Table 1.

Criteria for Identification of Cases as ET and ET-Plus

Classification	Criteria	%a
ET	No diagnosis of Parkinson’s Disease	100.0
	Meets criteria for one of the following:
	Diagnosis of definite ET	19.4
	Diagnosis of probable ET	50.7
	Diagnosis of possible ET	29.9
ET-Plusb	Identified as ET	100.0
	No diagnosis of Parkinson’s Disease	100.0
	Meets criteria for at least one of the following:
	Impaired tandem gait	51.9
	Impaired cognition	26.0
	Questionable dystonic posturing	17.6c
	Questionable dystonic posturing	13.0
	Mild dystonia	4.6d
	Mild neurologic signs of unknown significance	45.0e
	Intention tremor	31.3
	Rest tremor	19.8

^aPercent ET or ET-plus cases in final sample meeting each criterion

^bSee text for detailed definitions of criteria for identification of impaired tandem gait, impaired memory (i.e., impaired cognition), questionable dystonic posturing, and mild neurologic signs of unknown significance.

^cIncluding both questionable dystonic posturing and mild dystonia.

^dNo probands with mild dystonia were enrolled; thus, all ET-plus cases with mild dystonia were family members.

^eET-plus cases meeting criteria for intention tremor, rest tremor, or both.