow alterations in the patients with ALBP and CLBP. These results may suggest that the dysfunction of the prefrontal cortex could lead to the appearance of unconscious pain behavior controlled by the cerebellum in the patients with CLBP.     

Characteristics affecting cervical sagittal alignment in patients with chronic low back pain

BackgroundSagittal spino-pelvic malalignment in patients with chronic low back pain (CLBP) have been reported in the past, which may also affect cervical spine lesions. The purpose of this study is to investigate the cervical alignment in patients with CLBP.MethodOf the patients who visited an orthopedic specialist due to low back pain lasting more than three months, 121 cases (average 71.5-years-old, 46 male and 75 female) with whole standing spinal screening radiographs were reviewed (CLBP group). Cervical parameters included cervical lordosis (CL), C2–C7 sagittal vertical axis (C2-7 SVA), and the T1 slope minus CL (T1S-CL). Cervical spine deformity was defined as C2-7 SVA >4 cm, CL <0°, or T1S-CL ≧20°. We compared the cervical alignment of these patients with 121 age and gender matched volunteers (control group).ResultsThe prevalence of cervical spine deformity was significantly higher in the CLBP group than in the control group (20.7% vs. 10.7%, P = 0.034). The mean CL was smaller in the CLBP group than in the control group (16.1° vs. 21.4°, P = 0.002). The mean C2-7 SVA was 17.6 mm vs. 18.7 mm in the CLBP group and in the control group, respectively (P = 0.817). The mean T1S-CL was larger in the CLBP group than in the control group (9.1° vs. 3.5°, P < 0.001). Multivariate analysis showed that people with CLBP were more likely to have cervical deformities than people without CLBP (odds ratio 2.16, 95% confidence interval 1.006 to 4.637).ConclusionsThis study results suggest that people with CLBP present with worse cervical sagittal alignment and higher prevalence of cervical spine deformities than age and gender matched volunteers with no CLBP. This means CLBP impacts cervical spine lesions negatively.Level of evidenceⅣ     

Prevalence of low back pain and factors associated with chronic disabling back pain in Japan

Purpose

This study aimed to report lifetime and 4-week low back pain (LBP) prevalence and examine factors associated with chronic LBP and back pain disability over a lifetime in a Japanese adult population.

Methods

In February 2011, 1,063,083 adults aged 20–79 years registered as internet research volunteers were randomly selected to participate in a questionnaire survey. The data from 65,496 respondents were analyzed to calculate age-standardized lifetime and 4-week prevalence. Chronic LBP and back pain disability were defined as LBP lasting for ≥3 months and a consecutive ≥4-day-long absence, respectively. Factors associated with chronic disabling back pain over a lifetime were examined by multiple logistic regression modeling.

Results

The lifetime LBP prevalence was 83 % and 4-week prevalence was 36 %; majority of the respondents had disability-free LBP. Smoking [adjusted odds ratio (aOR): 1.17; 95 % CI: 1.05, 1.30], lower educational level (aOR: 1.21; 95 % CI: 1.09, 1.34), history of disabling back pain among family members and/or significant others (aOR: 1.46; 95 % CI: 1.27, 1.67), occupational LBP (aOR: 1.34; 95 % CI: 1.16, 1.55), traffic injury (aOR: 2.81; 95 % CI: 2.07, 3.81), compensated work injury (aOR: 2.42; 95 % CI: 1.92, 3.05), radiating pain (aOR: 4.94; 95 % CI: 4.45, 5.48), low back surgery (aOR: 10.69; 95 % CI: 9.02, 12.68), and advice to rest upon back pain consultation (aOR: 3.84; 95 % CI: 3.36, 4.40) were associated with chronic disabling back pain over a lifetime.

Conclusions

LBP is common in Japan as in other industrialized countries. The association between the advice to rest and chronic disabling back pain supports recent treatment guidelines emphasizing continuation of daily activities.     

Repositioning error in low back pain. Comparing trunk repositioning error in subjects with chronic low back pain and control subjects

STUDY DESIGN: Repositioning error of the trunk was tested in 20 subjects with chronic low back pain and in 20 control subjects. The 3Space Tracker (Polhemus, Colchester, VT), a device that measures three-dimensional position in space, was used to determine the subject's trunk position. OBJECTIVES: To determine whether repositioning error is different in subjects with chronic low back pain than in control subjects. SUMMARY OF BACKGROUND DATA: Proprioception allows the body to maintain proper orientation during static and dynamic activities. In peripheral joint injuries, researchers have demonstrated a loss of some aspects of proprioception and improvement in outcome with retraining. Although the components of proprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that can be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of proprioception, repositioning error, was examined. METHODS: The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. RESULTS: No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. CONCLUSIONS: Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of proprioception was measured in an indirect manner, provides important background information on low back position sense. Further studies analyzing aspects of proprioception in subjects with low back pain are recommended.     

Clinical impact of JOABPEQ mental health scores in patients with low back pain: Analysis using the neuropathic pain screening tool painDETECT

Background

In patients with low back pain (LBP) who combine psychosocial factors with clinical findings of pain, there is a possibility that the psychosocial factors modify the pain. In the current study, we investigated the relationship between the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) mental health score and the characteristics of LBP.

Lumbar spine kinesthesia in patients with low back pain.

STUDY DESIGN: Single-group, posttest only, using a sample of convenience. OBJECTIVE: To measure the repositioning error of subjects with low back pain for lumbar sagittal movement using a simple kinesthetic test previously described. BACKGROUND: Patients with low back pain are commonly observed to have difficulty in adopting a mid or neutral position of the lumbar spine. METHODS AND MEASUREMENTS: Twenty subjects with low back pain were required to reproduce an upright neutral posture of the lumbar spine following movement into flexion in a sitting position. Trunk positioning accuracy was measured with an electromagnetic tracking device. RESULTS: The mean absolute value of the repositioning error in the sagittal plane was 2.25 degrees +/-0.88 degrees on day 1 and 2.32 degrees +/-1.62 degrees on day 2. The performance of patients with low back pain was similar to that of asymptomatic patients in a previous study, although subjects with low back pain overshot the neutral position more frequently (79%) than did nonimpaired subjects (50%). CONCLUSIONS: Subjects with low back pain may have attempted to use extra mechanoreceptive cues to compensate for some kinesthetic deficit. Nevertheless, the kinesthetic test used was not sensitive enough to detect any repositioning deficits, and reasons for this are explored.