General Overview of Tourette's


Schematic representation of the clinical elements of Tourette’s syndrome
Schematic representation of the clinical elements of Tourette’s syndrome

Gilles de la Tourette Syndrome also known as Tourette’s Syndrome (TS) is an inherited, childhood-onset neurodevelopmental disorder, diagnosed before the age of 18, by spontaneous motor and vocal tics which vary in severity depending on the individual case and fluctuate over time, usually remitting by early adulthood.(Tallur) These tics are caused by a combination of hyperactivity in motor pathways as well as hypo-activity in control areas of the cortico-striato-thalamo-cortical (CSTC) circuits, also including neurotransmitter activity levels, as well as influence by the basal ganglia to the cortices, and must persist for at least a year, with maximum of a 3 month remission, according to the DSM-IV-TR criteria.(Tallur, Wang) Causes of TS are currently known to be multi-factorial, and include genetic, autoimmune, and neurobiochemical factors. Studies have confirmed the SLITRK1 gene to be found in the CSTC circuits, and are associated with TS, however causality is currently under investigation.(Tallur) Approximately 88% of TS patients are affected with one or more co-morbid conditions, commonly Obsessive-Compulsive Disorder (11-80%), Attention Deficit Hyperactivity Disorder (60-80%), Depression (severity increases with TS duration), as well as other neuropsychological disorders.(Tallur) Treatments for tics of TS vary depending on the case, and generally target the neurobiochemical aspect of TS, common ones include: alpha2 adrenergic agonists, dopamine receptor blockers, serotonin inhibitors.(Tallur) Other treatments are usually needed for co-morbidities such as: selective norepinephrine re-uptake inhibitors (for ADHD); SSRIs and tri-cyclic antidepressants (for OCD). Behavioural approaches such as Cognitive Behavioural Therapy are also used with pharmacotherapy, and are generally more effective when concurrent.(Tallur)





1.Symptoms and Diagnosis

(a) Motor and Vocal Tics

Tic Urges Photo by eMedicine
Tic Urges Photo by eMedicine

Gilles de la Tourette Syndrome also known as Tourette’s Syndrome (TS) is an inherited, childhood-onset neurodevelopmental disorder. (Tallur) Thus, it is usually diagnosed before the age of 18, but are usually first seen between ages 3-8 (Deng, Leckman)
The deterministic symptoms of Tourette’s are motor and vocal tics, which vary in severity between individual cases, as well as within an individual over time, and occur various times in a day, almost every day for over a year, with no periods of remission for more than 3 months, according to the DSM-IV-T3 criteria. (Leckman, Deng) These tics, described as involuntary actions, are generally muscular contractions (motor) or sudden utterances (vocal), which are persistent, brief, and repetitive in nature, and usually consequently retrospective. (Bloch, Singer) For simpler cases, these symptoms tend to peak in intensity early in the early teen years, and drop towards the later of the teen years, and usually include eye blinking or facial twitching. (Leckman) For more severe cases, the symptoms tend to exacerbate in early adulthood, and can include hitting, biting, and obsessive shouting of obscenities (coprolalia), and for these cases treatment would be more necessary. (Leckman)Some commonly misdiagnosed symptoms include eye blinking, ocular tics or chronic coughing. (Singer)
These symptoms have a significant impact on the lives of these affected individuals, particularly since they are all either children or very young adults when they become diagnosed, and even more so with more severe cases which cause disruption of daily activities and functioning. Approximately 20% of individuals aged 20 describe the tics as functionally impairing to their daily life. (Bloch) Some individuals also experience some forms of social rejection and social functioning difficulties, as well as academic difficulties, as can be associated with the stigmatization of neuropsychiatric disorders in general. (Marcks) Further, they may feel embarrassed from the unwanted attention that their tics may attract (Me), and research has even showed that children with TS are looked upon as more socially withdrawn and less popular. (Marcks) Statistically, the mean ratio of male to female affected individuals 4.3:1. (Freeman)

(b) Co-Morbidities


Further symptoms of behavioural problems such as anger management issues, sleep difficulties, coprolalia, self-injurious behavior also manifest in individuals with TS, but only reach notable levels in those with co-morbidities. (Freeman) On average, TS individuals have just over two co-morbid (additional) disorders (comorbidity score of 2.06), with the prevalence being significantly higher in males (2.11) than in females (1.83). (Freeman) Significant predominance of males over females was also reported in ADHD, specific learning disability, pervasive developmental disorders (PDD), anger management issues, stuttering, social skills problems, and pre-/perinatal problems .(Freeman) A review of the progress of TS showed that co-morbidities were the major source of impairment for affected individuals, than the TS symptoms themselves. (Swain)


2.Causes and Neural Correlates

external image BasalGanglia.JPG
Diagram of the Brain highlighting the Basal Ganglia, Thalamus, and Cortex - Structures implicated in Tourette Syndrome (diagram also includes other brain structures)
Diagram of the Brain highlighting the Basal Ganglia, Thalamus, and Cortex - Structures implicated in Tourette Syndrome (diagram also includes other brain structures)

Overview of Related Brain Structures (http://www.dana.org/uploadedImages/Images/Content_Images/bw0205_3.jpg)
Overview of Related Brain Structures (http://www.dana.org/uploadedImages/Images/Content_Images/bw0205_3.jpg)


(a) Of Tic-Generation
CSTC_circuits.gif
Cortico-striato-thalamo-cortical Circuits

(i) Dysregulation in maturation of cortico-striato-thalamo-cortical circuits and Basal Ganglia dysfunction

CSTC_circuits_2.jpg
Cortico-striato-thalamo-cortical Circuits and their associated Neurotransmitters; Implications in Tourette Syndrome

(ii) Neurotransmitter Activity

Diagram of a Basic Dopamine Synapse in the brain - This is dysregulated in TS patients
Diagram of a Basic Dopamine Synapse in the brain - This is dysregulated in TS patients

(b) Of Co-morbidities

(i) Neurotransmitter Activity


3.Treatment Options

(a) Pharmaco-therapy

(b) Cognitive Behavioural Therapy




References:
(1)Tallur, K., Minns, R. (2010). Tourette’s Syndrome. Paediatrics and Child Health, 20(2), 88 93. Retreived from http://journals2.scholarsportal.info.myaccess.library.utoronto.ca/tmp/159434798241739 1674.pdf

(2)Wang, Z., Maia, T., Marsh, R., Collibazi, T., & Gerber, A. (2011). The neural circuits that generate tics in tourette’s syndrome. Psychiatry, 168(12), 1326-1337. Retrieved from http://bf4dv7zn3u.search.serialssolutions.com.myaccess.library.utoronto.ca/?rft.title=A erican journal of psychiatry&sid=sersol:
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