Task 8 Flashcards
What is Tourettes Syndrome?
It is a neurological disorder characterized by sudden motor and/or phonic tics which are either simple or complex.
What can increase or decrease tics?
Stress, anticipation and excitement can increase tics, while tasks requiring concentration can decrease.
Describe the ontogeny of Tourettes Syndrome
Motor tics develop earlier (around 3-4 years) and phonic tic follows its development
Tics peak just before puberty and decrease with age, but there is waxing and waning where it can come and go.
What happens if tics are suppressed?
Their rebound is worse than the usual tic occurence
Tics occur in bouts. What does that mean?
Tics occur for short periods in seconds, minutes, hours etc…
What is the prevalence of Tourettes Syndrome?
- Average onset is 5.6 years old
- Has high comorbidities, and a lot of individuals with TS also has OCC and ADHD
How is Tourettes Syndrome Diagnosed?
- Category 1: there must be multiple motor & one or more vocal tics present for more than a year before the age of 18.
- Category 2 (persistent): there must be single or multiple motor or vocal tics present for more than a year before 18 years.
- Category 3 (provisional tic): there must be single or multiple motor and/or vocal tics present for less than a year before the age of 18.
What are the neural causes of Tics?
- Due to dysfunctions of the cortico-striatal thalamocortical circuits (CSTCC), which affects the direct pathway. Under normal conditions the direct pathway involves the striatum’s inhibition of the SNr and GPi which the disinhibit the thalamus, thus leading to movement. In the indirect pathway, the GPe is inhibited by striatum which stops it from inhibiting the STN. Thus the STN excites the SNr & GPi which inhibit the thalamus so it stops involuntary movements. In TA there are more inhibition of the SNr & GPi in direct pathway so while TS can sometimes suppress their tics through the indirect pathway, most times they cannot because of this over inhibition of the aforementioned structures.
- The striatum receives input from the PFC (executive functions, control) and the limbic systems (emotions, rewards). In normal conditions there are more matrix neurons, which receive input from the PFC & motor/sensorimotor cortex, than striosome neurons (receiving input from limbic and dopamine input). Thus, there is more cortical control.
- However, in TS, there are more striosome neurons than matrix, thus more sensitivity to rewards.
What are the treatments of Tourettes Syndrome?
- Firstline: Comprehensive behaviour therapy (e.g. habit reversal) & agonists (e.g. guanfanine & chlonidide)
- Second line: atypical dopamine & serotonin receptor antagonists (e.g. risperidone) & typical (e.g. primozide)
- Third is deep brain stimulation which targets the thalamus.
What is the first line treatment of Tourettes Syndrome?
Comprehensive behaviour therapy (e.g. habit reversal) & agonists (e.g. guanfanine & chlonidide)
What is the second line of treatments for Tourettes Syndrome?
atypical dopamine & serotonin receptor antagonists (e.g. risperidone) & typical (e.g. primozide)
What is the third line of treatments for Tourettes Syndrome?
Third is deep brain stimulation which targets the thalamus.
Describe the habit reversal therapy for treating Tourettes
- Patient is trained to describe tic and reenact it in the mirror
- Response detection: therapist points out when tic occurs
- Practice to help patient identidy sign of its occurence
- Competing responses: patients are taught to produce incompatible physical responses dependent on the urge to perform a tic
Which brain areas do deep brain stimulation target?
Basal ganglia-thalamo-cortical circuits
What are examples of simple phonic tics?
Grunting
Squeaking
Coughing
Sniffing
Snorting
Throat clearing
