The experimental procedure of thalmic deep brain stimulation (DBS) reduces the involuntary movements and vocal outbursts experienced by young adults with severe cases of Tourette syndrome, a New York University study found.
A new study led by investigators from NYU Langone Medical Centre is a retrospective review of Tourette patients who underwent an experimental technique known as thalamic deep brain stimulation (DBS) at NYU Langone. The findings, according to the researchers, add to a growing body of evidence supporting DBS as a safe and effective treatment for severe cases of Tourette syndrome – and may ultimately lead to approval by the US Food and Drug Administration.
“Our study shows that deep brain stimulation is a safe, effective treatment for young adults with severe Tourette syndrome that cannot be managed with current therapies,” says Dr Alon Mogilner, an associate professor in the departments of neurosurgery and anaesthesiology, at NYU Langone, and director of its Centre for Neuromodulation. “This treatment has the potential to improve the quality of life for patients who are debilitated through their teenage years and young adulthood.”
Tourette syndrome begins in childhood and many patients improve as they get older. However, for some, the symptoms become so severe that they become socially isolated and unable to work or attend school.
Mogilner and his colleague, Dr Michael H Pourfar, an assistant professor in the departments of neurosurgery and neurology and co-director of the Centre for Neuromodulation, have pioneered the largest US case series of thalamic DBS to treat severe Tourette syndrome in young adults. Worldwide, only an estimated 160 cases have been performed to date.
In a multi-stage procedure, they insert two electrodes into a region of the brain called the medial thalamus, part of the brain circuit that functions abnormally in Tourette’s. During a second surgery the following day or a few days later, a pacemaker-like device called a neuro-stimulator is connected to the electrodes to emit electrical impulses into the medial thalamus. These impulses are adjusted during a series of follow-up outpatient visits to find the combination of settings that best control symptoms.
In the study, the NYU Langone team followed 13 patients with at least six months of follow-up visits. Study participants ranged in age from 16 years to 33 years. To determine the effectiveness of the procedure, the researchers measured the severity of tics before and after surgery using the Yale Global Tic Severity Scale (YGTSS). They found that the severity of tics decreased on average 37% from the time of the operations to the first follow-up visit. At their latest visit, patients’ tic scores decreased by an average of 50%.
Equally significant, all patients reported in a survey six months after surgery that their symptoms improved either “much” or “very much,” and all said they would have the surgery again – even those who had complications or experienced relatively less pronounced responses. “The survey represents an important aspect of the study,” Pourfar says, “because the YGTSS, though a validated scale, may not fully capture the impact of DBS on quality of life for a person with Tourette syndrome.”
Since the study completed, four more patients have undergone DBS surgery for Tourette syndrome.
DBS has been used to treat other neurological conditions that cannot be adequately controlled by medication, including Parkinson’s disease, essential tremor, dystonia and epilepsy.
Because the FDA has not yet approved DBS for the treatment of Tourette syndrome, it is still considered investigational. As a result, a committee of independent specialists reviews each case to ensure that patients have tried alternate therapies and that the disability is severe enough to warrant undergoing the procedure.
Objective: Tourette syndrome (TS) is a complex neuropsychiatric disorder characterized by multiple motor and phonic tics. While pharmacological and behavioral therapy can be effective in most patients, a subset of patients remains refractory to treatment. Increasing clinical evidence from multiple centers suggests that deep brain stimulation (DBS) of the medial thalamus can be effective in many cases of refractory TS.
Methods: The authors retrospectively reviewed outcomes in 13 patients with refractory TS who underwent medial thalamic DBS performed by their team over a 7-year period. Patients were evaluated by a multidisciplinary team, and preoperative objective assessments were performed using the Yale Global Tic Severity Scale (YGTSS) and Yale-Brown Obsessive Compulsive Scale. YGTSS scores were calculated at visits immediately postoperatively and at the most recent follow-up in patients with a minimum of 6 months of postoperative follow-up. Coordinates of the active DBS contacts were calculated and projected onto each patient’s pre- and postoperative images.
Results: Patients showed an average decrease of 37% (p = 0.0063) in the total tic severity at their first postoperative visit. At their latest visit, their scores achieved significance, decreasing from preoperative scores by an average of 50% (p = 0.0014). The average position of the active contact was noted to be at the junction of the posterior ventralis oralis internus/centromedian-parafascicular nuclei. Device-related complications occurred in 2 patients, necessitating additional surgeries. All patients continued to use the system at last follow-up.
Conclusions: The authors’ data are consistent with the small but growing body of literature supporting DBS of the ventralis oralis internus/centromedian-parafascicular thalamus as an effective and relatively safe treatment for severe, refractory TS.
Richard S Dowd, Michael Pourfar, Alon Y Mogilner
NYU Langone Medical Centre/New York University School of Medicine material[/link]
Journal of Neurosurgery abstract