Cervical spine nerve root compression. An analysis of neuroforaminal pressures with varying head and arm positions.

STUDY
DESIGN: Pressure measurements were taken in the neural foramina of C5, C6, and C7 nerve roots at various positions of the head and ipsilateral arm in eight fresh cadavers.
OBJECTIVES: The purpose of the study was to correlate clinical signs and symptoms with pressures generated in the neural foramen of patients with cervical radiculopathy. SUMMARY OF BACKGROUND DATA: The reliability of the clinical signs used to diagnose cervical disc herniations has remained controversial. Previous studies have shown the active relationship of the cord and nerve roots to the various movements of the spine.
METHODS: A standard anterior approach was made to the cervical spine and the C5-C7 roots identified. A balloon catheter, attached to a pressure transducer and monitor, was inserted in the neural foramen. The head was then taken through varying degrees of flexion and extension in combination with the arm neutral or abducted.
RESULTS: Increasing neck extension led to significant pressure changes at each root tested. With the movement of the arm from the neutral to abducted position, the pressure was significantly relieved. The results with neck flexion were variable.
CONCLUSIONS: The significance of this study is that it offers an explanation for the clinical observation of increasing radicular symptoms with neck extension and relief of these symptoms with the shoulder abduction relief maneuver in the setting of a cervical radiculopathy.