Case series: Ultrasonography may assist epidural insertion in scoliosis patients

Epidural cannulation is a difficult technique in the patient undergoing scoliosis repair, due to axial rotation of the vertebral bodies, as well as angulation of the spinal processes. This case series was performed to investigate whether ultrasonography could facilitate epidural insertion in patients with scoliosis, by assessing the degree of vertebral body rotation.

Eleven patients scheduled for corrective scoliosis surgery were studied. The spine was examined ultrasonically using a portable ultrasound system with a 38-mm linear probe in two-dimensional B mode. The angulation of the probe head (measured using an inclinometer held in alignment with its long axis) at which the echo signals from the laminae became level on the screen was taken to correspond to the degree of vertebral rotation. The least rotated (most neutral) vertebral interspace was located, and a supervised anesthesiology trainee then performed epidural catheter insertion, using a loss-of-resistance technique. Bupivacaine 0.125% with fentanyl 4 mug.mL(-1) was infused after surgery, and successful epidural placement was indicated by the presence of effective analgesia and loss of sensation to cold stimuli. In ten patients, the neutral space could be identified, while in one, the least rotated space was measured at 15 degrees from the horizontal. Epidural catheterization was successful in eight of 11 patients at the identified level. In two other patients, the space above was employed. The information was described as helpful in seven patients.

We conclude that ultrasonography may have a potential role to facilitate insertion of epidural catheters in patients with scoliosis.