Sleep in rheumatic diseases and other painful conditions

Difference between subjects in early chronic phase of low back pain with and without neuropathic component: observational cross-sectional study

BACKGROUND

Neuropathic pain in early chronic low back pain is insufficiently recognized and treated.

AIM

The aim of this study was to establish if there is a difference among chronic low back pain subjects with and without neuropathic pain and healthy subjects, in clinical characteristic and the level of trunk muscle activation.

DESIGN

Cross sectional observational study.

SETTING

Rehabilitation clinic, inpatient and outpatient.

POPULATION

Thirty-three subjects in early chronic phase of low back pain and 26 healthy subjects were included in this research.

METHODS

Clinical characteristics and relative thickness change of lumbar multifidus and transversal abdominal muscle, measured by ultrasound, in neuropathic, non-neuropathic chronic low back pain and healthy subjects were analyzed.

RESULTS

Chronic low back pain subjects with neuropathic pain reported higher level of pain on Visual Analog Scale (VAS) (back pain P=0.016, leg pain P=0.006), had higher Oswestry Disability Score (P=0.029), had lower motor (P=0.001) and sensory leg scores (P=0.000), and decreased level of activation of transversal abdominal muscle (P=0.000) comparing to chronic low back pain group without neuropathic pain. Low back pain subjects with leg pain ≥5 on VAS were 11.2 times more prone to develop neuropathic pain. Motor leg score ≤47 increases this chance 35 times. Sensory leg score ≤25 increases this chance 14 times. Reduced activation of transversal abdominal muscle for 40-50% increases this chance 7-24 times.

CONCLUSIONS

Chronic low back pain subjects with neuropathic pain were more painful and disabled, had lower motor and sensory scores, and lower relative thickness change of transversal abdominal muscle comparing to the low back pain group without neuropathic pain. Self -reported leg pain intensity of 5 or more on VAS, motor score of 47 and less, sensory scores of 25 and less and diminished activation of transversal abdominal muscle significantly increase the chance that chronic low back pain subject has neuropathic component of pain.

CLINICAL REHABILITATION IMPACT

Neuropathic pain in early chronic low back pain subjects might be more readily recognized if patients with radiculopathy and diminished activation of transversal abdominal muscle were regularly screened for neuropathic pain.

Rethinking chronic pain in a primary care setting

Chronic pain substantially impacts patient function and quality of life and is a burden to society at large in terms of increased health care utilization and loss of productivity. As a result, there is an increasing recognition of chronic pain as a public health crisis. However, there remains wide variability in clinical practices related to the prevention, assessment, and treatment of chronic pain. Certain fundamental aspects of chronic pain are often neglected including the contribution of the psychological, social, and contextual factors associated with chronic pain. Also commonly overlooked is the importance of understanding the likely neurobiological mechanism(s) of the presenting pain and how they can guide treatment selection. Finally, physicians may not recognize the value of using electronic medical records to systematically capture data on pain and its impact on mood, function, and sleep. Such data can be used to monitor onset and maintenance of treatments effects at the patient level and evaluate costs at the systems level. In this review we explain how these factors play a critical role in the development of a coordinated, evidence-based treatment approach tailored to meet specific needs of the patient. We also discuss some practical approaches and techniques that can be implemented by clinicians in order to enhance the assessment and management of individuals with chronic pain in primary care settings.

Structural brain correlates of human sleep oscillations

Sleep is strongly conserved within species, yet marked and perplexing inter-individual differences in sleep physiology are observed. Combining EEG sleep recordings and high-resolution structural brain imaging, here we demonstrate that the morphology of the human brain offers one explanatory factor of such inter-individual variability. Gray matter volume in interoceptive and exteroceptive cortices correlated with the expression of slower NREM sleep spindle frequencies, supporting their proposed role in sleep protection against conscious perception. Conversely, and consistent with an involvement in declarative memory processing, gray matter volume in bilateral hippocampus was associated with faster NREM sleep spindle frequencies. In contrast to spindles, gray matter volume in the homeostatic sleep-regulating center of the basal forebrain/hypothalamus, together with the medial prefrontal cortex, accounted for individual differences in NREM slow wave oscillations. Together, such findings indicate that the qualitative and quantitative expression of human sleep physiology is significantly related to anatomically specific differences in macroscopic brain structure.

What characterizes persons who do not report musculoskeletal pain? Results from a 4-year Population-based longitudinal study (the Epifund study)

OBJECTIVE

To identify and characterize persons in the population who do not report musculoskeletal pain.

METHODS

This was a population-based 4-year prospective longitudinal study by postal questionnaire. Population sample recruited from general practice registers in North-West England followed up at 15 months and 4 years.

RESULTS

Of respondents, 17.4% [95% confidence interval (CI) 16.1%-19.7%] reported no pain in the previous month at all 3 measurement intervals over 4 years. They were characterized by low levels of psychological distress [relative risk (RR) low vs high levels of psychological distress 2.3; 95% CI 1.7-2.9], low levels of depression (2.7; 95% CI 2.0-3.6), low levels of anxiety (2.1; 95% CI 1.6-2.7), low health anxiety (1.6; 95% CI 1.2-2.1), and low illness behavior scores (5.8; 95% CI 4.0-8.3), good quality sleep (3.4; 95% CI 2.6-4.4), no somatic symptoms (RR 0 vs 3 or more, 3.1; 95% CI 1.6-6.3) and no adverse life events in the 6 months prior to baseline data collection (RR 0 vs 3 or more, 3.2; 95% CI 1.6-6.2). On multivariable analysis, good quality sleep, low illness behavior, low psychological distress, and absence of recent adverse life events remained statistically independent predictors of musculoskeletal health. In total, 46% of persons who had all 4 of these characteristics consistently reported being free of pain, compared to only 5% of those who had none.

CONCLUSION

In a general population sample, over a period of 4 years, only around 1 in 6 persons do not report musculoskeletal pain. These persons report low levels of psychological distress and high quality sleep, both of which are potentially modifiable risk factors for the targeting of interventional or preventive strategies.