Reflex tics in two patients with Gilles de la Tourette syndrome

Phenomenology and Clinical Correlates of Stimulus-Bound Tics in Gilles de la Tourette Syndrome

Introduction: Stimulus-bound tics (SBTs) belong to stimulus-induced behaviors and are defined as tics that occur in response to internal or external stimuli. The aim of the study was to assess the prevalence and associations of SBTs with other stimulus-triggered behaviors, premonitory urges and stimulus sensitization in Gilles de la Tourette syndrome (GTS). Methods: We performed a prospective, one-registration study in a cohort of 140 consecutive patients with GTS. Duration of GTS was 10.6 ± 8.7 years (range: 0-39 years). SBTs were diagnosed during the interview. Results: SBTs occurred at some point in the lifetime of 20.7% of patients. The presence of SBTs in adults was four times as frequent as in children (35.5% vs. 9.0%) with the most frequent onset in adolescence (58.8%) and adulthood (29.4%). These tics started 9.1 ± 4.7 years after the onset of tics. One stimulus and mental stimulus preceded tics most frequently, 44.8 and 33.3%, respectively. There was no established pattern of tics triggered by stimuli. Multivariate logistic regression analysis showed significant associations of SBTs with age at evaluation, tic severity, and palilalia but not with any co-morbid psychiatric disorders. 80% of patients showed at least one stimulus-triggered behavior. Premonitory urges and stimulus sensitization were reported by 60.0 and 40.7% of patients, respectively. No significant correlations between SBTs, premonitory urges and stimulus sensitization were found. Conclusion: SBTs are a part of the tic spectrum and should be taken into account by clinicians who deal with GTS patients. These tics fall at the tic end of the continuum of stimulus-induced behaviors.

An Investigation of Tic Suppression and the Rebound Effect in Tourette’s Disorder

Many patients, parents of children with Tourette’s disorder, and professionals have suggested that following a period of suppression, tics will rebound to a rate that will exceed the average rate of occurrence. At present, there are no empirical data to support or refute such an effect. This experiment utilized an A-B-A design with replication to test this hypothesized effect. Following baseline observation, participants were instructed to refrain from exhibiting tics while watching videotapes, engaging in conversation, or while alone in a room with no activity. Observation continued following the suppression phase. Results of this experiment showed suppression of tics in almost one half of all sessions, with adults demonstrating suppression more frequently. Furthermore, results of this experiment failed to support a commonly held perception that following a period of voluntary suppression tics will rebound to a rate that will exceed the average rate of occurrence.

Targeted ablation of cholinergic interneurons in the dorsolateral striatum produces behavioral manifestations of Tourette syndrome

Gilles de la Tourette syndrome (TS) is characterized by tics, which are transiently worsened by stress, acute administration of dopaminergic drugs, and by subtle deficits in motor coordination and sensorimotor gating. It represents the most severe end of a spectrum of tic disorders that, in aggregate, affect ∼ 5% of the population. Available treatments are frequently inadequate, and the pathophysiology is poorly understood. Postmortem studies have revealed a reduction in specific striatal interneurons, including the large cholinergic interneurons, in severe disease. We tested the hypothesis that this deficit is sufficient to produce aspects of the phenomenology of TS, using a strategy for targeted, specific cell ablation in mice. We achieved ∼ 50% ablation of the cholinergic interneurons of the striatum, recapitulating the deficit observed in patients postmortem, without any effect on GABAergic markers or on parvalbumin-expressing fast-spiking interneurons. Interneuron ablation in the dorsolateral striatum (DLS), corresponding roughly to the human putamen, led to tic-like stereotypies after either acute stress or d-amphetamine challenge; ablation in the dorsomedial striatum, in contrast, did not. DLS interneuron ablation also led to a deficit in coordination on the rotorod, but not to any abnormalities in prepulse inhibition, a measure of sensorimotor gating. These results support the causal sufficiency of cholinergic interneuron deficits in the DLS to produce some, but not all, of the characteristic symptoms of TS.

Sensory Phenomena in Tourette Syndrome: Their Role in Symptom Formation and Treatment

The primary symptoms of Tourette Syndrome (TS) are motor and vocal tics, but increasingly, researchers have examined the role of sensory phenomena in biobehavioral models of the disorder. These sensory phenomena involve tic-related premonitory urge sensations as well as potential abnormalities in the perceptual and behavioral experiences associated with external sensory input. As such, dysfunctional sensorimotor integration might represent a key facet of TS pathology. The current paper reviews the literature on sensory phenomena in tic disorders and highlights possible connections to TS symptoms and directions for future research.

Brief review of habit reversal training for Tourette syndrome

It is well established that Tourette syndrome has a neurobiologic origin. Although pharmacotherapy is the most commonly prescribed intervention, there is considerable evidence to support the use of behavior therapy, specifically habit reversal training, as an alternative or adjunct treatment for some individuals with Tourette syndrome. Unfortunately, many professionals are unfamiliar with habit reversal training. The purpose of this review is to provide readers with a brief review of empiric studies on habit reversal training, update readers on the current state and future of behavior therapy for Tourette syndrome, and provide resources for those readers interested in additional information.

A cognitive-behavioral/psychophysiological model of tic disorders

This article discusses current cognitive behavioral, as well as neurophysiological, accounts of the development and maintenance of tic behavior in chronic (simple or complex) tic disorders. A cognitive psychophysiological model is further elaborated, highlighting the reciprocal interplay of background cognitive and physiological factors preceding tic onset. According to the model, cognitive factors such as perfectionist concerns and heightened sensory awareness and self-attention, as well as physiological factors such as a high level of motor activation and accompanying elevated muscle tension, play a role in tic habits. Negative appraisals of tics and counter-productive coping strategies developed by clients as a means to suppress or to disguise the tic behavior may also locally reinforce tic onset. Neurochemical factors are viewed largely as concomitants of behavioral adaptations or compensations to the tic problem rather than as independent markers or precursors of tic onset. Clinically, the model emphasizes the role of cognitive-behavioral factors in tic onset, and suggests that tic management is best accomplished through cognitive behavioral interventions designed to prevent build up of both tension and pre-monitory urge in tic-affected muscles, rather than reverse the tic at the onset of the premonitory urge. The clinical validity of parts of the model is supported by recent experimental, psychometric and clinical studies. Other parts of the model remain speculative but at least yield testable predictions. A strength of the model is its ability to account for findings over diverse psychological and biological domains.

Clinical and psychological features distinguishing obsessive-compulsive and chronic tic disorders

Medical and biogenetic research has suggested that obsessive-compulsive disorder and chronic (multiple) tic disorder may share a common etiology. This article reviews corresponding evidence for psychological similarities and differences between the two disorders. There are similarities in self-management strategies, psychological traits (both report high scores on different aspects of perfectionism) and in the ego-syntonic-ego-dystonic cycle of the impulsive-compulsive behavior. Situational cues likely to elicit or worsen the problem differ between the disorders as do associated emotions, comorbidity and background styles of action. In both disorders, cognitive factors, such as anticipations and appraisals of the problem, can play a role in onset and maintenance of the problem, and this raises the question as to whether cognitive or behavioral factors are best addressed in treatment. Psychological characteristics, such as lack of confidence, may contribute to apparent performance deficit. Psychological evaluation, particularly functional analysis, may aid in differential diagnosis between the two disorders, lead to improvement in treatment matching, and in understanding of the multidetermined etiology.

Muscle control in chronic tic disorders

EMG was recorded in nine subjects suffering from chronic tic disorder. Six subjects suffered asymmetrical tics and three had symmetrical tics. EMG in tic-affected and contralateral nonaffected sites was recorded at rest, during a baseline period, and at postbiofeedback training. All subjects received 2-4 biofeedback training sessions aimed at enhancing their ability to control levels of muscle contraction in both affected and nonaffected sites. All nine subjects met the criterion of discriminating unaided between levels of 0, 25%, 50%, and 75% of their fullest contraction. Five of the six people with asymmetrical tics showed lower resting EMG on the affected side at baseline, but EMG significantly increased in tic-affected but not nonaffected muscles after exercises aimed at enhancing muscle control. Six subjects reported a clinically significant > or = 40% decrease in tic frequency. The reflexlike quality of tic muscles can modified by biofeedback training and this constitutes a useful and relatively quickly acquired aid to tic management.

Stimulus induced behaviours in Tourette's syndrome

Three cases of Gilles de la Tourette's syndrome (GTS) who experienced different tic related behaviours in response to both external and internal stimuli are described. Such behaviours might represent sensory tics, reflex motor tics, exaggerated startle responses, or obsessive compulsive behaviours. It is suggested that there is a continuum of stimulus induced behaviours, and that, in some cases, separations into individual descriptive entities may be difficult. There also seems to be a continuum between internal and external phenomena that induce the behaviours. Implications for the relation between GTS and obsessive compulsive disorder are also discussed.