Deep brain stimulation for Tourette syndrome: modulation of the limbic-motor interface network

OBJECTIVE

Deep brain stimulation (DBS) is an effective treatment for medically refractory Tourette syndrome (TS). Several effective targets have been reported, but there is still controversy about the networks involved in the efficacy of DBS for TS. Here, the authors aimed to identify the basal ganglia-thalamo-cortical networks associated with tic and obsessive-compulsive behavior (OCB) improvement and the network link between the two main targets for TS.

METHODS

A retrospective analysis of 21 patients treated with pallidal and thalamic DBS was performed. Tics and OCB scores were recorded before and after DBS. The authors localized the electrodes in standard MNI (Montreal Neurological Institute) space and calculated the volume of tissue activated with the settings at the last follow-up to obtain areas of maximal improvement ("sweet spots") among all patients for the pallidal and thalamic targets. Tractography was used to show the white matter pathways associated with maximal tic and OCB improvement.

RESULTS

Ten patients treated with pallidal DBS and 11 patients treated with thalamic DBS were included. Responder rates were 80% in the pallidal and 64% in the thalamic target groups. Sweet spots for tics and OCB clustered in several areas across the basal ganglia and thalamus delineated two main networks. Tic reduction in the pallidal target mapped to a limbic pallidothalamic network and in the thalamic target to the premotor thalamocortical network. Putting these two networks together will form the main output of the so-called limbic-motor interface network. However, OCB reduction mapped a dorsomedial prefrontal cortex/dorsal anterior cingulate (dmPFC/dACC) network.

CONCLUSIONS

The authors demonstrated the involvement of the limbic-motor interface network during effective DBS for tics in patients with TS. OCB redution was associated with the additional involvement of dmPFC/dACC connections passing dorsal to the head of the globus pallidus pars externa on its way to the thalamus and midbrain.

EANS Basic Brain Course (ABC): combining simulation to cadaver lab for a new concept of neurosurgical training

BACKGROUND

Neurosurgical training has traditionally been based on an apprenticeship model that requires considerable time and exposure to surgeries. Unfortunately, nowadays these requirements are hampered by several limitations (e.g., decreased caseload, worktime restrictions). Furthermore, teaching methods vary among residency programs due to cultural differences, monetary restrictions, and infrastructure conditions, with the possible consequence of jeopardizing residents' training.

METHODS

The EANS Basic Brain Course originated from a collaboration between the Besta NeuroSim Center in Milano and the Swiss Foundation for Innovation and Training in Surgery in Geneva. It was held for 5 neurosurgical residents (PGY1-3) who participated to this first pilot experience in January 2019. The main goal was to cover the very basic aspects of cranial surgery, including both technical and non-technical skills. The course was developed in modules, starting from the diagnostic paths and communication with patients (played by professional actors), then moving to practical simulation sessions, rapid theoretical lessons, and discussions based on real cases and critical ethical aspects. At the end, the candidates had cadaver lab sessions in which they practiced basic emergency procedures and craniotomies. The interaction between the participants and the faculties was created and maintained using role plays that smoothly improved the cooperation during debriefs and discussions, thus making the sessions exceedingly involving.

RESULTS

At the end of the course, every trainee was able to complete the course curriculum and all the participants expressed their appreciation for this innovative format, with a particular emphasis on the time spent learning non-technical skills, confirming that they feel this to be a fundamental aspect of a comprehensive training in neurosurgery.

CONCLUSIONS

It is possible that this combined concept of training on technical and non-technical skills, using emerging technologies along with pedagogic techniques and cadaver dissection, may become the state-of-the-art for European Neurosurgical training programs in the next future.