Similarities between explaining dizziness and explaining pain? Exploring common patient experiences, theoretical models, treatment approaches and potential therapeutic narratives for persistent dizziness or pain.

Pain and dizziness are common experiences throughout the lifespan. However, nearly a quarter of those with acute pain or dizziness experience persistence, which is associated with disability, social isolation, psychological distress, decreased independence, and poorer quality of life. Thus, persistent pain or dizziness impacts peoples' lives in similarly negative ways. Conceptual models of pain and dizziness also have many similarities. Many of these models are more expansive than explaining mere symptoms; rather they describe pain or dizziness as holistic experiences that are influenced by biopsychosocial and contextual factors. These experiences also appear to be associated with multi-modal bodily responses related to evaluation of safety, threat detection and anticipation, as influenced by expectations, and predictions anticipation, not simply a reflection of tissue injury or pathology. Conceptual models also characterize the body as adaptable and therefore capable of recovery. These concepts may provide useful therapeutic narratives to facilitate understanding, dethreaten the experience, and provide hope for patients. In addition, therapeutic alliance, promoting an active movement-based approach, building self-efficacy, and condition-specific approaches can help optimize outcomes. In conclusion, there are significant overlaps in the patient experience, theoretical models and potential therapeutic narratives that guide care for people suffering with persistent pain or dizziness.

Reliability of the straight leg raise test for suspected lumbar radicular pain: A systematic review with meta-analysis.

BACKGROUND: The passive straight leg raise (SLR) and crossed SLR are recommended tests for lumbar radicular pain. There are no recent reviews of test reliability. OBJECTIVES: To summarize SLR and crossed SLR reliability in patients with suspected lumbar radicular pain. DESIGN: Systematic review with meta-analysis. METHOD: MEDLINE and CINAHL were searched for studies published before April 2021 that reported SLR or crossed SLR reliability in patients with low back-related leg pain. Supplemental analyses also included patients with low back pain only. Study selection, risk of bias assessment (QAREL), and data extraction were performed in duplicate. Kappa, intraclass correlation coefficients, and smallest detectable difference (SDD95) quantified reliability. Meta-analysis was performed when appropriate. Confidence in the evidence was determined by applying GRADE principles. RESULTS/FINDINGS: Fifteen studies met selection criteria. One-hundred-eighty-nine participants had low back-related leg pain. Four-hundred-thirty-nine were included in supplemental analyses. Meta-analyses showed at least fair inter-rater reliability when a positive SLR required provocation of lower extremity symptoms or pain. SLR reliability was at least moderate when testing included structural differentiation (e.g., ankle dorsiflexion). A low prevalence of positive crossed SLR tests led to wide-ranging reliability estimates. Confidence in the evidence for identifying a positive SLR or crossed SLR was moderate to very low. SDD95 values for different raters measuring SLR range of motion ranged from 13 to 20°. CONCLUSIONS: Reliability data support testing SLR with structural differentiation manoeuvres. Crossed SLR reliability data are inconclusive. Measurement error likely prohibits using SLR range of motion for clinical decision-making.

Virtual reality as an analgesic for acute and chronic pain in adults: a systematic review and meta-analysis.

Background: Previous studies have shown that virtual reality (VR) is effective in reducing acute and chronic pain both in adults and in children. Given the emergence of new VR technology, and the growing body of research surrounding VR and pain management, an updated systematic review is warranted. Purpose: The purpose of this systematic review is to compare the effectiveness of VR in reducing acute and chronic pain in adults. Data Sources: A search was conducted in three databases (PubMed, CINAHL, Trip) using standardized search terms. Study Selection: Twenty experimental and quasi-experimental trials published between January 2007 and December 2018 were included based on prespecified inclusion and exclusion criteria. Pain intensity was the primary outcome. Data Extraction: We extracted data and appraised the quality of articles using either the PEDro or Modified Downs and Black risk of bias tools. Data Synthesis: The majority of studies supported the use of VR to reduce acute pain both during the procedure and immediately after. Numerous studies found VR reduced chronic pain during VR exposure but there is insufficient evidence to support lasting analgesia. There was considerable variability in patient population, pain condition and dosage of VR exposure. Limitations: Due to heterogeneity, we were unable to perform meta-analyses for all study populations and pain conditions. Conclusions: VR is an effective treatment for reducing acute pain. There is some research that suggests VR can reduce chronic pain during the intervention; however, more evidence is needed to conclude that VR is effective for lasting reductions in chronic pain.

Safety of lower extremity neurodynamic exercises in adults with diabetes mellitus: a feasibility study.

OBJECTIVES: Neurodynamic exercises aim to improve neural mechanosensitivity in order to promote pain-free movement and function. People with diabetes mellitus (DM) may be candidates for neurodynamic exercises to address common DM-related impairments such as reduced lower extremity range of motion (ROM) and altered neural mechanosensitivity. However, no studies have examined the safety and immediate effects of neurodynamic exercise in people with DM. This study aims to determine the feasibility of applying neurodynamic exercises in adults with DM by evaluating the rate of adverse events and quantifying immediate changes in straight leg raise (SLR) ROM. METHODS: This quasi-experimental study included 20 people with DM who performed a series of neurodynamic exercises on their right leg. Their left leg was used as an internal control. SLR testing was performed before and immediately after these exercises. Adverse events were monitored, including provocation of their neuropathy symptoms or discomfort or pain. RESULTS: All participants completed the neurodynamic exercises without provocation of their neuropathy symptoms. No pain was reported and only one participant had minor discomfort with one exercise; a <30-s calf cramp. The right SLR ROM increased by an average of 5.2°-5.3° (p < 0.01) with no change on the left. DISCUSSION: This study demonstrated that lower extremity neurodynamic exercises are safe in adults with DM and may create small immediate improvements in SLR testing. Further research is indicated to investigate the safety and efficacy of neurodynamic exercises performed over multiple sessions. LEVEL OF EVIDENCE: 3b.

Mechanosensitivity in the upper extremity following breast cancer treatment.

STUDY DESIGN: Descriptive, cross-sectional. INTRODUCTION: Breast cancer (BC) treatments place the nervous system at risk, which may contribute to upper extremity (UE) mechanosensitivity. PURPOSE OF THE STUDY: To evaluate elbow extension range of motion (EE-ROM) during upper limb neurodynamic testing (ULNT) post-BC treatment. METHODS: ULNT EE-ROM was measured for 145 women post-BC treatment. Women were sub-grouped by presence/absence of pain and lymphedema. RESULTS: Mean EE-ROM during ULNT1 was -22.3° (SD 11.9°) on the unaffected limb and -25.99° (SD 13.1°) on the affected limb. The women with pain and lymphedema had the greatest limitation in EE-ROM during ULNT1 testing, particularly of their affected limb (-33.8°, SD 12.9). Symptoms were reported more frequently in the affected chest, shoulder, arm, elbow, and hand. The intensity of symptoms was greater at the affected chest (p = 0.046), shoulder (p = 0.033) and arm (p = 0.039). CONCLUSIONS: Women with lymphedema and pain after BC treatment may present with altered neural mechanosensitivity. LEVEL OF EVIDENCE: 3a.

Altered tibial nerve biomechanics in patients with diabetes mellitus.

INTRODUCTION: Hyperglycemia associated with diabetes mellitus (DM) has adverse impacts on peripheral nerve connective tissue structure, and there is preliminary evidence that nerve biomechanics may be altered. METHODS: Ultrasound imaging was utilized to quantify the magnitude and timing of tibial nerve excursion during ankle dorsiflexion in patients with DM and matched healthy controls. RESULTS: Tibial nerve longitudinal excursion at the ankle and knee was reduced, and timing was delayed at the ankle in the DM group. Severity of neuropathy was correlated with larger reductions in longitudinal excursion. Nerve cross-sectional area was increased at the ankle in the DM group. CONCLUSIONS: Larger tibial nerve size within the tarsal tunnel in patients with DM may restrict longitudinal excursion, which was most evident with more severe neuropathy. It is hypothesized that these alterations may be related to painful symptoms during functional activities that utilize similar physiological motions through various biomechanical and physiological mechanisms.

Impact of movement sequencing on sciatic and tibial nerve strain and excursion during the straight leg raise test in embalmed cadavers.

STUDY DESIGN: Laboratory study, repeated-measures design. OBJECTIVES: To quantify differences in sciatic and tibial nerve biomechanics (strain and excursion) during common variations of the straight leg raise (SLR) test. BACKGROUND: Hip flexion and ankle dorsiflexion are the primary movement components of the SLR. It has been suggested that the nervous system is loaded differently when ankle dorsiflexion is added before or after hip flexion. There are, however, no data to either support or refute this suggestion. METHODS: Strain and excursion in the sciatic and tibial nerve were measured in the hip, knee, and ankle regions during 2 movement sequences for the SLR test in 10 embalmed cadavers. The proximal-to-distal sequence consisted of hip flexion followed by ankle dorsiflexion; the distal-to-proximal sequence consisted of ankle dorsiflexion followed by hip flexion. RESULTS: In the SLR end position, strain and excursion were comparable for both sequences for the sciatic and tibial nerve at the knee (P>.24). Strain in the tibial nerve at the ankle was greater with the proximal-to-distal sequence (P = .008), but the actual difference was small (0.8%). The pattern of strain increase and nerve excursion varied between sequences (P≤.009), with nerve strain increasing earlier and being maintained longer in regions closest to the joint that was moved first in the movement sequence. CONCLUSION: Varying the movement sequence does not substantially impact excursion and strain in the end position of the SLR. Therefore, if neurodynamic test sequencing is useful in the differential diagnosis of neuropathies, it is not likely due to differences in strain in the end position of testing.

Normal inter-limb differences during the straight leg raise neurodynamic test: a cross sectional study.

BACKGROUND: The straight leg raise (SLR) neurodynamic test is commonly used to examine the sensitivity of the lower quarter nervous system to movement. Range of motion during the SLR varies considerably, due to factors such as age, sex and activity level. Knowing intra-individual, inter-limb differences may provide a normative measure that is not influenced by such demographic characteristics. This study aimed to determine normal asymmetries between limbs in healthy, asymptomatic individuals during SLR testing and the relationship of various demographic characteristics. METHODS: The limb elevation angle was measured using an inclinometer during SLR neurodynamic testing that involved pre-positioning the ankle in plantar flexion (PF/SLR) and neutral dorsiflexion (DF/SLR). Phase 1 of the study included 20 participants where the ankle was positioned using an ankle brace replicating research testing conditions. Phase 2 included 20 additional participants where the ankle was manually positioned to replicate clinical testing conditions. RESULTS: The group average range of motion during PF/SLR was 57.1 degrees (SD: 16.8 degrees) on the left and 56.7 degrees (SD: 17.2 degrees) on the right while during DF/SLR the group average was 48.5 degrees (SD: 16.1 degrees) on the left and 48.9 degrees (SD: 16.4 degrees) on the right. The range of motion during SLR was moderately correlated to weight (-0.40 to -0.52), body mass index (-0.41 to -0.52), sex (0.40 to 0.42) and self-reported activity level (0.50 to 0.57). Intra-individual differences between limbs for range of motion during PF/SLR averaged 5.0 degrees (SD: 3.5 degrees) (95% CI: 3.8 degrees, 6.1 degrees) and during DF/SLR averaged 4.1 degrees (SD: 3.2 degrees) (95% CI: 3.1 degrees, 5.1 degrees) but were not correlated with any demographic characteristic. There were no significant differences between Phase 1 and Phase 2. CONCLUSIONS: Overall range of motion during SLR was related to sex, weight, BMI and activity level, which is likely reflected in the high variability documented. We can be 95% confident that inter-limb differences during SLR neurodynamic testing fall below 11 degrees in 90% of the general population of healthy individuals. In addition, inter-limb differences were not affected by demographic factors and thus may be a more valuable comparison for test interpretation.

The pattern of tibial nerve excursion with active ankle dorsiflexion is different in older people with diabetes mellitus.

BACKGROUND: The peripheral nervous system has an inherent capability to tolerate the gliding (excursion), stretching (increased strain), and compression associated with limb motions necessary for functional activities. The biomechanical properties during joint movements are well studied but the influence of other factors such as limb pre-positioning, age and the effects of diabetes mellitus are not well established for the lower extremity. The purposes of this pilot study were to compare the impact of two different hip positions on lower extremity nerve biomechanics during an active ankle dorsiflexion motion in healthy individuals and to determine whether nerve biomechanics are altered in older individuals with diabetes mellitus. METHODS: Ultrasound imaging was used to quantify longitudinal motion of the tibial nerve and transverse plane motion of the tibial and common fibular nerves in the popliteal fossa during active ankle movements. FINDINGS: In healthy individuals, ankle dorsiflexion created mean tibial nerve movement of 2.18 mm distally, 1.36 mm medially and 3.98 mm superficially. When the hip was in a flexed position there was a mean three-fold reduction in distal movement. In people with diabetes mellitus there was significantly less distal movement of the tibial nerve in the neutral hip position and less superficial movement of the nerve in both hip positions compared to healthy individuals. INTERPRETATION: We have documented reductions in tibial nerve excursion due to limb pre-positioning thought to pre-load the nervous system using a non-invasive methodology. Thus, lower limb pre-positioning impacts nerve biomechanics during ankle motions common in functional activities. Additionally, our findings indicate that nerve biomechanics have the potential to be altered in older individuals with diabetes mellitus compared to younger healthy individuals.

Measurement properties of a hand-held inclinometer during straight leg raise neurodynamic testing.

OBJECTIVES: The most common lower quarter neurodynamic test is the straight leg raise (SLR) test. Quantification of limb motion during SLR testing should utilize reliable and valid measurement tools that are highly sensitive to change. The purpose of this study was to determine the psychometric properties of a hand-held inclinometer commonly utilized during SLR testing. DESIGN: Cross-sectional measurement, intra-rater reliability and validity study. SETTING: Research laboratory. PARTICIPANTS: Twenty individuals without pain in their low back or extremities and no history of nerve injury participated in the study. MAIN OUTCOME MEASURES: Two repetitions of the SLR were performed in each limb in two ankle positions (plantar flexion and dorsiflexion). A digital inclinometer and digital goniometer were utilized as the comparisons for range of motion measurements. RESULTS: Intra-rater reliability for the hand-held inclinometer during SLR testing was excellent (ICCs, 0.95 to 0.98). The standard error of measurement was between 0.54° and 1.22° and the minimal detectable change was between 1.50° and 3.41°. Construct validity revealed hand-held inclinometer measurements were highly correlated with both the digital inclinometer and digital goniometer measures. The mean difference scores between hand-held inclinometer and digital inclinometer (∼1.5°) and digital goniometer (∼10°) suggest that the hand-held inclinometer better matches the construct measured by the digital inclinometer (limb elevation angle) compared to the digital goniometer (hip flexion angle). CONCLUSIONS: The hand-held inclinometer is a valid method for measuring limb elevation angle during the SLR neurodynamic test in a research setting. The hand-held inclinometer has high reliability and low minimal detectable change when used in healthy individuals.

Peripheral nerve: from the microscopic functional unit of the axon to the biomechanically loaded macroscopic structure.

Peripheral nerves are composed of motor and sensory axons, associated ensheathing Schwann cells, and organized layers of connective tissues that are in continuity with the tissues of the central nervous system. Nerve fiber anatomy facilitates conduction of electrical impulses to convey information over a distance, and the length of these polarized cells necessitates regulated axonal transport of organelles and structural proteins for normal cell function. Nerve connective tissues serve a protective function as the limb is subjected to the stresses of myriad limb positions and postures. Thus, the tissues are uniquely arranged to control the local nerve fiber environment and modulate physical stresses. In this brief review, we describe the microscopic anatomy and physiology of peripheral nerve and the biomechanical properties that enable nerve to withstand the physical stresses of everyday life.

The influence of scapular depression on upper limb neurodynamic test responses.

OBJECTIVES: Upper limb neurodynamic testing (ULNT) can be used clinically to assist in identifying neural tissue involvement in patients with upper quarter pain and dysfunction. Consideration for scapular positioning is a crucial component of ULNT standardization, as variations in positioning may dramatically impact sensory and motor responses. This study aimed to determine if there was a meaningful difference in test outcomes when the ULNT was performed in alternative scapular positions. METHODS: This cross-sectional study included 40 asymptomatic individuals. Repeated ULNT testing was performed on the dominant limb with the scapula blocked in neutral (ULNTb) and in scapular depression (ULNTd). Sensory responses, muscle activity, and range of motion outcomes were compared between the two test variations. RESULTS: Pre-positioning in scapular depression (ULNTd) led to reduced elbow extension range of motion, provoked greater upper trapezius muscle activity and an earlier onset and broader area of sensory responses compared to ULNTb. DISCUSSION: During ULNTb, the limbs were taken further into range and elicited reduced muscle activation and more localized sensory response providing a less vigorous version of the test. This study demonstrates that scapular positioning has a meaningful impact on ULNT test outcomes in healthy, asymptomatic individuals. The ULNTd can be considered a more vigorous version that may be appropriate when the cervical motions commonly utilized for structural differentiation are limited or contraindicated.

Common interlimb asymmetries and neurogenic responses during upper limb neurodynamic testing: implications for test interpretation.

STUDY DESIGN: Clinical measurement pilot study. INTRODUCTION: Upper limb neurodynamic testing (ULNT1) uses interlimb comparisons to investigate nerve sensitivity to movement. PURPOSE OF THE STUDY: To establish the magnitude of range of motion asymmetries between limbs and the frequency of neurogenic sensory responses during ULNT1. METHODS: Elbow extension range of motion (EE-ROM) and sensory responses were measured during ULNT1 in dominant and nondominant limbs for 40 asymptomatic participants. Structural differentiation was performed to examine if sensory responses were associated with neurogenic sources. RESULTS: The average intraindividual EE-ROM asymmetry was 7.28 deg (6.68 standard deviation) (95% confidence interval: 5.18, 9.28). Sensory responses in the limbs during ULNT1 were altered by structural differentiation in 95% of participants. An intraindividual, interlimb difference of ≥10 deg exceeds the range of common asymmetry during ULNT1. CONCLUSIONS: Neurogenic sensory responses are common findings in healthy individuals and should be acknowledged when interpreting ULNT1 findings. LEVEL OF EVIDENCE: 3a.

Mechanosensitivity during lower extremity neurodynamic testing is diminished in individuals with Type 2 Diabetes Mellitus and peripheral neuropathy: a cross sectional study.

BACKGROUND: Type 2 Diabetes Mellitus (T2DM) and diabetic symmetrical polyneuropathy (DSP) impact multiple modalities of sensation including light touch, temperature, position sense and vibration perception. No study to date has examined the mechanosensitivity of peripheral nerves during limb movement in this population. The objective was to determine the unique effects T2DM and DSP have on nerve mechanosensitivity in the lower extremity. METHODS: This cross-sectional study included 43 people with T2DM. Straight leg raise neurodynamic tests were performed with ankle plantar flexion (PF/SLR) and dorsiflexion (DF/SLR). Hip flexion range of motion (ROM), lower extremity muscle activity and symptom profile, intensity and location were measured at rest, first onset of symptoms (P1) and maximally tolerated symptoms (P2). RESULTS: The addition of ankle dorsiflexion during SLR testing reduced the hip flexion ROM by 4.3° ± 6.5° at P1 and by 5.4° ± 4.9° at P2. Individuals in the T2DM group with signs of severe DSP (n = 9) had no difference in hip flexion ROM between PF/SLR and DF/SLR at P1 (1.4° ± 4.2°; paired t-test p = 0.34) or P2 (0.9° ± 2.5°; paired t-test p = 0.31). Movement induced muscle activity was absent during SLR with the exception of the tibialis anterior during DF/SLR testing. Increases in symptom intensity during SLR testing were similar for both PF/SLR and DF/SLR. The addition of ankle dorsiflexion induced more frequent posterior leg symptoms when taken to P2. CONCLUSIONS: Consistent with previous recommendations in the literature, P1 is an appropriate test end point for SLR neurodynamic testing in people with T2DM. However, our findings suggest that people with T2DM and severe DSP have limited responses to SLR neurodynamic testing, and thus may be at risk for harm from nerve overstretch and the information gathered will be of limited clinical value.

Mechanosensitivity of the lower extremity nervous system during straight-leg raise neurodynamic testing in healthy individuals.

STUDY DESIGN: Cross-sectional, observational study. OBJECTIVES: To explore how ankle position affects lower extremity neurodynamic testing. BACKGROUND: Upper extremity limb movements that increase neural loading create a protective muscle action of the upper trapezius, resulting in shoulder girdle elevation during neurodynamic testing. A similar mechanism has been suggested in the lower extremities. METHODS: Twenty healthy subjects without low back pain participated in this study. Hip flexion angle and surface electromyographic measures were taken and compared at the onset of symptoms (P1) and at the point of maximally tolerated symptoms (P2) during straight-leg raise tests performed with ankle dorsiflexion (DF-SLR) and plantar flexion (PF-SLR). RESULTS: Hip flexion was reduced during DF-SLR by a mean +/- SD of 5.5 degrees +/- 6.6 degrees at P1 (P = .001) and 10.1 degrees +/- 9.7 degrees at P2 (P<.001), compared to PF-SLR. DF-SLR induced distal muscle activation and broader proximal muscle contractions at P1 compared to PF-SLR. CONCLUSION: These findings support the hypothesis that addition of ankle dorsiflexion during straight-leg raise testing induces earlier distal muscle activation and reduces hip flexion motion. The straight-leg test, performed to the onset of symptoms (P1) and with sensitizing maneuvers, allows for identification of meaningful differences in test outcomes and is an appropriate end point for lower extremity neurodynamic testing.

Deviations in gait pattern in experimental models of hindlimb paresis shown by a novel pressure mapping system.

Injuries to the central and peripheral nervous system result in varying degrees of paresis and as such alter gait. We developed novel quantitative measures to assess compensatory patterns of gait in experimental models of unilateral and bilateral hindlimb paresis. We hypothesized that hindlimb paresis results in unique alterations in the gait cycle that reflect the symmetry of the initial lesion. To test this hypothesis, adult, male Sprague-Dawley rats were subjected to a unilateral sciatic nerve crush injury or a moderately severe spinal cord contusion injury at T8. Kinematic and timing parameters were captured simultaneously in all four limbs and alterations in gait were then compared to relevant sham controls. Gait analysis consisted of walking trials through a gait tunnel positioned over a Tekscan pressure sensor grid. After sciatic nerve injury, animals unweighted the injured limb by shifting their center of mass toward the contralateral forelimb and hindlimb. These changes in weight-bearing occurred simultaneously with an increase in stance time on the contralateral limbs. As might be expected spinal cord injured animals unweighted their hindlimbs, as shown by reduced hindlimb contact force and contact pressure. These adjustments coincided with a shortening of forelimb stance time and stride length. These findings show both alterations and compensatory changes in gait that reflect the symmetry of the initial injury.

Structure and biomechanics of peripheral nerves: nerve responses to physical stresses and implications for physical therapist practice.

The structural organization of peripheral nerves enables them to function while tolerating and adapting to stresses placed upon them by postures and movements of the trunk, head, and limbs. They are exposed to combinations of tensile, shear, and compressive stresses that result in nerve excursion, strain, and transverse contraction. The purpose of this appraisal is to review the structural and biomechanical modifications seen in peripheral nerves exposed to various levels of physical stress. We have followed the primary tenet of the Physical Stress Theory presented by Mueller and Maluf (2002), specifically, that the level of physical stress placed upon biological tissue determines the adaptive response of the tissue. A thorough understanding of the biomechanical properties of normal and injured nerves and the stresses placed upon them in daily activities will help guide physical therapists in making diagnoses and decisions regarding interventions.

Strain and excursion in the rat sciatic nerve during a modified straight leg raise are altered after traumatic nerve injury.

PURPOSE: This study investigated the biomechanics of the sciatic nerve with hind limb positioning in live and euthanized Sprague-Dawley rats after traumatic nerve injury. METHODS: With radiographic analysis, sciatic nerve excursion and strain were measured in situ during a modified straight leg raise, which included sequential hip flexion and ankle dorsiflexion. Comparisons were made between nerves in uninjured, sham-injured and mild crush-injured rats at the 7-day and 21-day recovery times. RESULTS: Significant strain and proximal excursion of the sciatic nerve were observed in all groups during hip flexion, and additional increased strain was noted during dorsiflexion. Seven days after nerve injury, strain increased significantly during hip flexion (17.64+/-14.12%; p=0.0091) and dorsiflexion (22.56+/-15.47%; p=0.0082) compared to the sham-injured controls. At 21 days after injury, the strains were similar between the injured and sham-injured groups. CONCLUSIONS: Nerve bed elongation during straight leg raise causes sciatic nerve strain and excursion towards the moving joint with the greatest movement nearest the moving joint. In the first week after injury, the maximal strain exceeded the level previously shown to impair nerve conduction and circulation.