Identification of the Correct Cervical Level by Palpation of Spinous Processes

BACKGROUND: The ability to identify the correct vertebral level through examination is an important skill for clinicians who are performing nerve blocks without fluoroscopy. The conventional palpation method, which identifies the most prominent cervical spinous process as the seventh cervical (C7) spinous process is unreliable in many cases. We compared the accuracy of 2 different palpation methods used for identifying C7. METHODS: Ninety-six patients scheduled for cervical spine procedures under fluoroscopy guidance were randomized into either the control group or the flexion-extension group. The control group was examined with the conventional method, and the flexion-extension group was examined through assisted flexion and extension of the patient's cervical spine and identifying the lowest freely moving spinous process as C6 and the following stationary cervical spinous process as C7. A single anesthesiologist attempted to identify the C7 spinous process by using either the conventional method or the flexion-extension method and marked the presumed C7 spinous process with a radiopaque indicator. The actual vertebral level was then confirmed by fluoroscopy. The accuracy of the 2 different palpation techniques was compared, and the influence of patients' age, gender, and body mass index (BMI) was also examined. RESULTS: The C7 spinous process was correctly identified in 77.1% of patients in the flexion-extension group, compared with 37.5% in the control group (P < 0.001). The C6 spinous process was identified as the most prominent cervical spinous process instead of C7 in 47.9% of patients in the control group, showing that errors are more common in the cephalad direction with the conventional method. The accuracy of the flexion-extension method was significantly higher than the conventional method regardless of the patient's age, gender, and BMI. Particularly, this difference in accuracy was seen not only in patients with a BMI >= 25 kg/m(2), but also in those with a BMI >= 25 kg/m(2) (BMI < 25 kg/m(2), P = 0.006 vs BMI >= 25 kg/m2, P = 0.008). CONCLUSIONS: The flexion-extension method is more accurate than the conventional method when identifying cervical vertebral level. (Anesth Analg 2011; 112: 1232-5)