Michel W. Coppieters

Positioning in anesthesiology - Toward a better understanding of stretch-induced perioperative neuropathies

Background Stretch-induced neuropathy of the brachial plexus and median nerve in conventional perioperative care remains a relatively frequent and poorly understood complication. Guidelines for positioning have been formulated, although the protective effect of most recommendations remains unexamined. The similarity between the stipulated potentially dangerous positions and the components of the brachial plexus tension test (BPTT) justified the analysis of the BPTT to quantify the impact of various arm and neck positions on the peripheral nervous system. Methods Four variations of the BPTT in three different shoulder positions were performed in 25 asymptomatic male participants. The impact of arm and neck positions on the peripheral nervous system was evaluated by analyzing the maximal available range of motion, pain intensity, and type of elicited symptoms during the BPTT. Results Cervical contralateral lateral flexion, lateral rotation of the shoulder and fixation of the shoulder girdle in a neutral position in combination with shoulder abduction, and wrist extension all significantly reduced the available range of motion. Elbow extension also challenged the nervous system substantially. A cumulative impact could be observed when different components were simultaneously added, and a neutralizing effect was noted when an adjacent region allowed for unloading of the nervous system. Conclusions The experimental findings support the experientially based guidelines for positioning. Especially when simultaneously applied, submaximal joint positions easily load the nervous system, which may substantially compromise vital physiologic processes in and around the nerve. Therefore, even when the positioning of all upper limb joints is carefully considered, complete prevention of perioperative neuropathy seems almost inconceivable.

New insight into motor adaptation to pain revealed by a combination of modelling and empirical approaches

Movement changes in pain. Unlike the somewhat stereotypical response of limb muscles to pain, trunk muscle responses are highly variable when challenged by pain in that region. This has led many to question the existence of a common underlying theory to explain the adaptation. Here, we tested the hypotheses that (1) adaptation in muscle activation in acute pain leads to enhanced spine stability, despite variation in the pattern of muscle activation changes; and (2) individuals would use a similar ‘signature’ pattern for tasks with different mechanical demands.

Postural activity of the pelvic floor muscles is delayed during rapid arm movements in women with stress urinary incontinence

The aim of this study was to determine whether postural activity of the pelvic floor (PF) and abdominal muscles differs between continent and incontinent women during rapid arm movements that present a postural challenge to the trunk. A further aim was to study the effect of bladder filling. Electromyographic activity (EMG) of the PF, abdominal, erector spinae (ES), and deltoid muscles was recorded with surface electrodes. During rapid shoulder flexion and extension, PF EMG increased before that of the deltoid in continent women, but after the deltoid in incontinent women (p = 0.002). In many incontinent women, PF EMG decreased before the postural activation. Although delayed, postural PF EMG amplitude was greater in women with incontinence (p = 0.010). In both groups, PF EMG decreased and abdominal and ES EMG increased when the bladder was moderately full. These findings would be expected to have negative consequences for continence and lumbopelvic stability in women with incontinence.

Reliability of clinical tests to evaluate nerve function and mechanosensitivity of the upper limb peripheral nervous system.

BackgroundClinical tests to assess peripheral nerve disorders can be classified into two categories: tests for afferent/efferent nerve function such as nerve conduction (bedside neurological examination) and tests for increased mechanosensitivity (e.g. upper limb neurodynamic tests (ULNTs) and nerve palpation). Reliability reports of nerve palpation and the interpretation of neurodynamic tests are scarce. This study therefore investigated the intertester reliability of nerve palpation and ULNTs. ULNTs were interpreted based on symptom reproduction and structural differentiation. To put the reliability of these tests in perspective, a comparison with the reliability of clinical tests for nerve function was made.MethodsTwo experienced clinicians examined 31 patients with unilateral arm and/or neck pain. The examination included clinical tests for nerve function (sensory testing, reflexes and manual muscle testing (MMT)) and mechanosensitivity (ULNTs and palpation of the median, radial and ulnar nerve). Kappa statistics were calculated to evaluate intertester reliability. A meta-analysis determined an overall kappa for the domains with multiple kappa values (MMT, ULNT, palpation). We then compared the difference in reliability between the tests of mechanosensitivity and nerve function using a one-sample t-test.ResultsWe observed moderate to substantial reliability for the tests for afferent/efferent nerve function (sensory testing: kappa = 0.53; MMT: kappa = 0.68; no kappa was calculated for reflexes due to a lack of variation). Tests to investigate mechanosensitivity demonstrated moderate reliability (ULNT: kappa = 0.45; palpation: kappa = 0.59). When compared statistically, there was no difference in reliability for tests for nerve function and mechanosensitivity (p = 0.06).ConclusionThis study demonstrates that clinical tests which evaluate increased nerve mechanosensitivity and afferent/efferent nerve function have comparable moderate to substantial reliability. To further investigate the clinometric properties of these tests, more studies are needed to evaluate their validity.

Neural tissue management provides immediate clinically relevant benefits without harmful effects for patients with nerve-related neck and arm pain: a randomised trial

QUESTION What are the benefits and harms of neural tissue management in the short term for treating nerve-related neck and arm pain? DESIGN Randomised controlled trial. PARTICIPANTS Sixty participants with non-traumatic nerve-related neck and unilateral arm pain were randomised to experimental (n=40) or control (n=20) groups. INTERVENTION Both groups were advised to continue usual activities. The experimental group also received education, manual therapy, and nerve gliding exercises in 4 treatments over 2 weeks. OUTCOME MEASURES Primary outcomes were participant-reported improvement and worsening on a Global Rating of Change scale. Secondary outcomes were neck pain, arm pain, the Neck Disability Index, the Patient-Specific Functional Scale, and adverse events related to treatment. Follow-up occurred 3-4 weeks after baseline. RESULTS Numbers needed to treat favoured the experimental intervention for participant-reported improvement (2.7, 95% CI 1.7 to 6.5), neck pain (3.6, 95% CI 2.1 to 10), arm pain (3.6, 95% CI 2.1 to 10), Neck Disability Index (4.3, 95% CI 2.4 to 18.2), and Patient-Specific Functional Scale (3.0, 95% CI 1.9 to 6.7). The prevalence of worsening in the experimental (13%) and control (20%) groups were not different (RD -7%, 95% CI -28 to 13). Adverse events had minimal impact on daily activities and did not reduce the chance of improving with the experimental intervention (RR = 1.03, 95% CI 0.58 to 1.84). CONCLUSION These results enable physiotherapists to inform patients that neural tissue management provides immediate clinically relevant benefits beyond advice to remain active with no evidence of harmful effects. TRIAL REGISTRATION ACTRN 12610000446066.

Local and remote immune-mediated inflammation after mild peripheral nerve compression in rats.

After experimental nerve injuries that extensively disrupt axons, such as chronic constriction injury, immune cells invade the nerve, related dorsal root ganglia (DRGs), and spinal cord, leading to hyperexcitability, raised sensitivity, and pain. Entrapment neuropathies, such as carpal tunnel syndrome, involve minimal axon damage, but patients often report widespread symptoms. To understand the underlying pathology, a tube was placed around the sciatic nerve in 8-week-old rats, leading to progressive mild compression as the animals grew. Immunofluorescence was used to examine myelin and axonal integrity, glia, macrophages, and T lymphocytes in the nerve, L5 DRGs, and spinal cord after 12 weeks. Tubes that did not constrict the nerve when applied caused extensive and ongoing loss of myelin, together with compromise of small-, but not large-, diameter axons. Macrophages and T lymphocytes infiltrated the nerve and DRGs. Activated glia proliferated in DRGs but not in spinal cord. Histologic findings were supported by clinical hyperalgesia to blunt pressure and cold allodynia. Tubes that did not compress the nerve induced only minor local inflammation. Thus, progressive mild nerve compression resulted in chronic local and remote immune-mediated inflammation depending on the degree of compression. Such neuroinflammation may explain the widespread symptoms in patients with entrapment neuropathies.

Reliability and Size of the Measurement Error when Determining the Cross-Sectional Area of the Tibial Nerve at the Tarsal Tunnel with Ultrasonography

An in depth analysis of the reliability of ultrasonography to measure the cross-sectional area of the tibial nerve or any other peripheral nerve is not available in the literature. This study determined the reliability and size of the measurement error of high-resolution ultrasound to measure the size of the tibial nerve at the tarsal tunnel. The cross-sectional area of the tibial nerve was measured by two experienced sonographers at 1 cm proximal to the medial malleolus. Measurements were made in 10 healthy participants without plantar heel pain. Intra and intertester reliability were determined by calculation of intraclass correlation coefficients (ICC), measurement error magnitude and smallest detectable difference (SDD). A direct (tracing) and indirect (ellipsoid formula) method were evaluated. Results demonstrated that the intra and intertester reliability were excellent (ICC, all > or =0.86). The measurement error and SDD were very small, especially when measurements from three scans were averaged (measurement error: 0.4-0.9 mm2; SDD: 1.1-2.5 mm2). The findings of this study support the view that high-resolution ultrasound is reliable to measure the cross-sectional area of a peripheral nerve. As a result of the small measurement error, a side-to-side difference as small as approximately 1.8 mm2 can be interpreted meaningfully in an individual patient. This difference is much smaller than the swelling reported in the literature for patients with tibial neuropathy.

Biomechanical evaluation of two clinical tests for plantar heel pain : The dorsiflexion-eversion test for tarsal tunnel syndrome and the windlass test for plantar fasciitis

Background: Plantar heel pain may result from several conditions such as tarsal tunnel syndrome (TTS) and plantar fasciitis. The dorsiflexion-eversion test is used to diagnose TTS, whereas the windlass test is used for plantar fasciitis. Given the similarity between both tests, the purpose of this study was to evaluate whether these tests are able to selectively load the structures which they aim to examine. Methods: Both tests were evaluated in six cadavers by measuring strain in the plantar fascia, tibial nerve, lateral plantar nerve (LPN), and medial plantar nerve (MPN) using miniature displacement transducers. Longitudinal excursion of the nerves was measured with a digital caliper. Results: With the dorsiflexion-eversion test, dorsiflexion and eversion of the ankle in combination with extension of the metatarsophalangeal (MTP) joints significantly increased strain in the tibial nerve (+1.1%), LPN (+2.2%), and MPN (+3.3%) but also in the plantar fascia (+1.2%) (all: p = 0.016). Both components (dorsiflexion-eversion and MTP extension) resulted in significant increases. With the windlass test, extension of all MTP joints significantly increased strain in the plantar fascia (+0.4%, p = 0.016), but also in the tibial nerve (+0.4%, p = 0.016), LPN (+0.8%, p = 0.032) and MPN (+2.0%, p = 0.016). Excursion of the nerves was always in the distal direction but only reached significance for the tibial nerve (6.9 mm, p = 0.016) and LPN (2.2 mm, p = 0.032) during the dorsiflexion-eversion test. Conclusions: Both tests mechanically challenge various structures that have been associated with plantar heel pain. This questions the usefulness of the tests in the differential diagnosis of plantar heel pain.

Effect of experimentally induced low back pain on postural sway with breathing

Although breathing perturbs balance, in healthy individuals little sway is detected in ground reaction forces because small movements of the spine and lower limbs compensate for the postural disturbance. When people have chronic low back pain (LBP), sway at the ground is increased, possibly as a result of reduced compensatory motion of the trunk. The aim of this study was to determine whether postural compensation for breathing is reduced during experimentally induced pain. Subjects stood on a force plate with eyes open, eyes closed, and while breathing with hypercapnoea before and after injection of hypertonic saline into the right lumbar longissimus muscle to induce LBP. Motion of the lumbar spine, pelvis, and lower limbs was measured with four inclinometers fixed over bony landmarks. During experimental pain, motion of the trunk in association with breathing was reduced. However, despite this reduction in motion, there was no increase in postural sway with breathing. These data suggest that increased body sway with breathing in people with chronic LBP is not simply because of reduced trunk movement, but instead, indicates changes in coordination by the central nervous system that are not replicated by experimental nociceptor stimulation.

Changes in sitting posture induce multiplanar changes in chest wall shape and motion with breathing

This study examined the effect of sitting posture on regional chest wall shape in three dimensions, chest wall motion (measured with electromagnetic motion analysis system), and relative contributions of the ribcage and abdomen to tidal volume (%RC/V(t)) (measured with inductance plethysmography) in 7 healthy volunteers. In seven seated postures, increased dead space breathing automatically increased V(t) (to 1.5 V(t)) to match volume between conditions and study the effects of posture independent of volume changes. %RC/V(t) (p<0.05), chest wall shape (p<0.05) and motion during breathing differed between postures. Compared to a reference posture, movement at the 9th rib lateral diameter increased in the thoracolumbar extension posture (p<0.008). In slumped posture movement at the AP diameters at T1 and axilla increased (p<0.00001). Rotation postures decreased movement in the lateral diameter at the axilla (p<0.0007). The data show that single plane changes in sitting posture alter three-dimensional ribcage configuration and chest wall kinematics during breathing, while maintaining constant respiratory function.