M. I. V. Jayson

Nerve ingrowth into diseased intervertebral disc in chronic back pain

BACKGROUND In the healthy back only the outer third of the annulus fibrosus of the intervertebral disc is innervated. Nerve ingrowth deeper into diseased intervertebral disc has been reported, but how common this feature is and whether it is associated with chronic pain are unknown. We examined nerve growth into the intervertebral disc in the pathogenesis of chronic low back pain. METHODS We collected 46 samples of intervertebral discs from 38 patients during spinal fusion for chronic back pain. 30 samples were from pain levels clinically established by discography and 16 samples were from adjacent vertebral levels with no pain. We obtained 34 control samples of intervertebral disc from previously healthy individuals with normal histology within 8 h of recorded death. We used standard immunohistochemical techniques to test for a general nerve marker, a nociceptive neurotransmitter (substance P), and a protein expressed during axonogenesis (growth-associated protein 43 [GAP43]). FINDINGS We identified nerve fibres in the outer third of the annulus fibrosus in 48 (60%) of the 80 samples of intervertebral discs. Nerves were restricted to the outer or middle third of the annulus fibrosus in the 34 control samples. Among the patients with chronic low back pain, nerves extended into the inner third of the annulus fibrosus and into the nucleus pulposus in 21 (46%) and ten (22%) samples, respectively. Nerves usually accompanied blood vessels, but in 14 of the samples from back-pain patients, isolated nerve fibres were seen in the discal matrix. Both types of nerve fibres expressed substance P, but only non-vessel-associated fibres expressed GAP43. Deep nerve ingrowth into the inner third of the annulus fibrosus, the nucleus pulposus, or both was seen in four (25%) of 16 biopsy samples from non-pain levels and in 17 (57%) samples from pain levels. Of the 16 paired samples from both pain and non-pain levels, five pain-level samples and one non-pain-level sample showed deep nerve ingrowth. INTERPRETATION Our finding of isolated nerve fibres that express substance P deep within diseased intervertebral discs and their association with pain suggests an important role for nerve growth into the intervertebral disc in the pathogenesis of chronic low back pain.

Predicting who develops chronic low back pain in primary care: a prospective study.

Abstract Objectives: To quantify the relative contribution of premorbid and episode specific factors in determining the long term persistence of disabling symptoms of low back pain. Design:Prospective cohort study. Setting: Two general practices in the south Manchester area. Participants: 180 patients, who previously participated in a cross sectional population survey, who consulted because of low back pain during the study period. They were followed at 1 week and 3 and 12 months after consultation. Main outcome measure: Persistent disabling low back pain in the 12 months after the consultation. Results: Disabling low back pain persisted in one third of participants after consultation and was more common with increasing age, among those with a history of low back pain, and in women. Persistence of symptoms was associated with “premorbid” factors (high levels of psychological distress (odds ratio 3.3; 95% confidence interval 1.5 to 7.2), poor self rated health (3.6; 1.9 to 6.8), low levels of physical activity (2.8; 1.4 to 5.6), smoking (2.1; 1.0 to 4.3), dissatisfaction with employment (2.4; 1.3 to 4.5)) and factors related to the episode of low back pain (duration of symptoms, pain radiating to the leg (2.6; 1.3 to 5.1), widespread pain (6.4; 2.7 to 15), and restriction in spinal mobility). A multivariate model based on six factors identified groups whose likelihood of persistent symptoms ranged from 6% to 70%. Conclusions: The presence of persistent low back pain is determined not only by clinical factors associated with pain but also by the premorbid state

Risk factors for neck pain: a longitudinal study in the general population

&NA; The objective of the study was to examine the 1‐year cumulative incidence of episodic neck pain and to explore its associations with individual risk factors, including a history of previous neck injury. A baseline cross‐sectional survey of an adult general population sample made up of all 7669 adults aged 18–75 years, registered with two family practices in South Manchester, United Kingdom, identified the study population of adults with no current neck pain. This study population was surveyed again 12 months later to identify all those who had experienced neck pain during the follow‐up period. At follow‐up, cumulative 1‐year episode incidence of neck pain was estimated at 17.9% (95% confidence interval 16.0–19.7%). Incidence was independent of age, but was more common in women. A history of previous neck injury at baseline was a significant risk factor for subsequent neck pain in the follow‐up year (risk ratio 1.7, 95% confidence interval 1.2–2.5), independent of gender and psychological status. Other independent baseline risk factors for subsequent neck pain included number of children, poor self‐assessed health, poor psychological status and a past history of low back pain. We have carried out a prospective study in a general population sample and demonstrated that established risk factors for chronic pain predict future episodes of neck pain, and shown that in addition a history of neck injury is an independent and distinct risk factor. This finding may have major public health and medicolegal implications.

Estimating the prevalence of low back pain in the general population. Evidence from the South Manchester Back Pain Survey.

Study Design This report gives the results of a population-based cross-sectional mailed questionnaire, with prospective follow-up of survey responders and nonresponders. Objective To determine the 1-month period prevalence of low back pain in an adult population in the United Kingdom and to estimate the effect of nonresponse bias. Summary of Background Data Previous United Kingdom population studies have reported a 1-year period prevalence of low back pain of 37%. However, the definitions of low back pain have varied, and the influence of nonresponse rarely has been reported. Methods The study population was made up of all 7669 adults (18 to 75 years old) registered with two family practices in a sociodemographically mixed suburban area. The questionnaire, including a pain drawing to identify the site of any pain, was mailed to the entire study population. Two repeat mailings were sent to nonresponders. Family practice consultations about low back pain by individuals from the study population were monitored over the following 12 months using computerized records of all surgery contacts. Results Of the study population, 4501 (59%) responded. The 1-month period prevalence of low back pain was 39% (35% in males, 42% in females). The age distribution was unimodal, with peak prevalence in those aged 45 to 59 years old. Responders to the first mailing had a small but nonsignificant increase in prevalence compared with those who responded to the second or third mailing. Nonresponders had a subsequent consultation rate for low back pain that was 22% lower than that for the survey responders. Conclusions After considering potential differences in nonresponders, the estimated 1-month prevalence of low back pain was between 35% and 37%. Prevalence figures in survey responders may overestimate the true population prevalence by a modest amount.

Psychologic distress and low back pain. Evidence from a prospective study in the general population.

Study Design The present is a prospective population-based cohort study. Objectives To determine whether psychologic distress in patients free of low back pain predicts future new episodes of such pain. Summary of Background Data An association between symptoms of depression and anxiety and low back pain has been described in cross-sectional studies. It is unclear whether this represents cause or effect or whether it is found only in chronic pain sufferers attending specialist clinics. There is a need to investigate this prospectively in the general population. Methods The study population was 4501 adults aged 18–75 years who responded to a questionnaire survey mailed to all those registered with two family practices in the United Kingdom. The survey inquired about low back pain during the previous month and included the 12-item General Health Questionnaire, a validated schedule for measuring psychologic distress in the general population. New episodes of low back pain during the 12 months after the survey were identified by two methods-continuous monitoring of all primary care consulters and a second postal survey at the end of the 12-month period to determine occurrences for which consultation had not been sought. Results Among 1638 subjects free of current low back pain in the baseline survey, the likelihood of developing a new episode of nonconsulting low back pain was higher among those with General Health Questionnaire scores in the upper third of the range compared with the lower third (adjusted odds ratio, 1.8[1.4, 2.4]). This could not be explained either by age and gender differences or by general physical health. The increased risk persisted when analysis was restricted to those who at baseline could not recall ever having had low back pain in the past and to those with full-time employment. Conclusion Symptoms of psychologic distress in individuals without back pain predict the subsequent onset of new episodes of low back pain. We calculate from these data that the proportion of new episodes of low back pain that might be attributable to such psychologic factors in the general population is 16%.

Psychosocial factors in the workplace--do they predict new episodes of low back pain? Evidence from the South Manchester Back Pain Study.

Study Design. A prospective, population‐based cohort study of working adults. Objectives. To determine whether work‐related psychosocial factors and social status predict the occurrence of new episodes of low back pain and influence consultation behavior. Summary and Background Data. Dissatisfaction with work and social status has been associated with low back pain in several studies; few of these studies have been prospective or population based. Methods. An initial postal survey was returned by 4,501 (59%) adults (18‐75 years old) registered with two primary care practices. From this, a cohort of 1,412 people currently in employment and free of low back pain was identified, and baseline information on work‐related psychosocial factors and psychologic distress was obtained. Social class was derived from current occupation using a standardized classification. New episodes of low back pain occurring in the next 12 months were identified by continuous monitoring of primary care consulters and by mailing a second questionnaire a year later to identify occurrences of low back pain for which no consultation was sought. Results. The baseline cross‐sectional survey showed modest but significant associations between low back pain and perceived inadequacy of income (risk ratio 1.3), dissatisfaction with work (risk ratio 1.4) and social class IV/V (risk ratio 1.2). In the follow‐up year, the risk of reporting low back pain for which no consultation was sought doubled in those dissatisfied with their work. Both perceived inadequacy of income (odds ratio 3.6) and social class IV/V (odds ratio 4.8) were strongly associated with consulting with a new episode of low back pain during the follow‐up year, an association more marked in women. The associations with work dissatisfaction and perceived adequacy of income were not explained by general psychologic distress or social status. Conclusion. People dissatisfied with work are more likely to report low back pain for which they do not consult a physician, whereas lower social status and perceived inadequacy of income are independent risks for working people to seek consultation because of low back pain.

Development and validation of a questionnaire to assess disabling foot pain

Abstract This study outlines the design and validation of a new self‐administered instrument for assessing foot pain and disability. The 19‐item questionnaire was tested on 45 rheumatology patients, 33 patients who had attended their general practitioner with a foot‐related problem and 1000 responders to a population survey of foot disorders. Levels of reported disability were found to be greatest for rheumatology patients and least for community subjects. In addition, the instrument was able to detect differences in disability levels reported by community subjects who did and did not consult with a health care professional and those who did and did not have a history of past and current foot pain. A good level of agreement was found when items on the questionnaire were compared with similar items on the ambulation sub‐scale of the Functional Limitation Profile questionnaire. A Cronbachs alpha value of 0.99 and item‐total correlation values between 0.25 and 0.62 confirmed the internal consistency of the instrument. Finally the results of a principal components analysis identified three constructs that reflected disabilities that are associated with foot pain: functional limitation, pain intensity and personal appearance. The design of the foot disability questionnaire makes it a suitable instrument for assessing the impact of painful foot conditions in both community and clinical populations.

The grading of hallux valgus. The Manchester Scale.

This article describes a new, noninvasive method of assessing the severity of hallux valgus deformity by means of a set of standardized photographs. Six podiatrists were independently asked to grade the level of deformity of 13 subjects (26 feet) on a scale of 1 (no deformity) to 4 (severe deformity). The reliability of the four-point scale for the severity of hallux valgus was investigated by means of kappa-type statistics for more than two raters. The results showed that the grading method had excellent interobserver repeatability with a combined kappa-type statistic of 0.86, making it a suitable instrument for clinical and research purposes.

Influence of previous pain experience on the episode incidence of low back pain: results from the South Manchester Back Pain Study.

Background: A pathological cause cannot be identified for most new episodes of low back pain (LBP) presenting to the general practitioner. One important potential influence on susceptibility is previous pain experience. To accurately investigate the contribution of this phenomenon to the onset of new episodes of LBP a prospective population study is required. Aims: To determine the relationship of prior pain in the back and other musculoskeletal sites to risk of subsequent new episodes of LBP. Methods: The population studied included all 2715 adults from the South Manchester Back Pain Study who were free of LBP during the month prior to the baseline survey. At baseline a detailed musculoskeletal pain history was obtained. New episodes of LBP over the subsequent 12 months were ascertained by: (i) prospectively monitoring all primary care consultations in the study cohort (consulting episodes) and (ii) a follow‐up survey after 1 year to determine new episodes during that 12‐month period not leading to consultation (non‐consulting episodes). Results: The 12‐month cumulative incidence of new consulting episodes was 3% in males and 5% in females, and for new non‐consulting episodes 31% in males and 32% in females. Those with a history of previous LBP had twice the rate of new episodes, both consulting and non‐consulting, compared to those with no LBP in the past. Neck pain or pain in other musculoskeletal sites at baseline also doubled the risk of a subsequent new episode of LBP. Adjusting for psychological distress and the other pain variables had little influence on the findings. Conclusion: In those currently free of LBP a previous history of the symptom substantially increases the risk of a further episode, with pain in other sites an equally strong independent predictor of subsequent LBP.

Intervertebral foramen venous obstruction. A cause of periradicular fibrosis

Disc herniation into the intervertebral foramen (IVF) or osteophytic outgrowths from the margins of the apophyseal joints that project into the IVF may compress the neural structures, but in this cadaveric study of 160 lumbar foramens (age range, 35–91 years), the authors have found that they were much more commonly associated with compression and distortion of the large venous plexus within the IVF. In the absence of direct nerve compression (seen in only eight specimens), the most severe neural changes were associated with compression, congestion, and resultant dilatation of foraminal veins. Pathologic changes within and around the nerve root complex included peri- and intraneural fibrosis, edema of nerve roots, and focal demyelination. Inflammatory cells were notably absent. Vascular changes within the thickened fibrous sheath about damaged nerves, namely, basement membrane thickening, suggestive of endothelial cell injury also were observed. The association between vascular compression, tissue fibrosis, and endothelial injury distant from the compression may be causal—probably due to ischemia as a result of reduced venous outflow. Such observations have led the authors to propose that venous obstruction may be an important pathogenic mechanism in the development of perineural and intraneural fibrosis.