Differential movement of the sciatic nerve and hamstrings during the straight leg raise with ankle dorsiflexion: Implications for diagnosis of neural aspect to hamstring disorders

Effect of cervical contralateral lateral flexion on the median nerve and fascia at the wrist - Cadaveric study

BACKGROUND

Neurodynamic tests are an essential aspect of the physical examination of the patient when suspicion of neural involvement exists. A manoeuvre that is hypothesised to move nerves differentially relative to other structures (structural differentiation) has been proposed as a necessary part of neurodynamic testing for differential diagnosis. However, although the specificity of structural differentiation for peripheral nerve over muscle has been demonstrated in some body regions, no study has tested specificity of nerve movement relative to fascia.

OBJECTIVES

The aim of this study was to measure the effect of the cervical contralateral lateral flexion (CCLF) as an structural differentiation manoeuvre for the median nerve compared to fascia (superficial and deep) at the wrist during the upper limb neurodynamic test 1 (ULNT1).

DESIGN

A cross-sectional study was performed in 5 fresh frozen cadavers.

METHODS

Excursion and strain in the fascia (superficial and deep) and the median nerve were measured at the wrist with structural differentiation during the ULNT1. KINOVEA software was used to measure kinematic parameters.

RESULTS

CCLF resulted in significant proximal excursion in the median nerve (p < 0.001*) but not in the strain. CCLF neither produced changes in strain nor excursion in the superficial and deep fascia (p > 0.05).

CONCLUSION

This study showed that CCLF produced significant differential excursion in the median nerve at the wrist compared to the local superficial and deep fascia during the ULNT1. The data support CCLF in mechanical differentiation between nerve and fascia in this area in diagnosis of local sources of wrist pain.

Short-Term Effects of Three Types of Hamstring Stretching on Length, Neurodynamic Response, and Perceived Sense of Effort-A Randomised Cross-Over Trial

Background: Stretching techniques for hamstring muscles have been described both to increase muscle length and to evaluate nerve mechanosensitivity. Aim: We sought to evaluate the short-term effects of three types of hamstring stretching on hamstring length and report the type of response (neural or muscular) produced by ankle dorsiflexion and perceived sense of effort in asymptomatic subjects. Methods: A randomised cross-over clinical trial was conducted. A total of 35 subjects were recruited (15 women, 20 men; mean age 24.60 ± 6.49 years). Straight leg raises (SLR), passive knee extensions (PKE), and maximal hip flexion (MHF) were performed on dominant and non-dominant limbs. In addition, the intensity of the applied force, the type and location of the response to structural differentiation, and the perceived sensation of effort were assessed. Results: All stretching techniques increased hamstring length with no differences between limbs in the time*stretch interaction (p < 0.05). The perceived sensation of effort was similar between all types of stretching except MHF between limbs (p = 0.047). The type of response was mostly musculoskeletal for MHF and the area of more neural response was the posterior knee with SLR stretch. Conclusions: All stretching techniques increased hamstring length. The highest percentage of neural responses was observed in the SLR stretching, which produced a greater increase in overall flexibility.

Extending the straight leg raise test for improved clinical evaluation of sciatica: validity and diagnostic performance with reference to the magnetic resonance imaging

BACKGROUND

The straight leg raise test (SLR) is one of the most utilized and studied physical tests in patients with low back pain (LBP) for the detection of lumbar disc herniation (LDH), showing high sensitivity and heterogeneous or low specificity. The high incidence of asymptomatic 'pathologic' findings in the magnetic resonance imaging (MRI) scans may cause verification bias to these results. We studied an extended SLR (ESLR) by adding location-specific structural differentiation movements (hip internal rotation or ankle dorsiflexion) to the traditional SLR for it to better differentiate neural symptoms from musculoskeletal. Previously, the ESLR has shown almost perfect interrater reliability between examiners and ability to detect sciatic patients. In this study, we investigated whether a 'positive' ESLR finding is associated with pathology seen on MRI.

METHODS

Forty subjects comprised the study population, 20 in sciatic group and 20 in control group. The ESLR was performed 'blinded' to the subjects. After the ESLR, each subject's lumbar MRI was evaluated. The MRIs were analyzed independently by 2 senior radiologists and a spine specialist clinician. The ESLR and MRI results were cross-tabulated. To obtain the odds ratio (OR) with positive ESLR or SLR results for LDH or nerve root compression (NC), a binary logistic regression analysis with subjects' age, gender, height and weight was performed. ESLR's validity was assessed by combination of interrater agreement and percentage prevalence of both LDH and NC.

RESULTS

Of sciatic (ESLR+) patients, 85 % had LDH and 75 % NC in the MRI. Not surprisingly, MRI showed a very high incidence of 'false-positive' findings with the ESLR negative group. The ESLR showed 0.85 sensitivity and 0.45 specificity for LDH and 0.75 sensitivity and 0.50 specificity for NC. A positive result in the ESLR was found to be strongly associated with for both LDH and NC: the OR was 8.0 (p = 0.028) and 5.6 (p = 0.041), respectively.

CONCLUSIONS

The ESLR shows high validity in detecting neural symptoms and is strongly associated with pathology seen in the MRI when judged positive. We suggest the use of ESLR in clinical practice as a part of clinical examination, where it may prove to be a valuable tool in detecting patients with sciatic symptoms.

Extending the straight leg raise test for improved clinical evaluation of sciatica: reliability of hip internal rotation or ankle dorsiflexion

Background

The straight leg raise (SLR) is the most commonly applied physical tests on patients with sciatica, but the sensitivity and specificity ratings for disc hernia and neural compression leave areas for improvement. Hip internal rotation tensions the lumbosacral nerve roots and ankle dorsiflexion tensions the sciatic nerve along its course. We added these movements to the SLR (extended SLR = ESLR) as structural differentiators and tested inter-rater reliability in patients with LBP, with and without sciatica.

Methods

Forty subjects were recruited to the study by the study controller (SC), 20 in the sciatic group and in the control group. Two independent examiners (E1&E2) performed the ESLR and did not communicate to the subjects other than needed to determine the outcome of the ESLR. First, SLR was performed traditionally until first responses were evoked. At this hip flexion angle, a location-specific structural differentiation was performed to confirm whether the emerged responses were of neural origin. Cohen’s Kappa score (CK) for interrater reliability was calculated for ESLR result in detection of sciatic patients. Also, the examiners’ ESLR results were compared to the traditional SLR results.

Results

The interrater agreement between Examiner 1 and Examiner 2 for the ESLR was 0.85 (p < 0.001, 95%CI: 0.71–0.99) translating to almost perfect agreement as measured by Cohen’s Kappa When the ESLR was compared to the traditional SLR, the overall agreement rate was 75% (30/40). Kappa values between the traditional SLR and the E1’s or E2’s ESLR results were 0.50 (p < 0.0001; 95%CI 0.27–0.73) and 0.54 (p < 0.0001; 95%CI 0.30–0.77), respectively.

Conclusions

ESLR with the addition of location-specific structural differentiation is a reliable and repeatable tool in discerning neural symptoms from musculoskeletal in patients with radiating low back pain. We recommend adding these movements to the standard SLR with aim of improving diagnostic ability.

Effect of cervical contralateral lateral flexion on displacement and strain in the median nerve and flexor digitorum superficialis at the wrist during the ULNT1 - Cadaveric study

INTRODUCTION

A key issue in neurodynamic testing is whether a manoeuvre designed to produce differential biomechanical behaviour (structural differentiation) of nerve compared to adjacent muscle is mechanically accurate. The aim of this study was to investigate the capacity of cervical contralateral lateral flexion to produce differential biomechanical behaviour of the median nerve at the wrist (mechanical specificity) in relation to the adjacent muscle (flexor digitorum superficialis) at different ranges of upper limb neurodynamic test 1 in cadavers.

MATERIAL AND METHODS

A cross-sectional study was carried out. In fresh frozen cadavers, with microstrain devices and Vernier calipers, strain and excursion in the median nerve and flexor digitorum superficialis muscle were measured during cervical contralateral lateral flexion at 0°, 30°, 60° and 90° of elbow flexion of the upper limb neurodynamic test 1.

RESULTS

The cervical movement resulted in proximal excursion and significant changes in strain in the median nerve at 0°, 30° and 60° of elbow flexion during the upper limb neurodynamic test 1 (p < 0.05). In contrast, the structural differentiation manoeuvre did not affect the strain nor the excursion in the muscle at any position of the elbow (p > 0.05).

CONCLUSION

Adding CCLF to each ULNT1 median elbow angle increased strain and created proximal excursion of the median nerve at the wrist. Neck movement produced no changes in strain nor excursion of the flexor digitorum superficialis. This study adds to evidence that, in certain circumstances, neck movement may be used in differentiation of nerve and muscle disorders in the wrist.