A loss-of-resistance-to-negative-pressure test for subarachnoid puncture with narrow-gauge needles.

Background And Objectives: Approximately 5-10% of attempted myelograms are spoiled by partial subdural injection. Similar spillage of local anesthetics may underlie the wide variability of segmental spread reported for spinal anesthesia. A technique of applied negative pressure to avoid accidental subdural injection and to facilitate subarachnoid puncture with narrow gauge needles is described.