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April 1965

A Sign of Intracranial Mass With Impending Uncal Herniation

Author Affiliations

From the Division of Neurology, Department of Medicine, University of Rochester School of Medicine and Dentistry. Associate Professor of Neurology (Dr. Norris); formerly USPHS Fellow in Psychiatry (Dr. Fawcett).

Arch Neurol. 1965;12(4):381-386. doi:10.1001/archneur.1965.00460280051003

Introduction  AMASS lesion of the brain may increase the intracranial pressure and distort normal anatomical relationships. The well-known syndrome of ipsilateral dilatation of the pupil and contralateral hemiplegia is associated with actual or incipient uncal herniation, and thus might indicate compression of the oculomotor nerve or the midbrain.1-3 Sometimes there is an initial miosis which might be due to hyperexcitability early in the course of compression; mydriasis develops later and could reflect loss of function from further compression.4-6A nonreactive, dilated pupil ipsilateral to a mass lesion was first described by Hutchinson in 1867.7 A curious historical footnote is that later he emphasized bilateral mydriasis, and in 1898 wrote about "the non-significance of a (unilateral) fixed and dilated pupil."8 MacEwen9 should be credited with an early correlation of unilateral mydriasis with a mass lesion and, significantly, loss of consciousness.The purpose of this article is

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