Safety of intracranial electrodes in an MRI environment: a technical report.

INTRODUCTION: Intracranial electroencephalography (iEEG) involves placing intracranial electrodes to localise seizures in patients with medically refractory epilepsy. While magnetic resonance imaging (MRI) enables visualisation of electrodes within patient-specific anatomy, the safety of these electrodes must be confirmed prior to routine clinical utilisation. Therefore, the purpose of this study was to evaluate the safety of iEEG electrodes from a particular manufacturer in a 3.0-Tesla (3.0T) MRI environment. METHODS: Measurements of magnetically induced displacement force and torque were determined for each of the 10 test articles using standardised techniques. Test articles were subsequently evaluated for radiofrequency-induced heating using a Perspex phantom in both open and 'fault' conditions. Additionally, we assessed radiofrequency (RF)-induced heating with all test articles placed into the phantom simultaneously to simulate an implantation, again in both open and 'fault' conditions. Finally, each test article was evaluated for MRI artefacts. RESULTS: The magnetically induced displacement force was found to be less than the force on the article due to gravity for all test articles. Similarly, the maximum magnetically induced torque was less than the worst-case torque due to gravity for all test articles apart from the 8-contact strip - for which it was 11% greater - and the depthalon cap. The maximum temperature change for any portion of any test article assessed individually was 1.7°C, or 1.2°C for any device component meant to be implanted intracranially. In the implantation configuration, the maximum recorded temperature change was 0.7°C. CONCLUSIONS: MRI may be safely performed for localising iEEG electrodes at 3.0T under certain conditions.

Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies.

BACKGROUND AND OBJECTIVES: Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy. METHODS: A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella-sphenoid angle (a representation of the coronal slope of FO). Mann-Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation. RESULTS: Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella-sphenoid angles (median = 52.00° vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically. CONCLUSION: We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

No change in network connectivity measurements between separate rsfMRI acquisition times.

The role of resting state functional MRI (rsfMRI) is increasing in the field of epilepsy surgery because it is possible to interpolate network connectivity patterns across the brain with a high degree of spatial resolution. Prior studies have shown that by rsfMRI with scalp electroencephalography (EEG), an epileptogenic network can be modeled and visualized with characteristic patterns of connectivity that are relevant to both seizure-related and neuropsychological outcomes after surgery. The aim of this study is to show that a 5-min acquisition time provides reproducible results related to the relevant connectivity metrics when compared to a separately acquired 5-min scan. Fourteen separate rsfMRI sessions from ten different patients were used for comparison, comprised of patients with temporal lobe epilepsy both pre- and post-operation. Results showed that there was no significant difference in any of the connectivity metrics when comparing both 5-min scans to each other. These data support the continued use of a 5-min scan for epileptogenic network modeling in future studies because the inter-scan variability is sufficiently low as not to alter the output metrics characterizing the network connectivity.

Does Head Positioning After Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Matter?

BACKGROUND: Percutaneous glycerol rhizotomy (PGR) is a minimally invasive procedure for patients with trigeminal neuralgia who are not candidates for microvascular decompression. PGR has widely varying success rates. It has been postulated that differences in post-injection head positioning might account for the various success rates. METHODS: By comparing glycerol dispersion after injection at various head positions, we provide the first evidence supporting post-injection head flexion positioning. Furthermore, we study the clival-Meckel cave (CMC) angle as a predictor of beneficial glycerol flow, measured on computed tomography images. Twenty-two dissected cadaveric specimens were injected with dyed glycerol through the Hartel approach. The glycerol dispersion was measured at prespecified intervals for 1 hour. The Mann-Whitney U and χ2 tests were used to determine the most ideal angle of head flexion to avoid posterior glycerol dispersion and ensure V1-V3 branch glycerol submersion. RESULTS: We found that 30° of anterior head flexion provided optimal trigeminal nerve glycerol submersion (81.82%) in comparison to neutral (27.27%) and 15° (68.18%), P < 0.001. There was minimal unfavorable dispersion beyond 30 minutes at all angles. More obtuse CMC angles were associated with higher rates of unfavorable BC dispersion (U = 6.0; P = 0.001). For specimens with CMC angles >75°, unfavorable BC dispersion was prevented by head flexion (U = 4.5; P = 0.021). We show that 30° of lateral head tilt achieves V1 submersion in all specimens by 30 minutes [X2(1,N = 44) = 22.759; P < 0.001]. CONCLUSIONS: We found that 30° anterior head flexion for >30 minutes provides ideal conditions for PGR to avoid BC dispersion and ensure V1-V3 branches achieve glycerol submersion. For patients with V1 symptoms, contralateral head flexion might help optimize treatment effects.

Deep brain stimulation for chronic pain: a systematic review and meta-analysis.

Background: Deep brain stimulation (DBS) has shown promise in effectively treating chronic pain. This study aimed to assess the efficacy of DBS in this context. Methods: We conducted a systematic literature search using PubMed, Scopus, and Web of Science, following the PRISMA guidelines. A well-constructed search strategy was utilized. Our literature search identified two groups of subjects: one group underwent DBS specifically for chronic pain treatment (DBS-P), while the second group received DBS for other indications (DBS-O), such as Parkinson's disease or dystonia, with pain perception investigated as a secondary outcome in this population. Meta-analysis was performed using R version 4.2.3 software. Heterogeneity was assessed using the tau^2 and I^2 indices, and Cochran's Q-test was conducted. Results: The analysis included 966 patients in 43 original research studies with chronic pain who underwent DBS (340 for DBS-P and 625 for DBS-O). Subgroup analysis revealed that DBS-P exhibited a significant effect on chronic pain relief, with a standardized mean difference (SMD) of 1.65 and a 95% confidence interval (CI) of [1.31; 2.00]. Significant heterogeneity was observed among the studies, with an I^2 value of 85.8%. However, no significant difference was found between DBS-P and DBS-O subgroups. Subgroup analyses based on study design, age, pain diseases, and brain targets demonstrated varying levels of evidence for the effectiveness of DBS across different subgroups. Additionally, meta-regression analyses showed no significant relationship between age or pain duration and DBS effectiveness for chronic pain. Conclusion: These findings significantly contribute to the expanding body of knowledge regarding the utility of DBS in the management of chronic pain. The study underscores the importance of conducting further research to enhance treatment outcomes and elucidate patient-specific factors that are associated with treatment response. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=428442, identifier CRD42023428442.

Deep brain stimulation for substance use disorder: a systematic review and meta-analysis.

Objective: Substance use disorder (SUD) is a significant public health issue with a high mortality rate. Deep brain stimulation (DBS) has shown promising results in treating SUD in certain cases. In this study, we conducted a meta-analysis to evaluate the efficacy of DBS in the treatment of SUD and reduction of relapse rates. Methods: We performed a thorough and methodical search of the existing scientific literature, adhering to the PRISMA guidelines, to identify 16 original studies that fulfilled our inclusion criteria. We used the evidence levels recommended by the Oxford Centre for Evidence-Based Medicine to assess bias. The R version 4.2.3 software was utilized to calculate the mean effect size. We estimated study heterogeneity by employing tau2 and I2 indices and conducting Cochran's Q test. Results: The results showed that DBS treatment resulted in a significant improvement in the clinical SUD scales of patients, with an average improvement of 59.6%. The observed relapse rate was 8%. The meta-analysis estimated a mean effect size of 55.9 [40.4; 71.4]. Heterogeneity analysis showed a large degree of heterogeneity among the included studies. Subgroup and meta-regression analysis based on age and SUD type suggested that DBS may be more effective for patients above 45 years of age, and for alcohol and opioid addiction compared to nicotine addiction. Conclusion: The current literature suggests that DBS has a moderate effect on SUD symptoms. However, the limited number of studies and small sample size indicate that more research is needed to better understand the factors that influence its effectiveness.

Effects of Very Low- and High-Frequency Subthalamic Stimulation on Motor Cortical Oscillations During Rhythmic Lower-Limb Movements in Parkinson's Disease Patients.

BACKGROUND: Standard high-frequency deep brain stimulation (HF-DBS) at the subthalamic nucleus (STN) is less effective for lower-limb motor dysfunctions in Parkinson's disease (PD) patients. However, the effects of very low frequency (VLF; 4 Hz)-DBS on lower-limb movement and motor cortical oscillations have not been compared. OBJECTIVE: To compare the effects of VLF-DBS and HF-DBS at the STN on a lower-limb pedaling motor task and motor cortical oscillations in patients with PD and with and without freezing of gait (FOG). METHODS: Thirteen PD patients with bilateral STN-DBS performed a cue-triggered lower-limb pedaling motor task with electroencephalography (EEG) in OFF-DBS, VLF-DBS (4 Hz), and HF-DBS (120-175 Hz) states. We performed spectral analysis on the preparatory signals and compared GO-cue-triggered theta and movement-related beta oscillations over motor cortical regions across DBS conditions in PD patients and subgroups (PDFOG-and PDFOG+). RESULTS: Both VLF-DBS and HF-DBS decreased the linear speed of the pedaling task in PD, and HF-DBS decreased speed in both PDFOG-and PDFOG+. Preparatory theta and beta activities were increased with both stimulation frequencies. Both DBS frequencies increased motor cortical theta activity during pedaling movement in PD patients, but this increase was only observed in the PDFOG + group. Beta activity was not significantly different from OFF-DBS at either frequency regardless of FOG status. CONCLUSION: Results suggest that VL and HF DBS may induce similar effects on lower-limb kinematics by impairing movement speed and modulating motor cortical oscillations in the lower frequency band.

Therapies, Research Funding, and Racial Diversity in Essential Tremor: A Systematic Review of the Literature.

Background: Essential tremor (ET) is one of the most common tremor disorders in the world. Despite this, only one medication, propranolol, is approved by the Food and Drug Administration to treat it. Objectives: We analyzed controlled clinical trials in ET, spanning the last 50 years, to identify potential shortcomings in the therapeutic clinical pipeline. Methods: Outcomes reviewed included demographics (specifically gender and race), therapeutic modalities, funding information, location of research, and trends over time. Clinical trials published in English were identified in scientific databases (Pubmed, SCOPUS, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform from 1970 through December 2021. Included trials were prospective, either single- or double-blinded (including blinded video assessments for surgical trials), with change in limb, head, or voice tremor as the primary outcome measure. Results: One hundred and eighty-six controlled clinical trials were accepted for extraction, including 4207 patients. Of the 145 trials that included gender, males comprised 59% of the patient population. Only 6.4% of studies provided racial demographics; in these studies, 70.5% of patients were Caucasian. The most common therapeutic modality over the past 50 years was "pharmaceutical" (56%), and the most common pharmaceutical studied was propranolol (32%). 41% of clinical trials reported no specific funding. Conclusions: Future efforts should focus on increasing funding for clinical trial research in ET worldwide, and trials should be designed to be more inclusive of disadvantaged minorities.

Necessity and feasibility of remote tele-programming of deep brain stimulation systems in Parkinson's disease.

INTRODUCTION: Outcomes after deep brain stimulation (DBS) therapy are dependent on good surgical placement in the target nucleus and optimized stimulation parameters through multiple programming sessions. This often requires frequent travel to a specialized DBS center, which presents a challenge for those with limited access. Recently, the FDA approved a remote tele-programming solution for DBS. To determine if remote tele-programming of DBS systems is beneficial and useful for Parkinson's Disease (PD) patients, Parkinson's Foundation hosted a survey in collaboration with Abbott Labs. METHODS: The survey was conducted to assess the need for telemedicine among PD patients with DBS and the usability of the telehealth interface for DBS teleprogramming. The survey included two validated instruments: The Effective Accessibility and Accommodation survey (EAA) and the Telehealth Usability Questionnaire (TUQ). RESULTS: 47 patients completed the EAA and 41 completed the TUQ. Results from the EAA revealed more than a third of PD patients cannot easily get to a clinic for various reasons, and more than a quarter reported difficulty contacting their clinic for advice. Results from the TUQ revealed overall satisfaction with the DBS remote programming telehealth interface and care provided. The majority of respondents reported that remote tele-programming visits are similar in quality to in-person visits. CONCLUSION: This study provides support for the use of telehealth and tele-programming for DBS management in PD patients. The ability to use remote technologies for care will increase access to DBS and mitigate the disparities that currently prevent access to care.

A retrospective comparison of cognitive performance in individuals with advanced Parkinson's Disease in Hong Kong and Canada.

A deeper understanding of the cross-cultural applicability of cognitive tests across countries and cultures is needed to better equip neuropsychologists for the assessment of patients from diverse backgrounds. Our study compared cognitive test scores in patients with advanced Parkinson's disease (PD) at the Prince of Wales Hospital (n = 63; Hong Kong) and the Foothills Medical Center (n = 20; Calgary, Canada). The groups did not differ in age or sex (p > .05), but Western patients had significantly more years of education (M = 14.2, SD = 2.7) than Asian patients (M = 10.33, SD = 4.4). Cognitive tests administered to both groups included: digit span, verbal fluency (animals), the Boston Naming Test, and verbal memory (California Verbal Learning Test or Chinese Auditory Verbal Learning Test). Testing was completed before and 12 months after deep brain stimulation surgery. Results showed cognitive performance was similar across time, but significant group differences were found on digit span forward (longer among patients from Hong Kong; F(1, 75) = 44.155, p < .001) and the Boston Naming Test (higher percent spontaneous correct among patients from Canada; F(1, 62) = 7.218, p = .009, η2 = 0.104), after controlling for age, sex, and years of education. In conclusion, our findings provide preliminary support for the similarity of Chinese versions of tests originally developed for Western populations. Also, we caution that some aspects of testing may be susceptible to cultural bias and therefore warrant attention in clinical practice and refinement in future test development for Asian patients.

Clinical outcomes of globus pallidus deep brain stimulation for Parkinson disease: a comparison of intraoperative MRI- and MER-guided lead placement.

OBJECTIVE: Deep brain stimulation (DBS) lead placement is increasingly performed with the patient under general anesthesia by surgeons using intraoperative MRI (iMRI) guidance without microelectrode recording (MER) or macrostimulation. The authors assessed the accuracy of lead placement, safety, and motor outcomes in patients with Parkinson disease (PD) undergoing DBS lead placement into the globus pallidus internus (GPi) using iMRI or MER guidance. METHODS: The authors identified all patients with PD who underwent either MER- or iMRI-guided GPi-DBS lead placement at Emory University between July 2007 and August 2016. Lead placement accuracy and adverse events were determined for all patients. Clinical outcomes were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) part III motor scores for patients completing 12 months of follow-up. The authors also assessed the levodopa-equivalent daily dose (LEDD) and stimulation parameters. RESULTS: Seventy-seven patients were identified (MER, n = 28; iMRI, n = 49), in whom 131 leads were placed. The stereotactic accuracy of the surgical procedure with respect to the planned lead location was 1.94 ± 0.21 mm (mean ± SEM) (95% CI 1.54-2.34) with frame-based MER and 0.84 ± 0.007 mm (95% CI 0.69-0.98) with iMRI. The rate of serious complications was similar, at 6.9% for MER-guided DBS lead placement and 9.4% for iMRI-guided DBS lead placement (RR 0.71 [95% CI 0.13%-3.9%]; p = 0.695). Fifty-seven patients were included in clinical outcome analyses (MER, n = 16; iMRI, n = 41). Both groups had similar characteristics at baseline, although patients undergoing MER-guided DBS had a lower response on their baseline levodopa challenge (44.8% ± 5.4% [95% CI 33.2%-56.4%] vs 61.6% ± 2.1% [95% CI 57.4%-65.8%]; t = 3.558, p = 0.001). Greater improvement was seen following iMRI-guided lead placement (43.2% ± 3.5% [95% CI 36.2%-50.3%]) versus MER-guided lead placement (25.5% ± 6.7% [95% CI 11.1%-39.8%]; F = 5.835, p = 0.019). When UPDRS III motor scores were assessed only in the contralateral hemibody (per-lead analyses), the improvements remained significantly different (37.1% ± 7.2% [95% CI 22.2%-51.9%] and 50.0% ± 3.5% [95% CI 43.1%-56.9%] for MER- and iMRI-guided DBS lead placement, respectively). Both groups exhibited similar reductions in LEDDs (21.2% and 20.9%, respectively; F = 0.221, p = 0.640). The locations of all active contacts and the 2D radial distance from these to consensus coordinates for GPi-DBS lead placement (x, ±20; y, +2; and z, -4) did not differ statistically by type of surgery. CONCLUSIONS: iMRI-guided GPi-DBS lead placement in PD patients was associated with significant improvement in clinical outcomes, comparable to those observed following MER-guided DBS lead placement. Furthermore, iMRI-guided DBS implantation produced a similar safety profile to that of the MER-guided procedure. As such, iMRI guidance is an alternative to MER guidance for patients undergoing GPi-DBS implantation for PD.

Long-Term Outcomes of Endoscopic Third Ventricle Colloid Cyst Resection: Case Series With a Proposed Grading System.

BACKGROUND: Endoscopic resection of colloid cysts has gained recent widespread practice. However, reported complication and recurrence rates are variable, possibly, in part, because of a lack of consistency with reporting of the extent of cyst capsule removal. OBJECTIVE: To present the long-term outcomes of endoscopic resection of third ventricle colloid cysts without complete capsule removal and propose a grading system to allow consistent description of surgical outcomes. METHODS: A retrospective review of 74 patients who underwent endoscopic resection of symptomatic third ventricle colloid cysts between 1995 and 2018 was performed. Kaplan-Meier analyses were used to assess recurrence-free survival rates. RESULTS: Median patient age and cyst diameter were 48.0 (13.0-80.0) yr and 12.0 (5.0-27.0) mm, respectively. Complete emptying of cyst contents with capsule coagulation was achieved in 73 (98.6%) patients. All patients improved or remained stable postoperatively, with a median follow-up duration of 10.3 (0.3-23.7) yr. Radiographic recurrence occurred in 6 (8.1%) patients after their initial surgery, 5 (6.8%) of whom underwent redo endoscopic resection. No major complications or mortality was encountered at primary or recurrence surgery. CONCLUSION: Endoscopic resection of third ventricle colloid cysts without emphasizing complete capsule removal is a viable option for successfully treating colloid cysts of the third ventricle. Long-term follow-up demonstrates that it is associated with low risks of complications, morbidity, mortality, and recurrence. The proposed extent of the resection grading scheme will permit comparison between the different surgical approaches and facilitate the establishment of treatment guidelines for colloid cysts.

Computer-assisted planning for minimally invasive anterior two-thirds laser corpus callosotomy: A feasibility study with probabilistic tractography validation.

BACKGROUND: Anterior two-thirds corpus callosotomy is an effective palliative neurosurgical procedure for drug-refractory epilepsy that is most commonly used to treat drop-attacks. Laser interstitial thermal therapy is a novel stereotactic ablative technique that has been utilised as a minimally invasive alternative to resective and disconnective open neurosurgery. Case series have reported success in performing laser anterior two-thirds corpus callosotomy. Computer-assisted planning algorithms may help to automate and optimise multi-trajectory planning for this procedure. OBJECTIVE: To undertake a simulation-based feasibility study of computer-assisted corpus callostomy planning in comparison with expert manual plans in the same patients. METHODS: Ten patients were selected from a prospectively maintained database. Patients had previously undergone diffusion-weighted imaging and digital subtraction angiography as part of routine SEEG care. Computer-assisted planning was performed using the EpiNav™ platform and compared to manually planned trajectories from two independent blinded experts. Estimated ablation cavities were used in conjunction with probabilistic tractography to simulate the expected extent of interhemispheric disconnection. RESULTS: Computer-assisted planning resulted in significantly improved trajectory safety metrics (risk score and minimum distance to vasculature) compared to blinded external expert manual plans. Probabilistic tractography revealed residual interhemispheric connectivity in 1/10 cases following computer-assisted planning compared to 4/10 and 2/10 cases with manual planning. CONCLUSION: Computer-assisted planning successfully generates multi-trajectory plans capable of LITT anterior two-thirds corpus callosotomy. Computer-assisted planning may provide a means of standardising trajectory planning and serves as a potential new tool for optimising trajectories. A prospective validation study is now required to determine if this translates into improved patient outcomes.

Seizure Freedom After Epilepsy Surgery and Higher Baseline Cognition May Be Associated With a Negatively Correlated Epilepsy Network in Temporal Lobe Epilepsy.

Background: Brain regions positively correlated with the epileptogenic zone in patients with temporal lobe epilepsy vary in spread across the brain and in the degree of correlation to the temporal lobes, thalamus, and limbic structures, and these parameters have been associated with pre-operative cognitive impairment and seizure freedom after epilepsy surgery, but negatively correlated regions have not been as well studied. We hypothesize that connectivity within a negatively correlated epilepsy network may predict which patients with temporal lobe epilepsy will respond best to surgery. Methods: Scalp EEG and resting state functional MRI (rsfMRI) were collected from 19 patients with temporal lobe epilepsy and used to estimate the irritative zone. Using patients' rsfMRI, the negatively correlated epilepsy network was mapped by determining all the brain voxels that were negatively correlated with the voxels in the epileptogenic zone and the spread and average connectivity within the network was determined. Results: Pre-operatively, connectivity within the negatively correlated network was inversely related to the spread (diffuseness) of that network and positively associated with higher baseline verbal and logical memory. Pre-operative connectivity within the negatively correlated network was also significantly higher in patients who would go on to be seizure free. Conclusion: Patients with higher connectivity within brain regions negatively correlated with the epilepsy network had higher baseline memory function, narrower network spread, and were more likely to be seizure free after surgery.

Management of Early Parkinson Disease.

Early Parkinson disease is the approximate time period between initial diagnosis and the onset of motor fluctuations. Treatment requires an integrative approach, including identification of motor and nonmotor symptoms, choice of pharmacologic treatment, and emphasis on exercise. Patients should be treated for motor symptoms, whereas medications may be delayed for milder symptoms. The choice of treatment in patients with early Parkinson disease must be weighed against financial considerations, ease of administration, and potential long-term adverse events. Nonmotor symptoms should also be identified and treated. Exercise is an important component for treatment of Parkinson disease at any stage.

Clinical outcomes of pallidal deep brain stimulation for dystonia implanted using intraoperative MRI.

OBJECTIVE: Lead placement for deep brain stimulation (DBS) using intraoperative MRI (iMRI) relies solely on real-time intraoperative neuroimaging to guide electrode placement, without microelectrode recording (MER) or electrical stimulation. There is limited information, however, on outcomes after iMRI-guided DBS for dystonia. The authors evaluated clinical outcomes and targeting accuracy in patients with dystonia who underwent lead placement using an iMRI targeting platform. METHODS: Patients with dystonia undergoing iMRI-guided lead placement in the globus pallidus pars internus (GPi) were identified. Patients with a prior ablative or MER-guided procedure were excluded from clinical outcomes analysis. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores were assessed preoperatively and at 6 and 12 months postoperatively. Other measures analyzed include lead accuracy, complications/adverse events, and stimulation parameters. RESULTS: A total of 60 leads were implanted in 30 patients. Stereotactic lead accuracy in the axial plane was 0.93 ± 0.12 mm from the intended target. Nineteen patients (idiopathic focal, n = 7; idiopathic segmental, n = 5; DYT1, n = 1; tardive, n = 2; other secondary, n = 4) were included in clinical outcomes analysis. The mean improvement in BFMDRS score was 51.9% ± 9.7% at 6 months and 63.4% ± 8.0% at 1 year. TWSTRS scores in patients with predominant cervical dystonia (n = 13) improved by 53.3% ± 10.5% at 6 months and 67.6% ± 9.0% at 1 year. Serious complications occurred in 6 patients (20%), involving 8 of 60 implanted leads (13.3%). The rate of serious complications across all patients undergoing iMRI-guided DBS at the authors' institution was further reviewed, including an additional 53 patients undergoing GPi-DBS for Parkinson disease. In this expanded cohort, serious complications occurred in 11 patients (13.3%) involving 15 leads (10.1%). CONCLUSIONS: Intraoperative MRI-guided lead placement in patients with dystonia showed improvement in clinical outcomes comparable to previously reported results using awake MER-guided lead placement. The accuracy of lead placement was high, and the procedure was well tolerated in the majority of patients. However, a number of patients experienced serious adverse events that were attributable to the introduction of a novel technique into a busy neurosurgical practice, and which led to the revision of protocols, product inserts, and on-site training.

Use of a Subtemporal Approach for a Salvage Placement of a Trigeminal Ganglion Stimulating Electrode for the Treatment of Trigeminal Neuropathic Pain.

BACKGROUND: Trigeminal ganglion stimulation can be effective for trigeminal neuralgia. For patients who respond well to neurostimulation delivered percutaneously through the foramen ovale but require extensive revision and removal of instrumentation, a subtemporal approach for stimulation of the trigeminal ganglion is an alternative option as a salvage procedure. CASE DESCRIPTION: We report on a 47-year-old woman who responded well to neurostimulation for trigeminal neuropathic pain over a 1-year period from 2008 to 2009. Her preoperative pain on the numerical rating scale (NRS) was between 7 and 8 out of 10, which decreased to 2 out of 10 postoperatively. However, she developed lead migration because of a motor vehicle accident. After revision surgeries to correct this, she continued to experience pain relief until 2011. At follow-up, signs of infection prompted removal of instrumentation and subsequent return of her pain. She continued to experience persistent and severe pain (NRS score 7 of 10), which was intractable to pharmacologic treatment over 5 years. She returned in 2016 to discuss neurosurgical options, and the original approach was ruled out because of her history of lead migration, erosion, and scarring. A subtemporal approach was pursued as a salvage option, which provided several advantages for this patient. CONCLUSIONS: The subtemporal approach for salvage placement of the trigeminal ganglion stimulating electrode was effective in this patient and minimized risks given her history of erosion and multiple operations. This suggests that the subtemporal approach is a viable salvage operation for trigeminal ganglion stimulation for trigeminal neuropathic pain.

A neurosurgeon`s view: Laser interstitial thermal therapy of mesial temporal lobe structures.

Stereotactic laser ablation of mesial temporal structures is a promising new surgical intervention for patients with mesial temporal lobe epilepsy (MTLE). Since this procedure was first used to treat MTLE in 2010, the literature contains reports of 37 patients that underwent MR-guided stereotactic laser amygdalohippocampotomy (SLAH) using Laser Interstitial Thermal Therapy (LITT) with at least 1year of follow-up. This early body of data suggests that SLAH is a safe and effective treatment for MTLE in properly selected patients. Moreover, SLAH is substantially less invasive when compared with open surgical procedures including standard anterior temporal lobectomy and its more selective variants, results in immediate destruction of tissue in contrast to radiosurgical treatments for MTLE, and can more readily ablate larger volumes of tissue than is possible with techniques employing radiofrequency ablation. Finally, evidence is accruing that SLAH is associated with lower overall risk of neuropsychological deficits compared to open surgery. Thus, LITT constitutes a novel minimally invasive tool in the neurosurgeon's armamentarium for managing medically refractory seizures that may draw eligible patients to consider surgical interventions to manage their seizures.

Occipital Nerve Stimulation for the Treatment of Refractory Occipital Neuralgia: A Case Series.

BACKGROUND: Occipital neuralgia is a chronic pain syndrome characterized by sharp, shooting pains in the distribution of the occipital nerves. Although relatively rare, it associated with extremely debilitating symptoms that drastically affect a patient's quality of life. Furthermore, it is extremely difficult to treat as the symptoms are refractory to traditional treatments, including pharmacologic and procedural interventions. A few previous case studies have established the use of a neurostimulation of the occipital nerves to treat occipital neuralgia. OBJECTIVE: The following expands on that literature by retrospectively reviewing the results of occipital nerve stimulation in a relatively large patient cohort (29 patients). METHODS: A retrospective review of 29 patients undergoing occipital nerve stimulation for occipital neuralgia from 2012 to 2017 at a single institution with a single neurosurgeon. RESULTS: Of those 29 patients, 5 were repair or replacement of previous systems, 4 did not have benefit from trial stimulation, and 20 saw benefit to their trial stage of stimulation and went on to full implantation. Of those 20 patients, even with a history of failed procedures and pharmacological therapies, there was an overall success rate of 85%. The average preoperative 10-point pain score dropped from 7.4 ± 1.7 to a postoperative score of 2.9 ± 1.7. However, as with any peripheral nerve stimulation procedure, there were complications (4 patients), including infection, hardware erosion, loss of effect, and lead migration, which required revision or system removal. CONCLUSION: Despite complications, the results suggest, overall, that occipital nerve stimulation is a safe and effective procedure for refractory occipital neuralgia and should be in the neurosurgical repertoire for occipital neuralgia treatment.

High frequency stimulation of the infralimbic cortex induces morphological changes in rat hippocampal neurons.

BACKGROUND: Although a significant subset of patients with major depressive disorder (MDD) fail to respond to medical or behavioural therapy, deep brain stimulation (DBS) applied to the subgenual cingulate cortex (SCC; sg25) has been shown to reduce depressive symptoms in a subset of patients. This area receives projections from neurons in the CA1 region and subiculum of the hippocampus (HC), a brain region implicated in the pathobiology and treatment of MDD. OBJECTIVE: To assess whether high frequency stimulation (HFS) of the infralimbic cortex is associated with changes in cellular morphology in the HC. METHODS: Rats were subjected to either infralimbic HFS or sham-stimulation. Measures of cellular morphology, including dendritic length and complexity, were assessed in pyramidal neurons in the CA1 region of the HC by means of the Golgi-Cox histological stain. RESULTS: Dendritic length (p = 0.013) and number of branch points (p = 0.004) were significantly increased across the entire dendritic tree in animals subjected to HFS. Subsequent Scholl analysis revealed that for dendritic length these effects were localized to the region between 80 and 160 µm from the soma (p < 0.001 for either 40 µm interval) in the basal dendritic tree, while branch point number was predominantly increased between 120 and 160 µm from the soma (p < 0.001) in the apical dendritic tree. CONCLUSIONS: High-frequency stimulation of the infralimbic cortex increases the complexity of apical dendrites and the length of basal dendritic trees of pyramidal neurons located in the CA1 hippocampal subfield relative to sham-stimulated animals.