Background: Insertion of a needle into the lumbar subarachnoid space may cause damage to the spinal cord. Current techniques to identify a safe interspace have limitations. Ultrasound was investigated as a means to improve anatomical accuracy.
Methods: Seventeen patients attending for elective magnetic resonance imaging (MRI) of the spine were studied. Ultrasonic identification of the L3-4 interspace was attempted by an anaesthetist and a marker was placed. A radiologist identified the anatomical location of the marker on the MRI scan.
Results: Thirteen out of 17 markers were at the L3-4 interspace; four were at the L2-3 interspace.
Conclusions: These results suggest that ultrasonography may be a useful adjunct to safe subarachnoid anaesthesia.