Is it a tic?-Twenty seconds to make a diagnosis

Extra Movements in Healthy People: Challenging the Definition and Diagnostic Practice of Tic Disorders

The occurrence of motor/vocal tics, that is, "extra movements" and/or "extra vocalizations," is the leading diagnostic criterion for tic disorders. We show that extra movements are common also in healthy controls, so that a surplus of movements per se is not indicative of the presence of a tic disorder. This questions the usefulness of Diagnostic and Statistical Manual of Mental Disorders, 5th edition criteria for tic disorders in clinical practice. Apparently, it is not solely a surplus of movements that defines tic disorders. Instead, movement characteristics and patterns seem to play a crucial role. ANN NEUROL 2023;93:472-478.

Urge-tic associations in children and adolescents with Tourette syndrome

Premonitory urges preceding tics are a cardinal feature of Gilles de la Tourette syndrome (GTS), a developmental disorder usually starting during middle childhood. However, the temporal relation between urges and tics has only been investigated in adults. In 25 children and adolescents with GTS (8–18 years), we assess urge-tic associations, including inter-individual differences, correlation to clinical measures, and in comparison to a previously reported sample of adult GTS patients. Group-level analyses confirmed positive associations between urges and tics. However, at the individual level, less than half of participants showed positive associations, a similar proportion did not, and in two participants, the association was reversed. Tic expression and subjective urge levels correlated with corresponding clinical scores and participants with more severe tics during the urge monitor exhibited stronger urge-tic associations. Associations between reported urge levels and instantaneous tic intensity tended to be less pronounced in children and adolescents than in adult GTS patients. The observed heterogeneity of urge-tic associations cast doubt on the notion that tics are directly caused by urges. More severe tics may facilitate anticipation of tics and thereby lead to more pronounced urge-tic associations, consistent with a hypothesis of urges as a byproduct of tics.

The Phenomenology of Tics and Tic-Like Behavior in TikTok

BACKGROUND

Pediatricians and pediatric subspecialists worldwide have reported a marked increase in functional (conversion) disorders with tic-like behaviors during the COVID-19 pandemic. These patients often report frequent viewing of Tourette syndrome (TS) TikTok videos, suggesting disease modeling. We aimed to evaluate tic phenomenology in videos posted on TikTok.

METHODS

The 100 most-viewed videos under #tourettes in TikTok were randomly assigned to two of three primary reviewers (<2 years independent practice), all pediatric neurologists specializing in movement disorders, for extraction and classification of tic phenomenology. Initial disagreements were solved by consensus. If not resolved, one of five senior reviewers (>2 years independent pediatric movement disorder practice) served as a tiebreaker. In addition, two primary and one senior reviewer rated each video on a Likert scale from 1 = "All the tics are typical of TS" to 5 = "None of the tics are typical of TS". Median scores and Spearman correlation between primary and senior reviewers were calculated.

RESULTS

Six videos without tic-like behaviors were excluded. Most videos depicted coprophenomena (coprolalia: 53.2%; copropraxia: 20.2%), often with unusual characteristics. Frequently, videos demonstrated atypical phenomenology such as very strong influence by the environment (motor: 54.3%; phonic: 54.3%), aggression (19.1%), throwing objects (22.3%), self-injurious behaviors (27.7%), and long phrases (>3 words; 45.7%). Most videos portrayed atypical, nontic behaviors (median [IQR] Likert ratings: 5 [4-5]). Primary vs. senior rater scores demonstrated moderate agreement (r = 0.46; P < 0.001).

CONCLUSIONS

TS symptom portrayals on highly viewed TikTok videos are predominantly not representative or typical of TS.

Questioning the definition of Tourette syndrome-evidence from machine learning

Tics in Tourette syndrome are often difficult to discern from single spontaneous movements or vocalizations in healthy people. In this study, videos of patients with Tourette syndrome and healthy controls were taken and independently scored according to the Modified Rush Videotape Rating Scale. We included n = 101 patients with Tourette syndrome (71 males, 30 females, mean age 17.36 years ± 10.46 standard deviation) and n = 109 healthy controls (57 males, 52 females, mean age 17.62 years ± 8.78 standard deviation) in a machine learning-based analysis. The results showed that the severity of motor tics, but not vocal phenomena, is the best predictor to separate and classify patients with Tourette syndrome and healthy controls. This finding questions the validity of current diagnostic criteria for Tourette syndrome requiring the presence of both motor and vocal tics. In addition, the negligible importance of vocalizations has implications for medical practice, because current recommendations for Tourette syndrome probably also apply to the large group with chronic motor tic disorders.

Increased scale-free and aperiodic neural activity during sensorimotor integration-a novel facet in Tourette syndrome

Tourette syndrome is a common neurodevelopmental disorder defined by multiple motor and phonic tics. Tics in Tourette syndrome resemble spontaneously occurring movements in healthy controls and are therefore sometimes difficult to distinguish from these. Tics may in fact be mis-interpreted as a meaningful action, i.e. a signal with social content, whereas they lack such information and could be conceived a surplus of action or 'motor noise'. These and other considerations have led to a 'neural noise account' of Tourette syndrome suggesting that the processing of neural noise and adaptation of the signal-to-noise ratio during information processing is relevant for the understanding of Tourette syndrome. So far, there is no direct evidence for this. Here, we tested the 'neural noise account' examining 1/f noise, also called scale-free neural activity as well as aperiodic activity, in n = 74 children, adolescents and adults with Tourette syndrome and n = 74 healthy controls during task performance using EEG data recorded during a sensorimotor integration task. In keeping with results of a previous study in adults with Tourette syndrome, behavioural data confirmed that sensorimotor integration was also stronger in this larger Tourette syndrome cohort underscoring the relevance of perceptual-action processes in this disorder. More importantly, we show that 1/f noise and aperiodic activity during sensorimotor processing is increased in patients with Tourette syndrome supporting the 'neural noise account'. This implies that asynchronous/aperiodic neural activity during sensorimotor integration is stronger in patients with Tourette syndrome compared to healthy controls, which is probably related to abnormalities of GABAergic and dopaminergic transmission in these patients. Differences in 1/f noise and aperiodic activity between patients with Tourette syndrome and healthy controls were driven by high-frequency oscillations and not lower-frequency activity currently discussed to be important in the pathophysiology of tics. This and the fact that Bayesian statistics showed that there is evidence for the absence of a correlation between neural noise and clinical measures of tics, suggest that increased 1/f noise and aperiodic activity are not directly related to tics but rather represents a novel facet of Tourette syndrome.

Inter-individual differences in urge-tic associations in Tourette syndrome

Premonitory urges are a cardinal feature in Tourette syndrome (GTS) and are commonly viewed as a driving force of tics. However, inter-individual differences in experimentally measured urges, tics and urge-tic associations, as well as possible relations to clinical characteristics and abnormal perception-action processing recently demonstrated in these patients have not been investigated in detail. Here, we analyze the temporal associations between urges and tics in 21 adult patients with GTS including inter-individual differences and the relation of such associations with clinical measures and experimentally tested perception-action coupling. At the group level, our results confirm known positive associations between subjective urges and tics, with increased tic frequency and tic intensity during periods of elevated urge. Inter-individual differences in the associations between urges and tics were, however, substantial. While most participants (57-66 % depending on the specific measure) showed positive associations as expected, several participants did not, and two even had negative associations with tic occurrence and intensity being reduced at times of increased urges. Subjective urge levels and tic occurrence correlated with corresponding clinical scores, providing converging evidence. Measures of the strength of urge-tic associations did not correlate with clinical measures nor the strength of perception-action coupling. Taken together, urge-tic associations in GTS are complex and heterogenous, casting doubt on the notion that tics are primarily driven by urges.

A neural noise account of Gilles de la Tourette syndrome

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A neural noise account on Tourette syndrome is conceptualized.

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We outline how neurophysiological methods can be used to test this account.

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The neural noise account may lead to novel treatment options.

Tics, often preceded by premonitory urges, are the clinical hallmark of Tourette syndrome. They resemble spontaneous movements, but are exaggerated, repetitive and appear misplaced in a given communication context. Given that tics often go unnoticed, it has been suggested that they represent a surplus of action, or motor noise. In this conceptual position paper, we propose that tics and urges, but also patterns of the cognitive profile in Tourette syndrome might be explained by the principle of processing of neural noise and adaptation to it during information processing. We review evidence for this notion in the light of Tourette pathophysiology and outline why neurophysiological and imaging approaches are central to examine a possibly novel view on Tourette syndrome. We discuss how neurophysiological data at multiple levels of inspections, i.e., from local field potentials using intra-cranial recording to scalp-measured EEG data, in combination with imaging approaches, can be used to examine the neural noise account in Tourette syndrome. We outline what signal processing methods may be suitable for that. We argue that, as a starting point, the analysis of 1/f neural noise or scale-free activity may be suitable to investigate the role of neural noise and its adaptation during information processing in Tourette syndrome. We outline, how the neural noise perspective, if substantiated by further neurophysiological studies and re-analyses of existing data, may pave the way to novel interventions directly targeting neural noise levels and patterns in Tourette syndrome.

Altered urinary tetrahydroisoquinoline derivatives in patients with Tourette syndrome: reflection of dopaminergic hyperactivity?

Tetrahydroisoquinolines (TIQs) such as salsolinol (SAL), norsalsolinol (NSAL) and their methylated derivatives N-methyl-norsalsolinol (NMNSAL) and N-methyl-salsolinol (NMSAL), modulate dopaminergic neurotransmission and metabolism in the central nervous system. Dopaminergic neurotransmission is thought to play an important role in the pathophysiology of chronic tic disorders, such as Tourette syndrome (TS). Therefore, the urinary concentrations of these TIQ derivatives were measured in patients with TS and patients with comorbid attention-deficit/hyperactivity disorder (TS + ADHD) compared with controls. Seventeen patients with TS, 12 with TS and ADHD, and 19 age-matched healthy controls with no medication took part in this study. Free levels of NSAL, NMNSAL, SAL, and NMSAL in urine were measured by a two-phase chromatographic approach. Furthermore, individual TIQ concentrations in TS patients were used in receiver-operating characteristics (ROC) curve analysis to examine the diagnostic value. NSAL concentrations were elevated significantly in TS [434.67 ± 55.4 nmol/l (standard error of mean = S.E.M.), two-way ANOVA, p < 0.0001] and TS + ADHD patients [605.18 ± 170.21 nmol/l (S.E.M.), two-way ANOVA, p < 0.0001] compared with controls [107.02 ± 33.18 nmol/l (S.E.M.), two-way ANOVA, p < 0.0001] and NSAL levels in TS + ADHD patients were elevated significantly in comparison with TS patients (two-way ANOVA, p = 0.017). NSAL demonstrated an AUC of 0.93 ± 0.046 (S.E.M) the highest diagnostic value of all metabolites for the diagnosis of TS. Our results suggest a dopaminergic hyperactivity underlying the pathophysiology of TS and ADHD. In addition, NSAL concentrations in urine may be a potential diagnostic biomarker of TS.

Gilles de la Tourette Syndrome-A Disorder of Action-Perception Integration

Gilles de la Tourette syndrome is a multifaceted and complex neuropsychiatric disorder. Given that tics as motor phenomena are the defining and cardinal feature of Tourette syndrome, it has long been conceptualized as a motor/movement disorder. However, considering premonitory urges preceding tics, hypersensitivity to external stimuli and abnormalities in sensorimotor integration perceptual processes also seem to be relevant in the pathophysiology of Tourette syndrome. In addition, tic expression depends on attention and tics can, at least partly and transiently, be controlled, so that cognitive processes need to be considered as well. Against this background, explanatory concepts should encompass not only the motor phenomenon tic but also perceptual and cognitive processes. Representing a comprehensive theory of the processing of perceptions and actions paying particular attention to their interdependency and the role of cognitive control, the Theory of Event Coding seems to be a suitable conceptual framework for the understanding of Tourette syndrome. In fact, recent data suggests that addressing the relation between actions (i.e., tics) and perceptions (i.e., sensory phenomena like premonitory urges) in the context of event coding allows to gaining relevant insights into perception-action coding in Tourette syndrome indicating that perception action binding is abnormally strong in this disorder.

Non-invasive Brain Stimulation for the Treatment of Gilles de la Tourette Syndrome

Gilles de la Tourette Syndrome is a multifaceted neuropsychiatric disorder typically commencing in childhood and characterized by motor and phonic tics. Its pathophysiology is still incompletely understood. However, there is convincing evidence that structural and functional abnormalities in the basal ganglia, in cortico-striato-thalamo-cortical circuits, and some cortical areas including medial frontal regions and the prefrontal cortex as well as hyperactivity of the dopaminergic system are key findings. Conventional therapeutic approaches in addition to counseling comprise behavioral treatment, particularly habit reversal therapy, oral pharmacotherapy (antipsychotic medication, alpha-2-agonists) and botulinum toxin injections. In treatment-refractory Tourette syndrome, deep brain stimulation, particularly of the internal segment of the globus pallidus, is an option for a small minority of patients. Based on pathophysiological considerations, non-invasive brain stimulation might be a suitable alternative. Repetitive transcranial magnetic stimulation appears particularly attractive. It can lead to longer-lasting alterations of excitability and connectivity in cortical networks and inter-connected regions including the basal ganglia through the induction of neural plasticity. Stimulation of the primary motor and premotor cortex has so far not been shown to be clinically effective. Some studies, though, suggest that the supplementary motor area or the temporo-parietal junction might be more appropriate targets. In this manuscript, we will review the evidence for the usefulness of repetitive transcranial magnetic stimulation and transcranial electric stimulation as treatment options in Tourette syndrome. Based on pathophysiological considerations we will discuss the rational for other approaches of non-invasive brain stimulation including state informed repetitive transcranial magnetic stimulation.

Clinical Features That Evoke the Concept of Disinhibition in Tourette Syndrome

The capacity to efficiently control motor output, by either refraining from prepotent actions or disengaging from ongoing motor behaviors, is necessary for our ability to thrive in a stimulus-rich and socially complex environment. Failure to engage in successful inhibitory motor control could lead to aberrant behaviors typified by an excess of motor performance. In tic disorders and Tourette syndrome (TS) - the most common tic disorder encountered in clinics - surplus motor output is rarely the only relevant clinical sign. A range of abnormal behaviors is often encountered which are historically viewed as "disinhibition phenomena". Here, we present the different clinical features of TS from distinct categorical domains (motor, sensory, complex behavioral) that evoke the concept of disinhibition and discuss their associations. We also present evidence for their consideration as phenomena of inhibitory dysfunction and provide an overview of studies on TS pathophysiology which support this view. We then critically dissect the concept of disinhibition in TS and illuminate other salient aspects, which should be considered in a unitary pathophysiological approach. We briefly touch upon the dangers of oversimplification and emphasize the necessity of conceptual diversity in the scientific exploration of TS, from disinhibition and beyond.

Tics and functional tic-like movements: Can we tell them apart?

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.

[Neuronal plasticity and neuromodulation in pediatric neurology]

BACKGROUND

Neuronal plasticity is a core mechanism for learning and memory. Abnormal neuronal plasticity has emerged as a key mechanism in many neurological and neuropediatric diseases.

OBJECTIVE

Chances and perspectives of neuromodulation techniques in neurological and neuropediatric diseases with altered neuronal plasticity.

MATERIAL AND METHODS

Presentation and discussion of own results of neuronal plasticity investigations in patients with neurodevelopmental disorders including RASopathies, autism spectrum disorders (ASD) and Gilles de la Tourette syndrome (GTS).

RESULTS

The results of neuronal plasticity studies in patients with RASopathies, ASD and GTS underline the pathophysiological relevance of abnormal neuronal plasticity in these diseases. Transcranial magnetic stimulation (TMS) is a useful tool to examine and also induce neuronal plasticity in these patients.

CONCLUSION

Neuronal plasticity appears to be an important pathophysiological factor in neuronal developmental disorders and can be investigated using TMS. New and innovative techniques may offer novel approaches for individualized TMS applications, particularly in children with neuropediatric conditions.

Associative plasticity in supplementary motor area - motor cortex pathways in Tourette syndrome

The important role of the supplementary motor area (SMA) in the generation of tics and urges in Gilles de la Tourette syndrome (GTS) is underscored by an increased SMA-motor cortex (M1) connectivity. However, whether plasticity is also altered in SMA-M1 pathways is unclear. We explored whether SMA-M1 plasticity is altered in patients with Tourette syndrome. 15 patients with GTS (mean age of 33.4 years, SD = 9.9) and 19 age and sex matched healthy controls were investigated with a paired association stimulation (PAS) protocol using three transcranial magnetic stimulation (TMS) coils stimulating both M1 and the SMA. Standard clinical measures for GTS symptoms were collected. There was a significant PAS effect showing that MEP amplitudes measured in blocks during and after PAS were significantly higher compared to those in the first block. However, the degree of PAS was not differentially modulated between patients and controls as shown by a Bayesian data analysis. PAS effects in GTS correlated positively with the YGTSS motor tic severity. Plasticity previously reported to be altered in sensorimotor pathways in GTS is normal in SMA-M1 projections suggesting that the dysfunction of the SMA in GTS is not primarily related to altered plasticity in SMA-M1 connections.

Current Approaches and New Developments in the Pharmacological Management of Tourette Syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder of unknown etiology characterized by spontaneous, involuntary movements and vocalizations called tics. Once thought to be rare, TS affects 0.3-1% of the population. Tics can cause physical discomfort, emotional distress, social difficulties, and can interfere with education and desired activities. The pharmacologic treatment of TS is particularly challenging, as currently the genetics, neurophysiology, and neuropathology of this disorder are still largely unknown. However, clinical experience gained from treating TS has helped us better understand its pathogenesis and, as a result, derive treatment options. The strongest data exist for the antipsychotic agents, both typical and atypical, although their use is often limited in children and adolescents due to their side-effect profiles. There are agents in a variety of other pharmacologic categories that have evidence for the treatment of TS and whose side-effect profiles are more tolerable than the antipsychotics; these include clonidine, guanfacine, baclofen, topiramate, botulinum toxin A, tetrabenazine, and deutetrabenazine. A number of new agents are being developed and tested as potential treatments for TS. These include valbenazine, delta-9-tetrahydrocannabidiol, and ecopipam. Additionally, there are agents with insufficient data for efficacy, as well as agents that have been shown to be ineffective. Those without sufficient data for efficacy include clonazepam, ningdong granule, 5-ling granule, omega-3 fatty acids, and n-acetylcysteine. The agents that have been shown to be ineffective include pramipexole and metoclopramide. We will review all of the established pharmacologic treatments, and discuss those presently in development.

Modeling tics in rodents: Conceptual challenges and paths forward

BACKGROUND

Recent advances in our understanding of the neurobiology of tics have led to the development of novel rodent models capturing different pathophysiological and phenotypic aspects of Tourette syndrome. The proliferation of these models, however, raises vexing questions on what standards should be adopted to assess their theoretical validity and empirical utility. Assessing the homology of a rodent motoric burst with a tic remains problematic, due to our incomplete knowledge of the underpinnings of tics, their high phenotypic complexity and variability, limitations in our ability test key aspects of tic phenomenology (such as premonitory sensory phenomena) in animals, and between-species differences in neuroanatomy and behavioral repertoire. These limitations underscore that any interpretation of behavioral output in an animal model cannot exclusively rely on the recognition of features that bear superficial resemblance with tics, but must be supported by other etiological and convergent phenomenological criteria.

NEW METHOD

Here, we discuss two complementary approaches for the study and validation of tic-like manifestations in rodents, based respectively on the use of contextual modulators and accompanying features of repetitive motor manifestations and on the reproduction of pathogenic factors.

RESULTS

Neither strategy can by itself provide convincing evidence that a model informatively recapitulates tic pathophysiology. Their combination holds promise to enhance the rigorous evaluation and translational relevance of rodent models of tic disorders.

CONCLUSIONS

This systematic consideration of different approaches to the validation and study of animal models of tic pathophysiology provides a framework for future work in this area.

Trends in psychopharmacologic treatment of tic disorders in children and adolescents in Germany

Data on medical treatment of children and adolescents with tic disorders are scarce. This study examined the administrative prevalence of psychopharmacological prescriptions in this patient group in Germany. Data of the largest German health insurance fund were analysed. In outpatients aged 0-19 years with diagnosed tic disorder, psychotropic prescriptions were evaluated for the years 2006 and 2011. In 2011, the percentage of psychotropic prescriptions was slightly higher than in 2006 (21.2 vs. 18.6%). The highest prescription prevalence was found in Tourette syndrome (51.5 and 53.0%, respectively). ADHD drugs were most frequently prescribed, followed by antipsychotics. In 2011, prescriptions of second generation antipsychotics (SGA) were higher and prescriptions of first generation antipsychotics (FGA) lower than in 2006. Concerning prescribed antipsychotic substances, in 2011 risperidone prescriptions were higher and tiapride prescriptions lower. Paediatricians issued 37.4%, and child and adolescent psychiatrists issued 37.1% of psychotropic prescriptions. The FGA/SGA ratio was highest in GPs (1.25) and lowest in child and adolescent psychiatrists (0.96). From 2006 to 2011, there was only a slight increase in psychotropic prescriptions for children and adolescents with a diagnosis of tic disorder in Germany, which stands in contrast towards the significant increase in psychotropic prescriptions in other child and adolescent psychiatric disorders (e.g. ADHD). There were marked differences in treatment patterns by tic disorder subgroups, with Tourette syndrome patients receiving most frequently psychopharmacotherapy. Risperidone prescriptions increased, probably reflecting a switch in prescribing practice towards up-to-date treatment guidelines. In primary care physicians, dissemination of current tic disorder treatment guidelines might constitute an important educational goal.

The Semiology of Tics, Tourette's, and Their Associations

Gilles de la Tourette syndrome (GTS) is a prototypical neuropsychiatric disorder breaking the boundary of disciplinary dualism between neurology and psychiatry. The diagnosis of GTS is clinical and, in most cases, straightforward. Tics as a hallmark of GTS are usually easy to recognize and distinguish from other movement disorders as fragmented, repetitive, exaggerated movements resembling normal motor behavior, but appearing out of context. In complex cases, knowledge on additional characteristics and signs as, for example, tic distribution, suggestibility, voluntary tic inhibition, and presence of echo- or paliphenomena might further aid clinical diagnosis. However, although defining GTS, tics are rarely the main issue. The presence of comorbidities and coexisting psychopathologies often hampers normal development and negatively affects quality of life. Their recognition and treatment is paramount. Here, we review existing literature and provide a comprehensive update on the multifarious aspects of the movement disorder and neuropsychiatry of GTS. We also provide a list of associated movement disorders known to occur in GTS patients and discuss differential diagnoses to be considered in atypical cases. We finally comment on available treatment options.

The neural correlates of tic inhibition in Gilles de la Tourette syndrome

Tics in Gilles de la Tourette syndrome (GTS) resemble fragments of normal motor behaviour but appear in an intrusive, repetitive and context-inappropriate manner. Although tics can be voluntarily inhibited on demand, the neural correlates of this process remain unclear. 14 GTS adults without relevant comorbidities participated in this study. First, tic severity and voluntary tic inhibitory capacity were evaluated outside the scanner. Second, patients were examined with resting state functional magnetic resonance imaging (RS-fMRI) in two states, free ticcing and voluntary tic inhibition. Local synchronization of spontaneous fMRI-signal was analysed with regional homogeneity (ReHo) and differences between both states (free ticcing<tic inhibition) were contrasted. Clinical correlations of the resulting differential ReHo parameters between both states and clinical measures of tic frequency, voluntary tic inhibition and premonitory urges were also performed. ReHo of the left inferior frontal gyrus (IFG) was increased during voluntary tic inhibition compared to free ticcing. ReHo increases were positively correlated with participants׳ ability to inhibit their tics during scanning sessions but also outside the scanner. There was no correlation with ratings of premonitory urges. Voluntary tic inhibition is associated with increased ReHo of the left IFG. Premonitory urges are unrelated to this process.

Altered synaptic plasticity in Tourette's syndrome and its relationship to motor skill learning

Gilles de la Tourette syndrome is a neuropsychiatric disorder characterized by motor and phonic tics that can be considered motor responses to preceding inner urges. It has been shown that Tourette patients have inferior performance in some motor learning tasks and reduced synaptic plasticity induced by transcranial magnetic stimulation. However, it has not been investigated whether altered synaptic plasticity is directly linked to impaired motor skill acquisition in Tourette patients. In this study, cortical plasticity was assessed by measuring motor-evoked potentials before and after paired associative stimulation in 14 Tourette patients (13 male; age 18–39) and 15 healthy controls (12 male; age 18–33). Tic and urge severity were assessed using the Yale Global Tic Severity Scale and the Premonitory Urges for Tics Scale. Motor learning was assessed 45 minutes after inducing synaptic plasticity and 9 months later, using the rotary pursuit task. On average, long-term potentiation-like effects in response to the paired associative stimulation were present in healthy controls but not in patients. In Tourette patients, long-term potentiation-like effects were associated with more and long-term depression-like effects with less severe urges and tics. While motor learning did not differ between patients and healthy controls 45 minutes after inducing synaptic plasticity, the learning curve of the healthy controls started at a significantly higher level than the Tourette patients' 9 months later. Induced synaptic plasticity correlated positively with motor skills in healthy controls 9 months later. The present study confirms previously found long-term improvement in motor performance after paired associative stimulation in healthy controls but not in Tourette patients. Tourette patients did not show long-term potentiation in response to PAS and also showed reduced levels of motor skill consolidation after 9 months compared to healthy controls. Moreover, synaptic plasticity appears to be related to symptom severity.

[Tourette syndrome and other tic disorders in DSM-5 – a comment]

The classification of tic disorders has been revised in the new fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The previously expressed suggestion to categorize tic disorders within the "Anxiety and Obsessive Compulsive Disorders" was not implemented. The section "Disorders Usually First Diagnosed in Infancy, Childhood, or Adolescence" was revised and renamed as "Neurodevelopmental Disorders." Tic disorders are classified there as movement disorders. Most of the changes are distinct improvements from both a clinical and a scientific perspective. For example, by removing the adjective "stereotype," the definition of tics is more precise and unified. Also, the new time-oriented criteria are more practical in the clinical setting, e.g., the exclusion criterion of a tic-free interval more than 3 months given for chronic tic disorders has been deleted. The renamings from "Transient" to "Provisional Tic Disorder" as well as from "Chronic" to "Persistent Tic Disorder" are welcome changes from a clinical perspective. Overall, the revision of the criteria is an important step towards providing more clarity and feasibility. However, the revised classification of tic disorders is still based only on clinical experience and not on evidence. Future studies should show whether the revised and improved criteria truly provide the optimal classification.

Can Tics be Performed Convincingly by an Actor?

Background. In the German movie “Vincent will Meer” a healthy actor portrays a man with Tourette’s syndrome.Objective. The aim of this study was to investigate whether the performance of tics is convincing and whether this judgment depends on whether he/she suffers from tics or not.Methods. While the movie was broadcasted in German cinemas, we put an online survey (including 28 questions on different aspects related to the observation, performance, and authenticity of tics) on the web pages of the German self-help group. 276/296 surveys submitted could be used for further analyses.Results. 95.7% of all participants felt that the performance of tics was convincing. However, people with tics (n=26) were less convinced compared to those who had never met a person with tics (n=110) (P=0.020).Conclusions. Our results further support the hypothesis that tics are not “abnormal” but “physiological” movements that are only misplaced both in time and context.

Surgical treatment of Tourette syndrome

In severely affected, treatment resistant patients with Tourette syndrome (TS) new therapeutic strategies are urgently needed. Since 1999, 34 studies including more than 90 patients have been performed to investigate the efficacy and safety of deep brain stimulation (DBS) in the treatment of tics resulting in the vast majority of patients in an improvement of tics and in some patients even of comorbidities. Both surgery-related (e.g., bleeding, infection) and stimulation-related adverse events (e.g., loss of energy, blurred vision) seem to occur only in a minority of patients and not to cause significant impairment, respectively. Since randomized controlled studies including a larger number of patients are still lacking, up to now, no definite conclusion can be drawn. Therefore, at present time DBS is recommended only in adult, treatment resistant, and severely affected patients. However, most experts have no doubt that DBS is indeed effective in the treatment of tics. Future studies should aim to identify which target in which patient is optimal depending on the individual symptomatology.

The pathophysiology of echopraxia/echolalia: relevance to Gilles de la Tourette syndrome

Echopraxia and echolalia are subsets of imitative behavior. They are essential developmental elements in social learning. Their persistence or reemergence after a certain age, though, can be a sign of underlying brain dysfunction. Although echophenomena have been acknowledged as a typical sign in Gilles de la Tourette syndrome (GTS) since its first description, their clinical significance and neural correlates are largely unknown. Here, we review the course of their scientific historical development and focus on their clinical phenomenology and differential diagnosis with a particular view to GTS. The neural basis of echophenomena will also be addressed. © 2012 Movement Disorder Society.

Pharmacological treatment of tic disorders and Tourette Syndrome

The present review gives an overview of current pharmacological treatment options of tic disorders and Tourette Syndrome (TS). After a short summary on phenomenology, clinical course and comorbid conditions we review indications for pharmacological treatment in detail. Unfortunately, standardized and large enough drug trials in TS patients fulfilling evidence based medicine standards are still scarce. Treatment decisions are often guided by individual needs and personal experience of treating clinicians. The present recommendations for pharmacological tic treatment are therefore based on both scientific evidence and expert opinion. As first-line treatment of tics risperidone (best evidence level for atypical antipsychotics) or tiapride (largest clinical experience in Europe and low rate of adverse reactions) are recommended. Aripiprazole (still limited but promising data with low risk for adverse reactions) and pimozide (best evidence of the typical antipsychotics) are agents of second choice. In TS patients with comorbid attention deficit hyperactivity disorder (ADHD) atomoxetine, stimulants or clonidine should be considered, or, if tics are severe, a combination of stimulants and risperidone. When mild to moderate tics are associated with obsessive-compulsive symptoms, depression or anxiety sulpiride monotherapy can be helpful. In more severe cases the combination of risperidone and a selective serotonin reuptake inhibitor should be given. In summary, further studies, particularly randomized, double-blind, placebo-controlled trials including larger and/or more homogenous patient groups over longer periods are urgently needed to enhance the scientific basis for drug treatment in tic disorders. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.

Motor-cortical interaction in Gilles de la Tourette syndrome

Background

In Gilles de la Tourette syndrome (GTS) increased activation of the primary motor cortex (M1) before and during movement execution followed by increased inhibition after movement termination was reported. The present study aimed at investigating, whether this activation pattern is due to altered functional interaction between motor cortical areas.

Methodology/Principal Findings

10 GTS-patients and 10 control subjects performed a self-paced finger movement task while neuromagnetic brain activity was recorded using Magnetoencephalography (MEG). Cerebro-cerebral coherence as a measure of functional interaction was calculated. During movement preparation and execution coherence between contralateral M1 and supplementary motor area (SMA) was significantly increased at beta-frequency in GTS-patients. After movement termination no significant differences between groups were evident.

Conclusions/Significance

The present data suggest that increased M1 activation in GTS-patients might be due to increased functional interaction between SMA and M1 most likely reflecting a pathophysiological marker of GTS. The data extend previous findings of motor-cortical alterations in GTS by showing that local activation changes are associated with alterations of functional networks between premotor and primary motor areas. Interestingly enough, alterations were evident during preparation and execution of voluntary movements, which implies a general theme of increased motor-cortical interaction in GTS.

[Somatosensory phenomena and the role of sensorimotor circuits in Gilles de la Tourette syndrome]

Gilles de la Tourette syndrome (GTS) is characterized by multiple fluctuating motor and vocal tics. These tics are often preceded by premonitory phenomena including the urge to move, or by exaggerated bodily sensations that can lead to considerable disability and difficulties with attention and concentration. In the past the premonitory phenomena were interpreted as the driving force behind tics. However, there is not always a clear sequence of premonitory sensations followed by a tic. Also, the former typically develop around the age of 10 years, i.e. after the onset of the latter. Thus, the relationship between premonitory phenomena and tics is unclear. The present article reviews the current knowledge on this issue. Neurophysiological studies have shown some abnormalities of sensorimotor integration in GTS. In addition, structural imaging (MRT) has demonstrated a thinning of the sensorimotor cortex in children and adolescents with GTS. In contrast, an increase in fractional anisotropy as a marker of the directionality of white matter fibers underneath the pre- and postcentral gyrus has been demonstrated in adult GTS patients. These data underscore the role of developmental abnormalities and reorganisation in the somatosensory system in GTS warranting further studies. Multimodal studies including structural and functional imaging and electrophysiology in clinically well characterized GTS subgroups might foster a better understanding of somatosensory phenomena and the role of sensorimotor circuits in GTS.

Tourette's disorder and other tic disorders in DSM-5: a comment

Classification of tic disorders will be revised in the forthcoming edition of the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5). We do not support the suggestion to move tic disorders to "Anxiety and Obsessive-Compulsive Disorders", if the section "Disorders Usually First Diagnosed in Infancy, Childhood, or Adolescence" is not retained. Other than that, most proposed changes of the criteria for tic disorders contain a number of welcome improvements, e.g., the more unified definition of tics including the removal of the term "stereotyped" and the better capture of the temporal pattern of tics (e.g., removal of the maximum 3 months criterion for a tic-free period in chronic tic disorders). But, unfortunately there are some inconsistencies in detail, e.g., the unification of diagnostic criteria for tic disorders had not been consistently pursued in transient tic disorder. In sum, the proposed DSM-5 criteria could be seen as an important step forward particularly in clinical routine. However, continued research is needed to justify the existing and proposed classification of tic disorders as well as to better clarify what other changes should be made in the DSM-5 and beyond.