[Interscalenic block: accidental catheterization of the epidural space]

A case is reported of inadvertent insertion of a brachial plexus catheter into the cervical epidural space, at the sitting of an interscalene block for postoperative analgesia, during the recovery from general anaesthesia after surgical repair of a rupture of the rotator cuff of the shoulder. No features of cervical epidural anaesthesia were seen after the first injection of local anaesthetic, as it was made through the catheter insertion cannula. Once inserted, the catheter position was checked prior to the second injection of local anaesthetic. The X-ray obtained after catheter opacification showed the penetration of contrast medium into the epidural space. In our case, two out of the three means of prevention of this complication were not possible: a) sitting of the interscalene block before induction of anaesthesia, as the insertion conditions of the catheter are better in a conscious, sitting patient; b) adequate cannula orientation (namely medial, dorsal and slightly caudal); c) routine X-ray control of the catheter position before the first injection, associated with careful clinical monitoring for 30 min after each local anaesthetic injection.