(This article was originally published in Functional Neurosurgery Newsletter, 2014, No. 4, by Qiao Liang, M.D., Deputy Chief Physician, Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing Institute of Functional Neurosurgery) The Netherlands, with its idyllic scenery marked by windmills, wooden shoes and tulips, is a small country with advanced agriculture and animal husbandry, shipbuilding industry, high-tech industry and financial services. It is a Western European country with a developed economy and a high sense of well-being. Maastricht, located in the southeast of the Netherlands near the borders of Belgium and Germany, became famous when the Maastricht Treaty, which marked the birth of the European Union, was signed here in 1992. The Maas River runs north and south through the center of the historic city, which has a population of just over 100,000. The banks are lined with greenery, and the various churches, buildings and stores are hidden. The old mosaic-lined streets crisscross the city and lead to the Maastricht
Exhibition and Conference Center, where the four-day 21st European Conference on Stereotactic and Functional Neurosurgery is taking place. The Xuanwu Hospital of Capital Medical University functional neurosurgery Qiao Liang conference was medium sized with hundreds of participants. Doctors and scientists worked on various important topics in the field of stereotactic and functional neurosurgery in a variety of formats: congress keynote addresses, session presentations, live Q&A, poster presentations, case discussions, and more. The conference was comprehensive and specialized, with the focus (about half of the conference content) remaining on the use of stereotactic techniques in movement disorders. In addition, participants discussed research and treatment advances in other functional brain disorders such as neuropathic pain, epilepsy, and refractory depression. There were many hot spots, highlights and information points in the four-day conference, and I would like to summarize the following “notes from the conference” to share with readers.
Deep brain stimulation (DBS): Mechanisms: Although the efficacy of DBS in the treatment of movement disorders has long been and continues to be supported by a large body of literature and is widely recognized in clinical practice, its mechanism of action still needs to be studied in depth. Traditionally, it is generally believed that DBS inhibits neuronal firing in target structures through high-frequency electrical stimulation. However, a different interpretation has been proposed: DBS acts by excitation of inhibitory neurons within the target site. Recent studies have also suggested that DBS may work by altering the firing pattern of target neurons, for example, by inhibiting beta oscillations.
pattern of target neurons, such as increasing gamma activity by inhibiting beta oscillation. These suggest that the mechanism of action of DBS may be much more than the traditional belief of a simple or single mechanism. The meeting discussed the results of the comparison between the targets of DBS for Parkinson’s disease (thalamic nucleus STN or pallidum GPi), preliminary analysis of the advantages and limitations of each, and presented the progress of research on new targets (e.g. pontine nucleus PPN). It is generally believed that unilateral PPN stimulation is more suitable for patients with Parkinson’s disease whose balance/gait disorder is the main manifestation. There are also case reports that GPi may be more effective than the thalamic VIM nucleus for patients with primary tremor with dystonia. Surgical aspects: localization tools: The meeting summarized three current tools for intraoperative localization of targets in DBS: anatomical coordinates, imaging and microelectrode recording (MER). Prof. Yesin Temel, chair of the organizing committee of this meeting and chief of neurosurgery at Maastricht University, shared his team’s application of 7.0
Telsa MRI scans of the thalamic base nucleus. The high field intensity MRI and DTI images are clear and well defined, both of which offer the possibility of sub-regional subdivision and fine targeting of the STN. The session also focused on the role and limitations of MER in the intraoperative setting. Future advances in DBS devices (such as multi-directional current stimulation or feedback stimulation) may help to avoid the side effects of suboptimal electrode placement or improve the efficiency of postoperative DBS parameter modulation. (2) Intraoperative stimulation test: Some scholars have proposed to abandon the intraoperative stimulation test (trial stimulation) and rely on intraoperative nuclear stimulation.
(2) Intraoperative stimulation test: It has been suggested that the possibility of abandoning intraoperative stimulation test (trial stimulation), verifying electrode position based on intraoperative MRI or O-arm, and performing DBS under general anesthesia in the future. This approach significantly reduces intraoperative discomfort, but does not verify the stimulation effect or side effects, and is more dependent on the precise placement of the electrodes and their accurate correspondence with clinical outcomes. The majority of centers still perform electrode placement under local anesthesia. (3) Postoperative modulation: The study of the local field potential (LFP) at the end of the electrode
field potential (LFP), especially its spectral characteristics, offers the possibility to develop feedback electrical stimulation and shorten postoperative modulation time in the future. In addition, individualization of postoperative stimulation parameters is not only necessary, but also provides clues to study the mechanisms of DBS and functional encephalopathy by correlating stimulation parameters and efficacy. (4) Postoperative complications: In the case discussion session, Andres Lozano, a leading neurosurgeon from the University of Toronto, Canada, shared a case of DBS.
Prof. Lozano shared a case of postoperative infection that required removal of the DBS device; he performed target disruption through the electrodes before removing them, thus preserving the therapeutic effect. Another Italian scholar, Andrea
Trezza reported a case of significant bilateral edema in the puncture tract after DBS implantation, which was analyzed to be due to the patient’s hypersensitivity and completely resolved after intravenous hormonal treatment. A similar case was observed in our department in 2013 in a patient with Parkinson’s who developed significant bilateral punctal tract edema after STN-DBS. The above suggests that a very small number of patients may develop pathway edema after DBS due to hypersensitivity status, which is a rare but should receive adequate attention and timely management as a complication after DBS. Indications: The meeting extensively explored the use of DBS in the treatment of functional brain disorders other than movement disorders, such as epilepsy (target: anterior thalamic nucleus ANT), neuropathic pain (target: pars intermedia pars intermedia), psychiatric disorders, Tourette’s syndrome and even Alzheimer’s disease (target: fornix of the fornix). DBS has shown considerable promise as a reversible, minimally invasive approach for the treatment of functional brain disorders. For example, DBS has been approved in Europe and Canada for the control of refractory partial epilepsy, as evidenced by the SANTE (Stimulation of the Anterior Nucleus of Thalamus for Epilepsy) program, which lasted up to 5 years. The US FDA is currently requesting additional data support from Medtronic in this area. In addition, a summary of multiple cases of DBS for Tourette’s syndrome was reported. Dr. Zhang Xiaohua, the deputy chief physician of our department, and Dr. Dong Sheng, a postdoctoral fellow, are also conducting research and summaries on related topics, with more cases and promising results. 2.
It has been more than half a century since the introduction of ablative brain surgery, and some scholars have described this technique as a pendulum that has experienced the ups and downs of boom, bust, and boom again. Each boom has been underpinned by scientific advances and breakthroughs that have led to the expansion of clinical applications. At present, deep brain nucleus destruction still attracts many scholars to study its mechanism and clinical application in depth due to its effectiveness and relative economy. The proposed basal ganglia model (direct pathway
pathway and indirect pathway indirect
Professor Mahlon DeLong of Emory University, who proposed the direct pathway and the indirect pathway, suggested that the medial pallidum (GPi), as one of the important output structures of the basal ganglia, deserves sufficient attention and research because of its precise effect on the treatment of Parkinson’s disease. 3. The application of neuromodulation technology in this field has become a hot spot for doctors and scholars. According to the pain transmission pathway, neuromodulation can take different forms: peripheral nerve stimulation
nerve stimulation), dorsal root ganglion stimulation (dorsal
The conference discusses these forms of neuromodulation, including peripheral nerve stimulation, dorsal root ganglion stimulation, spinal cord stimulation, deep brain stimulation, and motor cortex stimulation. The effects and mechanisms of these forms of neuromodulation on various sites and pathological types of pain were discussed, revealing great potential for application. It is predicted that neuromodulation will become the main treatment modality for refractory pathological pain due to its effectiveness, minimally invasive and reversible nature. The analysis of indications, target selection, parameter settings, and postoperative management are in urgent need of more detailed, large-sample, and in-depth studies, which also provide numerous valuable subject options. Although it is not possible to summarize everything, we hope that readers will find it enlightening. Before the end of the conference, the organizing committee made a special announcement: Professor Alim-Louis Benabid from Joseph Fourier University, France, and Professor Mahlon DeLong from Emory University, USA, were jointly awarded the 2014 Lasker DeBakey Clinical Medical Research Award for their outstanding contributions to the application of DBS in the treatment of Parkinson’s disease. The Lasker Prize is awarded by the Albert and Mary Lasker Foundation, which is a highly professional and credible award in the medical field and is often referred to as the wind of the Nobel Prize. The enthusiastic applause of all the attendees in the room conveyed the reverence and pride of the two masters in their field. I couldn’t help but remember that just a few weeks ago, Prof. DeLong came to China to give a lecture, and he visited our institute (Beijing Institute of Functional Neurosurgery) after the meeting. The 76-year-old man, thin and hale, with a gleaming gaze, visited every operating room, monitoring room and ward in detail, and also exchanged questions and answers with the director, Prof. Li Yongjie, and his colleagues. While I admired Professor DeLong’s energy, I deeply felt the strong interest in medicine and the persistence in the pursuit of science behind it. Passionate devotion, independence and objectivity, perseverance and tenacity are probably the common traits of successful scientists! The wind from Europe, the fresh wind, the wind has the taste of freedom —–