Pharmacological studies
A comprehensive and systematic review of pharmacological treatments for patients with TS was provided by Farhat and colleagues \citep{Farhat2023}, confirming that antipsychotic drugs are the most efficacious intervention for tics, followed by α-2 agonists.
Abi-Jaoude and colleagues compared the efficacy and tolerability of single doses of three vaporized medical cannabis products and placebo in reducing tics in adults with GTS \citep{Abi-Jaoude2022}. Each participant received a vaporized single 0.25 g dose of Δ9-tetrahydrocannabinol (THC) 10%, THC/cannabidiol (CBD) 9%/9%, CBD 13%, and placebo at 2-week intervals. There were no statistically significant differences in tic severity for any of the cannabis-based medicine in primary outcome, but THC 10% was significantly better than placebo on the secondary outcome measures.
An interesting first study randomized 34 children with TS/CTD 1:1 to either a combination of the amino acid L-theanine 200mg/d and low-dose vitamin B6 2.8mg/d, or to 8 sessions of psychoeducation, for two months. There was no blinding, but the results were interesting: in the medication group, 71% were responders (YGTSS total tic score decrease by at least 30%), compared to 18% of the control group. The authors appropriately note that these results need confirmation in a larger trial with blinded assessment and matching placebo pills.
Neurosurgery
An elegant study by Ganos and colleagues \citep{Ganos_2022} offers new insights regarding our knowledge of tic network and the effects of deep brain stimulation (DBS). They studied 22 patients with secondary tics caused by various types of brain lesions and employed lesion network mapping to identify a common neural network implicated in tics generation. Their methodological approach combined: (i) a comparison of brain lesions which induced tics (n=22) to control brain lesions which did not induce tics (n=717); (ii) they built a functional lesion network using healthy subjects’ fMRI (n=1000) and using the lesion location they found in the first step as seed; (iii) they assessed the utility of this lesion network to predict tics decrease after thalamic deep brain stimulation surgery on patients with TS (n=30). They found that despite their very varied brain locations, tic-inducing lesions mapped to a common network encompassing the insular cortices, the cingulate gyrus, the striatum, the globus pallidus internus (GPi) and the cerebellum. The connectivity of the anterior striatum was significantly associated with tics compared to lesions inducing other types of movement disorders. They then collected data from 30 patients with TS who had undergone thalamic or pallidal neurostimulation and found that the overlap between the site of neurostimulation and the lesion network map was predictive of tic improvement.