Konstantin V. Slavin

The aim . To present the fi rst results of intraoperative microneurography of the trigeminal root in patients with classic trigeminal neuralgia and to assess the relationship between recorded electrical activity and pain regression or persistence after microvascular decompression. Materials and methods . The study included 13 patients with classic trigeminal neuralgia who underwent microvascular decompression (MVD) and 4 patients with posterior cranial fossa tumors (control group). Patients were divided into three groups: Group 1 – MVD with tactile stimulation (n = 9); Group 2 – MVD without stimulation (n = 4); Group 3 – control group with tactile stimulation (n = 4). Electrical activity of the nerve root was recorded before and after decompression. Pain assessment was performed using the Visual Analog Scale and the BNI scale. Results . In all patients of Group 1, deep tactile stimulation evoked electrical activity of the trigeminal root before surgery, whereas superfi cial stimulation was not accompanied by recordable activity. After MVD, a signifi cant reduction in electrical activity was observed in 67 % of cases (6 out of 9), which correlated with pain regression. In three patients with persistent pain (Group 1), electrical activity was also recorded after surgery. In Group 2, no spontaneous ectopic activity was detected. In the control group, no electrical activity characteristic of classic trigeminal neuralgia was found. The signal-to-background amplitude ratio in patients with persistent pain after surgery was signifi cantly greater than 1 compared to the pain regression group (p = 0.003). Conclusion . Intraoperative microneurography allows the detection of pathological electrical activity of the trigeminal root in patients with classic trigeminal neuralgia, which correlates with the presence of pain and its regression after surgical intervention. The proposed parameter – the ratio of electrical activity amplitude to background – may be considered a potential criterion for the eff ectiveness of decompression, but requires further study in an expanded cohort.

Background/Objectives: Vagus nerve stimulation (VNS) has evolved from a laboratory experiment to a standard of care in several neurological disorders like epilepsy, depression and stroke rehabilitation at present. Methods: We reviewed the published literature relevant to its origins in animal models leading to various clinical applications. Results: Bailey and Bremer published their observations following VNS in animals while further studies established its utility in some forms of epilepsy. Subsequent observations in epilepsy patients treated with VNS revealed the unequivocal improvement in psychological and behavioral disorders. Consequently, VNS received approval for its application in resistant depression disorders. Multiple studies revealed changes due to neuronal plasticity following VNS that could result in the significant clinical recovery of motor function in chronic ischemic stroke patients. Chronic incomplete cervical spinal cord injury, head injury and peripheral nerve injury deficits are also being studied for recovery patterns. Transcutaneous approaches and closed-loop stimulation are showing encouraging results that may facilitate the extension of the application of neuromodulation using VNS. Conclusions: For the recovery of motor function following paralysis in stroke patients or cervical spinal cord injuries, the timing of the stimulation after physical activity during rehabilitation has been identified as a key factor. In addition to the timing of the stimulation, the titration of the parameters is also being studied to obtain optimized recovery in cases of motor, sensory, or sphincter deficits.

Background Psychiatric disorders are increasingly contributing to global disability. Despite advances in conservative management, the prevalence of treatment-resistant cases remains high. Meanwhile, neurosurgery for psychiatric disorders (NPD) remains underused, largely due to strict regulations and historical concerns, particularly those related to neuropsychological side effects (NPSE). Objective To address this issue, we conducted a systematic review with meta-analysis to compare NPSE associated with radiofrequency ablative NPD to those observed in neuro-oncological, neurovascular and epilepsy surgeries. Methods PubMed, Embase and LILACS databases were searched in April 2024 for articles published in English/Spanish from 1990 to 2022, following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Results A total of 48 articles with 2678 participants were included. The frequency of transient and permanent NPSE in the NPD group ranged from 0.94% to 11.50% and 0.94% to 2.03%, respectively, comparable to the other surgical groups (epilepsy: 0.31–11.70%; vascular: 0.52–22.90%; oncology: 0.94–17.60% for transient NPSE; epilepsy: 0.31–12%; vascular: 0.40–1.96% and oncology: 0.84–1.48% for permanent NPSE). Regarding permanent NPSE, arguably the most critical consideration, the NPD group showed better outcomes in memory, language and social cognition than the epilepsy group, but worse outcomes in executive and perceptual-motor functions. Compared with the vascular group, the NPD group had better executive function but worse complex attention. Finally, the NPD group had fewer permanent deficits than the oncology group in executive function, complex attention and perceptual-motor domains, although language performance was lower. Conclusions Contemporary NPD apparently carries a similar risk of NPSE as other conventional neurosurgical procedures, challenging misconceptions and this unjustified barrier to its broader use.

Peripheral nerve stimulation (PNS) has evolved substantially over recent decades in terms of hardware and evidence supporting efficacy. Treatment targets continue to expand and address both pain and functional applications. The American Society of Pain and Neuroscience (ASPN) seeks to substantially update and expand upon a review of the evidence supporting PNS as well as provide guidelines for clinical practice. A diverse multidisciplinary panel of experts was selected to provide opinions and guidance based on evidence-graded assessment and clinical knowledge. This document aims to serve as a resource for clinicians and payors in the interest of expanding awareness of the breadth of research in the field of PNS and expanding access to therapy.

Radiofrequency (RF) lesioning is a precise and established destructive technique in functional neurosurgery for treating chronic pain, movement disorders, and other conditions. This paper reviews its history, technical evolution, and key applications such as trigeminal gangliolysis, cordotomy, and deep brain lesioning. Despite being irreversible and less commonly practiced today due to the rise of neuromodulation, RF lesioning offers significant advantages like predictability, minimal invasiveness, and cost-effectiveness, making it a valuable option for specific patients, particularly in oncology pain care.

Peripheral nerve stimulation (PNS) is defined as the application of electric stimulation to the peripheral nervous system and to a specific nerve. For the most part, the goal of PNS has been treatment of pain. Later, PNS use expanded to indications other than pain including epilepsy and depression, which involves stimulation of the vagus nerve, sleep apnea with stimulation of the hypoglossal nerve, respiratory insufficiency, involving phrenic nerve stimulation, and many others. The overarching peripheral neuromodulation approach involves three modalities: conventional PNS, which implies direct placement of stimulating electrode leads over the affected peripheral nerve(s); percutaneous PNS, which implies insertion of stimulating electrode leads near the target nerve with appropriate guidance; and peripheral nerve field stimulation, which requires placement of electrode leads to stimulate smaller nerves and nerve endings in the affected target area. Monitoring peripheral nerves during surgery through electrophysiological methods is a highly valuable option, offering crucial real-time information to the surgical team. While preoperative testing provides helpful data for decision-making, intraoperative neurophysiological monitoring (IONM) fills in gaps that cannot be addressed by preoperative studies. IONM assesses the nervous system during surgery to prevent potential damage to critical neurological structures. It serves the next main purposes: detecting and minimizing iatrogenic injuries, mapping nervous structures to identify the target nerve, and assessing the functionality of the nerve. In this article we review currently available information about the utilization of IONM during PNS procedures.