Functional tic-like presentations differ strikingly from Provisional Tic Disorder

What is it about?

In the past couple of years, many more people have come to Tourette specialty clinics. Some were typical patients, with tics since childhood, doing worse during the pandemic. Others had sudden onset of severe tic-like movements or vocalizations in the late teen years or early adult years. Many clinicians described how these patients differed from typical Tourette patients and diagnosed Functional Neurological Symptom Disorder (FND). We show that, compared to children with recent onset of what we know later turned out to be typical Tourette syndrome, these new patients differ in many ways. We quantify the differences to show that some features by themselves are enough to make one strongly doubt the possibility of eventually diagnosing Tourette syndrome (TS). Others may be significantly different between groups but useless for diagnosis when considered alone. Of course, when several of the more useful differences are present, the odds are even farther against TS. In other words, it's quite clear that most such patients must have a different disorder from TS.

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Why is it important?

All Tourette patients by definition have had tics for at least a year, whereas these patients often came in within days or weeks of their first symptoms. The ideal comparison group, then, would be people seen as early as possible after the onset of tics, but who had Tourette syndrome diagnosed when seen 1 year after tic onset. We have possibly the only such data from a large group of children.

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