1 From the Department of Neurology (B.C.C.), University of Michigan, Ann Arbor; and Department of Neurology (J.R.S.), University of Utah, Salt Lake City. bcallagh@med.umich.edu.
2 From the Department of Neurology (B.C.C.), University of Michigan, Ann Arbor; and Department of Neurology (J.R.S.), University of Utah, Salt Lake City.