OPTIMAL POSITIONING FOR CERVICAL IMMOBILIZATION

Study objective: We hypothesized that optimal positioning of the head and neck to protect the spinal cord during cervical spine immobilizati on can be determined with reference to external landmarks. In this stu dy we sought to determine the optimal position for cervical spine immo bilization using magnetic resonance imaging (MRI) and to define this o ptimal position in a clinically reproducible fashion. Methods: Our sub jects were 19 healthy adult volunteers (11 women, 8 men). In each, we positioned the head to produce various degrees of neck flexion and ext ension. This positioning was followed by quantitative MRI of the cervi cal spine. Results: The mean ratio of spinal canal and spinal cord cro ss-sectional areas was smallest at C6 but exceeded 2.0 at all levels f rom C2 to T1 (P<.05). At the C5 and C6 levels, the maximal area ratio was most consistently obtained with slight flexion (cervical-thoracic angle of 14 degrees) (P<.05). For a patient lying flat on a backboard, this corresponds to raising the occiput 2 cm. More extreme flexion or extension produced variable results. Conclusion: In healthy adults, a slight degree of flexion equivalent to 2 cm of occiput elevation prod uces a favorable increase in spinal canal/spinal cord ratio at levels C5 and C6, a region of frequent unstable spine injuries.