head-dropping test

n.
  1. A test used in the diagnosis of disease of the extrapyramidal system in which the head of a person in supine position is lifted by the examiner with one hand and allowed to fall into the other; in healthy individuals, the head falls suddenly, like a dead weight, whereas in extrapyramidal disease, it falls slowly.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.