Abduction extension cervical nerve root stress test: anatomical basis and clinical relevance

While the Lasègue straight leg raising test is an established test for lumbar nerve root compression, an established equivalent for cervical nerve root compression is missing. The aim of this bi-modal study was to find the most effective way to stretch the cervical nerve roots anatomically in cadavers and to assess its value in the clinical setting.

Three positional maneuvers of the upper limb were tested on three cadavers to determine the displacement by stretch of the nerve roots C5, C6 and C7. The maneuver which was most efficient in nerve root displacement was applied in 24 patients with confirmed symptomatic cervical nerve root compression (cases) and 65 controls to assess the clinical value of the test.

The most efficient way to displace the cervical nerve roots by stretch was to apply dorsal pressure on the humeral head with the shoulder in 80° of abduction and 30° of extension, with slight elbow flexion while the head is facing the contralateral side. This maneuver produced 4-5 mm of nerve root displacement in cadavers. This test aggravated radicular symptoms in 79% of the patients with cervical nerve root compression and was negative in 98% of the controls.

The described abduction extension test with posterior push on the humeral head creates a fulcrum over which the brachial plexus can be displaced to create stress on cervical nerve roots. This simple test is easy to perform clinically and aggravates radicular symptoms in most of the patients with cervical nerve root compression while it is negative in nearly all of the controls.