To the Editor:—A recent case report [1] suggests that the plea by Lanier and Warner that the anesthesia community discontinue its use of the term “compliance” in connection with the intracranial space has been heard. [2] Others who predicted that the misuse of the term compliance was too “well entrenched” to be changed have been proved wrong. [3] Elastance (elastance Delta P/Delta V) is the correct term when referring to the pressure changes that occur inside the cranium in response to changes in the volume of the intracranial contents, and compliance (compliance Delta V/Delta P), the inverse of elastance, is incorrect. However, the report by Sperry et al. suggests that we are experiencing some growing pains as we evolve toward the more appropriate use of terminology. [1] Sperry et al. begin with the premise that patients with a cerebrospinal fluid leak after dural puncture may coincidentally have intracranial pathology and that they “may have decreased intracranial elastance … and may be at risk for developing increased intracranial pressure when a mass effect is produced in the spinal epidural space during epidural blood patch.” The problem, of course, is one of increased elastance rather than decreased elastance. This may seem like a small matter to present to the correspondence section of an important journal, but the fact that the error passed by three authors, several reviewers, the Editor-in-Chief, and one or two copy editors suggests that our community is not accustomed to the use of this terminology and that a significant potential for miscommunication exists while we adapt to it.

John C. Drummond, M.D., Professor of Anesthesiology, University of California, San Diego, Anesthetist-in-Chief, VA Medical Center, San Diego, 3350 La Jolla Village Drive, San Diego, California 92161.

(Accepted for publication February 23, 1995.)


Sperry RJ, Gartrell A, Johnson JO: Epidural blood patch can cause acute neurologic deterioration. ANESTHESIOLOGY 82:303-305, 1995.
Lanier WI, Warner DO: Intracranial elastance versus intracranial compliance: Terminology should agree with that of other disciplines [letter]. ANESTHESIOLOGY 77:403-404, 1992.
Drummond JC, Shapiro HM: Cerebral physiology, Anesthesia. Anesthesia, 3rd edition. Edited by Miller RD, New York, Churchill Livingston, 1990. p. 630.