Tics and Tourette syndrome: SAQ

Question 1 (10 marks)

Outline how you would confirm the diagnosis in this child, the features that distinguish his movements from mimics, and the investigation you would perform. (10 marks)

Model answer

Diagnosis (4 marks). The child has Tourette disorder by DSM-5 criteria. He has multiple motor tics (eye-blinking, grimacing, shoulder-shrugging) plus at least one vocal tic (throat-clearing), present for over one year (18 months), with onset before age 18, in the absence of a substance or medical cause. Motor and vocal tics need not occur at the same time, and coprolalia is not required. The diagnosis is entirely clinical, made on the history and on home video, and the family history of paternal childhood tics supports it. ^[2]

Phenomenology distinguishing a tic from mimics (4 marks). The defining features that separate his tics from stereotypies and other movement disorders are the premonitory urge, the mounting tension relieved only by the movement, the brief suppressibility with rebound, and the waxing-and-waning, body-shifting course. A stereotypy, by contrast, is rhythmic, fixed, and purposeful-appearing and lacks the urge and suppressibility. The inattentive restlessness he shows at school is the motor restlessness of comorbid attention-deficit or hyperactivity disorder, which is a separate phenomenon from his discrete tics and which coexists in about 60 per cent of children with Tourette. ^{[2] [6]}

Investigation (2 marks). No routine blood test, scan, or electroencephalogram is indicated for a child with a typical history and a normal examination; the diagnosis is clinical and over-investigation causes harm. I would request home video to confirm the movements in their natural setting and would grade severity clinically, reserving any targeted test for an atypical feature such as a focal deficit, regression, or a fixed rather than fluctuating course. ^[2]