Minimally Invasive Anterolateral Cervical Cordotomy for Intractable Cancer Pain Using Microtubular Retractors: A Single Institution Case Series.

BACKGROUND AND OBJECTIVES: As advancements in cancer treatments have allowed patients with a high burden of disease to live longer, the number of patients who present with debilitating refractory pain has increased. Anterolateral cordotomy has long been used for the treatment of intractable unilateral cancer pain using either an imaging-guided percutaneous approach or an open surgical approach. In this report, we describe a novel minimally invasive modification to the open surgical approach. It combines the benefits of both approaches by providing direct visualization for lesioning without the collateral tissue damage of an open approach. METHODS: This retrospective study evaluated medical records, operative reports, and imaging studies of patients who underwent a minimally invasive cordotomy at a single institute between 2018 and 2022. The surgical technique involved a microscope-assisted C2 hemilaminectomy using microtubular retractors followed by dural opening and anterolateral cordotomy under direct visualization and with intraoperative neurophysiological monitoring. RESULTS: Eleven patients were included in the study. None were converted to an open approach, and no wound-related postoperative complications were observed. A clinically significant decrease in pain was observed after the procedure, and 10 of the 11 patients (91%) were ambulatory by the time of analysis. CONCLUSION: Compared with image-guided percutaneous cordotomy, anterolateral cervical cordotomy with microtubular retractors potentially improves the safety of the procedure through direct visualization while being less invasive than a conventional open approach. Our preliminary experience with this technique demonstrates the feasibility of the approach, as it was both safe and effective.

Progressive remodeling of structural networks following surgery for operculo-insular epilepsy.

Introduction: Operculo-insular epilepsy (OIE) is a rare condition amenable to surgery in well-selected cases. Despite the high rate of neurological complications associated with OIE surgery, most postoperative deficits recover fully and rapidly. We provide insights into this peculiar pattern of functional recovery by investigating the longitudinal reorganization of structural networks after surgery for OIE in 10 patients. Methods: Structural T1 and diffusion-weighted MRIs were performed before surgery (t0) and at 6 months (t1) and 12 months (t2) postoperatively. These images were processed with an original, comprehensive structural connectivity pipeline. Using our method, we performed comparisons between the t0 and t1 timepoints and between the t1 and t2 timepoints to characterize the progressive structural remodeling. Results: We found a widespread pattern of postoperative changes primarily in the surgical hemisphere, most of which consisted of reductions in connectivity strength (CS) and regional graph theoretic measures (rGTM) that reflect local connectivity. We also observed increases in CS and rGTMs predominantly in regions located near the resection cavity and in the contralateral healthy hemisphere. Finally, most structural changes arose in the first six months following surgery (i.e., between t0 and t1). Discussion: To our knowledge, this study provides the first description of postoperative structural connectivity changes following surgery for OIE. The ipsilateral reductions in connectivity unveiled by our analysis may result from the reversal of seizure-related structural alterations following postoperative seizure control. Moreover, the strengthening of connections in peri-resection areas and in the contralateral hemisphere may be compatible with compensatory structural plasticity, a process that could contribute to the recovery of functions seen following operculo-insular resections for focal epilepsy.

The human claustrum tracks slow waves during sleep.

Slow waves are a distinguishing feature of non-rapid-eye-movement (NREM) sleep, an evolutionarily conserved process critical for brain function. Non-human studies posit that the claustrum, a small subcortical nucleus, coordinates slow waves. We recorded claustrum neurons in humans during sleep. In contrast to neurons from other brain regions, claustrum neurons increased their activity and tracked slow waves during NREM sleep suggesting that the claustrum plays a role in human sleep architecture.

Statistical learning in epilepsy: Behavioral and anatomical mechanisms in the human brain.

OBJECTIVE: Statistical learning, the fundamental cognitive ability of humans to extract regularities across experiences over time, engages the medial temporal lobe (MTL) in the healthy brain. This leads to the hypothesis that statistical learning (SL) may be impaired in patients with epilepsy (PWE) involving the temporal lobe, and that this impairment could contribute to their varied memory deficits. In turn, studies done in collaboration with PWE, that evaluate the necessity of MTL circuitry through disease and causal perturbations, provide an opportunity to advance basic understanding of SL. METHODS: We implemented behavioral testing, volumetric analysis of the MTL substructures, and direct electrical brain stimulation to examine SL across a cohort of 61 PWE and 28 healthy controls. RESULTS: We found that behavioral performance in an SL task was negatively associated with seizure frequency irrespective of seizure origin. The volume of hippocampal subfields CA1 and CA2/3 correlated with SL performance, suggesting a more specific role of the hippocampus. Transient direct electrical stimulation of the hippocampus disrupted SL. Furthermore, the relationship between SL and seizure frequency was selective, as behavioral performance in an episodic memory task was not impacted by seizure frequency. SIGNIFICANCE: Overall, these results suggest that SL may be hippocampally dependent and that the SL task could serve as a clinically useful behavioral assay of seizure frequency that may complement existing approaches such as seizure diaries. Simple and short SL tasks may thus provide patient-centered endpoints for evaluating the efficacy of novel treatments in epilepsy.

Portable MRI to assess optic chiasm decompression after endoscopic endonasal resection of sellar and suprasellar lesions.

OBJECTIVE: Low-field portable MRI (pMRI) is a recent technological advancement with potential for broad applications. Compared with conventional MRI, pMRI is less resource-intensive with regard to operational costs and scan time. The application of pMRI in neurosurgical oncology has not been previously described. The goal of this study was to demonstrate the efficacy of pMRI in assessing optic nerve decompression after endoscopic endonasal surgery for sellar and suprasellar pathologies. METHODS: Patients who underwent endoscopic endonasal surgery for sellar and suprasellar lesions at a single institution and for whom pMRI and routine MRI were performed postoperatively were retrospectively reviewed to compare the two imaging systems. To assess the relative resolution of pMRI compared with MRI, the distance from the optic chiasm to the top of the third ventricle was measured, and the measurements were compared between paired equivalent slices on T2-weighted coronal images. The inter- and intrarater correlations were analyzed. RESULTS: Twelve patients were included in this study (10 with pituitary adenomas and 2 with craniopharyngiomas) with varying degrees of optic chiasm compression on preoperative imaging. Measurements were averaged across raters before calculating agreement between pMRI and MRI, which demonstrated significant interrater reliability (intraclass correlation coefficient [ICC] = 0.78, p < 0.01). Agreement between raters within the pMRI measurements was also significantly reliable (ICC = 0.93, p < 0.01). Finally, a linear mixed-effects model was specified to demonstrate that MRI measurement could be predicted using the pMRI measurement with the patient and rater set as random effects (pMRI ß coefficient = 0.80, p < 0.01). CONCLUSIONS: The results of this study suggest that resolution of pMRI is comparable to that of conventional MRI in assessing the optic chiasm position in relation to the third ventricle. Portable MRI sufficiently demonstrates decompression of the optic chiasm after endoscopic endonasal surgery. It can be an alternative strategy in cases in which cost, scan-time considerations, or lack of intraoperative MRI availability may preclude the ability to assess adequate optic nerve decompression after endoscopic endonasal surgery for sellar and suprasellar lesions.

Transfrontal Approach to the Amygdala for Ablation With Laser Interstitial Thermal Therapy: An Epilepsy Case Report.

BACKGROUND AND IMPORTANCE: Stereotactic laser amygdalohippocampotomy (SLAH) using laser interstitial thermal therapy is a minimally invasive surgery used to treat mesial temporal lobe epilepsy. It uses laser probes inserted through occipital and temporo-occipital trajectories to ablate the hippocampus and amygdala. However, these trajectories are limited in their ability to ablate the superior amygdala and entorhinal cortex (ERC). We present a trajectory through the middle frontal gyrus as an alternative to the temporo-occipital trajectory, which provides more complete ablation of the amygdala and anterior ERC through a single pass. CLINICAL PRESENTATION: A 70-year-old woman with seizures characterized by fear were localized to the left superomedial amygdala on intracranial electroencephalography. They developed after resection of a left temporal arteriovenous malformation and were refractory to medication. Her age and prior craniotomy made open resection less desirable. A frontal and occipital SLAH achieved Engel 1a at 1-year follow-up without decline in neuropsychological performance scores. CONCLUSION: Typical SLAH uses trajectories that have limited ability to ablate the superior and medial amygdala and ERC in a single passage. A combined approach using an occipital and frontal trajectory allows more complete ablation of the amygdala, hippocampus, and ERC.

Optimizing the surgical management of MRI-negative epilepsy in the neuromodulation era.

OBJECTIVE: To evaluate the role of intracranial electroencephalography monitoring in diagnosing and directing the appropriate therapy for MRI-negative epilepsy and to present the surgical outcomes of patients following treatment. METHODS: Retrospective chart review between 2015-2021 at a single institution identified 48 patients with no lesion on MRI, who received surgical intervention for their epilepsy. The outcomes assessed were the surgical treatment performed and the International League Against Epilepsy seizure outcomes at 1 year of follow-up. RESULTS: Eleven patients underwent surgery without invasive monitoring, including vagus nerve stimulation (10%), deep brain stimulation (8%), laser interstitial thermal therapy (2%), and callosotomy (2%). The remaining 37 patients received invasive monitoring followed by resection (35%), responsive neurostimulation (21%), and deep brain stimulation (15%) or no treatment (6%). At 1 year postoperatively, 39% were Class 1-2, 36% were Class 3-4 and 24% were Class 5. More patients with Class 1-2 or 3-4 outcomes underwent invasive monitoring (100% and 83% respectively) compared with those with poor outcomes (25%, P < .001). Patients with Class 1-2 outcomes more commonly underwent resection or responsive neurostimulation: 69% and 31%, respectively (P < .001). SIGNIFICANCE: The optimal management of MRI-negative focal epilepsy may involve invasive monitoring followed by resection or responsive neurostimulation in most cases, as these treatments were associated with the best seizure outcomes in our cohort. Unless multifocal onset is clear from the noninvasive evaluation, invasive monitoring is preferred before pursuing deep brain stimulation or vagal nerve stimulation directly.

Use of droxidopa for blood pressure augmentation after acute spinal cord injury: case reports.

Hypotension secondary to autonomic dysfunction is a common complication of acute spinal cord injury (SCI) that may worsen neurologic outcomes. Midodrine, an enteral α-1 agonist, is often used to facilitate weaning intravenous (IV) vasopressors, but its use can be limited by reflex bradycardia. Alternative enteral agents to facilitate this wean in the acute post-SCI setting have not been described. We aim to describe novel application of droxidopa, an enteral precursor of norepinephrine that is approved to treat neurogenic orthostatic hypotension, in the acute post-SCI setting. Droxidopa may be an alternative enteral therapy for those intolerant of midodrine due to reflex bradycardia. We describe two patients suffering traumatic cervical SCI who were successfully weaned off IV vasopressors with droxidopa after failing with midodrine. The first patient was a 64-year-old male who underwent C3-6 laminectomies and fusion after a ten-foot fall resulting in quadriparesis. Post-operatively, the addition of midodrine in an attempt to wean off IV vasopressors resulted in significant reflexive bradycardia. Treatment with droxidopa facilitated rapidly weaning IV vasopressors and transfer to a lower level of care within 72 hours of treatment initiation. The second patient was a 73-year-old male who underwent C3-5 laminectomies and fusion for a traumatic hyperflexion injury causing paraplegia. The addition of midodrine resulted in severe bradycardia, prompting consideration of pacemaker placement. However, with the addition of droxidopa, this was avoided, and the patient was weaned off IV vasopressors on dual oral therapy with midodrine and droxidopa. Droxidopa may be a viable enteral therapy to treat hypotension in patients after acute SCI who are otherwise not tolerating midodrine in order to wean off IV vasopressors. This strategy may avoid pacemaker placement and facilitate shorter stays in the intensive care unit, particularly for patients who are stable but require continued intensive care unit admission for IV vasopressors, which can be cost ineffective and human resource depleting.

Management of patients with medically intractable epilepsy and anterior temporal lobe encephaloceles.

OBJECTIVE: Temporal lobe encephaloceles (TLENs) are a significant cause of medically refractory epilepsy, but there is little consensus regarding their workup and treatment. This study characterizes these lesions and their role in seizures and aims to standardize preoperative evaluation and surgical management. METHODS: Patients with TLEN who had undergone resective epilepsy surgery from December 2015 to August 2020 at a single institution were included in the study. Medical records were reviewed for each patient to collect relevant seizure workup information including demographics, radiological findings, surgical data, and neuropsychological evaluation. RESULTS: For patients who presented to the authors' program with suspected medically intractable temporal lobe epilepsy (219 patients), TLEN was considered to be the epileptogenic focus in 5.5%. Ten patients with TLEN had undergone resection and were included in this study. Concordance between ictal scalp electroencephalography (EEG) lateralization and TLEN was found in 9/10 patients (90%), and 4/10 patients (40%) had signs suggestive of idiopathic intracranial hypertension (IIH). Surgical outcome was reported in patients with at least 12 months of follow-up (9/10). Patients with scalp EEG findings concordant with the TLEN side had a good outcome (Engel class I: 7 patients, class II: 1 patient). One patient with discordant EEG findings had a bad outcome (Engel class III). No significant neuropsychological deficits were observed after the surgery. CONCLUSIONS: TLENs are epileptogenic lesions that should be screened for in patients with medically refractory epilepsy who have signs of IIH and no other lesions on MRI. Restricted resection is safe and effective in patients with scalp EEG findings concordant with TLEN.

Comprehensive RNA analysis of CSF reveals a role for CEACAM6 in lung cancer leptomeningeal metastases.

Non-small cell lung cancer (NSCLC) metastatic to the brain leptomeninges is rapidly fatal, cannot be biopsied, and cancer cells in the cerebrospinal fluid (CSF) are few; therefore, available tissue samples to develop effective treatments are severely limited. This study aimed to converge single-cell RNA-seq and cell-free RNA (cfRNA) analyses to both diagnose NSCLC leptomeningeal metastases (LM), and to use gene expression profiles to understand progression mechanisms of NSCLC in the brain leptomeninges. NSCLC patients with suspected LM underwent withdrawal of CSF via lumbar puncture. Four cytology-positive CSF samples underwent single-cell capture (n = 197 cells) by microfluidic chip. Using robust principal component analyses, NSCLC LM cell gene expression was compared to immune cells. Massively parallel qPCR (9216 simultaneous reactions) on human CSF cfRNA samples compared the relative gene expression of patients with NSCLC LM (n = 14) to non-tumor controls (n = 7). The NSCLC-associated gene, CEACAM6, underwent in vitro validation in NSCLC cell lines for involvement in pathologic behaviors characteristic of LM. NSCLC LM gene expression revealed by single-cell RNA-seq was also reflected in CSF cfRNA of cytology-positive patients. Tumor-associated cfRNA (e.g., CEACAM6, MUC1) was present in NSCLC LM patients' CSF, but not in controls (CEACAM6 detection sensitivity 88.24% and specificity 100%). Cell migration in NSCLC cell lines was directly proportional to CEACAM6 expression, suggesting a role in disease progression. NSCLC-associated cfRNA is detectable in the CSF of patients with LM, and corresponds to the gene expression profile of NSCLC LM cells. CEACAM6 contributes significantly to NSCLC migration, a hallmark of LM pathophysiology.

Depth Electrode Guided Anterior Insulectomy: 2-Dimensional Operative Video.

The insula is well established as an epileptogenic area.1 Insular epilepsy surgery demands precise anatomic knowledge2-4 and tailored removal of the epileptic zone with careful neuromonitoring.5 We present an operative video illustrating an intracranial electroencephalogram (EEG) depth electrode guided anterior insulectomy. We report a 17-yr-old right-handed woman with a 4-yr history of medically refractory epilepsy. The patient reported daily nocturnal ictal vocalization preceded by an indescribable feeling. Preoperative evaluation was suggestive of a right frontal-temporal onset, but the noninvasive results were discordant. She underwent a combined intracranial EEG study with a frontal-parietal grid, with strips and depth electrodes covering the entire right hemisphere. Epileptiform activity was observed in contact 6 of the anterior insula electrode. The patient consented to the procedure and to the publication of her images. A right anterior insulectomy was performed. First, a portion of the frontal operculum was resected and neuronavigation was used for the initial insula localization. However, due to unreliable neuronavigation (ie, brain shift), the medial and anterior borders of the insular resection were guided by the depth electrode reference. The patient was discharged 3 d after surgery with no neurological deficits and remains seizure free. We demonstrate that depth electrode guided insular surgery is a safe and precise technique, leading to an optimal outcome.

Aneurysmal subarachnoid hemorrhage in patients with migraine and tension headache: A cohort comparison study.

Migraine headache is a common condition with an estimated lifetime prevalence of greater than 20%. While it is a well-established risk factor for cardiovascular disease and ischemic stroke, its association with subarachnoid hemorrhage is largely unexplored. We sought to compare the incidence of aneurysmal subarachnoid hemorrhage in a cohort of migraine patients with a cohort of patients with tension headache. A cohort comparison study utilizing the MarketScan insurance claims database compared patients diagnosed with migraine who were undergoing treatment with abortive or prophylactic pharmacotherapy (treatment cohort) and patients diagnosed with tension headache who had never been diagnosed with a migraine and who were naïve to migraine pharmacotherapy (control cohort). Patients with major pre-existing risk factors for aSAH were excluded from the study, and minor risk factors such as smoking status and hypertension were accounted for using coarsened exact matching (CEM) and subsequent cox proportional-hazards (CPH) regression. More than 679,000 patients (~125,000 treatment and ~ 550,000 control) with an average follow-up of more than three years were analyzed for aneurysmal subarachnoid hemorrhage. CPH regression on matched data showed that treated migraine patients had a significantly lower hazard of aneurysmal subarachnoid hemorrhage compared with tension headache patients (HR = 0.40, 95% CI: 0.19 - 0.86, p = 0.02). This large cohort comparison study, analyzing more than 679,000 patients, demonstrated that migraine patients undergoing pharmacologic treatment had a lower hazard of aneurysmal subarachnoid hemorrhage than patients diagnosed with tension headaches. Future work specifically focusing on migraine medications may identify the mechanisms underlying this association.

Emergent neuroimaging for seizures in epilepsy: A population study.

We determined how often patients with epilepsy presented to the emergency department (ED) for seizure and the frequency and predictors for undergoing emergent neuroimaging during those visits. We conducted a retrospective population-based cohort study using administrative claims' data from 2007 to 2015. Adults with epilepsy were identified based on a diagnosis of epilepsy and an outpatient prescription for an antiepileptic medication. The Bonferroni corrected significance level was 0.0018. We identified 381,362 patients with a mean follow-up period of 1.99 years, of whom 35,015 (9.2%) patients presented to the ED for seizure at least once. Patients with at least one ED visit were younger, more likely to be male, had fewer comorbidities, and had longer follow-up as compared with those with no ED visit (all p < 0.001). Among the 35,015 patients presenting to the ED, 13.6% had neuroimaging, mostly commonly head computed tomography (CT; 95.5%). Patients undergoing neuroimaging were younger (46 versus 48 years) and with higher rates of psychosis (17.4% versus 13.8%) and depression (16.1% versus 12.2%; p < 0.001). This helps to quantify the burden of ED and emergent neuroimaging utilization for patients with epilepsy and can help inform efforts to curtail unnecessary neuroimaging.

Comparative effectiveness of neuroablation and deep brain stimulation for treatment-resistant obsessive-compulsive disorder: a meta-analytic study.

BACKGROUND: The safety and efficacy of neuroablation (ABL) and deep brain stimulation (DBS) for treatment refractory obsessive-compulsive disorder (OCD) has not been examined. This study sought to generate a definitive comparative effectiveness model of these therapies. METHODS: A EMBASE/PubMed search of English-language, peer-reviewed articles reporting ABL and DBS for OCD was performed in January 2018. Change in quality of life (QOL) was quantified based on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the impact of complications on QOL was assessed. Mean response of Y-BOCS was determined using random-effects, inverse-variance weighted meta-analysis of observational data. FINDINGS: Across 56 studies, totalling 681 cases (367 ABL; 314 DBS), ABL exhibited greater overall utility than DBS. Pooled ability to reduce Y-BOCS scores was 50.4% (±22.7%) for ABL and was 40.9% (±13.7%) for DBS. Meta-regression revealed no significant change in per cent improvement in Y-BOCS scores over the length of follow-up for either ABL or DBS. Adverse events occurred in 43.6% (±4.2%) of ABL cases and 64.6% (±4.1%) of DBS cases (p<0.001). Complications reduced ABL utility by 72.6% (±4.0%) and DBS utility by 71.7% (±4.3%). ABL utility (0.189±0.03) was superior to DBS (0.167±0.04) (p<0.001). INTERPRETATION: Overall, ABL utility was greater than DBS, with ABL showing a greater per cent improvement in Y-BOCS than DBS. These findings help guide success thresholds in future clinical trials for treatment refractory OCD.

Point-of-care Ultrasonography for Detecting the Etiology of Unexplained Acute Respiratory and Chest Complaints in the Emergency Department: A Prospective Analysis.

Introduction  Point-of-care ultrasound (POCUS) is increasingly used as a diagnostic tool in emergency departments. As the number and type of POCUS protocols expand, there is a need to validate their efficacy in comparison with current diagnostic standards. This study compares POCUS to chest radiography in patients with undifferentiated respiratory or chest complaints. Methods A prospective convenience sample of 59 adult patients were enrolled from those presenting with unexplained acute respiratory or chest complaints (and having orders for chest radiography) to a single emergency department in an academic tertiary-care hospital. After a brief educational session, a medical student, blinded to chest radiograph results, performed and interpreted images from the modified Rapid Assessment of Dyspnea in Ultrasound (RADiUS) protocol. The images were reviewed by a blinded ultrasound fellowship-trained emergency physician and compared to chest radiography upon chart review. The primary "gold standard" endpoint diagnosis was the diagnosis at discharge. A secondary analysis was performed using the chest computed tomography (CT) diagnosis as the endpoint diagnosis in the subset of patients with chest CTs. Results When using diagnosis at discharge as the endpoint diagnosis, the modified RADiUS protocol had a higher sensitivity (79% vs. 67%) and lower specificity (71% vs. 83%) than chest radiography. When using chest CT diagnosis as the endpoint diagnosis (in the subset of patients with chest CTs), the modified RADiUS protocol had a higher sensitivity (76% vs. 65%) and lower specificity (71% vs. 100%) than chest radiography. The medical student performed and interpreted the 59 POCUS scans with 92% accuracy. Conclusion The sensitivity and specificity of POCUS using the modified RADiUS protocol was not significantly different than chest radiography. In addition, a medical student was able to perform the protocol and interpret scans with a high level of accuracy. POCUS has potential value for diagnosing the etiology of undifferentiated acute respiratory and chest complaints in adult patients presenting to the emergency department, but larger clinical validation studies are required.

Intracranial Hemorrhage in Deep Vein Thrombosis/Pulmonary Embolus Patients Without Atrial Fibrillation.

Background and Purpose- Deep vein thrombosis (DVTs) is a common disease with high morbidity if it progresses to pulmonary embolus (PE). Anticoagulation is the treatment of choice; warfarin has long been the standard of care. Early experience with direct oral anticoagulants (DOACs) suggests that these agents may be may be a safer and equally effective alternative in the treatment of DVT/PE. Nontraumatic intracranial hemorrhage (ICH) is one of the most devastating potential complications of anticoagulation therapy. We sought to compare the rates of ICH in patients treated with DOACs versus those treated with warfarin for DVT/PE. Methods- The MarketScan Commercial Claims and Medicare Supplemental databases were used. Adult DVT/PE patients without known atrial fibrillation and with prescriptions for either a DOAC or warfarin were followed for the occurrence of inpatient admission for ICH. Coarsened exact matching was used to balance the treatment cohorts. Cox proportional-hazards regressions and Kaplan-Meier survival curves were used to estimate the association between DOACs and the risk of ICH compared with warfarin. Results- The combined cohort of 218 620 patients had a median follow-up of 3.0 months, mean age of 55.4 years, and was 52.1% women. The DOAC cohort had 26 980 patients and 8 ICH events (1.0 cases per 1000 person-years), and the warfarin cohort had 191 640 patients and 324 ICH events (3.3 cases per 1000 person-years; P<0.0001). The DOAC cohort had a lower hazard ratio for ICH compared with warfarin in both the unmatched (hazard ratio=0.26; P=0.0002) and matched (hazard ratio=0.20; P=0.0001) Cox proportional-hazards regressions. Conclusions- DOACs show superior safety to warfarin in terms of risk of ICH in patients with DVT/PE.

Brainstem Dose Constraints in Nonisometric Radiosurgical Treatment Planning of Trigeminal Neuralgia: A Single-Institution Experience.

BACKGROUND: CyberKnife stereotactic radiosurgery (SRS) for trigeminal neuralgia (TGN) administers nonisometric, conformational high-dose radiation to the trigeminal nerve with risk of subsequent hypoesthesia. METHODS: We performed a retrospective, single-institution review of 66 patients with TGN treated with CyberKnife SRS to compare outcomes from 2 distinct treatment periods: standard dosing (n = 38) and reduced dosing (n = 28). Standard and reduced dosing permitted a maximum brainstem dose of 45 Gy and 25 Gy, respectively, each with a prescription dose of 60 Gy. Primary and secondary outcomes were Barrow Neurologic Institute pain and numbness scores. Maximum brainstem dose, prepontine nerve length, and treatment history were recorded for their predictive contributions by logistic regression. RESULTS: After matching, patients in the standard dosing and reduced dosing groups were followed for a median of 25 months and 19.5 months, respectively. Mean trigeminal nerve length was 8.55 mm in the standard dosing group and 9.46 mm in the reduced dosing group. Baseline rates of poorly controlled pain were 97% and 88%, respectively, which improved to 23.4% and 8.3%, respectively (P < 0.001 for both). The baseline rates of bothersome numbness were null in both groups, and increased to 25% in the standard group (P = 0.006) and to 21% in the reduced group (P = 0.07). Regression analyses suggested that reduced brainstem exposure (P = 0.01), as well as a longer trigeminal nerve (P = 0.01), were predictive of durable pain control. CONCLUSIONS: These outcomes demonstrate that a lower maximum brainstem dose can provide excellent pain control without affecting facial numbness. Longer nerves may achieve better long-term outcomes and help optimize individual plans.

A review of potential applications of MR-guided focused ultrasound for targeting brain tumor therapy.

Magnetic resonance-guided focused ultrasound (MRgFUS) has been used extensively to ablate brain tissue in movement disorders, such as essential tremor. At a lower energy, MRgFUS can disrupt the blood-brain barrier (BBB) to allow passage of drugs. This focal disruption of the BBB can target systemic medications to specific portions of the brain, such as for brain tumors. Current methods to bypass the BBB are invasive, as the BBB is relatively impermeable to systemically delivered antineoplastic agents. Multiple healthy and brain tumor animal models have suggested that MRgFUS disrupts the BBB and focally increases the concentration of systemically delivered antitumor chemotherapy, immunotherapy, and gene therapy. In animal tumor models, combining MRgFUS with systemic drug delivery increases median survival times and delays tumor progression. Liposomes, modified microbubbles, and magnetic nanoparticles, combined with MRgFUS, more effectively deliver chemotherapy to brain tumors. MRgFUS has great potential to enhance brain tumor drug delivery, while limiting treatment toxicity to the healthy brain.