Tourette syndrome (also called Tourette’s syndrome, Tourette’s disorder, Gilles de la Tourette syndrome, GTS or, more commonly, simply Tourette’s or TS) is an inherited neuropsychiatric disorder with onset in childhood, characterized by multiple physical (motor) tics and at least one vocal (phonic) tic. These tics characteristically wax and wane, can be suppressed temporarily, and are preceded by a premonitory urge. Tourette’s is defined as part of a spectrum of tic disorders, which includes provisional, transient and persistent (chronic) tics.
Tourette’s was once considered a rare and bizarre syndrome, most often associated with the exclamation of obscene words or socially inappropriate and derogatory remarks (coprolalia), but this symptom is present in only a small minority of people with Tourette’s.
Tourette’s is no longer considered a rare condition, but it is not always correctly identified because most cases are mild and the severity of tics decreases for most children as they pass through adolescence. Between 0.4% and 3.8% of children ages 5 to 18 may have Tourette’s; the prevalence of other tic disorders in school-age children is higher, with the more common tics of eye blinking, coughing, throat clearing, sniffing, and facial movements. Extreme Tourette’s in adulthood is a rarity, and Tourette’s does not adversely affect intelligence or life expectancy.
Genetic and environmental factors play a role in the etiology of Tourette’s, but the exact causes are unknown. In most cases, medication is unnecessary. There is no effective treatment for every case of tics, but certain medications and therapies can help when their use is warranted. Education is an important part of any treatment plan, and explanation and reassurance alone are often sufficient treatment.
Comorbid conditions (co-occurring diagnoses other than Tourette’s) such as attention-deficit hyperactivity disorder (ADHD) and obsessive–compulsive disorder (OCD) are present in many patients seen in tertiary specialty clinics. These other conditions often cause more functional impairment to the individual than the tics that are the hallmark of Tourette’s; hence, it is important to correctly identify comorbid conditions and treat them.
The eponym was bestowed by Jean-Martin Charcot (1825–1893) on behalf of his resident, Georges Albert Édouard Brutus Gilles de la Tourette (1857–1904), a French physician and neurologist, who published an account of nine patients with Tourette’s in 1885.
Patients with Tourette syndrome diagnosed according to DSM-IV TR criteria with severe medication-recalcitrant disease referred to the Hazrat Rasool Hospital, Iran University of Medical Sciences, Tehran, Iran, were recruited for this study. They underwent bilateral anteromedial globus pallidus internus (amGPi) DBS with Medtronic Brain Neurostimulation Lead 3389. Patients were assessed using Yale Global Tic Severity Scale(YGTSS) and Gilles de la Tourette syndrome-quality of life scale (GTS-QOL) before and one year after DBS.
Six patients (four man and two women) with severe medication-recalcitrant TS, mean age of 26.33 ± 7.25 years fulfilled the follow up visits. All patients revealed significant improvement in tics severity one year after surgery. Based on YGTSS, total tic severity score decreased from 75.66 ± 16.54 to 28.33 ± 13.95, P-value:0.005. Quality of life improved significantly after DBS (26.66 ± 20.65 before and 70.00 ± 17.88 one year after surgery, P-value:0.02).
Results of this study in accordance to previous ones suggest AM-GPi DBS as an effective and well-tolerated therapeutic modality for patients with medication refractory TS 1).
Giorni et al. used intra-operative microelectrode recording during stereotactic neurosurgery to guide implantation of DBS lead.
Units in the medial anterior part of GPi of 7 Tourette’s syndrome patients under general anesthesia were firing at mean and median rate of 32.1 and 21 Hz respectively (n = 101), with 45% of spikes fired during bursts and 21.3 bursts per minute. In the latero-posterior part of GPi of 7 dystonic patients under local anesthesia the mean and median activity were 46.1 and 30.6 Hz respectively (n = 27), and a mean of 21.7 bursts per minute was observed, with 30% of all spikes occurring during these bursts.
Units activity pattern – slow-regular, fast-irregular or fast-regular were present in different proportions between the two targets.
The electrophysiological characteristics of the medial-anterior part of GPi and its latero-posterior portion can be used to assist DBS electrode targeting and also support the refinement of pathophysiological models of Tourette’s syndrome and Dystonia 2).
A study of 15 patients with long-term amGPi DBS for severe TS investigated whether a specific anatomical site within the amGPi correlated with optimal clinical outcome for the measures of tics, obsessive compulsive behaviour (OCB), and mood.
Validated clinical assessments were used to measure tics, OCB, quality of life, anxiety, and depression before DBS and at the latest follow-up (17-82 months). Electric field simulations were created for each patient using information on electrode location and individual stimulation parameters. A subsequent regression analysis correlated these patient-specific simulations to percentage changes in outcome measures in order to identify any significant voxels related to clinical improvement.
A region within the ventral limbic GPi, specifically on the medial medullary lamina in the pallidum at the level of the AC-PC, was significantly associated with improved tics but not mood or OCB outcome.
This study adds further support to the application of DBS in a tic-related network, though factors such as patient sample size and clinical heterogeneity remain as limitations and replication is required 3).
Richieri et al., report the first case of a patient with severe, intractable Tourette Syndrome (TS) with comorbid Obsessive Compulsive disorder(OCD), who recovered from both disorders with gamma knife stereotactic radiosurgery following deep brain stimulation (DBS). This case highlights the possible role of the internal capsule within the neural circuitries underlying both TS and OCD, and suggests that in cases of treatment-refractory TS and comorbid OCD, bilateral anterior capsulotomy using stereotactic radiosurgery may be a viable treatment option 4).