The Phantom Limb Sensation Expressed by Spinal Anesthesia

Choi, Yoon; Lee, Phil Hwan; Leem, Joong Woo; Yoon, Mi Ja; Shin, Ji Yeon; Yang, Hong Seuk; Lee, Dong Myung

Abstract

BACKGROUND: Phantom limb sensation is an unusual position sense of the extremity during nerve block that the position of extremity is misinterpreted as being flexed, or elevated, when actually they are in neutral position. Whether it is from the fixation of proprioceptive input at the time of motor blockade or from unmasking of the pattern which has been already present in the CNS is still controversial. We perfomed this study under the assumption that phantom limb sensation can still be reproduced without the influence of position at the time of nerve blockade.
METHODS
Thirty-six patients scheduled for elective orthopedic surgery were randomly assigned. For 26 patients, spinal anesthesia was performed with hyperbaric 0.5% tetracaine or bupivacaine at lateral decubitus position and the position was changed to supine immediately. Existence of phantom limb sensation and the level of anesthesia was recorded at 10 and 20 minutes after injection of local anesthetics. For 10 patients, same local anesthetics were injected after patient's legs were straightened in lateral decubitus position.
RESULTS
Forteen out of 26 patients whose position were changed to supine immediately after the injection of local anesthetics experienced phantom limb sensations. Five out of 10 patients whose legs were kept straight before the injection of local anesthetics experienced phantom limb sensations. Previous history of trauma was positively related to the expression of phantom limb sensation.
CONCLUSION
Our data showed that the expression of phantom limb sensation is reproducible. And this was not related to the position at the time of spinal anesthesia. Trauma seems to be an important factor related to the expression of phantom limb sensation.