Background: The loss-of-resistance test is the most popular method for identifying the epidural space, but it cannot confirm epidural puncture. Therefore, we developed a new method to confirm epidural puncture by assessing indirect changes in epidural pressure using the Queckenstedt-test procedure, which increases subarachnoid pressure by compressing the internal jugular veins. Because this new method depends on the dynamics of cerebrospinal fluid, blockade of cerebrospinal fluid flow, as with severe spinal stenosis, is predicted to reduce changes in epidural pressure. Thus, in this study, we examined the effect of spinal stenosis on the Queckenstedt-test procedure.
Methods: Epidural puncture using the loss-of-resistance test was utilized to insert an electrode in patients undergoing cervical spine surgery. Epidural pressure was monitored during bilateral compression of the internal jugular veins to confirm epidural puncture. The insertion of the electrode into the epidural space was confirmed by observation of muscle twitch evoked by electric stimulation.
Results: In 60 patients, epidural puncture was performed with the loss-of-resistance test; a second trial was required in 13 patients. Increased epidural pressure was observed in 57/73 trials. When increased epidural pressure was observed, epidural puncture was always successful. The sensitivity and specificity of this method was 92.0% and 100%, respectively. The positive and negative predictive values were 100% and 66.7%, respectively.
Conclusion: An increase in epidural pressure during bilateral compression of the internal jugular veins could offer a reliable method for confirming epidural puncture in combination with the loss-of-resistance test, even if patients have potential spinal canal narrowing.