The subjective perception of abnormal movements was determined in 170 patients with various hyperkinesias at the Movement Disorders Clinic, Toronto Western Hospital, Toronto, Ontario. 102 of 110 patients with nontic disorders thought that the abnormal movements were entirely involuntary whereas 41 of 60 tic disorder patients stated that all of their motor and phonic tics were intentional or voluntary. A “voluntary response” could be used to predict the correct diagnostic category (tic versus nontic) in 8 of 9 patients for whom the initial diagnosis was incorrect. A large proportion of the motor and phonic symptoms experienced by tic patients are irresistably, but purposefully executed and resemble compulsions rather than involuntary hyperkinesias. 
COMMENT: This recategorization of tics as intentional and purposeful actions is similar to that of compulsions which may be linked genetically.