Syndrome de Tourette et autres troubles des tics

Synonyms: Gilles de la Tourette syndrome (the eponym originating from the full surname), Brissaud's syndrome, Guinon's disease, compulsive swearing syndrome, coprolalia-compulsive syndrome, chronic motor tics

What is Tourette syndrome?

This is a neuropsychiatric syndrome, characterised by motor and vocal tics, which runs a fluctuating course. It may be associated with behavioural abnormalities and other psychological conditions - eg, obsessive-compulsive disorder (OCD).¹

Tics are relatively common hyperkinetic movement disorders seen mostly in children. Tics are defined as sudden, rapid, recurrent, non-rhythmic motor movements or vocalisation, generally preceded by urge. Tourette syndrome is defined as the presence of both motor and phonic tics for more than one year in patients with onset at less than 18 years of age. Most of these hyperkinetic movement disorders improve in adulthood.²

The International Classification of Diseases 11th edition (ICD-11) classifies tics as follows:³

• Disorders characterised by brief, sudden, repetitive movements (motor tics) or utterances (phonic or vocal tics) that are temporarily suppressible and are usually preceded by a strong urge to perform the tic. The most common cause of childhood-onset tics is Tourette syndrome.

• Primary tics or tic disorders are characterised by the presence of chronic motor and/or vocal (phonic) tics. Motor and vocal tics are defined as sudden, rapid, non-rhythmic, and recurrent movements or vocalisations, respectively. In order to be diagnosed, tics must have been present for at least one year, although they may not manifest consistently.

• A secondary tick is defined as a tic disorder that occurs as a direct physiological consequence of an antecedent infection, drugs or illness.

How common is Tourette syndrome?(Epidemiology)^{1 4}

• The prevalence is 0.3-1%, The typical age of onset is 5 to 6 years. Male:female ratio is 3-4.3:1.

• It is also thought to be more common in Ashkenazi jews (not confirmed in some studies) and patients of Mediterranean origin. 10% of patients have an affected first-degree relative and twin studies report 90% concordance in monozygotes.

• Onset is usually in childhood - 2-14 years of age (mean age of 7 years).

Étiologie⁵

The aetiology of Tourette syndrome is controversial and several theories have been proposed:

• There is a strong genetic component with a familial linkage to OCD.¹ Current studies suggest a single major autosomal dominant gene with pleiotropic expression (ie chronic motor tics, Tourette syndrome or OCD) and incomplete penetrance. Other recent studies suggest several genes rather than one and an interplay between genetic and environmental factors.

• Other theories include:
  

  • Reduced serotonin transmission.

  • Reduced blood tryptophan levels.

  • Abnormalities of dopamine regulation with excess dopamine. Abnormalities of dopamine in mesencephalic-mesolimbic system are thought to result in disinhibition of the limbic system. This is supported by differences in symmetry of the putamen and lenticular nuclei. Furthermore, dopamine D2 receptor antagonists relieve some of the symptoms.

  • Abnormal discharges in the frontal lobes.

  • Repeated streptococcal infections.

  • Prenatal and perinatal difficulties.

  • Cortical thinning and reduction in the size of the caudate nucleus.⁶

Tourette syndrome symptoms⁷

Tics can be defined as sudden, purposeless, repetitive, non-rhythmic, stereotyped movements or vocalisations - eg, eye twitching or blinking. Examples of vocal tics are throat clearing, grunting and barking.

Other features that may be seen in Tourette syndrome

• Echolalia - involuntary copying of others' words.

• Palilalia - repeating one's own words.

• Coprolalia - compulsory saying of dirty words, which is pathognomonic of the syndrome and is seen in about 10% of patients.

• Copropraxia - making obscene gestures.

• Echopraxia - involuntary copying of others' movements.

• Difficulty concentrating or easily distracted.

Tourette syndrome is associated with a number of other problems

The causes of these associations are not clearly understood but may be related to neurophysiological and/or genetic linkages.

Approach to a patient with tics⁸

• Full history (include age of onset, whether tics wax and wane and family history of Huntington's or Wilson's disease) and examination. Include a mental state examination. There are scales available - eg, MOVES scale for tic severity.

• Recognise co-existent disorders - eg, attention deficit hyperactivity disorder (ADHD), depression, sleep problems or learning disabilities. Each of these will need treatment.

• Differentiate tics from other movement disorders - eg, dystonias and chorea.

• Check TFT and consider a throat swab for streptococcus if there is rapid onset.

• An electroencephalogram (EEG) may help if there is concern regarding presence of epilepsy.

• A urine drug screen may help.

• Rule out secondary causes of tics:

• Genetic - eg, Huntington's chorea, Klinefelter's syndrome.

• Acquired - eg, encephalitis, CVA, hyperthyroidism, CO poisoning, streptococcus-induced autoimmune Tourette syndrome.

• Primary neuropsychiatric disorders - eg, schizophrenia.

• Drugs - eg, cocaine, amphetamines, lithium, antipsychotics, antidepressants, antihistamines and opiates.

Traitement

• Timely and accurate diagnosis is important. Remember that many patients are children and may have difficulty at school.

• Individualise treatment and include parents/carers.

• Education - should involve the nature and cause of tics; also to emphasise that anxiety, stress and fatigue and stimulants worsen tics. Offer reassurance and support.

• Treat any secondary causes of tics.

• Always look for comorbid conditions, especially as research suggests conditions such as ADHD and OCD will determine quality of life rather than tic severity.⁹

• If there is no underlying cause then the tics may be transient (in which case they will settle) or chronic (may be Tourette syndrome).

• If tics are mild - try observation or non-pharmacological measures:
  

  • Education, supportive therapy, counselling and psychotherapy have all been found to be helpful although the evidence base supporting them is small.

  • A literature survey concluded that behavioural and psychosocial interventions (BPIs) should be the first-line approach for children and adolescents with tic disorders.

  • Most evidence was found for habit reversal training (HRT) and the available but smaller evidence also supports the efficacy of exposure with response prevention (ERP).

  • HRT involves developing awareness about the tics, developing motivation to change behaviour, adopting new responses to replace the tics and practising these new-found techniques in challenging situations.¹⁰

  • ERP is a similar therapy which involves patients confronting their fears and discontinuing their escape response.¹¹

• Moderate-to-severe tics should be treated pharmacologically and the patient referred to specialists (eg, a neurologist, mental health specialists).¹²

Psychological interventions¹³

• Psychoeducation is recommended as an initial intervention regardless of symptom severity. Psychoeducation involves a therapist providing structured and specific information about diagnosis, symptoms, and the methods of treatment used.

• When psychoeducation alone is insufficient, both habit reversal training (HRT)/comprehensive behavioral intervention for tics (CBIT) and exposure and response prevention (ERP) are recommended as first-line interventions for tic disorders.

Traitement pharmacologique^{14 15}

• Alpha-adrenergic agonists (eg, clonidine) are often recommended as the first line. Tetrabenazine is also an option.

• The next step would be the second-generation, or atypical antipsychotics, with best evidence is for risperidone and weaker evidence for aripiprazole. Another consideration, perhaps preceding the atypicals, would be tetrabenazine.

• The next option is first-generation, or typical, antipsychotics (eg, pimozide, haloperidol or fluphenazine), which are more potent, but may have more side- effects.

• Focal injection of botulinum neurotoxin has been shown not only to reduce motor tics, but also sensory tics.

• Cannabinoids appear to also be effective for tics in Tourette syndrome, and the use of these agents is coming into the mainstream.

• Haloperidol is the only drug licensed for the control of tics in Tourette syndrome in the UK. All the other drugs are used off-label in the UK.¹⁶

Traitement chirurgical

• Stereotactic surgery has been used in Tourette syndrome, for patients with extremely debilitating symptoms.

• Both deep brain stimulation and ablative neurosurgical procedures have been used to manage refractory severe symptoms.¹⁷

• Surgery can also be performed to site electrodes to deliver deep brain stimulation. Studies so far have been encouraging but larger trials are needed. Bleeding, infection, sedation and anxiety are some of the side-effects reported.¹⁸

Other potential therapies¹²

Therapies supported anecdotally but which have not had the benefit of randomised trials include plasma exchange and intravenous immunoglobulin (where streptococcal infection has been implicated), buspirone, carbamazepine and metoclopramide.

Pronostic

Severity varies from person to person and peaks in the early teenage years. Studies suggest that one third of children are symptom-free as adults, one third will have mild tics and the remainder will require clinical attention.¹²