Tics and Tourette Syndrome

Mapping Gilles de la Tourette syndrome through the distress and relief associated with tic-related behaviors: an fMRI study

Personal distress associated with tic urges or inhibition and relief associated with tic production are defining features of the personal experience in Gilles de la Tourette syndrome (GTS). These affective phenomena have not been studied using fMRI, hindering our understanding of GTS pathophysiology and possible treatments. Here, we present a novel cross-sectional fMRI study designed to map tic-related phenomenology using distress and relief as predicting variables. We adopted a mental imagery approach and dissected the brain activity associated with different phases of tic behaviors, premonitory urges, and the ensuing tic execution or inhibition: these were compared with the mental simulation of "relaxed situations" and pre-determined stereotyped motor behaviors. We then explored whether the ensuing brain patterns correlated with the distress or relief perceived for the different phases of the tasks. Patients experienced a higher level of distress during the imagery of tic-triggering scenarios and no relief during tic inhibition. On the other hand, patients experienced significant relief during tic imagery. Distress during tic-triggering scenarios and relief during tic imagery were significantly correlated. The distress perceived during urges correlated with increased activation in cortical sensorimotor areas, suggesting a motor alarm. Conversely, relief during tic execution was positively associated with the activity of a subcortical network. The activity of the putamen was associated with both distress during urges and relief during tic execution. These findings highlight the importance of assessing the affective component of tic-related phenomenology. Subcortical structures may be causally involved in the affective component of tic pathophysiology, with the putamen playing a central role in both tic urge and generation. We believe that our results can be readily translated into clinical practice for the development of personalized treatment plans tailored to each patient's unique needs.

An investigation into mothers' experiences of their children's functional tic-like behaviour and tic attacks

OBJECTIVE

This is the first study to systematically explore the lived experiences of sudden and new onset of severe functional tics from the perspective of the mother's experiences and describes their attempts to access support services in the United Kingdom.

METHOD

Twenty-One mothers of young people aged between 12 to 17 years with functional tic-like behaviour (FTLB) took part in semi-structured interviews. Thematic analysis of the transcribed interviews revealed gaps and inconsistencies within the process of gaining access to professional services and a lack of support for the management of tics and functional tic-like movements, in addition to highlighting the impact it had on daily family life.

RESULTS

The themes generated included the occurrence and development of tics, the severity and intensity of symptoms, the psychological impact on the family and the need to make recommendations for a clear care pathway. Managing the impact of the FTLB and co-occurring conditions such as suicidal ideation and self-harm, as well as the physical and emotional trauma, commonly contributed to feelings of isolation and helplessness, which impacted negatively on the family's ability to function and participate in society.

CONCLUSIONS

The findings emphasize the urgent need to create a clear management pathway for those experiencing FTLB, including the need for more professionals with relevant knowledge, to improve the dialogue with families during the referral process, whilst prioritising the treatment of anxiety and other identified mental health concerns.

Social cognition in hyperkinetic movement disorders: a systematic review

Numerous lines of research indicate that our social brain involves a network of cortical and subcortical brain regions that are responsible for sensing and controlling body movements. However, it remains unclear whether movement disorders have a systematic impact on social cognition. To address this question, we conducted a systematic review examining the influence of hyperkinetic movement disorders (including Huntington disease, Tourette syndrome, dystonia, and essential tremor) on social cognition. Following the PRISMA guidelines and registering the protocol in the PROSPERO database (CRD42022327459), we analyzed 50 published studies focusing on theory of mind (ToM), social perception, and empathy. The results from these studies provide evidence of impairments in ToM and social perception in all hyperkinetic movement disorders, particularly during the recognition of negative emotions. Additionally, individuals with Huntington's Disease and Tourette syndrome exhibit empathy disorders. These findings support the functional role of subcortical structures (such as the basal ganglia and cerebellum), which are primarily responsible for movement disorders, in deficits related to social cognition.

The microstructural change of the brain and its clinical severity association in pediatric Tourette syndrome patients

BACKGROUND

Gilles de la Tourette syndrome (GTS) is a prevalent pediatric neurological disorder. Most studies point to abnormalities in the cortico-striato-thalamocortical (CSTC) circuits. Neuroimaging studies have shown GTS's extensive impact on the entire brain. However, due to participant variability and potential drug and comorbidity impact, the results are inconsistent. To mitigate the potential impact of participant heterogeneity, we excluded individuals with comorbidities or those currently undergoing medication treatments. Based on the hypothesis of abnormality within the CSTC circuit, we investigated microstructural changes in white matter using diffusion spectrum imaging (DSI). This study offers the first examination of microstructural changes in treatment-naïve pediatric patients with pure GTS using diffusion spectrum imaging.

METHODS

This single-center prospective study involved 30 patients and 30 age- and gender-matched healthy volunteers who underwent sagittal T1-weighted MRI and DSI. We analyzed generalized fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity.

RESULTS

No significant differences were observed in mean diffusivity and axial diffusivity values between the two groups. However, the patient group exhibited significantly higher generalized fractional anisotropy values in the right frontostriatal tract of the dorsolateral prefrontal cortex, the right frontostriatal tract of the precentral gyrus, and bilateral thalamic radiation of the dorsolateral prefrontal cortex. Additionally, the generalized fractional anisotropy value of the right frontostriatal tract of the precentral gyrus is inversely correlated with the total tic severity scores at the most severe condition.

CONCLUSION

Treatment-naïve pediatric GTS patients demonstrated increased connectivity within the CSTC circuit as per diffusion spectrum imaging, indicating possible CSTC circuit dysregulation. This finding could also suggest a compensatory change. It thus underscores the necessity of further investigation into the fundamental pathological changes in GTS. Nevertheless, the observed altered connectivity in GTS patients might serve as a potential target for therapeutic intervention.

Group comprehensive behavioral intervention for tics contribution to broader cognitive and emotion regulation in children

There is increasing evidence for the effectiveness of behavioral techniques in managing tics in youth with Tourette syndrome and tics disorders (TDs). One such intervention is Comprehensive Behavioral Intervention for Tics (CBIT), which focuses on reducing tic severity by training control and regulation. In view of the regulation deficits characteristic to TDs, in the current study, we aimed to explore the contribution of CBIT beyond tic control, to a wider expression of regulation abilities-cognitive inhibition and emotion regulation. A total of 55 participants with TDs, aged 8-15, who were randomly assigned to group-CBIT or group-Educational Intervention for Tics, were compared on cognitive inhibition tests and use of emotion-regulation strategies, pre- and post-intervention. Whereas on none of the scales a significant interaction effect was found reflecting superiority of CBIT over EIT, repeated measures ANOVA revealed a significant time effect, with post hoc analyses indicating that cognitive inhibition and cognitive reappraisal significantly increased following CBIT intervention only. Within the group-CBIT, the increase in cognitive reappraisal was associated with higher intellectual ability. These findings may lead to a broader understanding of CBIT contribution to more than tic control, but rather to better cognitive and emotional regulation abilities.

Developmental stuttering, physical concomitants associated with stuttering, and Tourette syndrome: A scoping review

BACKGROUND AND PURPOSE

Developmental stuttering and Tourette syndrome (TS) are common neurodevelopmental disorders. Although disfluencies may co-occur in TS, their type and frequency do not always represent pure stuttering. Conversely, core symptoms of stuttering may be accompanied by physical concomitants (PCs) that can be confused for tics. This scoping review aimed to explore the similarities and differences between stuttering and tics in terms of epidemiology, comorbidities, phenomenology, evolution, physiopathology, and treatment. We also described the nature of PCs in stuttering and disfluencies in TS.

METHODS

A literature search on Medline, Embase and PsycInfo was executed in March 2022. From 426 studies screened, 122 were included in the review (a majority being narrative reviews and case reports).

RESULTS

TS and stuttering have several epidemiological, phenomenological, comorbidity, and management similarities suggesting shared risk factors and physiopathology (involving the basal ganglia and their connections with speech and motor control cortical regions). PCs in stuttering commonly involve the face (eyelids, jaw/mouth/lip movements) and sometimes the head, trunk and limbs. PCs can be present from early stages of stuttering and vary over time and within individuals. The function of PCs is unknown. Some individuals with TS have a distinct disfluency pattern, composed of a majority of typical disfluencies (mostly between-word disfluencies), and a mix of cluttering-like behaviors, complex phonic tics (e.g. speech-blocking tics, echolalia, palilalia), and rarely, atypical disfluencies.

CONCLUSION

Future investigations are warranted to better understand the complex relationships between tics and stuttering and address the management of disfluencies in TS and PCs in stuttering.

What is the Intention to Move and When Does it Occur?

In 1983 Benjamin Libet and colleagues published a paper apparently challenging the view that the conscious intention to move precedes the brain's preparation for movement. The experiment initiated debates about the nature of intention, the neurophysiology of movement, and philosophical and legal understanding of free will and moral responsibility. Here we review the concept of "conscious intention" and attempts to measure its timing. Scalp electroencephalographic activity prior to movement, the Bereitschaftspotential, clearly begins prior to the reported onset of conscious intent. However, the interpretation of this finding remains controversial. Numerous studies show that the Libet method for determining intent, W time, is not accurate and may be misleading. We conclude that intention has many different aspects, and although we now understand much more about how the brain makes movements, identifying the time of conscious intention is still elusive.

Mapping a network for tics in Tourette syndrome using causal lesions and structural alterations

Tics are sudden stereotyped movements or vocalizations. Cases of lesion-induced tics are invaluable, allowing for causal links between symptoms and brain structures. While a lesion network for tics has recently been identified, the degree to which this network translates to Tourette syndrome has not been fully elucidated. This is important given that patients with Tourette syndrome make up a large portion of tic cases; therefore, existing and future treatments should apply to these patients. The aim of this study was to first localize a causal network for tics from lesion-induced cases and then refine and validate this network in patients with Tourette syndrome. We independently performed 'lesion network mapping' using a large normative functional connectome (n = 1000) to isolate a brain network commonly connected to lesions causing tics (n = 19) identified through a systematic search. The specificity of this network to tics was assessed through comparison to lesions causing other movement disorders. Using structural brain coordinates from prior neuroimaging studies (n = 7), we then derived a neural network for Tourette syndrome. This was done using standard anatomical likelihood estimation meta-analysis and a novel method termed 'coordinate network mapping', which uses the same coordinates, yet maps their connectivity using the aforementioned functional connectome. Conjunction analysis was used to refine the network for lesion-induced tics to Tourette syndrome by identifying regions common to both lesion and structural networks. We then tested whether connectivity from this common network is abnormal in a separate resting-state functional connectivity MRI data set from idiopathic Tourette syndrome patients (n = 21) and healthy controls (n = 25). Results showed that lesions causing tics were distributed throughout the brain; however, consistent with a recent study, these were part of a common network with predominant basal ganglia connectivity. Using conjunction analysis, coordinate network mapping findings refined the lesion network to the posterior putamen, caudate nucleus, globus pallidus externus (positive connectivity) and precuneus (negative connectivity). Functional connectivity from this positive network to frontal and cingulate regions was abnormal in patients with idiopathic Tourette syndrome. These findings identify a network derived from lesion-induced and idiopathic data, providing insight into the pathophysiology of tics in Tourette syndrome. Connectivity to our cortical cluster in the precuneus offers an exciting opportunity for non-invasive brain stimulation protocols.

Where Do Neurodevelopmental Disorders Go? Casting the Eye Away from Childhood towards Adulthood

Neurodevelopmental disorders (NDDs) encompass a group of complex conditions with onset during the early developmental period. Such disorders are frequently associated with a number of neuropsychiatric features, the most prevalent ones being autism spectrum disorder, attention-deficit/hyperactivity disorder, intellectual disability, communication and specific learning disorders, and motor disorders. These conditions are characterized by wide genetic and clinical variability, and although they were previously conceptualized as childhood-limited disorders, NDDs are progressively being recognized as persistent conditions with a potentially relevant impact on the quality of life and overall functioning during adult life. In addition, emerging evidence seems to point towards the hypothesis of a neurodevelopmental continuum, according to which NNDs could portray different time-dependent outcomes, depending on the severity of the altered brain development. Despite representing lifelong phenotypes, they are often not promptly identified and/or managed in adulthood. In this regard, specific guidelines on clinical and therapeutic approaches for these conditions have not yet been delineated. In this view, future research investigations should be encouraged to broaden available knowledge, characterize the clinical course of NDDs across an individual’s lifespan, and better understand the patterns of aging-related concerns in adults with an NDD diagnosis. Additionally, considering the difficulties many young adults encounter while transitioning from childhood to adult mental health services, new, specific programs should be developed and existing programs should be implemented to improve the transition process and for the management of NDDs in adulthood.

"Unvoluntary" Movement Disorders: Distinguishing between Tics, Akathisia, Restless Legs, and Stereotypies

Tics, stereotypies, akathisia, and restless legs fall at different places on the spectrum of discrete, unwanted and potentially disabling motor routines. Unlike tremor, chorea, myoclonus, or dystonia, this subgroup of abnormal movements is characterized by the subject's variable ability to inhibit or release undesired motor patterns on demand. Though it may be sometimes clinically challenging, it is crucial to distinguish these "unvoluntary" motor behaviors because secondary causes and management approaches differ substantially. To this end, physicians must consider the degree of repetitiveness of the movements, the existence of volitional control, and the association with sensory symptoms, or cognitive-ideational antecedent. This review aims to summarize the current existing knowledge on phenomenology, diagnosis, and treatment of tics, stereotypies, akathisia, and restless leg syndrome.

Impact of Tourette's syndrome tics on healing following dental trauma

The following case report outlines the impact of motor tics linked to Tourette's syndrome on dental development and healing following a dental injury to a maxillary central incisor. Emergency care and splinting of a mobile extruded maxillary left central incisor tooth was carried out at the local dentist on the same day as the dental trauma. A subsequent referral was made to the paediatric dental department for continued mobility of the maxillary central incisor on splint removal approximately 2 weeks later. A clinical and radiographic examination revealed shortened root length and apical root blunting associated with both maxillary anterior teeth. Further questioning revealed the likely cause of this to be related to the clenching and biting oral tics which the patient has experienced over the past 4 years. A removable splint has been fabricated for night-time wear and a mouthgaurd has been recommended for use during contact sports. Regular reviews will be conducted using a shared care approach between the patient's local dentist and the paediatric dental department.

Tourette syndrome and other tic disorders of childhood

Tics are repetitive, patterned, and nonrhythmic movements or vocalizations/audible sounds that are misplaced in context. Phenomenology and characteristics of tics (e.g., premonitory urge, suppressibility) differentiate them from compulsions, stereotypies, functional tic-like behaviors, and other types of hyperkinetic movement disorders. With a prevalence of approximately 1% in school-aged boys, Tourette syndrome (TS) is considered a common childhood-onset neurodevelopmental disorder, defined by the combination of at least two motor tics and at least one phonic tic lasting more than 1 year. TS is a highly heritable disorder, with a wide spectrum of severity. In some individuals, tics can cause pain, distress, functional impairment, or stigmatization. About 90% of individuals with TS have at least one mental health comorbidity (attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, anxiety/depressive disorders). These comorbidities significantly impact patients' quality of life and must therefore be screened and managed accordingly in this population. Treatment of tics is based on behavioral therapies targeting tics (habit reversal training included in the comprehensive behavioral intervention for tics, and exposure and response prevention for tics), in association with medication if needed (e.g., alpha-2-agonists, second-generation antipsychotics). Deep brain stimulation is considered an experimental option in the most severe, treatment-resistant patients. In adulthood, less than 25% of individuals still have moderate or severe tics.

The inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk involved in Tourette syndrome development

Background

Tourette syndrome (TS) is associated with immunological dysfunction. The DA system is closely related to TS development, or behavioral stereotypes. Previous evidence suggested that hyper-M1-polarized microglia may exist in the brains of TS individuals. However, the role of microglia in TS and their interaction with dopaminergic neurons is unclear. In this study, we applied iminodipropionitrile (IDPN) to establish a TS model and focused on the inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk.

Methods

Male Sprague-Dawley rats were intraperitoneally injected with IDPN for seven consecutive days. Stereotypic behavior was observed to verify the TS model. Striatal microglia activation was evaluated based on different markers and expressions of inflammatory factors. The striatal dopaminergic neurons were purified and co-cultured with different microglia groups, and dopamine-associated markers were assessed.

Results

First, there was pathological damage to striatal dopaminergic neurons in TS rats, as indicated by decreased expression of TH, DAT, and PITX3. Next, the TS group showed a trend of increased Iba-1 positive cells and elevated levels of inflammatory factors TNF-α and IL-6, as well as an enhanced M1-polarization marker (iNOS) and an attenuated M2-polarization marker (Arg-1). Finally, in the co-culture experiment, IL-4-treated microglia could upregulate the expression of TH, DAT, and PITX3 in striatal dopaminergic neurons vs LPS-treated microglia. Similarly, the TS group (microglia from TS rats) caused a decreased expression of TH, DAT, and PITX3 compared with the Sham group (microglia from control rats) in the dopaminergic neurons.

Conclusion

In the striatum of TS rats, microglia activation is M1 hyperpolarized, which transmits inflammatory injury to striatal dopaminergic neurons and disrupts normal dopamine signaling.

Myoclonus and other jerky movement disorders

Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.

European clinical guidelines for Tourette syndrome and other tic disorders-version 2.0. Part I: assessment

In 2011 a working group of the European Society for the Study of Tourette Syndrome (ESSTS) has developed the first European assessment guidelines for Tourette syndrome (TS). Now, we present an updated version 2.0 of these European clinical guidelines for Tourette syndrome and other tic disorders, part I: assessment. Therefore, the available literature has been thoroughly screened, supplemented with national guidelines across countries and discussions among ESSTS experts. Diagnostic changes between DSM-IV and DSM-5 classifications were taken into account and new information has been added regarding differential diagnoses, with an emphasis on functional movement disorders in both children and adults. Further, recommendations regarding rating scales to evaluate tics, comorbidities, and neuropsychological status are provided. Finally, results from a recently performed survey among ESSTS members on assessment in TS are described. We acknowledge that the Yale Global Tic Severity Scale (YGTSS) is still the gold standard for assessing tics. Recommendations are provided for scales for the assessment of tics and psychiatric comorbidities in patients with TS not only in routine clinical practice, but also in the context of clinical research. Furthermore, assessments supporting the differential diagnosis process are given as well as tests to analyse cognitive abilities, emotional functions and motor skills.

European clinical guidelines for Tourette syndrome and other tic disorders-version 2.0. Part III: pharmacological treatment

In 2011, the European Society for the Study of Tourette Syndrome (ESSTS) published the first European guidelines for Tourette Syndrome (TS). We now present an update of the part on pharmacological treatment, based on a review of new literature with special attention to other evidence-based guidelines, meta-analyses, and randomized double-blinded studies. Moreover, our revision took into consideration results of a recent survey on treatment preferences conducted among ESSTS experts. The first preference should be given to psychoeducation and to behavioral approaches, as it strengthens the patients' self-regulatory control and thus his/her autonomy. Because behavioral approaches are not effective, available, or feasible in all patients, in a substantial number of patients pharmacological treatment is indicated, alone or in combination with behavioral therapy. The largest amount of evidence supports the use of dopamine blocking agents, preferably aripiprazole because of a more favorable profile of adverse events than first- and second-generation antipsychotics. Other agents that can be considered include tiapride, risperidone, and especially in case of co-existing attention deficit hyperactivity disorder (ADHD), clonidine and guanfacine. This view is supported by the results of our survey on medication preference among members of ESSTS, in which aripiprazole was indicated as the drug of first choice both in children and adults. In treatment resistant cases, treatment with agents with either a limited evidence base or risk of extrapyramidal adverse effects might be considered, including pimozide, haloperidol, topiramate, cannabis-based agents, and botulinum toxin injections. Overall, treatment of TS should be individualized, and decisions based on the patient's needs and preferences, presence of co-existing conditions, latest scientific findings as well as on the physician's preferences, experience, and local regulatory requirements.

Effects of Chemogenetic Inhibition of D1 or D2 Receptor-Containing Neurons of the Substantia Nigra and Striatum in Mice With Tourette Syndrome

As tourette syndrome (TS) is a common neurobehavioral disorder, the primary symptoms of which include behavioral stereotypies. Dysfunction of the substantia nigra-striatum network could be the main pathogenesis of TS, which is closely associated with dopamine (DA) and its receptors. TS is often resistant to conventional treatments. Therefore, it is necessary to investigate the neurobiological mechanisms underlying its pathogenesis. In this study, we investigated whether chemogenetic activation or inhibition of dopaminergic D1 receptor (D1R)- or D2 receptor (D2R)-containing neurons in the substantia nigra pars compacta (SNpc) or dorsal striatum (dSTR) affected the stereotyped behavior and motor functions of TS mice. Intraperitoneal injection of 3,3'-iminodipropionitrile (IDPN) was used to induce TS in mice. Stereotyped behavior test and open-field, rotarod, and grip strength tests were performed to evaluate stereotyped behavior and motor functions, respectively. Immunofluorescence labeling was used to detect the co-labeling of virus fluorescence and D1R or D2R. We found that chemogenetic inhibition of D1R- or D2R-containing neurons in the SNpc and dSTR alleviated behavioral stereotypies and motor functions in TS mice. Chemogenetic activation of D1R-containing neurons in the dSTR aggravated behavioral stereotypies and motor functions in vehicle-treated mice, but neither was aggravated in TS mice. In conclusion, chemogenetic inhibition of D1R- or D2R-containing neurons in the SNpc and dSTR alleviated behavioral stereotypies of TS, providing a new treatment target for TS. Moreover, the activation of D1R-containing neurons in the dSTR may contribute to the pathogenesis of TS, which can be chosen as a more precise target for treatment.

Clinical Practice Patterns in Tic Disorders Among Movement Disorder Society Members

Background

Tic disorders belong to the broad spectrum of pediatric and adult movement disorders. The wide variability in clinical presentations, applied assessment tools, and treatments are poorly understood.

Objectives

To map practices and knowledge base of movement disorder clinicians concerning clinical features, pathophysiology, and treatment approaches in tic disorders.

Methods

A 33-item survey was developed by the Tic Disorders and Tourette syndrome Study Group members of the Movement Disorder Society. The survey was distributed to the complete society membership and included responses from 346 members, 314 of whom reported treating tic disorders.

Results

Approximately one third of survey respondents (35%) frequently evaluated patients with tics. The data revealed widespread use of existing guidelines (about 70%) and screening for comorbid disorders (>90%). The most common investigations used to rule out secondary causes of tics were imaging (92%), laboratory tests (66%) and neurophysiology (38%). Functional tics were the second most common tic etiology following primary tics. Only 27% of respondents reported confidence in knowledge about tic pathogenesis. Top rated interventions to treat tics were psychoeducation, cognitive behavioral intervention for tics (CBIT) and treatment for neuropsychiatric comorbidities. Antipsychotics were ranked as the most effective pharmacologic tic intervention.

Conclusions

The majority of movement disorders specialists do not frequently encounter tics. There was sparse knowledge about tic pathophysiology. Psychoeducation, CBIT, the treatment of neuropsychiatric comorbidities and use of antipsychotics emerged as the most common interventions to treat tics. These results provide insight into what will be needed to improve the diagnosis and treatment of tic disorders.

From Collar to Coccyx: Truncal Movement Disorders: A Clinical Review

Background

Movement disorders affecting the trunk remain a diagnostic challenge even for experienced clinicians. However, despite being common and debilitating, truncal movement disorders are rarely discussed and poorly reviewed in the medical literature.

Objectives

To review common movement disorders affecting the trunk and provide an approach for clinicians based on the truncal region involved (shoulder, chest, diaphragm, abdomen, pelvis, and axial disorders). For each disorder, clinical presentation, etiologic differential diagnosis, and "clinical clues" are discussed.

Conclusion

This review provides a clinically focused, practical approach to truncal movement disorders, which will be helpful for physicians in everyday practice.

Revisiting the structure of the Yale Global Tic Severity Scale (YGTSS) in a sample of Chinese children with tic disorders

BACKGROUND

To the best of our knowledge, although the Chinese version of the Yale Global Tic Severity Scale (YGTSS) is widely used in child psychiatry departments in China, there is very little evidence focusing on the psychometric characteristics of the Chinese version of YGTSS. In this present study, we aim to re-examine the structure of the Chinese version of YGTSS and investigate its reliability and validity.

METHODS

A total of 367 children and adolescents with tic disorders aged 5-16 years old participated in the study. The Cronbach's alpha, test-retest reliability and concurrent validity will be calculated. Confirmatory Factor Analysis (CFA) also will be performed to assess the structure of YGTSS.

RESULTS

The Cronbach's alpha of the motor tic subscale of YGTSS was 0.84, for the phonic tic subscale of YGTSS, it was 0.90, but for the whole scale, it was 0.58. The test-retest reliability of YGTSS was 0.84. For the results of CFA, the Comparative Fit Index (CFI) of YGTSS based on the Two-Factor Model and Three-Factor Model was 0.97 and 0.96 respectively. The measurement invariance analysis suggested that the Two-Factor model of YGTSS across different age and sex groups was at the accepted level (≥0.90).

CONCLUSION

Overall, according to the results of this research, it suggested that the Chinese version of YGTSS showed good psychometric properties. It can be used in the assessment of tic disorders in the Chinese population. In the future, more comprehensive tools for assessing tics need to be further developed, which can cover the symptoms of premonitory urge and tic related obsessive-compulsive symptoms.

The Phenomenon of Exquisite Motor Control in Tic Disorders and its Pathophysiological Implications

The unifying characteristic of movement disorders is the phenotypic presentation of abnormal motor outputs, either as isolated phenomena or in association with further clinical, often neuropsychiatric, features. However, the possibility of a movement disorder also characterized by supranormal or enhanced volitional motor control has not received attention. Based on clinical observations and cases collected over a number of years, we here describe the intriguing clinical phenomenon that people with tic disorders are often able to control specific muscle contractions as part of their tic behaviors to a degree that most humans typically cannot. Examples are given in accompanying video documentation. We explore medical literature on this topic and draw analogies with early research of fine motor control physiology in healthy humans. By systematically analyzing the probable sources of this unusual capacity, and focusing on neuroscientific accounts of voluntary motor control, sensory feedback, and the role of motor learning in tic disorders, we provide a novel pathophysiological account explaining both the presence of exquisite control over motor output and that of overall tic behaviors. We finally comment on key questions for future research on the topic and provide concluding remarks on the complex movement disorder of tic behaviors. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Immunological Dysfunction in Tourette Syndrome and Related Disorders

Chronic tic disorder and Tourette syndrome are common childhood-onset neurological diseases. However, the pathophysiology underlying these disorders is unclear, and most studies have focused on the disinhibition of the corticostriatal–thalamocortical circuit. An autoimmune dysfunction has been proposed in the pathogenetic mechanism of Tourette syndrome and related neuropsychiatric disorders such as obsessive–compulsive disorder, autism, and attention-deficit/hyperactivity disorder. This is based on evidence from animal model studies and clinical findings. Herein, we review and give an update on the clinical characteristics, clinical evidence, and genetic studies in vitro as well as animal studies regarding immune dysfunction in Tourette syndrome.

Enrichment and Correlation Analysis of Serum miRNAs in Comorbidity Between Arnold-Chiari and Tourette Syndrome Contribute to Clarify Their Molecular Bases

Due to its rarity, coupled to a multifactorial and very heterogeneous nature, the molecular etiology of Arnold-Chiari (AC) syndrome remains almost totally unknown. Its relationship with other neuropsychiatric disorders such as Tourette syndrome (TS) is also undetermined. The rare comorbid status between both disorders (ACTS) complicates the framework of diagnosis and negatively affects the patients' quality of life. In this exploratory study, we aimed to identify serum microRNA expression profiles as molecular fingerprints for AC, TS, and ACTS, by using a high-throughput approach. For this aim, 10 AC patients, 11 ACTS patients, 6 TS patients, and 8 unaffected controls (NC) were recruited. Nine miRNAs resulted significantly differentially expressed (DE): let-7b-5p (upregulated in ACTS vs. TS); miR-21-5p (upregulated in ACTS vs. AC; downregulated in AC vs. TS); miR-23a-3p (upregulated in TS vs. NCs; downregulated in AC vs. TS); miR-25-3p (upregulated in AC vs. TS and NCs; downregulated in ACTS vs. AC); miR-93-5p (upregulated in AC vs. TS); miR-130a-3p (downregulated in ACTS and TS vs. NCs); miR-144-3p (downregulated in ACTS vs. AC; upregulated in AC vs. TS); miR-222-3p (upregulated in ACTS vs. NCs); miR-451a (upregulated in AC vs. TS and NCs; in ACTS vs. NCs). Altered expression of miRNAs was statistically correlated to neuroimaging and neuropsychological anomalies. Furthermore, computational analyses indicated that DE miRNAs are involved in AC and TS pathomechanisms. Finally, we propose the dysregulation of the miRNA set as a potential molecular tool for supporting the current diagnosis of AC, TS, and ACTS by using liquid biopsies, in an unbiased and non-invasive way.

Anti-dopamine D2 receptor antibodies in chronic tic disorders

AIM

To investigate the association between circulating anti-dopamine D2 receptor (D2R) autoantibodies and the exacerbation of tics in children with chronic tic disorders (CTDs).

METHOD

One hundred and thirty-seven children with CTDs (108 males, 29 females; mean age [SD] 10y 0mo [2y 7mo], range 4-16y) were recruited over 18 months. Patients were assessed at baseline, at tic exacerbation, and at 2 months after exacerbation. Serum anti-D2R antibodies were evaluated using a cell-based assay and blinded immunofluorescence microscopy scoring was performed by two raters. The association between visit type and presence of anti-D2R antibodies was measured with McNemar's test and repeated-measure logistic regression models, adjusting for potential demographic and clinical confounders.

RESULTS

At exacerbation, 11 (8%) participants became anti-D2R-positive ('early peri-exacerbation seroconverters'), and nine (6.6%) became anti-D2R-positive at post-exacerbation ('late peri-exacerbation seroconverters'). The anti-D2R antibodies were significantly associated with exacerbations when compared to baseline (McNemar's odds ratio=11, p=0.003) and conditional logistic regression confirmed this association (Z=3.49, p<0.001) after adjustment for demographic and clinical data and use of psychotropic drugs.

INTERPRETATION

There is a potential association between immune mechanisms and the severity course of tics in adolescents with CTDs.

Tics induced by antiepileptic drugs: a pragmatic review

OBJECTIVE

The clinical spectrum of tics induced by antiepileptic drugs (AED), a form of 'secondary Tourettism', is largely unknown. Examining the literature aimed to help clinicians identify, understand and manage these cases. Understanding the mechanism of AED-induced tics could provide valuable insights into why certain patients may be vulnerable to this adverse event.

METHODS

A pragmatic systematic review, adapted from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed. Data sources included: PubMed, Medline and Cochrane Library. No lower date restrictions were employed, with December 2019 being the end date. Any tics reported in the presence of an AED were included in the review. Case reports were not excluded due to the scant evidence. Individual patient-level data was extracted from published material and the Naranjo Scale was applied to each case to assess the likelihood of causality.

RESULTS

181 unique papers were identified from the search. 24 manuscripts with a total of 43 subjects met eligibility for analysis. AED with different modes of action: carbamazepine, clonazepam, lacosamide, lamotrigine, levetiracetam, phenytoin and phenobarbital; were identified as causative AEDs. The clinical phenotype was broad, although a neuropsychiatric history characterised by reduced impulse control was more predictive than a previous tic in the adult population, phenomenology had a facial/truncal predominance and most tics resolved or improve with either AED withdrawal or dose reduction.

SIGNIFICANCE

Multiple AEDs with different modes of action can induce tic disorders, including newer AEDs. The cause is therefore unlikely to be an alteration to a single neurotransmitter, but rather an imbalance of networks, influenced further by individual factors.

Effects of Jian-Pi-Zhi-Dong Decoction on the Expression of 5-HT and Its Receptor in a Rat Model of Tourette Syndrome and Comorbid Anxiety

BACKGROUND Anxiety is one of the common comorbidities of Tourette syndrome (TS). The serotonin (5-HT) system is involved in both TS and anxiety. Jian-pi-zhi-dong decoction (JPZDD) is widely used. However, the mechanism remains unknown. In this study, a rat model of TS and comorbid anxiety was used to evaluate the effect of JPZDD on 5-HT and its receptor. MATERIAL AND METHODS 48 rats were divided into 4 groups randomly (n=12). The model was established by empty water bottle stimulation plus iminodipropionitrile injection for 3 weeks. Then the control and model groups were gavaged with saline, while the treatment groups were gavaged with fluoxetine hydrochloride (Flx) or JPZDD. Body weights were measured, and behavioral tests were evaluated with stereotypy and elevated plus maze. The morphologic characters were observed by hematoxylin and eosin staining. The content of 5-HT was detected by enzyme-linked immunosorbent assay and high-performance liquid chromatography. The expression of 5-HT2C receptor was detected by western blot and quantitative polymerase chain reaction. RESULTS The stereotypy score was lower and the time spent in the open arm was longer in the JPZDD group compared with the model group. After the treatment of Flx or JPZDD, the structure of neurons became gradually normal and the cells were arranged neatly. The contents of 5-HT in the treatment groups were higher compared with the model group in the striatum. The expression of 5-HT2C mRNA in the striatum of JPZDD and Flx groups decreased compared with the model group, and the JPZDD group was lower than the Flx group. CONCLUSIONS JPZDD alleviated both tic and anxiety symptoms and the mechanism may be via reducing the expression of 5-HT2C mRNA in the striatum, increasing the concentration of 5-HT, and enhancing the activity of the 5-HT system, which in turn exerts neuro-inhibition.

The cognitive neuropsychiatry of Tourette syndrome

Introduction: Converging evidence from both clinical and experimental studies has shown that Tourette syndrome (TS) is not a unitary condition, but a cluster of multiple phenotypes, which encompass both tics and specific behavioural and cognitive symptoms (mainly attention-deficit and hyperactivity disorder and obsessive-compulsive disorder). Methods: We conducted a narrative review of the recent literature on the cognitive neuropsychiatry of TS. Results: Although clinical research has shown that TS is not associated with cognitive deficits per se, the findings of recent studies have suggested the presence of subtle alterations in specific cognitive functions. A promising line of research on imitative behaviour could provide a common background for the alterations in executive control and social cognition observed in TS. Two different (but not mutually exclusive) neurocognitive theories have recently suggested that TS could originate from altered perception-action binding and social decision-making dysfunction, respectively. Conclusions: Since the presence of behavioural comorbidities influences individualised treatment approaches, it is likely that a more precise characterisation of TS phenotypes, including cognitive aspects, will result in improved levels of care for patients with tic disorders.

Late-onset oro-facial dyskinesia in Spinocerebellar Ataxia type 2: a case report

BACKGROUND

Genetic familiar causes of oro-facial dyskinesia are usually restricted to Huntington's disease, whereas other causes are often missed or underestimated. Here, we report the case of late-onset oro-facial dyskinesia in an elderly patient with a genetic diagnosis of Spinocerebellar Ataxia type 2 (SCA2).

CASE PRESENTATION

A 75-year-old man complained of progressive balance difficulty since the age of 60 years, associated with involuntary movements of the mouth and tongue over the last 3 months. No exposure to anti-dopaminergic agents, other neuroleptics, antidepressants, or other drugs was reported. Family history was positive for SCA2 (brother and the son of the brother). At rest, involuntary movements of the mouth and tongue were noted; they appeared partially suppressible and became more evident during stress and voluntary movements. Cognitive examination revealed frontal-executive dysfunction, memory impairment, and attention deficit. Brain magnetic resonance imaging (MRI) disclosed signs of posterior periventricular chronic cerebrovascular disease and a marked ponto-cerebellar atrophy, as confirmed by volumetric MRI analysis. A dopamine transporter imaging scan demonstrated a bilaterally reduced putamen and caudate nucleus uptake. Ataxin-2 (ATXN2) gene analysis revealed a 36 cytosine-adenine-guanine (CAG) repeat expansion, confirming the diagnosis of SCA2.

CONCLUSIONS

SCA2 should be considered among the possible causes of adult-onset oro-facial dyskinesia, especially when the family history suggests an inherited cerebellar disorder. Additional clinical features, including parkinsonism and motor neuron disease, may represent relevant cues for an early diagnosis and adequate management.

Late-onset oro-facial dyskinesia in Spinocerebellar Ataxia type 2: a case report

BACKGROUND

Genetic familiar causes of oro-facial dyskinesia are usually restricted to Huntington's disease, whereas other causes are often missed or underestimated. Here, we report the case of late-onset oro-facial dyskinesia in an elderly patient with a genetic diagnosis of Spinocerebellar Ataxia type 2 (SCA2).

CASE PRESENTATION

A 75-year-old man complained of progressive balance difficulty since the age of 60 years, associated with involuntary movements of the mouth and tongue over the last 3 months. No exposure to anti-dopaminergic agents, other neuroleptics, antidepressants, or other drugs was reported. Family history was positive for SCA2 (brother and the son of the brother). At rest, involuntary movements of the mouth and tongue were noted; they appeared partially suppressible and became more evident during stress and voluntary movements. Cognitive examination revealed frontal-executive dysfunction, memory impairment, and attention deficit. Brain magnetic resonance imaging (MRI) disclosed signs of posterior periventricular chronic cerebrovascular disease and a marked ponto-cerebellar atrophy, as confirmed by volumetric MRI analysis. A dopamine transporter imaging scan demonstrated a bilaterally reduced putamen and caudate nucleus uptake. Ataxin-2 (ATXN2) gene analysis revealed a 36 cytosine-adenine-guanine (CAG) repeat expansion, confirming the diagnosis of SCA2.

CONCLUSIONS

SCA2 should be considered among the possible causes of adult-onset oro-facial dyskinesia, especially when the family history suggests an inherited cerebellar disorder. Additional clinical features, including parkinsonism and motor neuron disease, may represent relevant cues for an early diagnosis and adequate management.

Learning volition: A longitudinal study of developing intentional awareness in Tourette syndrome

Tourette syndrome (TS) is characterized by the presence of involuntary movements (tics) which are, at least partly, generated within 'voluntary' motor pathways. Here we reassess 16 TS patients (age 19 ± 2.3 years) who participated in a mental chronometry study of volition 5.5 years previously (Ganos C et al. Cortex. 2015 Mar.; 64:47-54), and 16 age-matched controls. Participants estimated the time of their own voluntary movements (Libet's M judgement), or of conscious intention to make voluntary movements (Libet's W judgement), in separate blocks. We considered M judgement as a control condition. Therefore, the experience of an intention to move occurring prior to actual movement onset, as measured by the W-M gap, was taken as the cardinal feature of volition. Time estimates of the TS group did not differ significantly from controls, for either M or W judgement. Further, M and W time estimates in the TS group had not changed significantly between the two assessments. However, exploratory analyses revealed a strong relation between disease duration and the development of M- and W-judgements: the longer was the disease duration, the less was the developmental increase in the W-M gap (linear regression, p = .003). In conclusion, our results suggest compromised development of experience of volition in developing TS patients. The developmental difficulty in processing internal premotor signals for voluntary actions could reflect the chronic persistence of tics from adolescence to adulthood.

Voluntary Inhibitory Control of Chorea: A Case Series

Background

Volitional control of involuntary movements has so far been considered a hallmark of tic disorders. However, modulation of involuntary movements can also be observed in other hyperkinesias.

Cases

Here, we present 6 patients with chorea able to suppress their involuntary movements, on demand. In 3 of them, surface electromyography was used to quantify degree of suppression and confirmed a reduction of muscle activity up to 68%, during volitional control.

Conclusion

This observation represents a first step toward a description of a new clinical feature in choreic syndromes and an opportunity to redefine the role of volitional inhibition in hyperkinetic movement disorders.

Clinical Features of Tourette Syndrome

Tourette syndrome is a multifaceted disorder characterized by multiple motor and at least one vocal tics that start in childhood, persist for at least 1 year, and cannot be attributed to another medical condition or exposure to medications/drugs. Clinical diagnostic criteria are available, and identification of tics is typically straightforward based on characteristic appearance and features. Diagnostic uncertainty can rarely arise in cases of mild tics, atypical features, certain psychiatric comorbidities, and other non-tic movement disorders. Comorbid psychopathology, including attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive behaviors/obsessive-compulsive disorder, affects the majority of patients and is correlated with disease severity and the presence of additional psychiatric behaviors. The severity of tics often improves after adolescence, whereas psychiatric symptoms typically persist. The subset of patients in whom tics persist into adulthood experience higher rates of anxiety, and lower self-esteem, socioeconomic status, and quality of life; the relative contribution of motor tics and psychopathology is not fully understood. This article summarizes the clinical features of Tourette syndrome, including major diagnostic criteria, unique features of tics, and key aspects that differentiate tics from common mimics and chameleons. Comorbid psychiatric conditions and their impact on phenotype and quality of life are described. Finally, current understanding of the natural history is summarized, including limited research in adults with Tourette syndrome.

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.

The spectrum of involuntary vocalizations in humans: A video atlas

In clinical practice, involuntary vocalizing behaviors are typically associated with Tourette syndrome and other tic disorders. However, they may also be encountered throughout the entire tenor of neuropsychiatry, movement disorders, and neurodevelopmental syndromes. Importantly, involuntary vocalizing behaviors may often constitute a predominant clinical sign, and, therefore, their early recognition and appropriate classification are necessary to guide diagnosis and treatment. Clinical literature and video-documented cases on the topic are surprisingly scarce. Here, we pooled data from 5 expert centers of movement disorders, with instructive video material to cover the entire range of involuntary vocalizations in humans. Medical literature was also reviewed to document the range of possible etiologies associated with the different types of vocalizing behaviors and to explore treatment options. We propose a phenomenological classification of involuntary vocalizations within different categorical domains, including (1) tics and tic-like vocalizations, (2) vocalizations as part of stereotypies, (3) vocalizations as part of dystonia or chorea, (4) continuous vocalizing behaviors such as groaning or grunting, (5) pathological laughter and crying, (6) vocalizations resembling physiological reflexes, and (7) other vocalizations, for example, those associated with exaggerated startle responses, as part of epilepsy and sleep-related phenomena. We provide comprehensive lists of their associated etiologies, including neurodevelopmental, neurodegenerative, neuroimmunological, and structural causes and clinical clues. We then expand on the pathophysiology of the different vocalizing behaviors and comment on available treatment options. Finally, we present an algorithmic approach that covers the wide range of involuntary vocalizations in humans, with the ultimate goal of improving diagnostic accuracy and guiding appropriate treatment. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

A Review of Tics Presenting Subsequent to Traumatic Brain Injury

Purpose of review

This review summarizes case reports of patients with tics emerging subsequent to traumatic brain injury (TBI), with respect to demographics, post-TBI symptoms, tic onset latency and topography, clinical history, neuroimaging results and treatment outcome.

Recent findings

Patients were 22 adults and 3 youth. Trauma onset appeared to fall mostly in adulthood. Two-thirds of patients were male and head trauma was related to motor vehicle accidents in most cases. Loss of consciousness was reported in just below half (48.0%) of cases. Associated physical and cognitive symptoms (e.g., impaired memory, reduced sensory perception, poor balance, muscle weakness, attention problems, aggression/impulsivity, obsessions and compulsions, depression and anxiety) were commonly reported. The latency between head trauma and tic onset varied, but generally ranged from one day post-trauma to approximately one year post-trauma. Sole presentation of motor tics was common, with rostral to caudal development of motor tics in other cases. Simple and/or complex vocal tics were present in several cases, often emerging after motor tics. Post-trauma obsessive-compulsive symptoms were noted in five cases (20.0%). A personal or family history of tics was reported in four cases. Damage to the basal ganglia, ventricular system, and temporal region was observed across ten patients (40.0%). Pharmacological intervention varied, with tic symptoms deemed to have significantly or somewhat improved in 12 cases (48.0%). A comparison of post-TBI symptoms in youth with head trauma history relative to those with peripheral injury suggests tic symptoms are not a common post-TBI symptom in youth.

Summary

Ultimately, there has been limited study on the link between traumatic brain injury and tic expression, and methodological issues preclude the ability to draw definitive conclusions regarding this relationship. Nevertheless, findings do suggest there may be heterogeneity in brain dysfunction associated with tic expression. Future case reports should utilize more systematic and thorough assessment of TBI and tics using validated measures, evaluate medication effects using single-case designs, and perform more longitudinal follow-up of cases with repeated neuroimaging.

Critical aspects in the legal defence of patients with Tourette's Syndrome: An Italian case series

Tourette's syndrome (TS) is a developmental neurobehavioral disorder with childhood onset and relevant burden in terms of disability and reduced quality of life. In Italy the biological basis of this syndrome is still frequently ignored and TS is often recognised as a psychiatric manifestation, or even it is not recognised as pathology, which may result in inadequate treatment, social isolation and improper hospitalization. Indeed, the organic medical nature of TS needs to be taken into great consideration in evaluating causality of committing crimes in affected patients. In addition, delaying the diagnosis and consequently proper treatment has a devastating impact on social as well as legal aspects in patients with TS. The present report is aimed to present an Italian case series of 4 TS patients who faced legal problems related to their mental condition, in the intent to add further evidence, raise the level of awareness and encourage further investigation in the field, as in most of the cases, patients' illness was not taken into adequate account by the Justice. The relevant law is discussed in detail.

Dopaminergic Disturbances in Tourette Syndrome: An Integrative Account

Tourette syndrome (TS) is thought to involve dopaminergic disturbances, but the nature of those disturbances remains controversial. Existing hypotheses suggest that TS involves 1) supersensitive dopamine receptors, 2) overactive dopamine transporters that cause low tonic but high phasic dopamine, 3) presynaptic dysfunction in dopamine neurons, or 4) dopaminergic hyperinnervation. We review evidence that contradicts the first two hypotheses; we also note that the last two hypotheses have traditionally been considered too narrowly, explaining only small subsets of findings. We review all studies that have used positron emission tomography and single-photon emission computerized tomography to investigate the dopaminergic system in TS. The seemingly diverse findings from those studies have typically been interpreted as pointing to distinct mechanisms, as evidenced by the various hypotheses concerning the nature of dopaminergic disturbances in TS. We show, however, that the hyperinnervation hypothesis provides a simple, parsimonious explanation for all such seemingly diverse findings. Dopaminergic hyperinnervation likely causes increased tonic and phasic dopamine. We have previously shown, using a computational model of the role of dopamine in basal ganglia, that increased tonic dopamine and increased phasic dopamine likely increase the propensities to express and learn tics, respectively. There is therefore a plausible mechanistic link between dopaminergic hyperinnervation and TS via increased tonic and phasic dopamine. To further bolster this argument, we review evidence showing that all medications that are effective for TS reduce signaling by tonic dopamine, phasic dopamine, or both.

Gilles de la Tourette syndrome as a paradigmatic neuropsychiatric disorder

Gilles de la Tourette syndrome is a chronic and complex tic disorder accompanied by specific behavioral problems in the majority of patients. With its multifaceted interplay between motion and emotion, this condition is a paradigmatic example of the science and art of clinical neuropsychiatry. This review article encompasses the clinical phenomenology of motor and vocal tics and associated sensory experiences (premonitory urges), as well as the behavioral spectrum of the most common comorbidities, including obsessive-compulsive disorder, attention-deficit and hyperactivity disorder, affective symptoms, and impulsivity. Knowledge of the contributions of both tics and behavioral problems to patients' health-related quality of life across the lifespan should assist treating clinicians in formulating a targeted management plan. Although the exact pathophysiology of Gilles de la Tourette syndrome remains elusive, research into therapeutic interventions has expanded the range of available interventions across multiple domains. A thorough understanding of the neurology and psychiatry of this condition is of key importance to meet the needs of this patient population, from the formulation of an accurate diagnosis to the implementation of effective treatment strategies.

Altered dopaminergic regulation of the dorsal striatum is able to induce tic-like movements in juvenile rats

Motor tics are sudden, repetitive, involuntary movements representing the hallmark behaviors of the neurodevelopmental disease Tourette’s syndrome (TS). The primary cause of TS remains unclear. The initial observation that dopaminergic antagonists alleviate tics led to the development of a dopaminergic theory of TS etiology which is supported by post mortem and in vivo studies indicating that non-physiological activation of the striatum could generate tics. The striatum controls movement execution through the balanced activity of dopamine receptor D1 and D2-expressing medium spiny neurons of the direct and indirect pathway, respectively. Different neurotransmitters can activate or repress striatal activity and among them, dopamine plays a major role. In this study we introduced a chronic dopaminergic alteration in juvenile rats, in order to modify the delicate balance between direct and indirect pathway. This manipulation was done in the dorsal striatum, that had been associated with tic-like movements generation in animal models. The results were movements resembling tics, which were categorized and scored according to a newly developed rating scale and were reduced by clonidine and riluzole treatment. Finally, post mortem analyses revealed altered RNA expression of dopaminergic receptors D1 and D2, suggesting an imbalanced dopaminergic regulation of medium spiny neuron activity as being causally related to the observed phenotype.

Sensory aspects of Tourette syndrome

Motor and vocal tics have long been recognised as the core features of Tourette syndrome (TS). However, patients' first-person accounts have consistently reported that these involuntary motor manifestations have specific sensory correlates. These sensory symptoms are often described as feelings of mounting inner tension ("premonitory urges") and are transiently relieved by tic expression. Multimodal hypersensitivity to external stimuli, perceived as triggers and/or exacerbating factors for specific tic symptoms, is also commonly reported by patients with TS. This article focuses on the rapidly expanding literature on the clinical and neurobiological aspects of the premonitory urge and multimodal hypersensitivity in patients with TS, with particular attention to pathophysiological mechanisms and possible treatment implications. These findings suggest that TS is a neurobehavioural condition characterised by intrinsic perceptual abnormalities involving the insula and sensorimotor areas, in addition to basal ganglia dysfunction. Further research will clarify the role of sensory symptoms in TS, as well as the effects of external sensory input on underlying motor abnormalities.

Botulinum toxin for motor and phonic tics in Tourette's syndrome

BACKGROUND

Gilles de la Tourette syndrome, or Tourette's syndrome, is defined as the presence of both motor and vocal (phonic) tics for more than 12 months, that manifest before the age of 18 years, in the absence of secondary causes. Treatment of motor and phonic tics is difficult and challenging.

OBJECTIVES

To determine the safety and effectiveness of botulinum toxin in treating motor and phonic tics in people with Tourette's syndrome, and to analyse the effect of botulinum toxin on premonitory urge and sensory tics.

SEARCH METHODS

We searched the Cochrane Movement Disorders Group Trials Register, CENTRAL, MEDLINE, and two trials registers to 25 October 2017. We reviewed reference lists of relevant articles for additional trials.

SELECTION CRITERIA

We considered all randomised, controlled, double-blind studies comparing botulinum toxin to placebo or other medications for the treatment of motor and phonic tics in Tourette's syndrome for this review. We sought both parallel group and cross-over studies of children or adults, at any dose, and for any duration.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods to select studies, assess risk of bias, extract and analyse data. All authors independently abstracted data onto standardized forms; disagreements were resolved by mutual discussion.

MAIN RESULTS

Only one randomised placebo-controlled, double-blind cross-over study met our selection criteria. In this study, 20 participants with motor tics were enrolled over a three-year recruitment period; 18 (14 of whom had a diagnosis of Tourette's syndrome) completed the study; in total, 21 focal motor tics were treated. Although we considered most bias domains to be at low risk of bias, the study recruited a small number of participants with relatively mild tics and provided limited data for our key outcomes. The effects of botulinum toxin injections on tic frequency, measured by videotape or rated subjectively, and on premonitory urge, are uncertain (very low-quality evidence). The quality of evidence for adverse events following botulinum toxin was very low. Nine people had muscle weakness following the injection, which could have led to unblinding of treatment group assignment. No data were available to evaluate whether botulinum injections led to immunoresistance to botulinum.

AUTHORS' CONCLUSIONS

We are uncertain about botulinum toxin effects in the treatment of focal motor and phonic tics in select cases, as we assessed the quality of the evidence as very low. Additional randomised controlled studies are needed to demonstrate the benefits and harms of botulinum toxin therapy for the treatment of motor and phonic tics in patients with Tourette's syndrome.