[Neuroimaging techniques in the Gilles de la Tourette syndrome]

Tourette's syndrome (GdT) is a chronic neuropsychiatric disorder of unclear etiology characterized clinically by the presence of motor and phonic tics as well as a variety of behavioral and cognitive abnormalities such as Obsessive-Compulsive Disorder (TOC) and Attention Deficit Hyperactivity Disorder (ADHD). Dopaminergic pathway and movement control related structures may have some implications for pathogenesis. Neuroimaging techniques may yield relevant data for a better understanding of the symptoms and physiopathology of this disease. Among them, functional isotopic techniques such as PET and SPECT and other like quantitative EEG are the most remarkable. In this article we intend to perform a thorough review of the most recent literature, contributing with our own experience and discuss the pathogenesis of GdT.

Tourette syndrome and complex partial epilepsy--a case report

Controversy exists over the pathophysiology of Tourette syndrome (TS). The case reported is a 37-year-old unmarried man suffering from both TS and complex partial epilepsy (CPE). He began to have seizures at 2-3 months of age. The CPE featured dark vision, dizziness, followed by unresponsiveness, a blank stare, occasional loss of posture control, and occasional automatism consisting of going to the toilet to urinate. TS gradually began to develop when he was 3-4 years of age. The tics were characterized by stereotypic stuttering, vocalization, hiccups, grimacing, snorting, and jerky supination of both forearms. EEG sharp waves with phase reversal at the left frontotemporal region were present but they were not related to the tics. Magnetic resonance imaging revealed atrophy of the left temporal and frontal lobes, as well as absence of normal asymmetry of basal ganglia. This case supports the theory that TS is related to the left frontal lobe, limbic system, and basal ganglia, but contradicts the hypothesis that the tics are ictal events.

Tourette's syndrome: a disorder of cingulate and orbitofrontal function?

We discuss the clinical characteristics of tics and Tourette's syndrome (TS) and also possible treatment options. Based upon an overview of published pathophysiological and PET data, and the results of a recent PET study of changes in opioid receptor binding in TS, we hypothesize that the disease arises due to dysfunction within the cingulate and orbitofrontal cortex. The beneficial effects of dopamine receptor antagonists and dopamine-depleting agents in TS are suggested to be mediated via basal ganglia-thalamofrontal circuits, while opioid agents may act directly on the cingulate.

Auditory event-related potentials (ERPs) and mismatch negativity (MMN) in healthy children and those with attention-deficit or tourette/tic symptoms

The study compares 5 auditory event-related potential (ERP) components (P1 to P3) after 3 tones differing in pitch and rarity, and contrasts the mismatch negativity (MMN) between them in 12 children with attention-deficit hyperactivity disorder (ADHD; mean 10.2 years of age), 12 healthy controls pairwise matched for age (controls), and 10 with Chronic Tic or Tourette Syndrome (TS). Topographic recordings were derived from 19 scalp electrodes. Four major effects are reported. (a) Shorter latencies in ADHD patients were evident as early as 100 ms. (b) Both ADHD and TS groups showed very large P2 components where the maxima were shifted anteriorly. The differences in the later potentials were of a topographical nature. (c) Frontal MMN was non-significantly larger in the ADHD group but normalized data showed a left rather than a right frontal bias as in control subjects. Maxima for TS were usually posterior. (d) ADHD patients did not show the usual right-biased P3 asymmetry nor the frontal versus parietal P3 latency difference. From these results it is suggested that ADHD patients process perceptual information faster from an early stage (N1). Further, along with the TS group, ADHD patients showed an unusually marked inhibitory phase in processing (P2), interpreted as a reduction of the normal controls on further processing. Later indices of stimulus processing (N2-P3) showed a frontal impairment in TS and a right hemisphere impairment in ADHD patients. These are interpreted in terms of the difficulties in sustaining attention experienced by both ADHD and TS patients.

Simon effect and attention in Parkinson's disease: a comparison with Huntington's disease and Tourette's syndrome

Patients with hyperkinetic basal-ganglia disorders (Huntington's disease, HD; and Tourette's syndrome, TS) have difficulty with spatially incongruent stimulus-response configurations, the Simon effect, and with inhibiting inappropriate responses in a conditionality paradigm. However Parkinson's disease (PD) patients with hypokinetic basal-ganglia disorder show normal (for their age) conditionality and congruency effects, probably because the task is extremely sensitive to aging and PD patients are typically older than HD and TS individuals. Overall, HD patients were by far the most affected, reflecting the likely greater involvement of the caudate (with its predominantly cognitive role) than the putamen; the latter structure, with a predominantly motor involvement, is the more affected in PD.

Assessing risk for the Tourette spectrum of disorders among first-degree relatives of probands with Tourette syndrome

Previous studies have indicated that genetic investigations of Tourette syndrome (TS) should focus on a phenotype that includes not only TS, but chronic tics (CT) and obsessive-compulsive disorder (OCD) as well. These studies have shown that sex may play a role in determining which of the disorders in the TS spectrum is expressed in a susceptible individual. Female relatives of TS probands far more often express OCD, while male relatives more often express TS or CT. Data from the Yale Family Study of TS were used to model risk to first-degree relatives of probands with TS for a variety of TS disease phenotypes. Risk to relatives was modeled using multivariate Cox regression analysis, a method appropriate for assessing risk when there is correlation among disease onsets. This is the first known application of this method to family data. The study identified two proband characteristics that increase the risk for disease onset among both male and female relatives for all TS spectrum disorders, lending credence to the hypothesis that TS spectrum disorders share a common etiology. These were a relatively younger age-at-onset, and no experience of simple motor tics. The predictive ability of two additional factors varied by both sex and disease phenotype. These characteristics, i.e., proband onset with compulsive tics, and proband onset with range, appear to increase risk primarily in female relatives, and for the OCD part of the spectrum.

Effects of picotesla flux electromagnetic fields on dopaminergic transmission in Tourette's syndrome

Tourette's syndrome (TS), a chronic familial neuropsychiatric disorder of unknown etiology, is characterized clinically by the presence of motor and vocal tics that wax and wane in severity over the time and by the occurrence of a variety of neurobehavioral disorders. It is believed that the tics of TS result from increased dopamine (DA) activity caused by postsynaptic DA receptor supersensitivity. The synthesis and release of DA is regulated presynaptically by a specific class of DA D2 receptors, termed autoreceptors activation of which causes inhibition of DA synthesis and release. In experimental animals and humans administration of small doses of apomorphine, a DA D2 autoreceptor agonist, produces yawning. Recurrent episodes of yawning followed by increased motor tic activity was observed in two patients with TS during exposure to brief, extracranial applications of picotesla flux electromagnetic fields (EMFs). On the basis of these observations it is suggested that recurrent episodes of yawning in response to application of EMFs was induced by activation of presynaptic DA D2 autoreceptors while further exposure to these EMFs caused excessive stimulation of postsynaptic DA D2 receptors resulting in exacerbation of the tics. Thus, the dual effects of picotesla flux EMFs on the DA D2 autoreceptor and the postsynaptic receptor resemble the biphasic pharmacological and behavioral properties of apomorphine, a DA agonist which activates the autoreceptors in low doses while in higher doses causes stimulation of the postsynaptic receptors producing exacerbation of symptoms of TS. These findings demonstrate that picotesla flux EMFs applied extracerebrally may influence nigrostriatal DA transmission at pre- and postsynaptic DA D2 receptor sites.

[Psychopathological study on Gilles de la Tourette's Syndrome]

Ten cases of Gilles de la Tourette's Syndrome (GTS) are reported. Average age of onset of the syndrome was 6.3 years old. Many of them were eldest children. 40% of them were caused by hereditary factor, and 40% of them had some abnormalities at their birth, for verbal tics including coprolalia. The GTS were classified into two types, Type I and Type II, from psychopathological point of view. Type I is "sadistic self-conversion type" and Type II is "masochistic personality type." Type I have an experience of attacks from others first, and, then, the desire of sadism aroused by the others converts to themselves after the others are abandoned from their mind, but it remains the stage of self-injurious. Principal mechanisms of Type I are "turning round the desire upon oneself" and "identification of oneself to the aggression." Type II have basically masochistic personality. They desire to be loved by others, but frustration that they feel they are not loved by others arouse the tic symptoms that violate the prohibition. With the tic symptoms, they can gain "punishment" and "pleasure" at the same time. Their symptoms of tics have the meaning of "masochistic provocation." They have the mechanism of "avoidance of anxiety by demanding to be loved by others." Both types have a common psychopathology, that is, they can not grasp objects (self or others) as a whole. It is suggested that patients with the GTS stopped their growth at pre-sexual stage. There exists a phase of self-injurious tics and that of other-injurious (provocately) tics during the progress of the symptoms of complex motor tics and verbal tics (coprolalia). The phase when both tics turn over each other was also observed. Echo-phenomena were seen only for patients of Type I. It is suggested that the degree of organic dysfunction of the brain and spectrum of masochism are almost coincident.

Quantitative EEG analysis during motor function and music perception in Tourette's syndrome

Gilles de la Tourette's syndrome (TS) is a neurobehavioral disorder of childhood onset that is characterized by motor and vocal tics and associated behavioral disturbances including obsessive-compulsive symptoms. We performed 30 channel quantitative electroencephalograms (EEGs) on 13 Tourette patients and 26 controls and studied both resting and manumotor/music perception activation conditions. Resting EEGs did not show any differences between patients and controls, as known from the literature. However, during simple and complex hand movements, as well as music perception tasks, there were subtle differences predominantly in alpha frequency. They suggested reduced brain activation during motor tasks in frontal and central regions, and on music perception in temporal and parietal regions, respectively. These findings may add evidence to the functional neuroanatomy of Tourette syndrome, affecting more areas than disturbed motor circuits.

Sensorimotor gating in boys with Tourette's syndrome and ADHD: preliminary results

Deficits in sensorimotor gating, defined by prepulse inhibition (PPI), have been associated with subcortical dopaminergic overactivity in animal and clinical studies. Utilizing supraorbital nerve electrical stimulation, we produced adequate blink responses and measured decreases in amplitude resulting from electric prestimuli just above sensory threshold. Seven boys comorbid for attention-deficit hyperactivity disorder (ADHD) and a tic disorder had significantly reduced PPI, compared to 14 screened controls and seven boys with ADHD alone. If independently replicated, these results may reflect greater neurologic immaturity in these comorbid subjects. Alternatively, these findings, together with other converging lines of evidence, suggest that deficient pallidal inhibition may be etiologically related to tic and movement disorders.

Abnormal topography of EEG microstates in Gilles de la Tourette syndrome

Quantitative analysis of scalp EEGs was performed on 13 patients with Gilles de la Tourette syndrome (GTS) and 25 matched controls. The analysis method was adaptive segmentation, which describes the topography and sequence of brain electric fields in continuous EEG. The GTS patients showed an abnormal increase in fields with a right-frontal/left-posterior configuration. The GTS patient's EEGs did not differ from normal controls in the average duration of the brain electric microstates, field stability and EEG carrier frequency. To find out whether the abnormal activity is similar to movement-related activity a simple and a complex motor task were performed. Both tasks led to distinct changes of brain electric activity, but not to an increase in right-frontal-/left-posterior-oriented patterns. Motor-related activity was contrasted with two auditory tasks. We conclude that GTS patient's EEG show abnormal topographic patterns of brain electric activity. Unlike other psychiatric disorders, the temporal descriptors of the EEG aspects are unaffected. The abnormal EEG patterns in GTS patients are not similar to those elicited by simple or complex movements; thus, the presence of abnormally facilitated, near-threshold motor activity in GTS patients seems not a likely explanation.

Considerations of natural history and pathophysiology in the psychopharmacology of Tourette's syndrome

BACKGROUND

The increasing recognition of Tourette's syndrome is probably responsible for the broadening range of symptom severities seen in clinic patients. Greater clinical diversity also brings greater treatment challenges, particularly for children in whom the risks and benefits of medication for the developing central nervous system must be weighed against the long-term risks associated with the disorder itself. Knowledge of the natural history and pathophysiology of Tourette's syndrome is vitally important for informed clinical decision making.

METHOD

A MEDLINE literature search was undertaken to identify studies of the natural history and pathophysiology of Tourette's syndrome that would be relevant to clinical psychopharmacology.

RESULTS

Although impossible to predict with certainty for any given patient, the natural history of Tourette's syndrome is typically characterized by an early childhood onset, a prepubertal exacerbation, postpubertal attenuation, and an adult stabilization of symptoms. Symptoms fluctuate in all phases of the illness, often in response to stress. The natural history and clinical phenotype of Tourette's syndrome are thought to have both genetic and nongenetic determinants that are mediated through their effects on basal ganglia nuclei and related neural systems. Medications used in the treatment of Tourette's syndrome are thought to modulate the functioning of these neural systems.

CONCLUSION

Although medication decisions must consider tic symptom severity, expectations of the disorder's natural history, and the child's adaptive capacities-his or her comorbid illnesses, coping mechanisms, interpersonal relatedness, impulse control, affect regulation, and family and social supports-are the most important determinants of well-being and outcome. These therefore are the most important considerations when making treatment decisions, as well.

Contemporary approaches to pharmacotherapy in Tourette's syndrome and obsessive-compulsive disorder

TOPIC

Contemporary approaches used in the pharmacological treatment of children and adolescents with Tourette's syndrome or obsessive-compulsive disorder.

BACKGROUND

Tourette's syndrome (TS) and obsessive-compulsive disorder (OCD) now are recognized as more common than previously believed. Moreover, there is accumulating evidence that these two disorders may share common neurobiological underpinnings. Nonetheless, pharmacologic approaches to treatment may be quite different.

SOURCES

Using recently published information, this paper reviews current treatment for TS and OCD.

CONCLUSION

There have been major advances in the understanding of the pathophysiology of OCD and TS. These advances provides guidance for the treatment of children and adolescents with these disorders. However, additional research is needed to refine current treatment approaches.

Extracorporeal 'phantom' tics in Tourette's syndrome

Some tics are intentional movements made in an attempt to diminish uncomfortable sensations. These sensations, sometimes termed sensory tics, are focal and usually arise in the part of the body involved in the subsequent motor act. We report a patient whose sensations associated with tics were felt in other people and in objects. The discomfort associated with his out-of-body sensations was temporarily relieved by touching or scratching the object involved. The definition of premonitory sensations should be expanded to include extracorporeal sensations, and a history of external sensations should be sought in patients with Tourette's syndrome. Theories on the generation of tics must incorporate an explanation for extracorporeal sensations.

Comorbid Tourette's disorder and bipolar disorder: an etiologic perspective

OBJECTIVE

Using an epidemiologic approach, the authors attempt to elucidate relationships between Tourette's disorder and bipolar disorder.

METHOD

Of 205 patients with Tourette's disorder in the North Dakota Longitudinal Tourette Syndrome Surveillance Project, 15 had comorbid bipolar disorder. A subset of the patients with Tourette's disorder had been included in earlier population-based prevalence studies of Tourette's disorder in children, adolescents, and adults. Minimal risk ratios were calculated for the patients with Tourette's disorder plus bipolar disorder by age group (children/adolescents and adults). This information was used to estimate genetic risk indicators for comorbid Tourette's disorder and bipolar disorder.

RESULTS

The estimated risk of developing bipolar disorder among the study group of children, adolescents, and adults with Tourette's disorder was more than four times higher than the level expected by chance, but this finding did not reach statistical significance. It was indicative of trends, however.

CONCLUSIONS

Comorbidity between Tourette's disorder and bipolar disorder does not appear to be due to chance co-occurrence of the two disorders. Although a genetic mechanism may play a causal role, in the absence of family studies an explanatory model involving the concept of canalization of basal-ganglia-mediated dysfunctions is offered. In such a construct, Tourette's disorder would be a likely accompaniment to other conditions, including bipolar disorder, whose pathogenic determinants might channel through neural pathways involving the basal ganglia. The presence of significant developmental disabilities may further enhance factors culminating in comorbid Tourette's disorder and bipolar disorder.

The audiogenic startle response in Tourette's syndrome

We report the results of a study in which we examined the auditory startle responses (ASR) of 8 patients with Tourette's syndrome and 15 normal controls, none of whom reported or manifested exaggerated startle responses clinically. The ASR in two patients failed to habituate with repetition, a finding not present in any of the controls. There was no correlation between the presence or absence of exaggerated ASRs and the severity of the patients' tics. This study demonstrates that some patients with Tourette's syndrome have exaggerated audiogenic startle responses that may be clinically asymptomatic.

[The dopamine transporter: characterization and physiopathologic implications]

The dopamine transporter (DAT) is the carrier protein that transports dopamine across the presynaptic membrane. The DAT terminates the action of dopamine (DA) in the synapse via reuptake and thus regulates DA neurotransmission. The transporter has been studied by direct binding techniques using a variety of ligands which are inhibitors of DA transport. DAT binding, both in vivo (positron emission tomography) and in vitro (post mortem) may serve as a presynaptic marker to measure altered DA innervation in several neuropsychiatric diseases such as idiopathic Parkinson's disease, Tourette's disease, schizophrenia or cocaine addiction. In Parkinson's disease, a reduction in the density of binding sites could be due either to a degeneration of the terminal dopaminergic projections or to a compensatory readjustment in the level of dopamine synaptic transmission. This dopaminergic cell specific marker could also aid in attempts to elucidate the rate at which dopaminergic cells are lost in this disease. MPTP (a neurotoxin which induces a parkinsonian-like syndrome after conversion in MPP+) uses DAT to enter the neuron and exert its toxic effect which may be prevented by pretreatment with DA uptake blockers. In cocaine abuse, DAT mediates the addictive properties of cocaine. Cocaine binding sites on the carrier may be distinct from DA binding sites allowing the development of medication sparing the DA function but impairing the cocaine effects. In schizophrenia, functional DA uptake was reported to be increased in the striatum in post mortem brains, whereas the kinetic parameters of the uptake sites were unchanged using different transporter labeling ligands. Thus, this marker does not provide any evidence for the dopaminergic hypothesis, but an impairment of the DAT itself could possibly be involved in the etiology of schizophrenia. However, the possible interaction of drugs such as L-Dopa or neuroleptic treatment with transporter binding may be taken into account in the results analysis. Finally, the DAT gene is also an important candidate gene for psychiatric diseases such as schizophrenia or cocaine abuse.

Behavioral problems and severity of tics

This study examined the incidence of behavioral symptoms in youngsters with tic disorders. A total of 186 patients were studied using the Child Behavior Checklist and a Motor/Vocal Tic Severity Scale. The relationship between tic severity and the frequency of behavioral symptoms was found to be not simply linear, but influenced by the presence of patients without significant behavioral problems in spite of severe tics (resilient patients) and patients with very negative adjustment although their tic disorder was mild (vulnerable patients). Behavioral problems were not related to age. Patients who were receiving medication showed behavioral problems of different severity from those who were not receiving such agents; this result emphasizes the need for future studies to consider carefully the effects of medication.

The Simon effect and attention deficits in Gilles de la Tourette's syndrome and Huntington's disease

Tourette's syndrome and Huntington's disease have long been clinically associated with attentional deficits. In this study, we aimed to determine the nature and quantify the extent of such deficits. A technique was devised to ascertain the efficiency with which Tourette's syndrome and Huntington's disease patients could shift and direct attention away from naturally expected stimulus-response (S-R) linkages. This was done by varying the relationships formed between stimulus and response location. Attentional efficiency was indicated by relative speed of responding to relevant (congruent) and irrelevant (incongruent) stimuli, in a paradigm developed from the Simon effect. There were five conditions progressively increasing in complexity. The stimuli consisted of left and right pointing arrows and, in some cases, various conditionality manipulations were also employed, such that in the presence of a certain symbol (i.e. 'x') the nature of the response had to be reversed, whereas in the presence of an alternative symbol (i.e. '='), the response was compatible with the direction of the arrow. As predicted, Tourette's syndrome and Huntington's disease patients, regardless of medication or depression status and unlike controls, were particularly disadvantaged in responding to various conflicting S-R configurations. Tourette's syndrome and Huntington's disease patients may experience difficulties in making attentional shifts, or in inhibiting inappropriate responses; they may also be more susceptible (than controls) to the conflict that can arise when the spatial code formed for the stimulus is irrelevant for selecting the appropriate response. We conclude that our findings support the notion that cognitive deficits in Tourette's syndrome and Huntington's disease may stem from abnormalities of the major pathways interconnecting the basal ganglia and the frontal lobes.

[123I]beta-CIT SPECT imaging of striatal dopamine transporter binding in Tourette's disorder

OBJECTIVE

The authors examined whether subjects with Tourette's disorder have greater than normal striatal dopamine transporter densities, as suggested by previous post-mortem findings.

METHOD

Single photon emission computed tomography (SPECT) and [123I]2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([123I]beta-CIT) were used to assess dopamine transporter levels in five adult patients with Tourette's disorder and five age- and gender-matched healthy comparison subjects.

RESULTS

Striatal [123I]beta-CIT binding was a mean of 37% (range = 6%-79%) higher in the subjects with Tourette's disorder than in the comparison subjects, and each Tourette's disorder patient had a higher level than his or her paired comparison subject.

CONCLUSIONS

These findings corroborate post-mortem results and support the hypothesis of a dysregulation in presynaptic dopamine function in Tourette's disorder.

Brain perfusion abnormalities in Gilles de la Tourette's syndrome

BACKGROUND

Functional brain imaging with technetium-99m d,l-hexamethyl propyleneamine oxime (HMPAO) Single Photon Emission Tomography (SPET) allows us to explore the cerebral pathophysiology of Gilles de la Tourette's Syndrome (GTS).

METHOD

Fifty patients and 20 controls were examined. Patients were rated for tic severity and mood. Scans were analysed quantitatively using internal ratios to the occipital cortex.

RESULTS

Patients different from controls on measures of relative blood flow to the left caudate, anterior cingulate cortex and the left dorsolateral prefrontal cortex. Severity of tics was related to hypoperfusion of the left caudate and cingulate and a left medial temporal region. Hypoperfusion in the left dorsolateral prefrontal region was related to mood.

CONCLUSIONS

The areas found to be hypoperfused in this study are consistent with known functions of fronto-striatal circuits. A wide range of perfusion patterns is seen, however, and no characteristic patterns for behavioural subgroups has been documented with this technique.

Gilles de la Tourette syndrome in Papua New Guinea

Gilles de la Tourette syndrome is characterized by (a) onset usually in childhood and adolescence between 2 and 15 years of age, (b) violent facial tics and coprolalia, (c) increased excitability and apathy, (d) progressive increase in the intensity of symptoms, and (e) a chronic course. The syndrome is three times more common in males than in females. It is no longer considered the rarity it used to be, with a reported frequency of 1 to 5 per 10,000 population in western countries. This paper is the first report of Gilles de la Tourette syndrome in Papua New Guinea. The family history method and the family study method were used for this study after the index patient had been identified. The case report is presented with a diagram of the pedigree of the extended family of the index patient. A total of four cases of Gilles de la Tourette syndrome were reported in three generations of the extended family. In conclusion, further clinical and genetic research (including twin studies) into Gilles de la Tourette syndrome is recommended in Papua New Guinea.

Longitudinal evolution of prefrontal leucotomy in Tourette's syndrome

We report the case of a 69-year-old man with severe Tourette's syndrome (TS) who underwent a bilateral prefrontal leucotomy at the age of 29 years to alleviate coprolalia, copropraxia, and obsessive-compulsive disorder. No improvement was observed during the 5 years after the leucotomy. Tics and associated behavioral abnormalities disappeared thereafter, to recur at age 67. Long-term follow-up of single cases can help to estimate the role of neurosurgery in the treatment of TS.

Improvement of right hemispheric functions in a child with Gilles de la Tourette's syndrome by weak electromagnetic fields

Gilles de la Tourette's syndrome (GTS) is a chronic, familial neuropsychiatric disorder of unknown etiology characterized clinically by the occurrence of motor and vocal tics and by the presence of a variety of neurobehavioral and neurocognitive abnormalities including hyperactivity, self-multilatory behavior, obsessive-compulsive behavior, learning disabilities, and conduct disorder. On the basis of neuropsychological assessments it has been suggested that GTS is associated with greater right than left hemispheric dysfunction which accounts for decrements in visuospatial, visuoconstructional and visuomotor skills in these patients. Recent case studies have demonstrated that extracranial application of electromagnetic fields (EMFs) in the picotesla (pT) range intensity improves visuospatial and visuoperceptive functions in patients with neurodegenerative disorders including Parkinson's disease, multiple sclerosis and Alzheimer's disease. I now present a 6 1/2 year old boy with GTS in whom this treatment modality produced, in addition to symptomatic behavioral improvement, also improvement in visuoconstructional and visuomotor skills as evidenced on various drawing tasks particularly copy of the Rey-Osterrieth Complex Figure, a task which is especially vulnerable to right hemispheric functions. These findings suggest that pT range EMFs may be useful for the treatment of GTS and related disorders and also reverse some of the cognitive impairments associated with the disease which are related to right hemispheric dysfunction and which contribute to learning disabilities in these patients.

Exclusion of the 5-HT1A serotonin neuroreceptor and tryptophan oxygenase genes in a large British kindred multiply affected with Tourette's syndrome, chronic motor tics, and obsessive-compulsive behavior

OBJECTIVE

Previous studies have demonstrated a relationship between obsessive-compulsive disorder or behavior and Gilles de la Tourette syndrome. It has been hypothesized that the serotonergic system is implicated in the etiology of obsessive-compulsive disorder. Therefore, the authors investigated whether genetic variation in a serotonergic receptor and a modifying enzyme were associated with Tourette's syndrome.

METHOD

A linkage analysis using DNA and blood group markers was carried out in a large British kindred multiply affected with Tourette's syndrome, chronic motor tics, and obsessive-compulsive behavior.

RESULTS

There was no evidence to support the hypothesis that genetic variation in the serotonin 5-HT1A receptor and tryptophan oxygenase genes causes susceptibility to Tourette's syndrome and chronic multiple tics.

CONCLUSIONS

The results eliminate two possible candidate genes from having a role in the pathophysiology of Tourette's syndrome.

[Tics and Gilles de la Tourette syndrome]

The concept of tic was developed at the end of the XIX century, emerging from the "chaos of choreas". Tic is defined as involuntary contractions of agonist and antagonist muscles in one or more parts of the body. It can be suppressed by voluntary efforts for seconds or hours, followed by exacerbations. Gilles de la Tourette's original article was published in 1885, in which he described nine patients with tics, and vocalisations. The pathogenesis of Gilles de la Tourette syndrome remained obscure. However, three factors have been considered: the neurochemical factor, related to the increased dopaminergic activity at the basal ganglia; the genetic factor and the non-genetic factors, for which environment more than genetic factors are involved. Pathologic examinations failed to reveal structural lesions, but PET studies showed metabolic hypofunction on the frontal, cingulate and possibly insular cortex, and on the inferior corpus striatum. The motor tics as well as the vocal tics can be simple or complex and are present in all patients. Other signs can be added to the previous tics: sensory tics, echophilia, coprophilia, obsessions, compulsions and impulsions. Diagnostic criteria of Gilles de la Tourette syndrome are based on: age of onset; presence of motor and vocal tics; voluntary suppression of the movements; variation in number, type, location and severity of tics; duration of more than one year. Haloperidol is the drug of choice for the treatment of Tourette's syndrome.

Advance information and movement sequencing in Gilles de la Tourette's syndrome

Tourette's syndrome is a chronic neurological disorder manifested by involuntary motor tics and vocalisations. Because the basal ganglia have been implicated in the pathology underlying Tourette's syndrome, the present two procedures, both involving sequential movements, sought to determine the extent to which patients with Tourette's syndrome were reliant on, and could utilise different levels of advance information. Patients with Tourette's syndrome were found to be more reliant than controls on external visual cues to execute rather than to initiate a motor programme. When there was a high level of reduction in advance information--that is, a visual pathway to be followed was extinguished well in advance of each successive movement--executions progressively slowed as the sequence was traversed. Similarly, if no advance information was provided before each move, movement execution was slower than that of controls. The movement initiation times of patients with Tourette's syndrome were, however, similar to those of controls, as were their movement execution times when advance visual information was available. It seems that patients with Tourette's syndrome, like parkinsonian patients who are known to have a basal ganglia disorder, require external sensory cues to sequence a motor programme effectively. The present study found evidence consistent with the hypothesis that patients with Tourette's syndrome, like patients with Parkinson's disease, may be dysfunctional in internal switching mechanisms. Alternatively, with limited visual guidance, patients with Tourette's syndrome, regardless of medication or depression state, may require more time to plan and programme each next submovement, and under such conditions may require external visual cues to direct attention effectively to given targets. Although the underlying pathogenesis is still speculative, it is concluded that there is much to support the notion that Tourette's syndrome may stem from abnormalities of the major pathways between the basal ganglia and the frontal lobes.

Sleep features in Tourette's syndrome, neuroacanthocytosis and Huntington's chorea

Twenty-one patients affected by extrapyramidal disorders were polygraphically recorded during spontaneous nocturnal sleep for two consecutive nights to assess their sleep and movement patterns. The patients (pts) sample included: Gilles de La Tourette syndrome (TS, nine pts), neuroacanthocytosis (NA, six pts) and Hungtington's chorea (HC, six pts). Sleep recording included C3/A2, 01/A2, ROC/LOC, submental EMG, EKG, nasal airflow thoracoabdominal respirogram, bilateral anterior tibialis and other EMGs, in relation to the individual distribution of the abnormal movements. According to our observations, abnormal movements always decreased but never ceased completely during sleep. Sleep efficiency (SE) was nearly always poor with a high percentage of wakefulness after sleep onset (WASO) and increased number of arousals. REM sleep was often reduced and in some cases (3 TS pts) incompletely defined as far as its microstructural aspects. Slow wave sleep (SWS) was reduced in HC, normal in NA, and increased in all TS patients with the exception of the two adult subjects more severely affected, while the percentage of stage 2 was not affected. Spindling was increased in NA, HC and in the two most severely affected adult TS patients.

Bilineal transmission in Tourette's syndrome families

We assessed the frequency of bilineal (from maternal and paternal sides) transmission of Tourette's syndrome (TS) in two groups of pedigrees: (1) 39 high-density families in which five or more relatives were reported to have TS, and (2) the families of 39 consecutively ascertained probands referred for evaluation of TS. We used two designations for the TS phenotype (tics, tics or obsessive-compulsive behavior [OCB]), and we attempted to verify bilineal transmission with direct examinations. For the high-density pedigrees, bilineal transmission was evident in 33% (considering tics) and 41% (considering tics or OCB) of families, which was confirmed by examination in 77% of the kindreds. For the consecutive pedigrees, bilineal transmission was seen in 15% (tics) and 26% (tics or OCB) of families, which was verified by examination in 66% of the kindreds. Both parents of the proband were affected (tics or OCB) in 38% of the high-density pedigrees and 10% of the consecutive pedigrees. For the high-density families only, the frequency of bilineal transmission appeared to be related to the proband's severity of TS, and for both pedigree groups, the frequency of both parents being affected was higher in families in which the proband's symptoms were most severe. Our findings support the contention that bilineal transmission and homozygosity are common in TS. These genetic phenomena might play a role in determining severity of illness and may explain current difficulties in localizing the gene defect by linkage analysis.

Hypothesis II: Tourette's syndrome is part of a clinical spectrum that includes normal brain development

Several lines of evidence suggest that the typically associated clinical features of Tourette's syndrome (TS), ie, tics, obsessive-compulsive behavior, inattention, and hyperactivity, commonly occur during childhood development. I hypothesize that TS is expressed in children as a clinical spectrum that includes a range of increasing functional impairment, indicating various degrees of abnormality in basal ganglia development. The mildest form, "developmental" TS, includes largely asymptomatic features and is estimated to occur in at least 3% of all children. Further along the spectrum are children with mild to moderate TS, who have school and behavioral problems; up to 25% of children requiring special education may be classified within this group. At the extreme end of the spectrum is the smallest group, patients with "full-blown" TS, characterized by more severe and often disabling symptoms. I propose that genetic influences are most important in determining the severity of TS along the clinical spectrum but that environmental factors may play a role. This hypothesis has implications for the understanding and treatment of childhood school and behavioral problems and the search for the TS genetic defect.

The psychology of perserverative and stereotyped behaviour

Many forms of psychopathology in higher animals and humans include the production of maladaptive, repetitive behaviour. Behaviour which is both repetitive and excessive in amount can be described as stereotyped whereas behaviour which represents a restriction of behavioural possibilities without excessive production can be described as perseverative. Both types of repetition can result from pathology in the neural mechanisms which control either the production of motor output or the organisation of behaviour at a higher level. A number of forms of repetitive behaviour can be induced environmentally. Confinement in adulthood results in a functional disorder which rapidly dissipates when normal conditions are restored but confinement in infancy may have a permanent effect on the organism's ability to interact in a flexible and creative way with its environment. The permanence of these disorders suggests that the environment can affect the way in which the nervous system develops. Repetitive behaviour is also a feature of mental illness including schizophrenia, autism, OCD, addiction and some neurological disorders including frontal lobe lesions, Tourette's syndrome and PD. In experimental studies in animals, stereotyped behaviour seems to be related mainly to excess dopaminergic activity in the basal ganglia while perserverative behaviour can be produced by lesions of the frontal lobes. It is supposed that the level of dopamine activity in the basal ganglia affects the baseline level of behavioural activation such that excess activation results in the excessive execution of the most probable response to the environment to the exclusion of other possibilities (i.e. stereotypy) while deficient activation results in the production of only a few responses which can exceed the necessary activation level (i.e. perseveration). In either case behaviour is 'stimulus-bound', being driven by only the most salient feature of the environment. The symptoms of PD result from inadequate levels of dopamine in the basal ganglia while the stimulant psychoses result from excessive availability of dopamine. The frontal lobes have a modulating effect on (i) the activation of motor activity by the basal ganglia, (ii) in the generation of self-initiated behaviour, i.e. volition, and (iii) in the neural mechanisms which permit different modes of neural function (e.g. perceiving, remembering or thinking) to be identified. Failures in these three functions could result in excessive and repetitive motor activity, stimulus-bound behaviour, the paucity of volitional and creative behaviour, and the perceptual and experiential symptoms of psychosis.

Elevated cerebrospinal fluid levels of oxytocin in obsessive-compulsive disorder. Comparison with Tourette's syndrome and healthy controls

BACKGROUND

Limited neurobiological data have implicated central arginine vasopressin in the pathobiology of obsessive-compulsive disorder (OCD). Based on twin, family genetic, and pharmacological studies, some forms of OCD are etiologically related to Tourette's syndrome. The role of arginine vasopressin and related compounds such as oxytocin in Tourette's syndrome has not been previously explored.

METHODS

To compare cerebrospinal fluid (CSF) levels of arginine vasopressin and oxytocin, we collected CSF at midday in a standardized fashion from a total of 83 individuals (29 patients with OCD, 23 patients with Tourette's syndrome, and 31 normal controls). We also collected family study data on each subject to determine which subjects had a family history positive for Tourette's syndrome, OCD, or related syndromes.

RESULTS

In contrast to previous reports, we report similar concentrations of arginine vasopressin for all three groups but increased oxytocin levels in patients with OCD. Remarkably, this increase was observed only in a subset of patients with OCD (n = 22) independently identified as being without a personal or family history of tic disorders (P = .0003). In this subgroup of patients, the CSF oxytocin level was correlated with current severity of OCD (n = 19, r = .47, P < .05).

CONCLUSIONS

A possible role for oxytocin in the neurobiology of a subtype of OCD is suggested by the elevated CSF levels of oxytocin and by the correlation between CSF oxytocin levels and OCD severity. These findings reinforce the value of family genetic data in identifying biologically homogeneous (and perhaps more etiologically homogeneous) groups of patients with OCD. Together with emerging pharmacological data showing differential responsiveness to treatment of tic-related OCD vs non-tic-related OCD, these data also argue strongly for the incorporation of tic-relatedness as a variable in biological and behavioral studies of patients with OCD.

Executive function abilities in autism and Tourette syndrome: an information processing approach

This study used information processing paradigms to provide a detailed examination of executive function abilities in autism. The performance of non-retarded autistic children was compared with that of two matched control groups, one with Tourette Syndrome and the other developmentally normal. Autistic subjects performed as well as controls on tasks requiring global-local processing and inhibition of neutral responses. In contrast to both control groups, however, the autistic sample was significantly impaired on a measure of cognitive flexibility. The performance of children with Tourette Syndrome did not differ from that of normal controls on any task. These results refine our knowledge about executive dysfunction in autism and suggest a new conceptual framework and general method for investigating the cognitive underpinnings of neurodevelopmental disorders.

Neurobiological issues in Tourette syndrome

The Tourette syndrome (TS) represents an intriguing disorder that overlaps the clinical fields of neurology and psychiatry. Composed of a spectrum of familial, involuntary motor and vocal tics and co-morbid neuropsychological problems, this disorder has become a model for investigators interested in neurobehavioral research. Although the subject of numerous reports since Tourette's original description in 1885, over the past decade there has been a rapid expansion of knowledge pertaining to the phenomenology of tic syndromes and their associated problems, the role of genetic and environmental factors, and the underlying pathophysiology. The role of frontal-subcortical circuits, dopaminergic neurotransmission, and second messenger systems are highlighted. This report provides a framework for understanding current neurobiological issues in TS.

[Tourette syndrome in children. An analysis of everyday problems--neurology or emotional conflicts?]

Over a three year period, 109 children aged 5-17 were diagnosed as having Tourette syndrome. They were all evaluated by a team composed of persons with backgrounds in special education, physiotherapy or neuropsychology, and a paediatrician with experience in child neurology. All the children satisfied the criteria of several motor tics and at least one vocal tic lasting more than one year. Besides the tics the most common symptoms were attention deficit disorder and motor hyperactivity. These symptoms were present in 79 children (73%). 42 children (39%) met the criteria for minimal brain dysfunction. Problems relating to attention, activity, perception, motor control and language are generally considered to be part of a neurological dysfunction. We also investigated the children's emotional profile by looking into factors such as aggression, fluctuations of mood, peer relationships and impulsiveness. More than half of the children experienced serious problems in these areas. We believe that emotional problems of this nature are an integral part of their neurological dysfunction and that they can seldom be attributed to psychological factors in their families or to other events related to everyday life.

Altered attentional processing of background stimuli in Gilles de la Tourette syndrome: a study in auditory event-related potentials evoked in an oddball paradigm

In 24 adults and 29 children both with Gilles de la Tourette syndrome and in 24 control adults and 17 control children we studied auditory event-related potentials (ERP's) evoked in 2 different oddball paradigms: a passive listening paradigm (PLP) in which subjects had only to attend tones (260 standards, 40 deviants), followed by an active discrimination paradigm (ADP) in which subjects had to press a microswitch in response to the deviant tones. In the adult Tourette patients the PLP disclosed between 200-300 msec at all derivations (Fz, Cz, Pz, C3, C4, P3, P4) a significantly more negative activity than in the controls. In the Tourette children such a result was only found at Fz. In the ADP the differences between both adult groups disappeared, but the curves of the control children became now significantly more positive than those of the Tourette ones except at C3 and P3. Between 200-300 msec the curves of all 4 groups were significantly less negative in the ADP than in the PLP. This decrease in negativity was significantly larger in the adult Tourette patients than in the adult controls, but in the children groups the reverse occurred. It is hypothesized that the differences in amplitude between patients and controls and between both paradigms are due to differences in amplitude of an endogenous negative component overlapping the exogenous N100-N200 standard curve. Based on this hypothesis the results could suggest that one of the problems in Tourette syndrome is an increased attention to non-relevant stimuli.

Enhanced stress responsivity of Tourette syndrome patients undergoing lumbar puncture

Tourette's syndrome (TS) is a complex inherited neuropsychiatric disorder that is characterized by multiple motor and phonic tics. Stress-related fluctuations in symptom severity and medication responsiveness are common, and patients often report that tics are worsened by fatigue, emotional trauma, and anxiety. We examined the effects of lumbar puncture (LP) stress on plasma adrenocorticotropin (ACTH) and cortisol, urinary catecholamines, and self- and clinician ratings of anxiety in 13 medication-free TS patients and 10 normal controls, ages 17 to 41 years. The TS patients secreted significantly more ACTH than the normal controls in response to the stress of the lumbar puncture. Compared to the controls the TS patients had significantly greater postLP mean and postLP peak ACTH levels. The TS patients also excreted significantly more norepinephrine in the 20 hr preceding the lumbar puncture and reported higher levels of anxiety before and during the procedure than the controls. In addition, urinary norepinephrine excretion of the TS patients was significantly correlated with clinician ratings of tic severity. The results were not related to current levels of depression and anxiety. Taken together, these findings suggest that a subset of TS patients may be characterized by heightened reactivity of the hypothalamic-pituitary-adrenal axis and related noradrenergic sympathetic systems.

PET studies of the presynaptic and postsynaptic dopaminergic system in Tourette's syndrome

Dysfunction of the dopaminergic pathway has been postulated to underlie the symptomatology of Tourette's syndrome. Presynaptic functional integrity of dopaminergic terminals was assessed with 18F-dopa PET in 10 patients with Tourette's syndrome, three of whom were drug free and seven of whom were on neuroleptic treatment. Dopamine D2 receptor site density was measured with 11C-raclopride PET in a further group of five drug free patients with Tourette's syndrome. Mean caudate and putamen 18F-dopa influx constants were similar in patients with Tourette's syndrome and controls, and there was no difference in striatal 18F-dopa uptake between the treated and untreated Tourette's syndrome groups. Mean caudate and putamen 11C-raclopride binding potentials in patients with Tourette's syndrome were also similar to control values. The findings suggest that striatal metabolism of exogenous levodopa and the density of striatal D2 receptors are both normal in patients with Tourette's syndrome and that Tourette's syndrome does not arise from a primary dysfunction of dopaminergic terminals.

[The influence of sleep on abnormal waking movements]

Sleep decreases considerably the abnormal movements seen during waking in the degenerative extra-pyramidal diseases. However, the electrophysiologic recordings reveal that muscular contractions are not completely abolished. This decrease parallels the reduction of the waking system which act likely as a non-specific system of amplification. One can notice that sleep modifies the characteristics of the parkinsonian tremor and that some palatal myoclonias persist during sleep.

Electroencephalographic abnormalities in monozygotic twins with Tourette's syndrome

The association of attentional, neuropsychological, and behavioural abnormalities with Tourette's syndrome (TS) suggests that the abnormal function of the disorder extends beyond the motor circuits of the basal ganglia. To explore this possibility we studied, with conventional 18-channel electroencephalography, monozygotic twins ranging from 8 to 26 years of age, where at least one member of the twin pair suffered from TS. In nine out of the 11 twin pairs that differed in clinical severity of the tic disorder, the twin with the more severe course of illness had a significantly more abnormal electroencephalogram (EEG) by qualitative visual analysis. Most of the differences were due to excessive frontocentral theta activity, suggesting dysfunction outside the basal ganglia. There was also a significant relationship between a lower global neuropsychological testing score and a worse overall EEG. In eight of nine twin sets with different global neuropsychological testing scores, the twin with the lower score had a worse EEG. A similar relationship was found between birth weight and overall EEG quality. In the nine sets that differed in birth weight, the twin with a lower birth weight had a worse EEG in seven of the sets. The EEG findings are unlikely to be unlikely to be a medication effect because the same result was seen in the six twin pairs who had been medication-free for at least six months before entry into the study. The origin of this slowing may relate to the interaction between environmental insults to the central nervous system and the genetic component of TS, an interaction producing damage to the cortex, thalamus, or both.

Corpus callosum morphology from magnetic resonance images in Tourette's syndrome

We measured the midline cross-sectional area and other morphologic features of the corpus callosum (CC) from magnetic resonance (MR) images in 14 unmedicated patients with Tourette's syndrome (TS) and 14 normal control subjects matched for age, sex, handedness, and socioeconomic status. Each CC was manually circumscribed on midline images from a T1-weighted sagittal series, and the area of the entire CC and five anatomic subdivisions were measured. CC circumference, regional width, and mean callosal curvature were also measured. CC cross-sectional area correlated positively with brain size and basal ganglia volumes. The magnitude of reduction (17.7%) in total CC area in TS patients compared with control subjects was similar to the reductions seen in all CC subdivision areas. Analyses of covariance with total midsagittal cross-sectional head area as a covariate revealed the reductions to be statistically significant for the overall CC area and all subregion areas. CC width tended to be nonsignificantly thinner in all subdivisions (from 5% to 11%), and the overall length of the center line measured from rostrum to splenium was significantly reduced in the TS group (by 5.3%). Measures of mean callosal curvature suggested that CCs in TS patients are less rounded than those of normal control subjects. Worst-ever motor tic symptoms showed the strongest significant correlation with the length of the CC center line in TS patients (r = 0.88). These findings suggest that structural interhemispheric connectivity may be aberrant in the central nervous systems of TS patients, and they provide indirect supportive evidence for the presence of altered cerebral lateralization in the disorder.