Neurodynamic testing of the suprascapular nerve: An observational cadaveric study.

Background: Suprascapular neurodynamic tests are used to clinically test for suprascapular nerve mechanosensitivity. Various tests described in the literature are proposed to induce suprascapular nerve mechanical strain but their potential effects on nerve strain have not been established.

Methods: This observational cadaveric study used biomechanical measurements to evaluate and compare the strain undergone by the suprascapular nerve during five different neurodynamic positions: (1) Cervical contralateral rotation and scapular retraction; (2) Cervical contralateral sidebending + shoulder girdle depression; (3) Shoulder girdle depression, retraction, posterior tilt and downward rotation; (4) Position 3 + contralateral cervical sidebending; and (5) Scapular protraction + Cervical contralateral sidebending (protraction sidebending test). Suprascapular nerve strains were measured using two differential transducers, one placed before the nerve entry by the suprascapular notch (prescapular portion) and the second after the spine of the scapula in the infraspinal fossa (scapular portion).

Findings: Prescapular portion: all 5 positions induced a mean strain increase of 22.70 % (95 %CI 17.14, 28.26) with no significant differences between positions (p > 0.05). Scapular portion: the protraction sidebending test provoked the highest strain increase of 8.99 % (95 %CI 6.83, 11.15), significantly greater than the other positions (p < 0.05).

Interpretation: All 5 positions increased suprascapular nerve strain of the prescapular portion of the suprascapular nerve. The protraction sidebending test induced the highest strain of the scapular portion of the nerve. As it is likely to influence both portions of the suprascapular nerve, the protraction sidebending test is the most suitable neurodynamic test to test for suprascapular heightened mechanosensitivity.