Rates and Predictors of Pain Reduction With Intracranial Stimulation for Intractable Pain Disorders.

BACKGROUND AND OBJECTIVES: Intracranial modulation paradigms, namely deep brain stimulation (DBS) and motor cortex stimulation (MCS), have been used to treat intractable pain disorders. However, treatment efficacy remains heterogeneous, and factors associated with pain reduction are not completely understood. METHODS: We performed an individual patient review of pain outcomes (visual analog scale, quality-of-life measures, complications, pulse generator implant rate, cessation of stimulation) after implantation of DBS or MCS devices. We evaluated 663 patients from 36 study groups and stratified outcomes by pain etiology and implantation targets. RESULTS: Included studies comprised primarily retrospective cohort studies. MCS patients had a similar externalized trial success rate compared with DBS patients (86% vs 81%; P = .16), whereas patients with peripheral pain had a higher trial success rate compared with patients with central pain (88% vs 79%; P = .004). Complication rates were similar for MCS and DBS patients (12% vs 15%; P = .79). Patients with peripheral pain had lower likelihood of device cessation compared with those with central pain (5.7% vs 10%; P = .03). Of all implanted patients, mean pain reduction at last follow-up was 45.8% (95% CI: 40.3-51.2) with a 31.2% (95% CI: 12.4-50.1) improvement in quality of life. No difference was seen between MCS patients (43.8%; 95% CI: 36.7-58.2) and DBS patients (48.6%; 95% CI: 39.2-58) or central (41.5%; 95% CI: 34.8-48.2) and peripheral (46.7%; 95% CI: 38.9-54.5) etiologies. Multivariate analysis identified the anterior cingulate cortex target to be associated with worse pain reduction, while postherpetic neuralgia was a positive prognostic factor. CONCLUSION: Both DBS and MCS have similar efficacy and complication rates in the treatment of intractable pain. Patients with central pain disorders tended to have lower trial success and higher rates of device cessation. Additional prognostic factors include anterior cingulate cortex targeting and postherpetic neuralgia diagnosis. These findings underscore intracranial neurostimulation as an important modality for treatment of intractable pain disorders.

Dichotomous frequency-dependent phase synchrony in the sensorimotor network characterizes simplistic movement.

It is hypothesized that disparate brain regions interact via synchronous activity to control behavior. The nature of these interconnected ensembles remains an area of active investigation, and particularly the role of high frequency synchronous activity in simplistic behavior is not well known. Using intracranial electroencephalography, we explored the spectral dynamics and network connectivity of sensorimotor cortical activity during a simple motor task in seven epilepsy patients. Confirming prior work, we see a "spectral tilt" (increased high-frequency (HF, 70-100 Hz) and decreased low-frequency (LF, 3-33 Hz) broadband oscillatory activity) in motor regions during movement compared to rest, as well as an increase in LF synchrony between these regions using time-resolved phase-locking. We then explored this phenomenon in high frequency and found a robust but opposite effect, where time-resolved HF broadband phase-locking significantly decreased during movement. This "connectivity tilt" (increased LF synchrony and decreased HF synchrony) displayed a graded anatomical dependency, with the most robust pattern occurring in primary sensorimotor cortical interactions and less robust pattern occurring in associative cortical interactions. Connectivity in theta (3-7 Hz) and high beta (23-27 Hz) range had the most prominent low frequency contribution during movement, with theta synchrony building gradually while high beta having the most prominent effect immediately following the cue. There was a relatively sharp, opposite transition point in both the spectral and connectivity tilt at approximately 35 Hz. These findings support the hypothesis that task-relevant high-frequency spectral activity is stochastic and that the decrease in high-frequency synchrony may facilitate enhanced low frequency phase coupling and interregional communication. Thus, the "connectivity tilt" may characterize behaviorally meaningful cortical interactions.

Naturalistic acute pain states decoded from neural and facial dynamics.

Pain is a complex experience that remains largely unexplored in naturalistic contexts, hindering our understanding of its neurobehavioral representation in ecologically valid settings. To address this, we employed a multimodal, data-driven approach integrating intracranial electroencephalography, pain self-reports, and facial expression quantification to characterize the neural and behavioral correlates of naturalistic acute pain in twelve epilepsy patients undergoing continuous monitoring with neural and audiovisual recordings. High self-reported pain states were associated with elevated blood pressure, increased pain medication use, and distinct facial muscle activations. Using machine learning, we successfully decoded individual participants' high versus low self-reported pain states from distributed neural activity patterns (mean AUC = 0.70), involving mesolimbic regions, striatum, and temporoparietal cortex. High self-reported pain states exhibited increased low-frequency activity in temporoparietal areas and decreased high-frequency activity in mesolimbic regions (hippocampus, cingulate, and orbitofrontal cortex) compared to low pain states. This neural pain representation remained stable for hours and was modulated by pain onset and relief. Objective facial expression changes also classified self-reported pain states, with results concordant with electrophysiological predictions. Importantly, we identified transient periods of momentary pain as a distinct naturalistic acute pain measure, which could be reliably differentiated from affect-neutral periods using intracranial and facial features, albeit with neural and facial patterns distinct from self-reported pain. These findings reveal reliable neurobehavioral markers of naturalistic acute pain across contexts and timescales, underscoring the potential for developing personalized pain interventions in real-world settings.

MTL neurons phase-lock to human hippocampal theta.

Memory formation depends on neural activity across a network of regions, including the hippocampus and broader medial temporal lobe (MTL). Interactions between these regions have been studied indirectly using functional MRI, but the bases for interregional communication at a cellular level remain poorly understood. Here, we evaluate the hypothesis that oscillatory currents in the hippocampus synchronize the firing of neurons both within and outside the hippocampus. We recorded extracellular spikes from 1854 single- and multi-units simultaneously with hippocampal local field potentials (LFPs) in 28 neurosurgical patients who completed virtual navigation experiments. A majority of hippocampal neurons phase-locked to oscillations in the slow (2-4 Hz) or fast (6-10 Hz) theta bands, with a significant subset exhibiting nested slow theta × beta frequency (13-20 Hz) phase-locking. Outside of the hippocampus, phase-locking to hippocampal oscillations occurred only at theta frequencies and primarily among neurons in the entorhinal cortex and amygdala. Moreover, extrahippocampal neurons phase-locked to hippocampal theta even when theta did not appear locally. These results indicate that spike-time synchronization with hippocampal theta is a defining feature of neuronal activity in the hippocampus and structurally connected MTL regions. Theta phase-locking could mediate flexible communication with the hippocampus to influence the content and quality of memories.

Clinical Image: Contrast-Induced Encephalopathy Mimicking Subarachnoid Hemorrhage.

A 72-year-old female with a history of hypertension and hyperlipidemia presented to the emergency department from an outside hospital with acute confusion and global amnesia immediately following cervical epidural steroid injection with fluoroscopic guidance for radiculopathy relief. On exam, she was oriented to self, but disoriented to place and situation. Otherwise, she was neurologically intact with no deficits. Head computed tomography (CT) revealed diffuse subarachnoid hyperdensities most prominent in the parafalcine region concerning for diffuse subarachnoid hemorrhage and tonsillar herniation concerning for intracranial hypertension. CT angiograms of head and neck were negative for vascular abnormalities. Dual-energy head CT was subsequently performed 4 hours later without IV contrast. The 80 kV sequence revealed prominent diffuse hyperdensity throughout the cerebrospinal fluid spaces in bilateral cerebral hemispheres, basal cisterns, and posterior fossa consistent with the initial CT, but these corresponding regions were relatively less dense on the 150 kV sequence. These findings were consistent with contrast material in the cerebrospinal fluid spaces without evidence of intracranial hemorrhage or transcortical infarct. Three hours later, the patient's transient confusion resolved, and she was discharged home the next morning without any neurological deficit.

Preoperative Predictors of Survival in Patients With Spinal Metastatic Disease.

BACKGROUND: There remains a number of factors thought to be associated with survival in spinal metastatic disease, but evidence of these associations is lacking. In this study, we examined factors associated with survival among patients undergoing surgery for spinal metastatic disease. METHODS: We retrospectively examined 104 patients who underwent surgery for spinal metastatic disease at an academic medical center. Of those patients, 33 received local preoperative radiation (PR) and 71 had no PR (NPR). Disease-related variables and surrogate markers of preoperative health were identified, including age, pathology, timing of radiation and chemotherapy, mechanical instability by spine instability neoplastic score, American Society of Anesthesiologists (ASA) classification, Karnofsky performance status (KPS), and body mass index (BMI). We performed survival analyses using a combination of univariate and multivariate Cox proportional hazards models to assess significant predictors of time to death. RESULTS: Local PR (Hazard Ratio [HR] = 1.84, P = 0.034), mechanical instability (HR = 1.11, P = 0.024), and melanoma (HR = 3.60, P = 0.010) were significant predictors of survival on multivariate analysis when controlling for confounders. PR vs NPR cohorts exhibited no statistically significant differences in preoperative age (P = 0.22), KPS (P = 0.29), BMI (P = 0.28), or ASA classification (P = 0.12). NPR patients had more reoperations for postoperative wound complications (11.3% vs 0%, P < 0.001). CONCLUSIONS: In this small sample, PR and mechanical instability were significant predictors of postoperative survival, independent of age, BMI, ASA classification, and KPS and in spite of fewer wound complications in the PR group. It is possible that PR was a surrogate of more advanced disease or poor response to systemic therapy, independently portending a worse prognosis. Future studies in larger, more diverse populations are crucial for understanding the relationship between PR and postoperative outcomes to determine the optimal timing for surgical intervention. CLINICAL RELEVANCE: These findings are clinically relevent as they provide insight into factors associated with survival in metastatic spinal disease.

Tractography-Based Surgical Targeting for Thalamic Deep Brain Stimulation: A Comparison of Probabilistic vs Deterministic Fiber Tracking of the Dentato-Rubro-Thalamic Tract.

BACKGROUND: The ventral intermediate (VIM) thalamic nucleus is the main target for the surgical treatment of refractory tremor. Initial targeting traditionally relies on atlas-based stereotactic targeting formulas, which only minimally account for individual anatomy. Alternative approaches have been proposed, including direct targeting of the dentato-rubro-thalamic tract (DRTT), which, in clinical settings, is generally reconstructed with deterministic tracking. Whether more advanced probabilistic techniques are feasible on clinical-grade magnetic resonance acquisitions and lead to enhanced reconstructions is poorly understood. OBJECTIVE: To compare DRTT reconstructed with deterministic vs probabilistic tracking. METHODS: This is a retrospective study of 19 patients with essential tremor who underwent deep brain stimulation (DBS) with intraoperative neurophysiology and stimulation testing. We assessed the proximity of the DRTT to the DBS lead and to the active contact chosen based on clinical response. RESULTS: In the commissural plane, the deterministic DRTT was anterior (P < 10-4) and lateral (P < 10-4) to the DBS lead. By contrast, although the probabilistic DRTT was also anterior to the lead (P < 10-4), there was no difference in the mediolateral dimension (P = .5). Moreover, the 3-dimensional Euclidean distance from the active contact to the probabilistic DRTT was smaller vs the distance to the deterministic DRTT (3.32 ± 1.70 mm vs 5.01 ± 2.12 mm; P < 10-4). CONCLUSION: DRTT reconstructed with probabilistic fiber tracking was superior in spatial proximity to the physiology-guided DBS lead and to the empirically chosen active contact. These data inform strategies for surgical targeting of the VIM.

Ethical Issues in Intraoperative Neuroscience Research: Assessing Subjects' Recall of Informed Consent and Motivations for Participation.

BackgroundAn increasing number of studies utilize intracranial electrophysiology in human subjects to advance basic neuroscience knowledge. However, the use of neurosurgical patients as human research subjects raises important ethical considerations, particularly regarding informed consent and undue influence, as well as subjects' motivations for participation. Yet a thorough empirical examination of these issues in a participant population has been lacking. The present study therefore aimed to empirically investigate ethical concerns regarding informed consent and voluntariness in Parkinson's disease patients undergoing deep brain stimulator (DBS) placement who participated in an intraoperative neuroscience study.MethodsTwo semi-structured 30-minute interviews were conducted preoperatively and postoperatively via telephone. Interviews assessed participants' motivations for participation in the parent intraoperative study, recall of information presented during the informed consent process, and participants' postoperative reflections on the research study.ResultsTwenty-two participants (mean age = 60.9) completed preoperative interviews at a mean of 7.8 days following informed consent and a mean of 5.2 days prior to DBS surgery. Twenty participants completed postoperative interviews at a mean of 5 weeks following surgery. All participants cited altruism or advancing medical science as "very important" or "important" in their decision to participate in the study. Only 22.7% (n = 5) correctly recalled one of the two risks of the study. Correct recall of other aspects of the informed consent was poor (36.4% for study purpose; 50.0% for study protocol; 36.4% for study benefits). All correctly understood that the study would not confer a direct therapeutic benefit to them.ConclusionEven though research coordinators were properly trained and the informed consent was administered according to protocol, participants demonstrated poor retention of study information. While intraoperative studies that aim to advance neuroscience knowledge represent a unique opportunity to gain fundamental scientific knowledge, improved standards for the informed consent process can help facilitate their ethical implementation.

Social Determinants of Health and Neurosurgical Outcomes: Current State and Future Directions.

The relationship between social determinants of health (SDOH) and neurosurgical outcomes has become increasingly relevant. To date, results of prior work evaluating the impact of social determinants in neurosurgery have been mixed, and the need for robust data on this subject remains. The present review evaluates how gender, race, and socioeconomic status (SES) influence outcomes following various brain tumor resection procedures. Results from a number of prior studies from the senior author's lab are summarized, with all data acquired using the EpiLog tool (Epilog Laser). Separate analyses were performed for each procedure, evaluating the unique, isolated impact of gender, race, and SES on outcomes. A comprehensive literature review identified any prior studies evaluating the influence of these SDOH on neurosurgical outcomes. The review presented herein suggests that the effect of gender and race on outcomes is largely mitigated when equal access to care is attained, and socioeconomic factors and comorbidities are controlled for. Furthermore, when patients are matched upon for a number of clinically relevant covariates, SES impacts postoperative mortality. Elucidation of this disparity empowers surgeons to initiate actionable change to equilibrate future outcomes.

Theta Synchrony Is Increased near Neural Populations That Are Active When Initiating Instructed Movement.

Theta oscillations (3-8 Hz) in the human brain have been linked to perception, cognitive control, and spatial memory, but their relation to the motor system is less clear. We tested the hypothesis that theta oscillations coordinate distributed behaviorally relevant neural representations during movement using intracranial electroencephalography (iEEG) recordings from nine patients (n = 490 electrodes) as they performed a simple instructed movement task. Using high frequency activity (HFA; 70-200 Hz) as a marker of local spiking activity, we identified electrodes that were positioned near neural populations that showed increased activity during instruction and movement. We found that theta synchrony was widespread throughout the brain but was increased near regions that showed movement-related increases in neural activity. These results support the view that theta oscillations represent a general property of brain activity that may also play a specific role in coordinating widespread neural activity when initiating voluntary movement.

Postoperative Sagittal Spinal Alignment Changes Following Corrective Surgery in Adult Spinal Deformity.

BACKGROUND: There is a paucity of literature covering the spinal alignment changes following adult spinal deformities (ASD) corrective surgeries. In theory, patients' posture and overall alignment may vary with postoperative pain, bracing, and other external variables requiring further radiographic follow-up. The purpose of the study is to investigate changes in sagittal alignment in the first 3 months postoperatively. METHODS: This is a retrospective case series of ASD patients who underwent deformity surgeries from October 2015 to June 2018. Patients < 40 years old, had < 6 levels fused, had acute proximal junctional kyphosis (PJK) or failure, or lacked imaging were excluded. Physiologic measures, spine alignment changes measured in whole-spine radiographs. Lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) at immediate and 3-month postoperative time points were measured, then compared via 2-sample Student t tests. Furthermore, TK after upper thoracic to pelvis (UT-P) fusions was compared with lower thoracic to pelvis (LT-P) fusions via paired t test. RESULTS: Thirty-six patients (24 females, 67%) with a mean age of 61.5 years (range, 40-75 years) were included. Spinal alignment comparisons showed a significant increase in TK at the 3-month time point (P = 0.006). Additionally, wide variations in SVA (range, 47-144 mm) were noted, yet not statistically significant, likely due to the changes being in both positive and negative directions (P = 0.18). No significant difference was found when TK was compared in the UT-P vs LT-P groups. CONCLUSIONS: Our results suggest that as postoperative pain subsides and the body settles into its new alignment, significant changes occur in spine sagittal parameters in the subacute period following surgery. LEVEL OF EVIDENCE: 4.

Thoracolumbar Transverse Process Fractures Are More Frequently Associated with Nonspinal Injury than Clinically Significant Spine Fracture.

OBJECTIVE: We studied the risk of associated spinal and nonspinal injuries (NSIs) in the setting of observed thoracolumbar transverse process fracture (TPF) and examined the clinical management of TPF. METHODS: Patients treated at a Level I trauma center over a 5-year period were screened for thoracolumbar TPF. Prevalence of associated spinal fractures and NSIs as well as relationship to level of TPF was explored. Clinical management and follow-up outcomes were reviewed. RESULTS: A total of 252 patients with thoracolumbar TPFs were identified. NSIs were commonly observed (70.6%, n = 178); however, associated spinal fractures were more rarely seen (24.6%, n = 62, P < 0.0001). No patients had neurological deficits attributable to TPFs, and only 3 patients with isolated TPFs were treated with orthosis. Among patients with outpatient follow-up (70.6%, n = 178), none developed delayed-onset neurological deficits or spinal instability. Thoracic TPFs (odds ratio = 3.56, 95% confidence interval = 1.20-10.56) and L1 TPFs (odds ratio = 2.48, 95% confidence interval = 1.41-4.36) were predictive of associated thoracic NSIs. L5 TPF was associated with pelvic fractures (odds ratio = 6.30, 95% confidence interval = 3.26-12.17). There was no difference in rate of NSIs between isolated TPF (70.0%) and TPF with associated clinically relevant spinal fracture (72.6%, P = 0.70). CONCLUSIONS: NSIs are nearly 3 times more common in patients with thoracolumbar TPFs than associated clinically relevant spinal fractures. Spine service consultation for TPF may be unnecessary unless fracture is associated with a clinically relevant spinal injury, which represents a minority of cases. However, detection of TPF should raise suspicion for high likelihood of associated NSIs.

Focused Ultrasound Thalamotomy with Dentato-Rubro-Thalamic Tractography in Patients with Spinal Cord Stimulators and Cardiac Pacemakers.

Magnetic resonance image-guided high-intensity focused ultrasound (MRgFUS)-based thermal ablation of the ventral intermediate nucleus of the thalamus (VIM) is a minimally invasive treatment modality for essential tremor (ET). Dentato-rubro-thalamic tractography (DRTT) is becoming increasingly popular for direct targeting of the presumed VIM ablation focus. It is currently unclear if patients with implanted pulse generators (IPGs) can safely undergo MRgFUS ablation and reliably acquire DRTT suitable for direct targeting. We present an 80-year-old male with a spinal cord stimulator (SCS) and an 88-year-old male with a cardiac pacemaker who both underwent MRgFUS for medically refractory ET. Clinical outcomes were measured using the Clinical Rating Scale for Tremor (CRST). DRTT was successfully created and imaging parameter adjustments did not result in any delay in procedural time in either case. In the first case, 7 therapeutic sonications were delivered. The patient improved immediately and durably with a 90% CRST-disability improvement at 6-week follow-up. In our second case, 6 therapeutic sonications were delivered with durable, 75% CRST-disability improvement at 6 weeks. These are the first cases of MRgFUS thalamotomy in patients with IPGs. DRTT targeting and MRgFUS-based thermal ablation can be safely performed in these patients using a 1.5-T MRI.

Surface-Registration Frameless Stereotactic Navigation Is Less Accurate During Prone Surgeries: Intraoperative Near-Infrared Visualization Using Second Window Indocyanine Green Offers an Adjunct.

BACKGROUND: Frameless neuronavigation allows neurosurgeons to visualize and relate the position of surgical instruments to intracranial pathologies based on preoperative tomographic imaging. However, neuronavigation can often be inaccurate. Multiple factors have been proposed as potential causes, and new technologies are needed to overcome these challenges. OBJECTIVE: To evaluate the accuracy of neuronavigation systems compared to near-infrared (NIR) fluorescence imaging using Second Window Indocyanine Green, a novel technique, and to determine factors that lead to neuronavigation errors. METHODS: A retrospective analysis was conducted on 56 patients who underwent primary resections of intracranial tumors. Patients received 5 mg/kg ICG approximately 24 h preoperatively. Intraoperatively, neuronavigation was used to plan craniotomies to place the tumors in the center. After craniotomy, NIR imaging visualized tumor-specific NIR signals. The accuracy of neuronavigation and NIR fluorescence imaging for delineating the tumor boundary prior to durotomy was compared. RESULTS: The neuronavigation centers and NIR centers were 23.0 ± 7.7 % and 2.6 ± 1.1 % deviated from the tumor centers, respectively, relative to the craniotomy sizes. In 12 cases, significant changes were made to the planned durotomy based on NIR imaging. Patient position was a significant predictor of neuronavigation inaccuracy on both univariate and multivariate analysis, with the prone position having significantly higher inaccuracy (29.2 ± 8.1 %) compared to the supine (16.2 ± 8.1 %, p value < 0.001) or the lateral (17.9 ± 5.1 %, p value = 0.003) positions. CONCLUSION: Patient position significantly affects neuronavigation accuracy. Intraoperative NIR fluorescence imaging before durotomy offers an opportunity to readjust the neuronavigation image space to better align with the patient space.

Association of spinal instability due to metastatic disease with increased mortality and a proposed clinical pathway for treatment.

OBJECTIVE: Multidisciplinary treatment including medical oncology, radiation oncology, and surgical consultation is necessary to provide comprehensive therapy for patients with spinal metastases. The goal of this study was to review the use of radiation therapy and/or surgical intervention and their impact on patient outcomes. METHODS: In this retrospective series, the authors identified at their institution those patients with spinal metastases who had received radiation therapy alone or had undergone surgery with or without radiation therapy within a 6-year period. Data on patient age, chemotherapy, surgical procedure, radiation therapy, Karnofsky Performance Status (KPS), primary tumor pathology, Spinal Instability Neoplastic Score (SINS), and survival after treatment were collected from the patient electronic medical records. N - 1 chi-square testing was used for comparisons of proportions. The Student t-test was used for comparisons of means. A p value < 0.05 was considered statistically significant. A survival analysis was completed using a multivariate Cox proportional hazards model. RESULTS: Two hundred thirty patients with spinal metastases were identified, 109 of whom had undergone surgery with or without radiation therapy. Among the 104 patients for whom the surgical details were reviewed, 34 (33%) had a history of preoperative radiation to the surgical site but ultimately required surgical intervention. In this surgical group, a significantly increased frequency of death within 30 days was noted for the SINS unstable patients (23.5%) as compared to that for the SINS stable patients (2.3%; p < 0.001). The SINS was a significant predictor of time to death among surgical patients (HR 1.11, p = 0.037). Preoperative KPS was not independently associated with decreased survival (p > 0.5) on univariate analysis. One hundred twenty-six patients met the criteria for inclusion in the radiation-only analysis. Ninety-eight of these patients (78%) met the criteria for potential instability (PI) at the time of treatment, according to the SINS system. Five patients (5%) with PI in the radiation therapy group had a documented neurosurgical or orthopedic surgery consultation prior to radiation therapy. CONCLUSIONS: At the authors' institution, patients with gross mechanical instability per the SINS system had an increased rate of 30-day postoperative mortality, which remained significant when controlling for other factors. Surgical consultation for metastatic spine patients receiving radiation oncology consultation with PI is low. The authors describe an institutional pathway to encourage multidisciplinary treatment from the initial encounter in the emergency department to expedite surgical evaluation and collaboration.

Thalamic Deep Brain Stimulation for Essential Tremor: Relation of the Dentatorubrothalamic Tract with Stimulation Parameters.

BACKGROUND: In deep brain stimulation (DBS) for essential tremor, the primary target ventrointermedius (VIM) nucleus cannot be clearly visualized with structural imaging. As such, there has been much interest in the dentatorubrothalamic tract (DRTT) for target localization, but evidence for the DRTT as a putative stimulation target in tremor suppression is lacking. We evaluated proximity of the DRTT in relation to DBS stimulation parameters. METHODS: This is a retrospective analysis of 26 consecutive patients who underwent DBS with microelectrode recordings (46 leads). Fiber tracking was performed with a published deterministic technique. Clinically optimized stimulation parameters were obtained in all patients at the time of most recent follow-up (6.2 months). Volume of tissue activated (VTA) around contacts was calculated from a published model. RESULTS: Tremor severity was reduced in all treated hemispheres, with 70% improvement in the treated hand score of the Clinical Rating Scale for Tremor. At the level of the active contact (2.9 ± 2.0 mm superior to the commissural plane), the center of the DRTT was lateral to the contacts (5.1 ± 2.1 mm). The nearest fibers of the DRTT were 2.4 ± 1.7 mm from the contacts, whereas the radius of the VTA was 2.9 ± 0.7 mm. The VTA overlapped with the DRTT in 77% of active contacts. The distance from active contact to the DRTT was positively correlated with stimulation voltage requirements (Kendall τ = 0.33, P = 0.006), whereas distance to the atlas-based VIM coordinates was not. CONCLUSIONS: Active contacts in proximity to the DRTT had lower voltage requirements. Data from a large cohort provide support for the DRTT as an effective stimulation target for tremor control.

Assessing the utility of an IoS application in the perioperative care of spine surgery patients: the NeuroPath Pilot study.

BACKGROUND: In an attempt to improve care while decreasing costs and postoperative pain, we developed a novel IoS mobile health application, NeuroPath. The objective of this innovative app is to integrate enhanced recovery after surgery (ERAS) principles, patient education, and real-time pain and activity monitoring in a home setting with unencumbered two-way communication. METHODS: The NeuroPath application was built over 18 months, with support from Apple, Medable, the Department of Information-Technology and the Department of Neurosurgery. Target areas addressed by NeuroPath include patient prep for surgery, perioperative risk mitigation, activity monitoring, wound care, and opioid use management. These target areas are monitored through a provider app, which is downloaded to the care providers IPad Mini. The provider app permits real time viewing of wound healing (patient incision photographs), activity levels, pain levels, and narcotic usage. Participants are given a daily To-Do list, via the Care Card section of the interface. The To-Do list presents the patient with specific tasks for exercise, instructions to wash incision area, pre-operative instructions, directions for discussing medication with care team, among other patient specific recommendations. RESULTS: Of the 30 patients enrolled in the pilot study, there was a range of activity on the app. Patients with high involvement in the app logged in nearly every day from a week pre-op to >45 days post-op. Data for patients that utilized the app and uploaded regularly show trends of appropriately healing wounds, decreasing levels of pain, increasing step counts, and discontinuation of narcotics. CONCLUSIONS: This pilot study of the NeuroPath app demonstrates its potential utility for improving quality of patient care without increased costs. Participants who regularly used the app showed consistent improvement throughout the post-operative recovery period (increasing ambulation, decreasing pain and guided reduction in narcotic usage).

Association of Overlapping Neurosurgery With Patient Outcomes at a Large Academic Medical Center.

BACKGROUND: Limited data exist on the safety of overlapping surgery, a practice that has recently received widespread attention. OBJECTIVE: To examine the association of overlapping neurosurgery with patient outcomes. METHODS: A total of 3038 routinely scheduled, elective neurosurgical procedures were retrospectively reviewed at a single, multihospital academic medical center. Procedures were categorized into any overlap or no overlap and further subcategorized into beginning overlap (first 50% of procedure only), end overlap (last 50% of procedure only), and middle overlap (overlap at the midpoint). RESULTS: A total of 1030 (33.9%) procedures had any overlap, whereas 278 (9.2%) had beginning overlap, 190 (6.3%) had end overlap, and 476 (15.7%) had middle overlap. Compared with no overlap patients, patients with any overlap had lower American Society of Anesthesiologists scores (P = .0018), less prior surgery (P < .0001), and less prior neurosurgery (P < .0001), though they tended to be older (P < .0001) and more likely in-patients (P = .0038). Any-overlap patients had decreased overall mortality (2.8% vs 4.5%; P = .025), 30- to 90-d readmission rate (3.1% vs 5.5%; P = .0034), 30- to 90-d reoperation rate (1.0% vs 2.0%; P = .03), 30- to 90-d emergency room (ER) visit rate (2.1% vs 3.7%; P = .018), and future surgery on index admission (2.8% vs 7.3%; P < .0001). Multiple regression analysis validated noninferior outcomes for overlapping surgery, except for the association of increased future surgery on index admission with middle overlap (odds ratio 3.99; 95% confidence interval [1.91, 8.33]). CONCLUSION: Overlapping neurosurgery is associated with noninferior patient outcomes that may be driven by surgeon selection of healthier patients, regardless of specific overlap timing.

Surgical Management of Idiopathic Thoracic Spinal Cord Herniation.

BACKGROUND: Idiopathic spinal cord herniation is a rare condition that involves spinal cord herniation through a defect in the ventral dura. CASE DESCRIPTION: We present a case of a 61-year-old woman who initially presented in 2016 with an approximately 1-year history of burning right lower extremity pain and gait instability. Her neurologic examination was consistent with thoracic Brown-Sequard syndrome, and spinal magnetic resonance imaging showed a focal defect in the ventral dura at the superior aspect of T4 with the left aspect of the cord herniating into the defect. In 2018, she underwent a T3-T4 laminectomy with T3 pedicle take down and medial facetectomy, with reduction of the herniated cord. CONCLUSIONS: Idiopathic spinal cord herniation is an uncommon spinal cord disorder with a paucity of data reported. Our case report of a classic case of idiopathic spinal cord herniation presenting as Brown-Sequard syndrome and managed surgically will contribute to the data in this field.

Assessing variability in surgical decision making among attending neurosurgeons at an academic center.

OBJECTIVE: Although it is known that intersurgeon variability in offering elective surgery can have major consequences for patient morbidity and healthcare spending, data addressing variability within neurosurgery are scarce. The authors performed a prospective peer review study of randomly selected neurosurgery cases in order to assess the extent of consensus regarding the decision to offer elective surgery among attending neurosurgeons across one large academic institution. METHODS: All consecutive patients who had undergone standard inpatient surgical interventions of 1 of 4 types (craniotomy for tumor [CFT], nonacute redo CFT, first-time spine surgery with/without instrumentation, and nonacute redo spine surgery with/without instrumentation) during the period 2015-2017 were retrospectively enrolled (n = 9156 patient surgeries, n = 80 randomly selected individual cases, n = 20 index cases of each type randomly selected for review). The selected cases were scored by attending neurosurgeons using a need for surgery (NFS) score based on clinical data (patient demographics, preoperative notes, radiology reports, and operative notes; n = 616 independent case reviews). Attending neurosurgeon reviewers were blinded as to performing provider and surgical outcome. Aggregate NFS scores across various categories were measured. The authors employed a repeated-measures mixed ANOVA model with autoregressive variance structure to compute omnibus statistical tests across the various surgery types. Interrater reliability (IRR) was measured using Cohen's kappa based on binary NFS scores. RESULTS: Overall, the authors found that most of the neurosurgical procedures studied were rated as "indicated" by blinded attending neurosurgeons (mean NFS = 88.3, all p values < 0.001) with greater agreement among neurosurgeon raters than expected by chance (IRR = 81.78%, p = 0.016). Redo surgery had lower NFS scores and IRR scores than first-time surgery, both for craniotomy and spine surgery (ANOVA, all p values < 0.01). Spine surgeries with fusion had lower NFS scores than spine surgeries without fusion procedures (p < 0.01). CONCLUSIONS: There was general agreement among neurosurgeons in terms of indication for surgery; however, revision surgery of all types and spine surgery with fusion procedures had the lowest amount of decision consensus. These results should guide efforts aimed at reducing unnecessary variability in surgical practice with the goal of effective allocation of healthcare resources to advance the value paradigm in neurosurgery.