[Report of 2 cases of irreversible Horner syndrome after puncture of the internal jugular vein].

Two cases are presented with irreversible Horner's syndrome after cannulation of the internal jugular vein during the intraoperative period. In the first case the cannulation succeeded only after several attempts. In the second case the cannulation succeeded the first time. All cannulations were performed by experienced anaesthesiologists. This means, that a strict indication for the cannulation of the internal jugular vein must be considered, because of the possibility of irreversible damage, even if the cannulation is performed by an experienced physician.