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Correspondence  |   June 2001
Phantom Limb Sensation: A Need for More Elaborated Studies
Author Notes
  • Centre Médico-chirurgical Saint-Vincent, Saint-Grégoire, France. Marc.Gentili@wanadoo.fr or mgentili@cpa-sante.com
Article Information
Correspondence
Correspondence   |   June 2001
Phantom Limb Sensation: A Need for More Elaborated Studies
Anesthesiology 6 2001, Vol.94, 1148. doi:
Anesthesiology 6 2001, Vol.94, 1148. doi:
To the Editor:—
I read with interest the article by Isaacson et al.  1 that examined phantom limb sensations during subarachnoid block. Abnormal phantom sensation has been described previously, not only during spinal 2 and epidural anesthesia 3,4 but also during brachial plexus blocks 3,4 and intravenous regional anesthesia. 4 I would like to comment on a few issues.
First, the period of clinical observation after subarachnoid injection seems to be too short to permit a full form of phantom sensations. With both epidural anesthesia and peripheral nerve blocks, phantom sensations are reported 20–30 min after the onset of anesthesia. Although the onset time of subarachnoid block is more rapid than that of these other forms of anesthesia, more information might have been gained with a longer period of observation. Second, the authors conclude that proprioceptive memory involves a dynamic neuroplastic imprinting process that is influenced by limb position before the onset of regional anesthesia, rather than the classic “fixed body” schema. 2,5 This is consistent with a previous study with spinal anesthesia in which Moriyama et al.  5 noted that the incidence of false answers was related to the perceived position of the lower limb before the block and was not influenced by subsequent general anesthesia. These authors argued that when input from the limb was blocked, the “short-term” memory became a more persistent “long-term” memory.
There is perhaps no absolute contradiction between the classic “body schema”2 and the “additive neuroplastic process.”1 The reappearance of phantom limb pain after administration of a regional anesthetic supports some role for transient deafferentation produced by the block. The “flexed” position in the “body schema” concept does not represent a position of rest but is the memory of an archaic “tetrapod” schema disinhibited by anesthesia. Regardless, understanding this process remains an exciting challenge.
References
Isaacson S, Funderburk M, Yang J: Regulation of proprioceptive memory by subarachnoid regional anesthesia. Anesthesiology 2000; 93: 55–61Isaacson, S Funderburk, M Yang, J
Prevoznick SJ, Eckenhoff JE: Phantom sensation during spinal anesthesia. Anesthesiology 1964; 25: 767–70Prevoznick, SJ Eckenhoff, JE
Bromage PR, Melzack R: Phantom limbs and the body schema. Can Anaesth Soc J 1974; 21: 267–74Bromage, PR Melzack, R
Gentili M, Bernard JM, Bonnet F, Mazoit JX: Phantom limb sensation under upper limb regional block and clinical criteria of efficiency. Anesthesiology 1999; 91: A991Gentili, M Bernard, JM Bonnet, F Mazoit, JX
Moriyama A, Takenoshita A, Kaminoh Y, Yoshikawa K: Impaired repainting of short term memory? The prior perception of leg posture is retained during spinal anesthesia. Anesthesiology 1993; 79: A813Moriyama, A Takenoshita, A Kaminoh, Y Yoshikawa, K