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tractotomy

[trăk-tŏt′ə-mē]
n.
  1. Incision of a nerve tract in the brainstem or spinal cord, usually for the relief of pain.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.