by Matteo Pasca
The third Plenary Session of the EAN 2024 Congress in Helsinki, on ‘Invasive neuromodulation: Hot topics and future directions’ provided an engaging overview of current advancements and applications in the field. It covered a range of topics including deep brain stimulation (DBS), ultrasound techniques, vagal nerve stimulation (VNS) and spinal cord stimulation, each discussed by leading experts. The session attracted a large audience, indicating high interest and enthusiasm for these emerging therapies.
EAN President-Elect, Elena Moro offered a comprehensive overview of the current state of DBS, especially in treating Parkinson’s disease and dystonia. She emphasised how DBS is becoming more precise and tailored to individual patients. The use of advanced electrodes and the integration of neuroimaging and neurophysiological techniques allow for highly accurate targeting of brain structures. This precision facilitates the exploration of new stimulation targets. Notably, some studies have shown promising results with the stimulation of the globus pallidus and cerebellum for dystonia, as well as the subthalamic nucleus and substantia nigra for Parkinson’s. Artificial intelligence further enhances DBS by adapting stimulation parameters based on the activity of the targeted structures during both wakefulness and sleep.
Martinez Fernandez discussed the role of high-frequency focused ultrasound in creating lesioning effects in the basal ganglia. Techniques such as thalamotomy, subthalamotomy, and pallidotomy can significantly reduce tremors in Parkinson’s disease, with effects lasting over time. The precision of these methods is enhanced by MRI guidance, making them increasingly selective and effective. Recent pilot studies have also demonstrated the efficacy of high-frequency ultrasound stimulation in treating conditions like neuropathic pain, obsessive-compulsive disorder, and epilepsy, opening new research avenues.
Low-frequency focused ultrasound also offers exciting possibilities. By increasing the permeability of the blood-brain barrier, it can facilitate the delivery of drugs like aducanumab for Alzheimer’s disease and chemotherapeutics for brain tumours. This approach represents a novel way to enhance the efficacy of pharmacological treatments.
EAN President Paul Boon highlighted the efficacy of VNS and DBS in the anterior nucleus of the thalamus for refractory epilepsy. More than 40% of patients respond positively to VNS. He also discussed the comparative effectiveness of VNS and DBS, with DBS being slightly more effective, while VNS offers cost reductions. Innovative techniques like chemogenetics and optogenetics could be considered to treat epilepsy by selectively targeting hyperactive cells. Although still in the preclinical stage, these methods show promise due to their specificity, despite challenges such as high costs and invasiveness.
Cecile de Vos discussed spinal cord stimulation for chronic pain, particularly for persistent spinal pain syndrome and complex regional pain syndrome. This method involves placing electrodes at the level of A-beta fibres in the epidural space. Despite high costs and variability in stimulation methods, more than 50% of patients experience significant relief. Although spinal cord stimulation has become more precise and effective over the years, there is a lack of multicentre randomised clinical trials against placebo. The need for objective measures to assess pain and treatment efficacy was also emphasised. In summary: the session on neuromodulation provided valuable insights into the current and future landscape of neurological treatments. From the precision of DBS and innovative use of ultrasound to the potential of VNS and emerging genetic techniques, the discussions highlighted both advancements and ongoing challenges in the field. All the speakers emphasised that, through the increasing understanding of the pathophysiological mechanisms of neuronal networks and the technological development of neuromodulation devices, it is possible to deliver increasingly effective and precise therapy. However, the high costs of these therapies limit their study through multicentre randomised clinical trials, which could provide even more precise information.
