[Phantom phenomena during regional anesthesia].

Phantom phenomena were studied following the administration of peridural (PDA), spinal (SA) and brachial plexus anaesthesia (PB) to 200 patients undergoing a peripheral surgical procedure. 18% of the subjects in PDA, 40% in SA and 63% in the PB group reported a typical, phantom of lower, respect. upper extremities as already described in the literature. Various additional (atypical) forms of phantoms were observed: 10% in PDA, 24% in SA and 6% in PB group. Sex, age, tourniquet, premedication and type of local anaesthetic did not influence substantially the occurrence of phantom. The latter was however directly related to the total dose (mg) of local anaesthetic administered. The appearance of phantom was not always a guarantee of successful block. The possible mechanisms of painless phantoms are discussed.