Do ‘sliders’ slide and ‘tensioners’ tension? An analysis of neurodynamic techniques and considerations regarding their application

Effects of upper extremity neural mobilization on thermal pain sensitivity: a sham-controlled study in asymptomatic participants

STUDY DESIGN

A single-blinded, quasi-experimental, within- and between-sessions assessment.

OBJECTIVES

To investigate potential mechanisms of neural mobilization (NM), using tensioning techniques in comparison to sham NM on a group of asymptomatic volunteers between the ages of 18 and 50.

BACKGROUND

NM utilizing tensioning techniques is used by physical therapists in the treatment of patients with cervical and/or upper extremity symptoms. The underlying mechanisms of potential benefits associated with NM tensioning techniques are unknown.

METHODS AND MEASURES

Participants (n = 62) received either a NM or sham NM intervention 2 to 3 times a week for a total of 9 sessions, followed by a 1-week period of no intervention to assess carryover effects. A-delta (first pain response) and C-fiber (temporal summation) mediated pain perceptions were tested via thermal quantitative sensory testing procedures. Elbow extension range of motion (ROM) and sensory descriptor ratings were obtained during a neurodynamic test for the median nerve. Data were analyzed with repeated-measures analysis of variance (ANOVA).

RESULTS

No group differences were seen for A-delta mediated pain perception at either immediate or carryover times. Group differences were identified for immediate C-fiber mediated pain perception (P = .032), in which hypoalgesia occurred for the NM group but not the sham NM group. This hypoalgesic effect was not maintained at carryover (P = .104). Group differences were also identified for the 3-week and carryover periods for elbow extension ROM (P = .004), and for the participant sensory descriptor ratings (P = .018), in which increased ROM and decreased sensory descriptor ratings were identified in participants in the NM group but not the sham NM group.

CONCLUSION

This study provides preliminary evidence that mechanistic effects of tensioning NM differ from sham NM for asymptomatic participants. Specifically, NM resulted in immediate, but not sustained, C-fiber mediated hypoalgesia. Also, NM was associated with increased elbow ROM and a reduction in sensory descriptor ratings at 3-week and carryover assessment times. These differences provide potentially important information on the mechanistic effects of NM, as well as the description of a sham NM for use in future clinical trials.

Different nerve-gliding exercises induce different magnitudes of median nerve longitudinal excursion: an in vivo study using dynamic ultrasound imaging

STUDY DESIGN

Controlled laboratory study using single-group, within-subject comparisons.

OBJECTIVES

To determine in an in vivo study whether different types of nerve-gliding exercises are associated with different amounts of longitudinal nerve excursion.

BACKGROUND

Different types of nerve-gliding exercises have been proposed. It is assumed that different exercises produce different amounts of excursion and strain in the peripheral nervous system. Although this has been confirmed in cadaveric experiments, in vivo studies are lacking.

METHODS

High-resolution ultrasound was used to measure longitudinal excursion of the median nerve in the upper arm during 6 different nerve-gliding exercises. Nerve mobilization techniques that involved the elbow and neck were evaluated in 15 asymptomatic volunteers (mean +/- SD age, 30 +/- 8 years). Nerve longitudinal excursion was calculated using a frame-by-frame cross-correlation analysis. A repeated-measures analysis of variance was used to analyze the data.

RESULTS

Different exercises induced different amounts of longitudinal nerve excursion (P<.0001). The "sliding technique" was associated with the largest excursion (mean +/- SD, 10.2 +/- 2.8 mm; P = .0001). The amount of nerve movement associated with the "tensioning technique" (mean +/- SD, 1.8 +/- 4.0 mm) was smaller than the nerve excursion induced with individual movements of the neck or elbow (mean +/- SD range, -3.4 +/- 0.9 to 5.6 +/- 2.1 mm; P = .0001).

CONCLUSION

These findings confirm that different types of neurodynamic techniques have different mechanical effects on the nervous system. Recognition of these differences may assist in the selection of treatment techniques. Having demonstrated differences in mechanical effects, future research will have to evaluate whether these different techniques are also associated with different physiological and therapeutic effects.

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

Background

Clinical 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.

Methods

Two 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.

Results

We 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).

Conclusion

This 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.

Surgical and therapeutic management of a complete proximal hamstring avulsion after failed conservative approach

STUDY DESIGN

Case report.

BACKGROUND

After 2 attempts at conservative care for a diagnosis of hamstring strain, the patient had a surgical hamstring allograft reconstruction. The purpose of this report is to describe the physical therapy approach to postoperative management of a hamstring reconstruction.

CASE DESCRIPTION

A 24-year-old female coach who sustained a complete avulsion of the proximal hamstring tendon while playing softball had a surgical hamstring reconstruction using an Achilles tendon allograft. Precautions concerning range of motion and stretching, weight-bearing status, and brace were followed to protect the surgical graft. Treatment incorporated cardiovascular, strength and proprioception exercises, and progressed with the focus on correct movement patterns and eccentric muscle control during functional movements.

OUTCOMES

The patient attended 25 physical therapy sessions over 7 months. Muscle strength improved from 4/5 to 5/5. Straight-leg raise range of motion decreased from 145 degrees to 90 degrees . Lower Extremity Functional Scale (LEFS) scores improved from 15/80 to 70/80.

DISCUSSION

A complete avulsion of the proximal insertion is rare. Conservative management of hamstring tears has traditionally focused on end-range passive stretching, modalities, and direct hamstring strengthening. New evidence recommends a program that is more protective of the injured tissue and includes exercises such as core stabilization; indirect hamstring strengthening may be beneficial in the treatment of hamstring injuries. This concept was taken into account when considering the rehabilitation protocol and progression for this patient.

LEVEL OF EVIDENCE

Therapy, level 4.

Strain in the Tibial and Plantar Nerves with Foot and Ankle Movements and the Influence of Adjacent Joint Positions

We studied the influence of different positions in neighboring joints on strain in the tibial and plantar nerves during ankle and toe movements. Tibial nerve strain at the ankle was measured during ankle dorsiflexion in ten cadavers; plantar nerve strain was measured during toe extension. Tibial nerve strain increased with ankle dorsiflexion (mean increase: 3.9%) and strain was higher when the nervous system was pretensioned by either knee extension or hip flexion (p ≤ .011). Strain was even higher when the nerve bed was elongated at both the hip and knee (p ≤ .006) before performing dorsiflexion. A similar trend was observed for the plantar nerves with ankle positioning. In conclusion, the change in nerve strain is strongly influenced by positions in neighboring joints. This insight into nerve biomechanics provides a foundation for progressive mobilization exercises for disorders such as tarsal tunnel syndrome.