FAILED SPINAL-ANESTHESIA - CAUSE IDENTIFIED BY MRI

Purpose: To determine the cause of failed spinal anaesthesia, magnetic resonance images of the lumbar spine were examined. Clinical futures: A 28-yr-old woman, scheduled for closure of a rectal fistula under sp inal anaesthesia, hyperbaric tetracaine 12.5 mg injected into the suba rachnoid space at L(3-4) repeatedly resulted in restricted sacral spre ad. Magnetic resonance imaging showed that the cylindrical dimension o f the lumbar spinal canal was wider than in normal subjects, suggestin g a larger volume of CSF within the dural sac below the termination of the cord. The summit of the lumbar convexity was located at L(3), whi ch was more cephalad than the L(3-4) puncture site. Conclusion: The un common anatomical characteristics of the lumbar spinal canal identifie d by magnetic resonance imaging were considered to be the reason for t he restricted sacral spread observed repeatedly in this patient.