Functional tic-like presentations differ strikingly from Provisional Tic Disorder

Abstract

Recent years have seen a dramatic increase in new “tic” cases in teens and young adults. These individuals often present with fulminant onset of distinct symptoms not commonly seen in Tourette syndrome (TS), and are often diagnosed with Functional Neurological Disorder (FND-tic). Some have questioned whether this illness truly differs from typical Provisional Tic Disorder (PTD) and Tourette syndrome. Here we address this concern by providing for the first time substantial data on clinical features during the first year after symptom onset in 89 patients with PTD who later were diagnosed with TS. Several clinical features dramatically distinguish the rapid-onset FND-tic patients from patients with typical PTD. For example, coprophenomena are reported at or shortly after symptom onset in over half of FND-tic patients, whereas we observed coprophenomena at presentation in only 1 of 89 children with PTD. A handful of clinical features have a positive predictive value (PPV) over 90%. These new data provide strong evidence supporting the diagnostic validity of FND-tic as distinct from TS.

Functional tic-like presentations differ strikingly from Provisional Tic Disorder

“…The feature list was drawn from a recent review of FND-tic, a narrative review that included all primary data publications on FND-tic known to its authors as of August, 2022. 3 The comparison data for FND-tic patients comes from 26 published reports, with pertinent data in 17 reports 4,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] describing a total of 336 patients (data file available as Underlying data 27 ). For quantitative variables, the weighted mean is provided (weighted by N in each report), along with the median and range of the summary values reported in each relevant publication.…”