Subdural placement of an epidural catheter detected by nerve stimulation.

PURPOSE

Subdural placement of an epidural catheter is rare and difficult to detect. Electrical stimulation of the epidural space can be useful to detect such an event. The purpose of the present case report is to confirm the efficacy of electrical stimulation to detect a subdural placement of an epidural catheter and to illustrate this unusual positioning by computed tomography (CT) scan images.

CLINICAL FEATURES

A 51-yr-old man was scheduled for an aorto-iliac bypass on a combined epidural and general anesthesia technique. Electrical epidural stimulation was used. A very low threshold of 0.3 mA was observed with diffuse response movement at T3 and at T10, without cerebrospinal fluid return on catheter aspiration. An injection of 12 mL of 2% lidocaine with epinephrine 1/200,000 produced signs of iv injection of local anesthetic and an extensive block. Subdural placement of the catheter, suspected by the low current threshold response to epidural catheter stimulation, was confirmed by CT scan imaging.

CONCLUSION

The present case report confirms that electrical stimulation of the epidural space is useful to detect misplacement of epidural catheter such as a subdural placement. CT scan imaging of subdural positioning of an epidural catheter is presented.