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Open Access Research article

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

Benjamin S Boyd1, Linda Wanek2, Andrew T Gray3 and Kimberly S Topp45*

Author Affiliations

1 Assistant Professor at Samuel Merritt University, Department of Physical Therapy, 450 30th Street, Oakland, CA 94609, USA

2 Professor and Director of Physical Therapy at San Francisco State University, Department of Physical Therapy, 1600 Holloway, Gym 105, San Francisco, CA 94132, USA

3 Associate Professor in Residence at the University of California, San Francisco, Department of Anesthesia, Box 1371, 1001 Potrero Ave, San Francisco General Hospital, CA. 94143-1371, USA

4 Professor and Director of Physical Therapy at the University of California, San Francisco, Graduate Program in Physical Therapy, 1318 7th Avenue, Box 0736, San Francisco, CA 94143-0736, USA

5 Professor in the Department of Anatomy, Box 0452, San Francisco, CA 94143-0452, USA

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BMC Neurology 2010, 10:75  doi:10.1186/1471-2377-10-75

Published: 28 August 2010

Abstract

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.