Barbara Cagnie

In fighter pilots neck muscle strengthening exercises are often recommended to protect the neck against pathologies. The aim of the current study was to compare the relative cross-sectional area (rCSA) and muscle:fat ratio of the cervical musculature of F-16 pilots experiencing neck pain and no neck pain (control) pilots. In addition, correlations between these morphometric characteristics, cervical range of motion (CROM), and neck muscle strength were evaluated. There were 35 male F-16 pilots who volunteered, of which 10 experienced bilateral neck pain. A standardized questionnaire was used to collect personal information. Magnetic resonance imaging (MRI) was assessed at the C5-C6 level to determine rCSA and muscle:fat ratio. The CROM (Zebris) and the maximum isometric strength (David F140 device) were measured. The rCSA of the semispinalis cervicis and multifidus was significantly larger in the neck pain group (left: 2.08 cm2; right: 1.81 cm2) on both the left and the right side, in comparison to the control population (left: 1.29 cm2; right: 1.26 cm2). In the pain group, the rCSA of the semispinalis cervicis and multifidus was significant larger on the left than on the right side (left: 2.08 cm2; right: 1.81 cm2). No differences in the muscle:fat ratio between control pilots and pilots with neck pain could be determined. Between groups no differences were found in the CROM and the neck muscle strength. It is hypothesized that the larger rCSA in the neck pain group compared to the control group might be caused by greater activity of the deep neck muscles in the neck pain group. The asymmetrical operation of the F-16 might cause the asymmetry within this group.

Background and Objective: As Light Emitting Diode (LED) devices are commercially introduced as an alternative for Low Level Laser (LLL) Therapy, the ability of LED in influencing wound healing processes at cellular level was examined. Study Design/Materials and Methods: Cultured fibroblasts were treated in a controlled, randomized manner, during three consecutive days, either with an infrared LLL or with a LED light source emitting several wavelengths (950 nm, 660 nm and 570 nm) and respective power outputs. Treatment duration varied in relation to varying surface energy densities (radiant exposures). Results: Statistical analysis revealed a higher rate of proliferation (p ≤ 0.001) in all irradiated cultures in comparison with the controls. Green light yielded a significantly higher number of cells, than red (p ≤ 0.001) and infrared LED light (p ≤ 0.001) and than the cultures irradiated with the LLL (p ≤ 0.001); the red probe provided a higher increase (p ≤ 0.001) than the infrared LED probe and than the LLL source. Conclusion: LED and LLL irradiation resulted in an increased fibroblast proliferation in vitro. This study therefore postulates possible stimulatory effects on wound healing in vivo at the applied dosimetric parameters.

Mixed model analysis of muscle functional magnetic resonance imaging (MRI) and electromyography (EMG) changes in lumbar muscles during trunk extension exercise at varying intensities. To gain insight within the relationship between muscle functional MRI and activity of the lumbar back muscles, which is related to exercise intensity. It is known that muscle activity during exercise induces a force-sensitive T2 increase; however, it is not known how sensitive this T2 change is. In addition, the association between MRI and EMG measurement was investigated. Multifidus and erector spinae muscle activity was investigated during a trunk extension exercise at 5 increasing loads (from 40% to 80% of 1 repetition maximum), with both MRI and EMG. Data were analyzed using mixed model analysis. Our results indicate a linear relationship between MRI and exercise intensity; for both muscles an increase of 10% exercise intensity corresponds with an increase of the T2 value with 1.18 (0.89, 1.47) ms. Also for EMG there is a linear relationship with exercise intensity; an increase of 10% exercise intensity corresponds with an increase of 6.98 (5.33, 8.62) microV. Furthermore, a linear association between MRI and EMG is acceptable. For the multifidus, an increase of 1 muV (EMG) corresponds with an increase of 0.168 (0.117, 0.219) ms (MRI). For the erector spinae, an increase of 1 microV corresponds with an increase of 0.078 (0.042, 0.114) ms. Both muscle functional MRI and EMG have specific (dis-) advantages and therefore have to be seen as complementary techniques. Nevertheless, our results support the validity of each method and indicate that MRI and EMG can be used independently to quantify lumbar muscle activity.

As a prerequisite to the use of a test battery based on electromyographic (EMG) analysis of the paraspinal muscles for identifying and remedying back muscle dysfunction, the intra- and inter-operator reliability was assessed. Fifteen volunteers underwent EMG tests on three occasions. The test subjects were asked to perform 22 exercises, subdivided into four categories: coordination, stabilization, balance and strength exercises. The time interval between the tests was one week. The myoelectric signals of the multifidus (MF) and iliocostalis lumborum pars thoracis (ICLT) were analysed with regard to amplitude (averaged EMG) and frequency (zero cross rate). The results indicated that the reliability was better for the MF than for the ICLT, and also for exercises at higher loads (strength exercises). In the intra-operator condition, the reproducibility of the averaged EMG was good (ICC>0.75), except for the balance exercises (ICC = 0.40-0.74). In general, the averaged EMG in the inter-operator condition and the zero cross rate in both the intra- and inter-operator conditions are less or poorly reliable. These results demonstrate that when back muscle function is evaluated during coordination, stabilization and strength exercises, only the averaged EMG parameter has acceptable reproducibility over time when assessed by the same operator.

The present pilot study investigated the analgesic efficacy of light-emitting diode (LED). In view of a standardised and controlled pain reduction study design, this in vivo trial was conducted on experimentally induced delayed-onset muscle soreness (DOMS). Thirty-two eligible human volunteers were randomly assigned to either an experimental (n=16) or placebo group (n=16). Immediately following the induction of muscle soreness, perceived pain was measured by means of a visual analog scale (VAS), followed by a more objective mechanical pain threshold (MPT) measurement and finally an eccentric/concentric isokinetic peak torque (IPT) assessment. The experimental group was treated with infrared LED at one of both arms, the other arm served as control. Irradiation lasted 6 min at a continuous power output of 160 mW, resulting in an energy density of 3.2 J/cm2. The subjects of the placebo group received sham irradiation at both sides. In post-treatment, a second daily assessment of MPT and VAS took place. The treatment and assessment procedure (MPT, VAS and IPT) was performed during 4 consecutive days. Statistical analysis (a general linear model followed by post hoc least significant difference) revealed no apparent significant analgesic effects of LED at the above-described light parameters and treatment procedure for none of the three outcome measures. However, as the means of all VAS and MPT variables disclose a general analgesic effect of LED irradiation in favour of the experimental group, precaution should be taken in view of any clinical decision on LED. Future research should therefore focus on the investigation of the mechanisms of LED action and on the exploration of the analgesic effects of LED in a larger randomised clinical trial and eventually in more clinical settings.

To investigate the effect of experimental neck muscle pain on the activation of the cervical extensor muscles during the performance of a cervical extension exercise by the use of muscle functional magnetic resonance imaging. The activity of the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis muscles was investigated bilaterally at 2 cervical levels (C2 to C3 and C7 to T1) in 15 healthy individuals. Measurements were taken at rest and after the performance of a cervical extension exercise without and with induced pain of the right upper trapezius (intramuscular injection of hypertonic saline). In the pain condition, the activity of the multifidus/semispinalis cervicis was reduced bilaterally at the C7 to T1 level (P=0.045). For the semispinalis capitis, there were no significant differences between both conditions. The splenius capitis showed a significantly higher T2 shift at the left side at the C2 to C3 level (P=0.008) and a lower T2 shift at the right side at the C7 to T1 level (P=0.023). This is the first study that has shown pain to immediately affect the activity of both deep and superficial cervical extensor muscle layers during a cervical extension exercise. The findings support recommendations for evaluation of cervical extensor muscle function early in the management of painful cervical spine injuries.

Experimental study of changes in muscle recruitment during trunk extension exercise at 40% of the repetition maximum, because of induced muscle pain. To investigate the effect of lumbar muscle pain on muscle activity of the trunk muscles using muscle functional magnetic resonance imaging. Changed muscle recruitment in patients has an important impact on the etiology and recurrence of low back pain. The mechanisms of these changes in muscle activity are still poorly understood. An experimental study investigating the cause-effect relationship of muscle pain on muscle recruitment patterns can help to clarify these mechanisms. In 15 healthy subjects, the muscle activity of the lumbar multifidus, lumbar erector spinae, and psoas muscles was investigated with muscle functional magnetic resonance imaging. Measurements at rest and after trunk extension exercise at 40% of repetition maximum were performed without and with induced pain. The lumbar multifidus and lumbar erector spinae were significantly active during the trunk extension exercise, whereas the psoas showed no significant activity. The activity of the lumbar multifidus, lumbar erector spinae, and psoas muscles, was reduced bilaterally and multilevel during the exercise with unilateral low back muscle pain. These data demonstrate that unilateral muscle pain can cause hypoactivity of muscles during trunk extension at 40% of the repetition maximum. The changes were not limited to the side and level of pain. Moreover, the inhibition was not limited to the multifidus muscle; also the lumbar erector spinae and psoas muscles showed decreased activity during the pain condition. Further research has to assess possible compensation mechanisms for this reduced activity in other muscles.

Neck pain is a common problem in F-16 pilots. A cross-sectional survey was used to determine the self-reported 1-yr prevalence of neck pain and to compare individual, work-related, and flight-related characteristics in F-16 pilots with and without neck pain. There were 90 male F-16 pilots of the Belgian Air Force and The Royal Netherlands Air Force who voluntarily completed an anonymous survey. The 1-yr prevalence of neck pain was 18.9%. Pilots were divided into two groups: healthy (HG) and neck pain group (NPG). This study could not identify individual or specific flight-related differences between these two groups. High force demands, often sitting for a long time, frequently holding the neck in a forward bent posture, and being physically tired were all physical work-related factors that were reported significantly more often in the NPG. The NPG also reported significantly more psychosocial factors, such as being mentally tired at the end of the day and being annoyed by others at the workplace. Since the specific flight-related factors were not significantly different between the HG and the NPG, physical and psychosocial factors could have been important factors in the development or maintenance of neck pain in F-16 pilots. The results of this study highlight for the first time that, in addition to flight-related issues, other aspects must be considered in analyzing neck pain. These other aspects stress the importance of a broader approach when considering neck pain, even in this population that is exposed to very high loads during flight.

The purpose of this study was to investigate the long-term effectiveness of a spine care education programme conducted in 9- to 11-year-old schoolchildren. The study sample included 96 intervention subjects and 98 controls (9- to 11-year-olds at baseline). Intervention consisted of a 6-week school-based back education programme (predominantly biomechanically oriented) and was implemented by a physical therapist. Self-reported outcomes on back care knowledge, spinal care behaviour, self-efficacy towards favourable back care behaviour, prevalence of back and neck pain during the week and fear-avoidance beliefs were evaluated by the use of questionnaires. Post-tests were performed within 1 week after programme completion, after 1 year and after 8 years. Whereas the educational back care programme resulted in increased back care knowledge up to adulthood (P < 0.001), intervention did not change spinal care behaviour or self-efficacy. Pain prevalence figures increased less in the experimental group compared to the controls over the 8-year time span, yet statistical significance was not reached. Dropout analysis revealed spinal pain prevalence rates to be different in both groups throughout the study, including at baseline. Back education at young age did not reinforce fear-avoidance beliefs up to adulthood. Predominantly biomechanical oriented back education in elementary schoolchildren is effective in improving the cognitive aspect of back care up to adulthood, yet not in changing actual behaviour or self-efficacy. The current study does not provide evidence that educational back care programmes have any impact on spinal pain in adulthood. The true long-term impact of school-based spinal health interventions on clinically relevant outcome measures merits further attention.

The vertebral artery (VA) is often involved in the occurrence of complications after spinal manipulative therapy. Due to osteophytes compressing the VA anteriorly from the uncinate process or posteriorly from the facet complex, the VAs are susceptible to trauma in the transverse foramina. Such altered anatomical configurations are of major clinical significance, as spinal manipulations may result in dissection of the VA with serious consequences for the blood supply to the vertebrobasilar region. The purpose of this study is to describe numerous structural features of the third to seventh cervical vertebrae in order to contribute to the understanding of pathological conditions related to the VA. The minimal and maximal diameter of 111 transverse foramina in dry cervical vertebrae were studied. The presence of osteophytes and their influence on the VA were evaluated at the vertebral body and at the superior and inferior articular facets. The diameter of the transverse foramina increased from C3 to C6, while the transverse foramina of C7 had the smallest diameter. At all levels the mean dimensions of the left foramina were greater than those of the right side. Osteophytes from the uncinate process of C5 and C6 vertebrae were found in over 60% of dry vertebrae. Osteophytes from the zygapophyseal joints were more frequent at C3 and C4 vertebrae. About half of the osteophytes of the uncinate and of the superior articular process partially covered the transverse foramina. This was less common with those of the inferior articular facets. Osteophytes covering the transverse foramen force the VAs to meander around these obstructions, causing narrowing through external compression and are potential sites of trauma to the VAs potentially even leading to dissection. We strongly advocate that screening protocols for vertebrobasilar insufficiency (VBI) be used prior to any manipulation of the cervical spine and should include not only extension and rotation but any starting position from which the planned manipulation will be performed.

The presence of atherosclerotic plaques and their influence on the vertebral artery is of clinical importance within the scope of spinal manipulation. Manipulation may stimulate the development of atherosclerotic plaques, could detach an embolus with ensuing infarction, injure the endothelium or may directly cause a dissection in the presence of atherosclerotic plaques. In order to identify the sites and frequency of atherosclerotic plaques and to determine its relation to the tortuous course of the vertebral artery, a cadaveric study was performed. The vertebral arteries of 57 human cadavers were studied. The vertebral artery was virtually divided into four segments: the pre-vertebral (V1), the vertebral (V2), the atlanto-axial (V3), and the intracranial segment (V4). Abnormalities in the origin and course of the vertebral artery were noted, along with any associated osseous, or cartilaginous anomalies in the neck. After dissection, the artery was opened and macroscopically screened for the presence of atherosclerotic plaques. In 22.8% of the cases, no atherosclerotic plaques were present. In 35.1% of the cases, the atherosclerotic plaques were unilateral, of which 60.0% was on the left side, 40.0% on the right side, and in 42.1%, the occurrence was bilateral. Atherosclerotic plaques were significantly more present in the V3 segment than in the V1 (0.007) and V2 segment (0.049). In the V1 (P=0.008) and V2 segment (P=0.002), there was a correlation between a tortuous course of the vessel and the occurrence of atherosclerotic plaques. In individuals with marked atherosclerotic disease, stretching and compression effects of rotational manipulative techniques on atherosclerotic vessels impose a further risk factor for vertebrobasilar insufficiency. As direct evidence of atherosclerotic plaques are rarely available, therapists should avoid manipulative techniques at all levels of the cervical spine in the presence of any indirect sign of atherosclerotic disease or in the presence of calcified arterial walls or tortuosities of the vessels visible on routinely available X-ray images of the cervical or thoracic spine. It is strongly recommended, that if any doubt exists about the nature of a clinical presentation, vigorous manual procedures should be avoided until either the diagnosis is definitive or gentle manual therapy has proven effective.

The introduction of light emitting diode (LED) devices as a novel treatment for pain relief in place of low-level laser warrants fundamental research on the effect of LED devices on one of the potential explanatory mechanisms: peripheral neurophysiology in vivo. A randomised controlled study was conducted by measuring antidromic nerve conduction on the peripheral sural nerve of healthy subjects (n=64). One baseline measurement and five post-irradiation recordings (2-min interval each) were performed of the nerve conduction velocity (NCV) and negative peak latency (NPL). Interventional set-up was identical for all subjects, but the experimental group (=32) received an irradiation (2 min at a continuous power output of 160 mW, resulting in a radiant exposure of 1.07 J/cm2) with an infrared LED device (BIO-DIO preprototype; MDB-Laser, Belgium), while the placebo group was treated by sham irradiation. Statistical analysis (general regression nodel for repeated measures) of NCV and NPL difference scores, revealed a significant interactive effect for both NCV (P=0.003) and NPL (P=0.006). Further post hoc LSD analysis showed a time-related statistical significant decreased NCV and an increased NPL in the experimental group and a statistical significant difference between placebo and experimental group at various points of time. Based on these results, it can be concluded that LED irradiation, applied to intact skin at the described irradiation parameters, produces an immediate and localized effect upon conduction characteristics in underlying nerves. Therefore, the outcome of this in vivo experiment yields a potential explanation for pain relief induced by LED.

This report covers a case in which the right vertebral artery (VA) did not participate in the formation of the basilar artery. The artery had an external diameter of about 1 mm. It ran trough the transverse foramina of C6 through C2, then turned backward and entered the spinal canal and the dural envelope between the posterior arch of C1 and the lamina of C2 as a medullary artery to end in the spinal arteries. The basilar artery was a continuation of the left VA only. Only very few cases of non-union of the VA with the basilar artery have been previously described. Cases with extreme reduction of one of the VAs are not exceptional. This variant is clinically important. On arteriography, this extremely rare condition could easily be misdiagnosed as an obstruction. In view of manipulative therapy and in the detection of vertebrobasilar insufficiency, one has to bear in mind that cases of non-union may influence the interpretation of these tests.