Search

The purpose of this report is to chronicle a 2-decade period of educational innovation and improvement, as well as governance reform, across the specialty of neurological surgery. Neurological surgery educational and professional governance systems have evolved substantially over the past 2 decades with the goal of improving training outcomes, patient safety, and the quality of US neurosurgical care. Innovations during this period have included the following: creating a consensus national curriculum; standardizing the length and structure of neurosurgical training; introducing educational outcomes milestones and required case minimums; establishing national skills, safety, and professionalism courses; systematically accrediting subspecialty fellowships; expanding professional development for educators; promoting training in research; and coordinating policy and strategy through the cooperation of national stakeholder organizations. A series of education summits held between 2007 and 2009 restructured some aspects of neurosurgical residency training. Since 2010, ongoing meetings of the One Neurosurgery Summit have provided strategic coordination for specialty definition, neurosurgical education, public policy, and governance. The Summit now includes leadership representatives from the Society of Neurological Surgeons, the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, the American Board of Neurological Surgery, the Review Committee for Neurological Surgery of the Accreditation Council for Graduate Medical Education, the American Academy of Neurological Surgery, and the AANS/CNS Joint Washington Committee. Together, these organizations have increased the effectiveness and efficiency of the specialty of neurosurgery in advancing educational best practices, aligning policymaking, and coordinating strategic planning in order to meet the highest standards of professionalism and promote public health.

Radiofrequency lesioning (RFL) is used to surgically manage trigeminal neuralgia (TN) secondary to multiple sclerosis (MS). However, the long-term outcome of RFL has not been established.To investigate the long-term clinical outcome of RFL in MS-related TN (symptomatic trigeminal neuralgia [STN]).During a 23-yr period, institutional data were available for 51 patients with STN who underwent at least one RFL procedure to treat facial pain. Patient outcome was evaluated at a mean follow-up of 69 mo (95% confidence interval; range 52-86 mo). No pain with no medication (NPNM) was the primary long-term outcome measure.After an initial RFL procedure, immediate pain relief was achieved in 50 patients (98%), and NPNM as assessed at 1, 3, and 6 yr was 86%, 52%, and 22%, respectively. At the last clinical visit after an initial RFL, 23 patients (45%) with pain recurrence underwent repeat RFL; NPNM at 1, 3, and 6 yr after a repeat RFL was 85%, 58%, and 32%, respectively. There was no difference in pain outcome after an initial and repeat RFL ( P = .77). Ten patients with pain recurrence underwent additional RFL procedures. Two patients developed mastication muscle weakness, one patient experienced a corneal abrasion, which resolved with early ophthalmological interventions, and one patient experienced bothersome numbness.RFL achieves NPNM status in STN and can be repeated with similar efficacy.

Background: Optical neuronavigation has been established as a reliable and effective adjunct to many neurosurgical procedures. Operations such as asleep deep brain stimulation (aDBS) benefit from the potential increase in accuracy that these systems offer. Built into these technologies is a degree of tolerated error that may exceed the presumed accuracy resulting in suboptimal outcomes. Objective: The objective of this study was to identify an underlying source of error in neuronavigation and determine strategies to maximize accuracy. Methods: A Medtronic Stealth system (Stealth Station 7 hardware, S8 software, version 3.1.1) was used to simulate an aDBS procedure with the Medtronic Nexframe system. Multiple configurations and orientations of the Nexframe-Nexprobe system components were examined to determine potential sources of, and to quantify navigational error, in the optical navigation system. Virtual entry point and target variations were recorded and analyzed. Finally, off-plan error was recorded with the AxiEM system and visual observation on a phantom head. Results: The most significant source of error was found to be the orientation of the reference marker plate configurations to the camera system, with the presentation of the markers perpendicular to the camera line of site being the most accurate position. Entry point errors ranged between 0.134 ± 0.048 and 1.271 ± 0.0986 mm in a complex, reproducible pattern dependent on the orientation of the Nexprobe reference plate. Target errors ranged between 0.311 ± 0.094 and 2.159 ± 0.190 mm with a similarly complex, repeatable pattern. Representative configurations were tested for physical error at target with errors ranging from 1.2 mm to 1.4 mm. Throughout data acquisition, no orientation was indicated as outside the acceptable tolerance by the Stealth software. Conclusions: Use of optical neuronavigation is expected to increase in frequency and variety of indications. Successful implementation of this technology depends on understanding the tolerances built into the system. In situations that depend on extremely high precision, surgeons should familiarize themselves with potential sources of error so that systems may be optimized beyond the manufacturer’s built-in tolerances. We recommend that surgeons align the navigation reference plate and any optical instrument’s reference plate spheres in the plane perpendicular to the line of site of the camera to maximize accuracy.

OBJECTIVEDespite rapid development and expansion of neuromodulation technologies, knowledge about device and/or therapy durability remains limited. The aim of this study was to evaluate the long-term rate of hardware and therapeutic failure of implanted devices for several neuromodulation therapies.METHODSThe authors performed a retrospective analysis of patients’ device and therapy survival data (Kaplan-Meier survival analysis) for deep brain stimulation (DBS), vagus nerve stimulation (VNS), and spinal cord stimulation (SCS) at a single institution (years 1994–2015).RESULTSDuring the study period, 450 patients underwent DBS, 383 VNS, and 128 SCS. For DBS, the 5- and 10-year initial device survival was 87% and 73%, respectively, and therapy survival was 96% and 91%, respectively. For VNS, the 5- and 10-year initial device survival was 90% and 70%, respectively, and therapy survival was 99% and 97%, respectively. For SCS, the 5- and 10-year initial device survival was 50% and 34%, respectively, and therapy survival was 74% and 56%, respectively. The average initial device survival for DBS, VNS, and SCS was 14 years, 14 years, and 8 years while mean therapy survival was 18 years, 18 years, and 12.5 years, respectively.CONCLUSIONSThe authors report, for the first time, comparative device and therapy survival rates out to 15 years for large cohorts of DBS, VNS, and SCS patients. Their results demonstrate higher device and therapy survival rates for DBS and VNS than for SCS. Hardware failures were more common among SCS patients, which may have played a role in the discontinuation of therapy. Higher therapy survival than device survival across all modalities indicates continued therapeutic benefit beyond initial device failures, which is important to emphasize when counseling patients.

OBJECTIVEThe pathophysiology of trigeminal neuralgia (TN) in patients without neurovascular compression (NVC) is not completely understood. The objective of this retrospective study was to evaluate the hypothesis that TN patients without NVC differ from TN patient with NVC with respect to brain anatomy and demographic characteristics.METHODSSix anatomical brain measurements from high-resolution brain MR images were tabulated; anterior-posterior (AP) prepontine cistern length, cerebellopontine angle (CPA) cistern volume, nerve-to-nerve distance, symptomatic nerve length, pons volume, and posterior fossa volume were assessed on OsiriX. Brain MRI anatomical measurements from 232 patients with either TN type 1 or TN type 2 (TN group) were compared with measurements obtained in 100 age- and sex-matched healthy controls (control group). Two-way ANOVA tests were conducted on the 6 measurements relative to group and NVC status. Bonferroni adjustments were used to correct for multiple comparisons. A nonhierarchical k-means cluster analysis was performed on the TN group using age and posterior fossa volume as independent variables.RESULTSWithin the TN group, females were found to be younger than males and less likely to have NVC. The odds ratio (OR) of females not having NVC compared to males was 2.7 (95% CI 1.3–5.5, p = 0.017). Patients younger than 30 years were much less likely to have NVC compared to older patients (OR 4.9, 95% CI 1.3–18.4, p = 0.017). The mean AP prepontine cistern length and symptomatic nerve length were smaller in the TN group than in the control group (5.3 vs 6.5 mm and 8.7 vs 9.7 mm, respectively; p < 0.001). The posterior fossa volume was significantly smaller in TN patients without NVC compared to those with NVC. A TN group cluster analysis suggested a sex-dependent difference that was not observed in those without NVC. Factorial ANOVA and post hoc testing found that findings in males without NVC were significantly different from those in controls or male TN patients with NVC and similar to those in females (female controls as well as female TN patients with or without NVC).CONCLUSIONSPosterior fossa volume in males was larger than posterior fossa volume in females. This finding, along with the higher incidence of TN in females, suggests that smaller posterior fossa volume might be an independent factor in the pathophysiology of TN, which warrants further study.

OBJECTIVEPain relief following microvascular decompression (MVD) for trigeminal neuralgia (TN) may be related to pain type, degree of neurovascular conflict, arterial compression, and location of compression. The objective of this study was to construct a predictive pain-free scoring system based on clinical and radiographic factors that can be used to preoperatively prognosticate long-term outcomes for TN patients following surgical intervention (MVD or internal neurolysis [IN]). It was hypothesized that contributing factors would include pain type, presence of an artery or vein, neurovascular conflict severity, and compression location (root entry zone).METHODSAt the authors’ institution 275 patients with type 1 or type 2 TN (TN1 or TN2) underwent MVD or IN following preoperative high-resolution brain MRI studies. Outcome data were obtained retrospectively by chart review and/or phone follow-up. Characteristics of neurovascular conflict were obtained from preoperative MRI studies. Factors that resulted in a probability value of < 0.05 on univariate logistic regression analyses were entered into a multivariate Cox regression analysis in a backward stepwise fashion. For the multivariate analysis, significance at the 0.15 level was used. A prognostic system was then devised with 4 possible scores (0, 1, 2, or 3) and pain-free survival analyses conducted.RESULTSUnivariate predictors of pain-free survival were pain type (p = 0.013), presence of any vessel (p = 0.042), and neurovascular compression severity (p = 0.038). Scores of 0, 1, 2, and 3 were found to be significantly different in regard to pain-free survival (log rank, p = 0.005). At 5 and 10 years there were 36%, 43%, 61%, and 69%, and 36%, 43%, 56%, and 67% pain-free survival rates in groups 0, 1, 2, and 3, respectively. While TN2 patients had worse outcomes regardless of score, a subgroup analysis of TN1 patients with higher neurovascular conflict (score of 3) had significantly better outcomes than TN1 patients without severe neurovascular conflict (score of 1) (log rank, p = 0.005). Regardless of pain type, those patients with severe neurovascular conflict were more likely to have arterial compression (99%) compared to those with low neurovascular conflict (p < 0.001).CONCLUSIONSPain-free survival was predicted by a scoring system based on preoperative clinical and radiographic findings. Higher scores predicted significantly better pain relief than lower scores. TN1 patients with severe neurovascular conflict had the best long-term pain-free outcome.

OBJECTIVE The globus pallidus internus (GPI) has been demonstrated to be an effective surgical target for deep brain stimulation (DBS) treatment in patients with medication-refractory Parkinson’s disease (PD). The ability of neurosurgeons to define the area of greatest therapeutic benefit within the globus pallidus (GP) may improve clinical outcomes in these patients. The objective of this study was to determine the best DBS therapeutic implantation site within the GP for effective treatment in PD patients. METHODS The authors performed a retrospective review of 56 patients who underwent bilateral GP DBS implantation at their institution during the period from January 2015 to January 2020. Each implanted contact was anatomically localized. Patients were followed for stimulation programming for at least 6 months. The authors reviewed preoperative and 6-month postsurgery clinical outcomes based on data from the Unified Parkinson’s Disease Rating Scale Part III (UPDRS III), dyskinesia scores, and levodopa equivalent daily dose (LEDD). RESULTS Of the 112 leads implanted, the therapeutic cathode was most frequently located in the lamina between the GPI external segment (GPIe) and the GP externus (GPE) (n = 40). Other common locations included the GPE (n = 24), the GPIe (n = 15), and the lamina between the GPI internal segment (GPIi) and the GPIe (n = 14). In the majority of patients (73%) a monopolar programming configuration was used. At 6 months postsurgery, UPDRS III off medications (OFF) and on stimulation (ON) scores significantly improved (z = −4.02, p < 0.001), as did postsurgery dyskinesia ON scores (z = −4.08, p < 0.001) and postsurgery LEDD (z = −4.7, p < 0.001). CONCLUSIONS Though the ventral GP (pallidotomy target) has been a commonly used target for GP DBS, a more dorsolateral target may be more effective for neuromodulation strategies. The assessment of therapeutic contact locations performed in this study showed that the lamina between GPI and GPE used in most patients is the optimal central stimulation target. This information should improve preoperative GP targeting.

When patients with trigeminal neuralgia can no longer achieve adequate pain relief and quality of life becomes poor, surgical procedures need to be considered. There is a lack of high-quality evidence to support surgical treatments so all the recommendations are based on low-grade evidence of prospective or retrospective series. Microvascular decompression, a neurosurgical operation, is the procedure of choice in patients with primary trigeminal neuralgia who have evidence of neurovascular compression of the trigeminal nerve on magnetic resonance imaging. Long-term pain relief of 10 years can be achieved with minimal long-term complications. All the other procedures, including stereotactic radiosurgery, balloon compression, glycerol rhizolysis, and radiofrequency thermocoagulation, are destructive and are suitable for patients who are poor candidates for microvascular decompression including those with significant medical comorbidities. They will result in varying sensory loss and pain relief on average for 4 years. Patients should be made aware of the range of options open to them and the pros and cons of each procedure.

OBJECTIVENervus intermedius neuralgia (NIN) or geniculate neuralgia is a rare facial pain condition consisting of sharp, lancinating pain deep in the ear and can occur alongside trigeminal neuralgia (TN). Studies on the clinical presentation, intraoperative findings, and ultimately postoperative outcomes are extremely limited. The aim of this study was to examine the clinical presentation and surgical findings, and determine pain-free survival after sectioning of the nervus intermedius (NI).METHODSThe authors conducted a retrospective chart review and survey of patients who were diagnosed with NIN at one institution and who underwent neurosurgical interventions. Pain-free survival was determined through chart review and phone interviews using a modified facial pain and quality of life questionnaire and represented as Kaplan-Meier curves.RESULTSThe authors found 15 patients with NIN who underwent microsurgical intervention performed by two surgeons from 2002 to 2016 at a single institution. Fourteen of these patients underwent sectioning of the NI, and 8 of 14 had concomitant TN. Five patients had visible neurovascular compression (NVC) of the NI by the anterior inferior cerebellar artery in most cases where NVC was found. The most common postoperative complaints were dizziness and vertigo, diplopia, ear fullness, tinnitus, and temporary facial nerve palsy. Thirteen of the 14 patients reportedly experienced pain relief immediately after surgery. The mean length of follow-up was 6.41 years (range 8 months to 14.5 years). Overall recurrence of any pain was 42% (6 of 14), and 4 patients (isolated NIN that received NI sectioning alone) reported their pain was the same or worse than before surgery at longest follow-up. The median pain-free survival was 4.82 years ± 14.85 months. The median pain-controlled survival was 6.22 years ± 15.78 months.CONCLUSIONSIn this retrospective review, sectioning of the NI produced no major complications, such as permanent facial weakness or deafness, and was effective for patients when performed in addition to other procedures. After sectioning of the NI, patients experienced 4.8 years pain free and experienced 6.2 years of less pain than before surgery. Alone, sectioning of the NI was not effective. The pathophysiology of NIN is not entirely understood. It appears that neurovascular compression plays only a minor role in the syndrome and there is a high degree of overlap with TN.

Background In trigeminal neuralgia type 1 (TN1), neurovascular compression (NVC) is often assumed to be the pain initiating mechanism. NVC can be surgically addressed by microvascular decompression (MVD). However, some patients with TN1 present without NVC (WONVC). Objective To characterize and analyze the clinical spectrum of a TN1 patient population WONVC. Methods A retrospective chart review of patients presenting with TN1 between 2007 and 2017 was performed. Patients who were potential candidates for MVD surgery underwent high-resolution imaging with 3-dimensional (3D) reconstruction to address the presence, or absence, of NVC. Demographic data about the populations with NVC (WNVC) and WONVC were collected. Results Of 242 patients with TN1, 32% did not have NVC. Patients WONVC were on average 10.6 yr younger than those WNVC. TN1 onset in patients WONVC was more frequent below 48.7 yr, and the opposite was found in patients WNVC. Compared to patients WNVC, those WONVC were predominantly female (odds ratio 4.8), on average were 4 yr younger at symptom onset (34.7 yr) and 7.8 yr younger at first clinic visit, and had a 3.7 yr shorter symptom duration. Conclusion Patients presenting with TN1 WONVC were predominantly females in their mid-30s with short symptom duration. In the absence of NVC, this subgroup of TN1 patients has limited surgical options, and potentially a longer condition duration that must be managed medically or surgically. This population WONVC might provide insights into the true pathophysiology of TN1.

Pain surgery is one of the historic foundations of neurological surgery. The authors present a review of contemporary concepts in surgical pain management, with reference to past successes and failures, what has been learned as a subspecialty over the past 50 years, as well as a vision for current and future practice. This subspecialty confronts problems of cancer pain, nociceptive pain, and neuropathic pain. For noncancer pain, ablative procedures such as dorsal root entry zone lesions and rhizolysis for trigeminal neuralgia (TN) should continue to be practiced. Other procedures, such as medial thalamotomy, have not been proven effective and require continued study. Dorsal rhizotomy, dorsal root ganglionectomy, and neurotomy should probably be abandoned. For cancer pain, cordotomy is an important and underutilized method for pain control. Intrathecal opiate administration via an implantable system remains an important option for cancer pain management. While there are encouraging results in small case series, cingulotomy, hypophysectomy, and mesencephalotomy deserve further detailed analysis. Electrical neuromodulation is a rapidly changing discipline, and new methods such as high-frequency spinal cord stimulation (SCS), burst SCS, and dorsal root ganglion stimulation may or may not prove to be more effective than conventional SCS. Despite a history of failure, deep brain stimulation for pain may yet prove to be an effective therapy for specific pain conditions. Peripheral nerve stimulation for conditions such as occipital neuralgia and trigeminal neuropathic pain remains an option, although the quality of outcomes data is a challenge to these applications. Based on the evidence, motor cortex stimulation should be abandoned. TN is a mainstay of the surgical treatment of pain, particularly as new evidence and insights into TN emerge. Pain surgery will continue to build on this heritage, and restorative procedures will likely find a role in the armamentarium. The challenge for the future will be to acquire higher-level evidence to support the practice of surgical pain management.

Background Infection is one of the most common complications of deep brain stimulation (DBS). Long-term infection rates beyond the immediate postoperative period are rarely evaluated. Objective To study short- and long-term DBS-related infection rates; to evaluate any potential seasonality associated with DBS-related infections. Methods We retrospectively reviewed all DBS surgeries performed in a 5-yr period at 1 hospital by a single surgeon. Infection rates and clinical characteristics were analyzed. Postoperative "infections" were defined as occurring within 6 mo of implantation of DBS hardware, while "erosions" were defined as transcutaneous exposure of hardware at ≥6 mo after implantation. Based on the date of surgery preceding an infection, rates of infection were calculated on a monthly and seasonal basis and compared using Chi square and logistic regression analyses. Results A total of 443 patients underwent 592 operations; 311 patients underwent primary DBS placement with 632 electrodes. Primary DBS placement infection incidence was 2.6%. DBS procedure infection and infection rate by electrode were 2.9% and 3.2%, respectively. Infectious complications presented later than 6 mo postoperatively in 38% of infected patients Summer (July-September) infection rate was significantly higher than other seasons (P = .002). The odds ratio of an infection related to a surgery performed in August was found to be 4.15 compared to other months (P = .021). Conclusion There is a persistent risk of DBS infection and erosion beyond the first year of DBS implantation. Start of the academic year was associated with increased infection rate at our institution.

Objective:To compare motor and nonmotor outcomes at 6 months of asleep deep brain stimulation (DBS) for Parkinson disease (PD) using intraoperative imaging guidance to confirm electrode placement vs awake DBS using microelectrode recording to confirm electrode placement.Methods:DBS candidates with PD referred to Oregon Health & Science University underwent asleep DBS with imaging guidance. Six-month outcomes were compared to those of patients who previously underwent awake DBS by the same surgeon and center. Assessments included an “off”-levodopa Unified Parkinson’s Disease Rating Scale (UPDRS) II and III, the 39-item Parkinson's Disease Questionnaire, motor diaries, and speech fluency.Results:Thirty participants underwent asleep DBS and 39 underwent awake DBS. No difference was observed in improvement of UPDRS III (+14.8 ± 8.9 vs +17.6 ± 12.3 points, p = 0.19) or UPDRS II (+9.3 ± 2.7 vs +7.4 ± 5.8 points, p = 0.16). Improvement in “on” time without dyskinesia was superior in asleep DBS (+6.4 ± 3.0 h/d vs +1.7 ± 1.2 h/d, p = 0.002). Quality of life scores improved in both groups (+18.8 ± 9.4 in awake, +8.9 ± 11.5 in asleep). Improvement in summary index (p = 0.004) and subscores for cognition (p = 0.011) and communication (p < 0.001) were superior in asleep DBS. Speech outcomes were superior in asleep DBS, both in category (+2.77 ± 4.3 points vs −6.31 ± 9.7 points (p = 0.0012) and phonemic fluency (+1.0 ± 8.2 points vs −5.5 ± 9.6 points, p = 0.038).Conclusions:Asleep DBS for PD improved motor outcomes over 6 months on par with or better than awake DBS, was superior with regard to speech fluency and quality of life, and should be an option considered for all patients who are candidates for this treatment.Clinicaltrials.gov identifier:NCT01703598.Classification of evidence:This study provides Class III evidence that for patients with PD undergoing DBS, asleep intraoperative CT imaging–guided implantation is not significantly different from awake microelectrode recording–guided implantation in improving motor outcomes at 6 months.

Background: Electromagnetic (EM) localization has typically been used to direct shunt catheters into the ventricle. The objective of this study was to determine if this method of EM tracking could be used in a deep brain stimulation (DBS) electrode cannula to accurately predict the eventual location of the electrode contacts. Methods: The Medtronic AxiEMTM system was used to generate the cannula tip location directed to the planned target site. Prior to clinical testing, a series of phantom modelling observations were made. Results: Phantom trials (n = 23) demonstrated that the cannula tip could be accurately located at the target site with an error of between 0.331 ± 0.144 and 0.6 ± 0.245 mm, depending on the orientation of the delivery system to the axis of the phantom head. Intraoperative EM localization of the DBS cannula was performed in 84 trajectories in 48 patients. The average difference between the planned target and the EM stylet location at the cannula tip was 1.036 ± 0.543 mm. The average error between the planned target coordinates and the actual target electrode location (by CT) was 1.431 ± 0.607 and 1.145 ± 0.636 mm for the EM stylet location in the cannula (p = 0.00312), indicating that EM localization reflected the position of the target electrode more accurately than the planned target. Conclusions: EM localization can be used to verify the position of DBS electrodes intraoperatively with a high accuracy.

ABBREVIATIONS AD, Alzheimer diseaseDBS, Deep brain stimulationFDA, Food and Drug AdministrationMER, Microelectrode recording.

OBJECT Lesioning of the dorsal root entry zone (DREZotomy) is an effective treatment for brachial plexus avulsion (BPA) pain. The role of preoperative assessment with MRI has been shown to be unreliable for determining affected levels; however, it may have a role in predicting pain outcomes. Here, DREZotomy outcomes are reviewed and preoperative MRI is examined as a possible prognostic factor. METHODS A retrospective review was performed of an institutional database of patients who had undergone brachial plexus DREZ procedures since 1995. Preoperative MRI was examined to assess damage to the DREZ or dorsal horn, as evidenced by avulsion of the DREZ or T2 hyperintensity within the spinal cord. Phone interviews were conducted to assess the long-term pain outcomes. RESULTS Between 1995 and 2012, 27 patients were found to have undergone cervical DREZ procedures for BPA. Of these, 15 had preoperative MR images of the cervical spine available for review. The outcomes were graded from 1 to 4 as poor (no significant relief), good (more than 50% pain relief), excellent (more than 75% pain relief), or pain free, respectively. Overall, DREZotomy was found to be a safe, efficacious, and durable procedure for relief of pain due to BPA. The initial success rate was 73%, which declined to 66% at a median follow-up time of 62.5 months. Damage to the DREZ or dorsal horn was significantly correlated with poorer outcomes (p = 0.02). The average outcomes in patients without MRI evidence of DREZ or dorsal horn damage was significantly higher than in patients with such damage (3.67 vs 1.75, t-test; p = 0.001). A longer duration of pain prior to operation was also a significant predictor of treatment success (p = 0.004). CONCLUSIONS Overall, the DREZotomy procedure has a 66% chance of achieving meaningful pain relief on long-term follow-up. Successful pain relief is associated with the lack of damage to the DREZ and dorsal horn on preoperative MRI.

OBJECTIVEHemifacial spasm (HFS), largely caused by neurovascular compression (NVC) of the facial nerve, is a rare condition characterized by paroxysmal, unilateral, involuntary contraction of facial muscles. It has long been suggested that these symptoms are due to compression at the transition zone of the facial nerve. The aim of this study was to examine symptom-free survival and long-term quality of life (QOL) in HFS patients who underwent microvascular decompression (MVD). A secondary aim was to examine the benefit of utilizing fused MRI and MRA post hoc 3D reconstructions to better characterize compression location at the facial nerve root exit zone (fREZ).METHODSThe authors retrospectively analyzed patients with HFS who underwent MVD at a single institution, combined with a modified HFS-7 telephone questionnaire. Kaplan-Meier analysis was used to determine event-free survival, and the Wilcoxon signed-rank test was used to compare pre- and postoperative HFS-7 scores.RESULTSThirty-five patients underwent MVD for HFS between 2002 and 2018 with subsequent 3D reconstructions of preoperative images. The telephone questionnaire response rate was 71% (25/35). If patients could not be reached by telephone, then the last clinic follow-up date was recorded and any recurrence noted. Twenty-four patients (69%) were symptom free at longest follow-up. The mean length of follow-up was 2.4 years (1 month to 8 years). The mean symptom-free survival time was 44.9 ± 5.8 months, and the average symptom-control survival was 69.1 ± 4.9 months. Four patients (11%) experienced full recurrence. Median HFS-7 scores were reduced by 18 points after surgery (Z = −4.013, p < 0.0001). Three-dimensional reconstructed images demonstrated that NVC most commonly occurred at the attached segment (74%, 26/35) of the facial nerve within the fREZ and least commonly occurred at the traditionally implicated transition zone (6%, 2/35).CONCLUSIONSMVD is a safe and effective treatment that significantly improves QOL measures for patients with HFS. The vast majority of patients (31/35, 89%) were symptom free or reported only mild symptoms at longest follow-up. Symptom recurrence, if it occurred, was within the first 2 years of surgery, which has important implications for patient expectations and informed consent. Three-dimensional image reconstruction analysis determined that culprit compression most commonly occurs proximally along the brainstem at the attached segment. The success of this procedure is dependent on recognizing this pattern and decompressing appropriately. Three-dimensional reconstructions were found to provide much clearer characterization of this area than traditional preoperative imaging. Therefore, the authors suggest that use of these reconstructions in the preoperative setting has the potential to help identify appropriate surgical candidates, guide operative planning, and thus improve outcome in patients with HFS.

Background Attending surgeons have dual obligations to deliver high-quality health care and train residents. In modern healthcare, lean principles are increasingly applied to processes preceding and following surgery. However, surgeons have limited data regarding variability and waste during any given operation. Objective To measure variability and waste during the following key functional neurosurgery procedures: retrosigmoid craniectomy (microvascular decompression [MVD] and internal neurolysis) and deep brain stimulation (DBS). Additionally, we correlate variability with residents' self-reported readiness for the surgical steps. The aim is to guide surgeons as they balance operative safety and efficiency with training obligations. Methods For each operation (retrosigmoid craniectomy and DBS), a standard workflow, segmenting the operation into components, was defined. We observed a representative sample of operations, timing the components, with a focus on variability. To assess perceptions of safety and risk among surgeons of various training levels, a survey was administered. Survey results were correlated with operative variability, attempting to identify areas for increasing value without compromising trainee experience. Results A sampling of each operation (n = 36) was observed during the study period. For MVD, craniectomy had the highest mean duration and standard deviation, whereas the MVD itself had the lowest mean duration and standard deviation. For DBS, the segments with largest standard deviation in duration were registration and electrode placement. For many steps of both procedures, there was a statistically significant relationship between increasing level of training and increasing perception of safety. Conclusion This proof-of-concept study introduces an educational and process-improvement tool that can be used to aid surgeons in increasing the efficiency of patient care.

OBJECTIVEGlossopharyngeal neuralgia (GN) is a rare pain condition in which patients experience paroxysmal, lancinating throat pain. Multiple surgical approaches have been used to treat this condition, including microvascular decompression (MVD), and sectioning of cranial nerve (CN) IX and the upper rootlets of CN X, or a combination of the two. The aim of this study was to examine the long-term quality of life and pain-free survival after MVD and sectioning of the CN X/IX complex.METHODSA combined retrospective chart review and a quality-of-life telephone survey were performed to collect demographic and long-term outcome data. Quality of life was assessed by means of a questionnaire based on a combination of the Barrow Neurological Institute pain intensity scoring criteria and the Brief Pain Inventory–Facial. Kaplan-Meier analysis was performed to determine pain-free survival.RESULTSOf 18 patients with GN, 17 underwent sectioning of the CN IX/X complex alone or sectioning and MVD depending on the presence of a compressing vessel. Eleven of 17 patients had compression of CN IX/X by the posterior inferior cerebellar artery, 1 had compression by a vertebral artery, and 5 had no compression. One patient (6%) experienced no immediate pain relief. Fifteen (88%) of 17 patients were pain free at the last follow-up (mean 9.33 years, range 5.16–13 years). One patient (6%) experienced throat pain relapse at 3 months. The median pain-free survival was 7.5 years ± 10.6 months. Nine of 18 patients were contacted by telephone. Of the 17 patients who underwent sectioning of the CN IX/X complex, 13 (77%) patients had short-term complaints: dysphagia (n = 4), hoarseness (n = 4), ipsilateral hearing loss (n = 4), ipsilateral taste loss (n = 2), and dizziness (n = 2) at 2 weeks. Nine patients had persistent side effects at latest follow-up. Eight of 9 telephone respondents reported that they would have the surgery over again.CONCLUSIONSSectioning of the CN IX/X complex with or without MVD of the glossopharyngeal nerve is a safe and effective surgical therapy for GN with initial pain freedom in 94% of patients and an excellent long-term pain relief (mean 7.5 years).

Deep brain stimulation (DBS) has become an established treatment for medically refractory movement disorders including Parkinson's disease, essential tremor, and dystonia. The field of DBS continues to evolve with advances in patient selection, target identification, electrode and pulse generator technology, and the development of more effective stimulation paradigms such as closed-loop stimulation. Furthermore, as the safety and efficacy of DBS improves through better hardware design and deeper understanding of its mechanisms of action, the indications for DBS will continue to expand to cover a wider range of disorders. Finally, the recent approval of MR-guided focused ultrasound for the treatment of essential tremor and potentially other movement disorders heralds a resurgence in lesion creation as a viable alternative to DBS for selected patients.

Deep brain stimulation (DBS) has become an established treatment for medically refractory movement disorders including Parkinson's disease, essential tremor, and dystonia. The field of DBS continues to evolve with advances in patient selection, target identification, electrode and pulse generator technology, and the development of more effective stimulation paradigms such as closed-loop stimulation. Furthermore, as the safety and efficacy of DBS improves through better hardware design and deeper understanding of its mechanisms of action, the indications for DBS will continue to expand to cover a wider range of disorders. Finally, the recent approval of MR-guided focused ultrasound for the treatment of essential tremor and potentially other movement disorders heralds a resurgence in lesion creation as a viable alternative to DBS for selected patients.

OBJECT Trigeminal neuralgia (TN) occurs and recurs in the absence of neurovascular compression (NVC). While microvascular decompression (MVD) is the most effective treatment for TN, it is not possible when NVC is not present. Therefore, the authors sought to evaluate the safety, efficacy, and durability of internal neurolysis (IN), or “nerve combing,” as a treatment for TN without NVC. METHODS This was a retrospective review of all cases of Type 1 TN involving all patients 18 years of age or older who underwent evaluation (and surgery when appropriate) at Oregon Health & Science University between July 2006 and February 2013. Chart reviews and telephone interviews were conducted to assess patient outcomes. Pain intensity was evaluated with the Barrow Neurological Institute (BNI) Pain Intensity scale, and the Brief Pain Inventory–Facial (BPI-Facial) was used to assess general and face-specific activity. Pain-free survival and durability of successful pain relief (BNI pain scores of 1 or 2) were statistically evaluated with Kaplan-Meier analysis. Prognostic factors were identified and analyzed using Cox proportional hazards regression. RESULTS A total of 177 patients with Type 1 TN were identified. A subgroup of 27 was found to have no NVC on high-resolution MRI/MR angiography or at surgery. These patients were significantly younger than patients with classic Type 1 TN. Long-term follow-up was available for 26 of 27 patients, and 23 responded to the telephone survey. The median follow-up duration was 43.4 months. Immediate postoperative results were comparable to MVD, with 85% of patients pain free and 96% of patients with successful pain relief. At 1 year and 5 years, the rate of pain-free survival was 58% and 47%, respectively. Successful pain relief at those intervals was maintained in 77% and 72% of patients. Almost all patients experienced some degree of numbness or hypesthesia (96%), but in patients with successful pain relief, this numbness did not significantly impact their quality of life. There was 1 patient with a CSF leak and 1 patient with anesthesia dolorosa. Previous treatment for TN was identified as a poor prognostic factor for successful outcome. CONCLUSIONS This is the first report of IN with meaningful outcomes data. This study demonstrated that IN is a safe, effective, and durable treatment for TN in the absence of NVC. Pain-free outcomes with IN appeared to be more durable than radiofrequency gangliolysis, and IN appears to be more effective than stereotactic radiosurgery, 2 alternatives to posterior fossa exploration in cases of TN without NVC. Given the younger age distribution of patients in this group, consideration should be given to performing IN as an initial treatment. Accrual of further outcomes data is warranted.

Background/Aims: Intraoperative imaging allows near-real-time assessment of stereotactic accuracy during implantation of deep brain stimulation (DBS) electrodes. Such technology can be used to examine factors impacting stereotactic error. Methods: Intraoperative CT imaging was reviewed in patients undergoing DBS placement at Oregon Health and Sciences University. Coordinates of the target electrode were compared to the operative plan to characterize the magnitude and direction of stereotactic error with respect to side of implantation, target, and electrode approach angles. Results: One hundred sixty-nine leads in 94 patients were examined. Targets were GPi (n = 86), STN (n = 31), and Vim (n = 52). The average Euclidean error was 1.63 mm (SD 0.87). The error magnitude was higher for Vim (1.95 mm) than for GPi (1.44 mm), while STN (1.65 mm) did not differ from either Vim or GPi (ANOVA: F = 6.15, p = 0.003). Electrodes targeting Vim and STN were significantly more likely to deviate medially compared to those targeting GPi (ANOVA: F = 9.13, p < 0.001). The coronal approach angle affected the error when targeting Vim (ρ = 0.338, p = 0.01). These findings were confirmed during multivariate analyses. Conclusions: This study shows a significant effect of target on the accuracy of electrode placement for DBS. Targeting Vim results in a greater Euclidean error and a greater medial deviation off target. These systematic deviations should be taken into account during electrode implantation.

Object Vascular compression of the trigeminal nerve is the most common factor associated with the etiology of trigeminal neuralgia (TN). Microvascular decompression (MVD) has proven to be the most successful and durable surgical approach for this disorder. However, not all patients with TN manifest unequivocal neurovascular compression (NVC). Furthermore, over time patients with an initially successful MVD manifest a relentless rate of TN recurrence. Methods The authors performed a retrospective review of cases of TN Type 1 (TN1) or Type 2 (TN2) involving patients 18 years or older who underwent evaluation (and surgery when indicated) at Oregon Health & Science University between July 2006 and February 2013. Surgical and imaging findings were correlated. Results The review identified a total of 257 patients with TN (219 with TN1 and 38 with TN2) who underwent high-resolution MRI and MR angiography with 3D reconstruction of combined images using OsiriX. Imaging data revealed that the occurrence of TN1 and TN2 without NVC was 28.8% and 18.4%, respectively. A subgroup of 184 patients underwent surgical exploration. Imaging findings were highly correlated with surgical findings, with a sensitivity of 96% for TN1 and TN2 and a specificity of 90% for TN1 and 66% for TN2. Conclusions Magnetic resonance imaging detects NVC with a high degree of sensitivity. However, despite a diagnosis of TN1 or TN2, a significant number of patients have no NVC. Trigeminal neuralgia clearly occurs and recurs in the absence of NVC.

Background: The effect of the surgical site of DBS on balance and gait in Parkinson’s Disease (PD) is uncertain. This is the first double-blind study of subjects randomized to either the STN (N 5 14) or GPi (N 5 14) who were assessed on a range of clinical balance measures. Methods: Balance testing occurred before and 6 months postsurgery. A control PD group was tested over the same period without surgery (N 5 9). All subjects were tested on and off medication and DBS subjects were also tested on and off DBS. The Postural Instability and Gait Disability items of the UPDRS and additional functional tests, which we call the Balance and Gait scale, were assessed. Activities of Balance Confidence and Activities of Daily Living questionnaires were also recorded. Results: Balance was not different between the besttreated states before and after DBS surgery for both sites. Switching DBS on improved balance scores, and scores further improved with medication, compared to the off state. The GPi group showed improved performance in the postsurgery off state and better ratings of balance confidence after surgery, compared to the STN group.

Background: Based on a classification scheme for facial pain syndromes and a binomial (yes/no) facial pain questionnaire, we previously reported on the ability of an artificial neural network (ANN) to recognize and correctly diagnose patients with different facial pain syndromes. Objectives: We now report on an updated questionnaire, the development of a secure web-based neural network application and details of ANNs trained to diagnose patients with different facial pain syndromes. Methods: Online facial pain questionnaire responses collected from 607 facial pain patients (395 female, 65%, ratio F/M 1.86/1) over 5 years and 7 months were used for ANN training. Results: Sensitivity and specificity of the currently running ANN for trigeminal neuralgia type 1 and trigeminal neuralgia type 2 are 92.4 and 62.5% and 87.8 and 96.4%, respectively. Sensitivity and specificity are 86.7 and 95.2% for trigeminal neuropathic pain, 0 and 100% for trigeminal deafferentation pain and 100% for symptomatic trigeminal neuralgia and postherpetic neuralgia. Sensitivity is 50% for nervus intermedius neuralgia (NIN) and 0% for atypical facial pain (AFP), glossopharyngeal neuralgia (GPN) and temporomandibular joint disorder (TMJ). Specificity for AFP, NIN and TMJ is 99% and for GPN, 100%. Conclusions: We demonstrate the utilization of question-based historical self-assessment responses used as inputs to design an ANN for the purpose of diagnosing facial pain syndromes (outputs) with high accuracy.