Tourette syndrome associated with unilateral cystic changes in the gyrus rectus

Practice parameter for the assessment and treatment of children and adolescents with tic disorders

Tic disorders, including Tourette's disorder, present with a wide range of symptom severity and associated comorbidity. This Practice Parameter reviews the evidence from research and clinical experience in the evaluation and treatment of pediatric tic disorders. Recommendations are provided for a comprehensive evaluation to include common comorbid disorders and for a hierarchical approach to multimodal interventions.

Cognitive inhibition in patients with medial orbitofrontal damage

Inhibition underlies cognitive processes such as overcoming habitual responses, suppressing of goal-irrelevant information, and switching of attention between stimuli or task rules. These processes are thought to depend on the frontal lobes. However, the precise role of the ventral frontal regions (orbitofrontal cortex) in these processes remains elusive. In the present study, our goal was to clarify the role of the orbitofrontal cortex in cognitive inhibition by examining the effects of focal lesions to the medial orbitofrontal cortex (posterior part of the gyrus rectus) on performance in tasks that required inhibitory control. Patients who had undergone surgery for an anterior communicating artery aneurysm and normal control subjects (C) participated in the study. The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). The Stroop Color-Word test, Trail Making B test, and the Category test were used as instruments for assessing response inhibition, switching between concrete stimuli, and switching between abstract task rules, respectively. In addition, the Digit Symbol test was used to examine sustained attention and processing speed. In the Stroop Color-Word test, the RGR+ group performed worse than all other groups. In the Trail Making B test, the RGR+ and LGR+ groups performed worse than both the GR- and C groups. In the Category test and Digit Symbol test, the groups did not differ significantly from each other. Our study indicates a specific contribution of the medial orbitofrontal cortex to response inhibition and stimulus-based switching of attention.

The insular lobe of Reil--its anatamico-functional, behavioural and neuropsychiatric attributes in humans--a review

There is considerable clinical and experimental research to explore the anatamico-functional correlations of the limbic lobe to establish its relevance in modern neuroscience. The insula being a pivotal structure in the concept of the greater limbic lobe, we have attempted to highlight in this review the topographical anatomy and development, the remarkable heterogeneity of the insular cortical architecture, the widespread multifaceted spectrum of functional connectivity patterns and how this is translated to its behavioural specialisation in humans. The insula serves as an intergration cortex for multimodal convergence of distributed neural networks such as the somesthetic-limbic, insulo-limbic, insulo-orbito-temporal and the prefrontal-striato-pallidal-basal forebrain. This provides the conceptual framework to facilitate functional and clinical considerations relevant to the various behavioural and neuropsychiatric disorders outlined in this review. The functional role of the insula in these disorders with particular reference to the current functional neuroimaging data has been also reviewed in this article.

Neurobiology of Tourette's syndrome: concepts of neuroanatomic localization and neurochemical abnormalities

Despite a preponderance of evidence suggesting an organic rather than psychogenic origin for Tourette syndrome, the precise neurobiological abnormality remains speculative. Neuroanatomically, there is expanding confirmation that cortico-striato-thalamo-cortical pathways represent the site of origin for tics and accompanying neuropsychiatric problems. Pathophysiological hypothesis are generally defined based on involvement of (1) a specific anatomical site (striato-thalamic circuits, striatal compartments), (2) physiologic abnormality (excess thalamic excitation, impaired intracortical inhibition), or (3) involvement of a specific neurotransmitter or synaptic component. This review provides information essential for understanding current and future proposals pertaining to the neurobiology of this intriguing disorder.

Control of volitional and reflexive saccades in Tourette's syndrome

We hypothesized that Tourette's syndrome (TS) patients would display abnormal control of saccades because of overlap between brain areas suspected in TS pathophysiology and those involved saccade control. Subjects were required to look toward (pro-saccade) or away from (anti-saccade) a visual target. Saccadic reaction times were elevated among TS subjects in all tasks. The occurrence of reflexive pro-saccades in the immediate anti-saccade task was normal, suggesting that the ability to inhibit reflexive saccades was not impaired in TS. However, timing errors (eye movements made prior to GO signal in delayed saccade tasks) were increased in TS indicating that ability to inhibit or delay planned motor programs is significantly impaired in TS.