RESUMEN
Obsessive-compulsive disorder (OCD) is among the most disabling chronic psychiatric disorders and has a significant negative impact on multiple domains of quality of life. For patients suffering from severe refractory OCD, deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been applied. Reviewing the literature of the last years we believe that through its central position within the cortico-basal ganglia-thalamocortical circuits, the STN has a coordinating role in decision-making and action-selection mechanisms. Dysfunctional information-processing at the level of the STN is responsible for some of the core symptoms of OCD. Research confirms an electrophysiological dysfunction in the associative and limbic (non-motor) parts of the STN. Compared to Parkinson׳s disease patients, STN neurons in OCD exhibit a lower firing rate, less frequent but longer bursts, increased burst activity in the anterior ventromedial area, an asymmetrical left-sided burst distribution, and a predominant oscillatory activity in the δ-band. Moreover, there is direct evidence for the involvement of the STN in both checking behavior and OCD symptoms, which are both related to changes in electrophysiological activity in the non-motor STN. Through a combination of mechanisms, DBS of the STN seems to interrupt the disturbed information-processing, leading to a normalization of connectivity within the cortico-basal ganglia-thalamocortical circuits and consequently to a reduction in symptoms. In conclusion, based on the STN׳s strategic position within cortico-basal ganglia-thalamocortical circuits and its involvement in action-selection mechanisms that are responsible for some of the core symptoms of OCD, the STN is a mechanism-based target for DBS in OCD.
Asunto(s)
Estimulación Encefálica Profunda/métodos , Trastorno Obsesivo Compulsivo/terapia , Núcleo Subtalámico , Humanos , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiopatología , Trastorno Obsesivo Compulsivo/fisiopatología , Trastorno Obsesivo Compulsivo/psicologíaRESUMEN
OBJECTIVE: Deep Brain Stimulation in psychiatric disorders is becoming an increasingly performed surgery. At present, seven different targets have been stimulated in Tourette Syndrome, including the internal globus pallidus. We describe the effects on tics and comorbid behavioral disorders of Deep Brain Stimulation of the anterior internal globus pallidus in five patients with refractory Tourette Syndrome. METHODS: This study was performed as an open label study with follow-up assessment between 12 and 38 months. Patients were evaluated twice, one month before surgery and at long-term follow-up. Primary outcome was tic severity, assessed by several scales. Secondary outcomes were comorbid behavioral disorders, mood and cognition. The final position of the active contacts of the implanted electrodes was investigated and side effects were reported. RESULTS: Three males and two females were included with a mean age of 41.6 years (SD 9.7). The total post-operative score on the Yale Global Tic Severity Scale was significantly lower than the pre-operative score (42.2±4.8 versus 12.8±3.8, P=0.043). There was also a significant reduction on the modified Rush Video-Based Tic Rating Scale (13.0±2.0 versus 7.0±1.6, P=0.041) and in the total number of video-rated tics (259.6±107.3 versus 49.6±24.8, P=0.043). No significant difference on the secondary outcomes was found, however, there was an improvement on an individual level for obsessive-compulsive behavior. The final position of the active contacts was variable in our sample and no relationship between position and stimulation effects could be established. CONCLUSION: Our study suggests that Deep Brain Stimulation of the anterior internal globus pallidus is effective in reducing tic severity, and possibly also obsessive-compulsive behavior, in refractory Tourette patients without serious adverse events or side-effects.