Tics and functional tic-like movements

Abstract

Within the broad spectrum of movement disorders, tics and functional tic-like movements belong to a particular clinical category. Both types of movements are within the range of normal movement kinematics and muscle synergies, but appear repetitive and without appropriate context embedment. Historically, there have been many attempts to separate the 2 types of movements, but because of their phenomenological overlap, clinical distinction may be prone to error, and misdiagnoses may often occur. Most importantly, the 2 types of movement may coexist. Here, we review the available literature on the 2 types of motor phenomena and demonstrate some of the difficulties in distinguishing tics from functional tic-like movements on clinical grounds. We also highlight similarities and differences in pathophysiologic characteristics, documenting the significance of action monitoring, attentional allocation, and behavioral reinforcement in both types of movements, as well as in their risk factors. We discuss the overlap of current behavioral treatments for tics and functional tic-like movements and emphasize implications of diagnostic mislabeling. Such implications include the need to tailor behavioral treatment approaches to individual phenomenological profiles and guiding decision making for severe patients requiring invasive interventions, such as deep brain stimulation. A deeper insight from clinicians with respect to persisting challenges in classifying and differentiating these motor phenomena could accelerate the development of reliable clinical and physiologic markers (i.e., next generation phenotyping) and a neurobiology-driven therapeutic approach for these motor phenomena.

Purposely Induced Tics: Electrophysiology

“…At the same time, we recognize the similar phenomenology between organic and functional tics. 8 There are some characteristics of the movement that may point to a functional syndrome. However, given that the patient has some control over the movement, a premonitory feeling, and no BP make us think it is reasonable to classify it as organic tic.…”

Gilles-de-la-Tourette-Syndrom

“…Schwieriger kann die Unterscheidung zwischen Tics bei GTS und einer funktionellen Störung mit Tic-ähnlichen Bewegungen sein, die wir hier etwas detaillierter ausführen [54]. Die bisher einzigen beiden Studien, die Gemeinsamkeiten und Unterschiede zwischen Tics und funktionellen Tics untersucht haben, kommen zu vergleichbaren Ergebnissen [55,56] und weisen auf klinische und anamnestische Merkmale hin, nach denen sich Tics und funktionelle Tics voneinander unterscheiden können.…”

Tiefe Hirnstimulation als Therapieoption für das Tourette-Syndrom

“…Wichtigste Voraussetzung für die Indikation der THS ist laut Expertenmeinung zunächst die korrekte Diagnose des TS nach internationalen Kriterien [1,30]. Besonders zu beachten ist hier die Abgrenzung des TS zu funktionellen Störungen [69]. Die THS sollte bei Patienten mit TS erst angewendet werden, wenn die Symptome trotz medikamentöser und behavioraler Therapie nicht ausreichend gut behandelbar sind.…”