scholarly journals Single-motor-unit discharge characteristics in lumbar multifidus muscle of acute low back pain patients

2019 ◽  
Vol 122 (4) ◽  
pp. 1373-1385 ◽  
Author(s):  
Lise R. Lothe ◽  
Tim J. L. Raven ◽  
Gunnar Sandbæk ◽  
Torsten Eken
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Motor Unit ◽  
Discharge Rate ◽  
Force Production ◽  
Low Back ◽  
Lumbar Multifidus ◽  
Acute Low Back Pain ◽  
Fine Wire ◽  
Common Drive

Acute low back pain (ALBP) causes rapid deterioration of paraspinal muscle function. The underlying neurophysiology is poorly understood. We therefore carried out this observational study in patients with ALBP to characterize motor unit (MU) activity in deep lumbar multifidus (LM) muscle and compare with our previous findings from pain-free subjects. Nine subjects (1 woman; age 26–59 yr) with ALBP duration of 1–21 days were recruited from outpatient clinics. Fine wire electromyography (EMG) electrodes were implanted bilaterally at the painful spinal level under computer tomography guidance. EMG was recorded during spontaneous sitting and standing, and during voluntary force production. Linear mixed models were utilized to test or control for the effects of a number of predefined variables. Compared with sitting, standing increased total duration of EMG activity, median MU discharge rate, interspike interval variability, and common drive measured as common drive coefficients (CDC) derived from concurrently active MU pairs. Median discharge rate in 73 MUs was 5.5 and 6.6 pulses per second (pps) during spontaneous sitting and standing, and 7.2 pps during voluntary force production. Interspike interval variability was lower during voluntary tasks than during spontaneous force production. Common drive was less pronounced in bilateral vs. unilateral unit pairs, also in spontaneous standing. This difference was not seen in our previous pain-free subjects, suggesting altered bilateral control of the spine in ALBP. The distribution of CDC values was not a homogeneous continuum but could be seen as two partially overlapping populations of CDC distributions. NEW & NOTEWORTHY We implanted fine-wire electrodes in the deepest part of axial postural muscles in patients with acute low back pain and characterized their motor unit activity. We found less pronounced common drive to the two sides of the spine compared with pain-free subjects, suggesting a different postural control strategy in patients with acute low back pain. An unexpected finding was that common drive coefficient values appeared to consist of two partially overlapping populations of normal distributions.

scholarly journals Single-motor-unit discharge characteristics in human lumbar multifidus muscle

2015 ◽  
Vol 114 (2) ◽  
pp. 1286-1297 ◽  
Author(s):  
Lise R. Lothe ◽  
Tim J. L. Raven ◽  
Torsten Eken
Keyword(s):  
Postural Control ◽  
Motor Unit ◽  
Interspike Interval ◽  
Discharge Rate ◽  
Force Production ◽  
Voluntary Activity ◽  
Multifidus Muscle ◽  
Lumbar Multifidus ◽  
Single Motor Unit ◽  
Common Drive

The underlying neurophysiology of postural control of the lower back in humans is poorly understood. We have characterized motor unit (MU) discharge activity in the deep lumbar multifidus (LM) muscle in nine healthy subjects (20–40 yr, 3 females). Bilateral fine wire electrodes were implanted at L4 spinal level using ultrasound guidance. EMG was recorded during spontaneous sitting and standing and during voluntary force production. Individual MUs were analyzed with regard to instantaneous discharge rate, interspike interval variability, alternation of activity between MUs, and cross correlation between concurrently active MUs quantified by the common drive coefficient (CDC). Significant effects of sitting vs. standing were seen on median discharge rate and interspike interval variability. Median discharge rate in 71 units was 5.4 and 6.9 pulses/s during spontaneous sitting and standing and 7.4 pulses/s during voluntary force production. Several MUs fired doublets. CDC analysis of 87 MU pairs showed a significantly higher common drive in spontaneous than in voluntary activity and significant differences between unilateral and bilateral pairs, although not when spontaneously active in standing. In spite of common drive, MUs were recruited from inactivity to tonic discharge lasting for several minutes without changes in discharge rate in already active MUs, and several instances were documented where activity was rotated between MUs. We argue that this behavior is indicative of self-sustained discharge in LM motoneurons, establishing intrinsic motoneuron properties as a central mechanism for postural control of deep back muscles.

Low Back Pain in Commercial Airline Pilots

2020 ◽  
Vol 91 (12) ◽  
pp. 940-947
Author(s):  
Matthias Albermann ◽  
Maria Lehmann ◽  
Christian Eiche ◽  
Joachim Schmidt ◽  
Johannes Prottengeier
Keyword(s):  
Risk Factors ◽  
Low Back Pain ◽  
Back Pain ◽  
Online Survey ◽  
German Population ◽  
Low Back ◽  
Airline Pilots ◽  
Acute Low Back Pain ◽  
Commercial Airline ◽  
Negative Effect

BACKGROUND: In their working life, airline pilots are exposed to particular risk factors that promote nonspecific low back pain (LBP). Because of the varying incidence internationally, we evaluated the point prevalences of acute, subacute, and chronic nonspecific LBP, as well as the current prevalences in German airline pilots. Furthermore, we compared the prevalence to the general German population and to European counterparts.METHODS: An anonymous online survey of 698 participating German airline pilots was evaluated. The impairment between groups was analyzed. Prevalences from our data were compared to existing data.RESULTS: The following point prevalences were found: 8.2% acute, 2.4% subacute, 82.7% chronic LBP; 74.1% of all individuals were suffering from current LBP when answered the questionnaire. A total time spent flying greater than 600 h within the last 12 mo was significantly related to acute nonspecific LBP. Individuals with any type of LBP were significantly impaired compared to those unaffected. It was found that German airline pilots suffer more often from current LBP than the general population and have a higher point prevalence of total LBP than their European counterparts.CONCLUSIONS: The evaluation showed a surprisingly high, previously unidentified, prevalence of nonspecific LBP in German airline pilots. Why German airline pilots suffer more often from LBP remains uncertain. The number of flying hours appears to have a negative effect on developing acute low back pain, but causation cannot be concluded. Other risk factors could not be confirmed.Albermann M, Lehmann M, Eiche C, Schmidt J, Prottengeier J. Low back pain in commercial airline pilots. Aerosp Med Hum Perform. 2020; 91(12):940947.

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