Erratum: Massive Gravitons as Feebly Interacting Dark Matter Candidates [Phys. Rev. Lett. 128, 081806 (2022)].

This corrects the article DOI: 10.1103/PhysRevLett.128.081806.

Urgent Spinal Surgery in a Lateral Decubitus on a Patient with a Left Ventricular Assist Device on Full Anticoagulation: A Case Report.

This case report aims to demonstrate the feasibility of performing spinal surgery in patients with a left ventricular assist device (LVAD), who are traditionally considered unsuitable candidates due to the need for anticoagulation and the challenges associated with the prone position. A case of a patient with an LVAD undergoing microdiscectomy in the left lateral decubitus position is presented. The procedure was carried out by a specialized interdisciplinary team with appropriate monitoring. The patient underwent the procedure safely, demonstrating that spinal surgery can be performed in patients with LVAD without reversing anticoagulation or resorting to the prone position. This approach mitigates the risk of thrombotic events and hemodynamic instability. This case study suggests that spinal surgery, specifically microdiscectomy, can be safely performed in patients with LVAD using the left lateral decubitus position. This finding has significant implications for patients who are unable to ambulate and therefore struggle to qualify for a heart transplant.

Management of Poor-Grade Aneurysmal Subarachnoid Hemorrhage and Key Pearls for Achieving Favorable Outcomes: An Illustrative Case.

Poor-grade aneurysmal subarachnoid hemorrhage (aSAH) is associated with high patient mortality. Despite recent advances in management strategies, the prognosis for poor-grade aSAH remains dismal. We present a challenging case of a patient presenting with poor-grade aSAH. A 46-year-old female presented to the emergency department after losing consciousness following a sudden headache. The examination showed a dilated left pupil and a Glasgow Coma Scale of 4. Imaging revealed a ruptured anterior communicating artery (ACoM) aneurysm, after which the patient was subsequently taken to the neuro-interventional radiology suite. We showed that carefully managing blood pressure and intracranial pressure (ICP) makes it possible to achieve a favorable outcome and reduce the risk of secondary brain injury in aSAH, regardless of patient presentation. We propose maintaining blood pressure at <160 mmHg prior to intervention, after which it can be permitted to increase to 160-240 mmHg for the purpose of preventing vasospasm. Additionally, transcranial doppler (TCD) is essential to detect vasospasm due to the subtility of symptoms in patients with aSAH. Once identified, vasospasm can be successfully treated with balloon angioplasty. Finally, targeted temperature management (TTM), mannitol, hypertonic saline, and neuromuscular paralysis are essential for the postoperative management of ICP levels.

Massive Gravitons as Feebly Interacting Dark Matter Candidates.

We detail our discovery of a chiral enhancement in the production cross sections of massive spin-2 gravitons, below the electroweak symmetry breaking scale, that makes them ideal dark matter candidates for the freeze-in mechanism. The result is independent of the physics at high scales and points toward masses in the keV-MeV range. The graviton is, therefore, a sub-MeV dark matter particle, as favored by the small scale galaxy structures. We apply the novel calculation to a Randall-Sundrum model with multiple branes, showing a significant parameter space where the first two massive gravitons saturate the dark matter relic density.

Z-Portal Continuum Dark Matter.

We examine the possibility that dark matter (DM) consists of a gapped continuum, rather than ordinary particles. A weakly interacting continuum (WIC) model, coupled to the standard model via a Z portal, provides an explicit realization of this idea. The thermal DM relic density in this model is naturally consistent with observations, providing a continuum counterpart of the "WIMP miracle." Direct detection cross sections are strongly suppressed compared to ordinary Z-portal WIMP, thanks to a unique effect of the continuum kinematics. Continuum DM states decay throughout the history of the Universe, and observations of cosmic microwave background place constraints on potential late decays. Production of WICs at colliders can provide a striking cascade-decay signature. We show that a simple Z-portal WIC model provides a fully viable DM candidate consistent with all current experimental constraints.

Management of post-cervical laminectomy fusion pain syndrome with a successful trial of spinal cord stimulation.

INTRODUCTION: Spinal cord stimulation has been shown to be beneficial in various postsurgical neuropathic pain syndromes, but the already small cervical epidural space due to epidural fibrosis makes cervical spinal cord stimulator placement very difficult. We present a case of successful cervical cord stimulator implantation in a patient with a history of anterior cervical discectomy and fusion, posterior cervical fusion, and significant epidural fibrosis. METHODS: A 48-year-old woman with a history of type 2 diabetes, nonalcoholic steatohepatitis, and fibromyalgia presented with trauma-induced cervicalgia and bilateral upper extremity radiculopathy. RESULTS: In a 4-day trial of stimulation, she reported an 80% reduction of her pain and significant improvement in her quality of life. DISCUSSION: Although anecdotal evidence and case series have shown spinal cord stimulation to be successful in cervical failed back surgery syndrome, we are the first to discuss the technical challenges and complications associated with epidural fibrosis.

Difficult removal of exposed peripheral nerve stimulator leads: a report of 2 cases.

INTRODUCTION: Peripheral nerve stimulators have emerged as a new generation of advanced modalities to treat chronic pain and avoid opioids. They transmit electrical stimulation through implanted leads and wireless, wearable, external generators. Common complications include infection, nerve damage, and migration of stimulating leads. This article describes 2 cases of complications from lead migration. METHODS: Case 1 describes a 61-year-old man with chronic groin pain who underwent an uncomplicated ultrasound-guided ilioinguinal peripheral nerve lead implantation. Case 2 describes a 54-year-old woman with left shoulder pain who underwent an uncomplicated ultrasound-guided percutaneous lead placement near the axillary nerve through a deltoid approach. Both peripheral nerve stimulators were confirmed with fluoroscopy, and each patient was followed up every 2 months for the following 2 years. RESULTS: Both patients experienced lead migration to the skin resulting in erythema and need for lead removal. Initial unsuccessful removal by traction resulted in retained fragments and need for open surgical removal. DISCUSSION: Neurologic complications of peripheral nerve stimulator implantation are rare, but device-associated complications, specifically lead migration, remain a source of long-term problems that can result in decreased coverage of the intended neural target. CONCLUSION: Thorough patient education, early postimplantation assessment, and extended routine follow-up are necessary to decrease lead-associated complications. If migration does occur, the potential impact of scar tissue on removal should be considered.

Fluid Restriction After Transsphenoidal Surgery for the Prevention of Delayed Hyponatremia: A Systematic Review and Meta-Analysis.

OBJECTIVE: Delayed hyponatremia is the primary cause of readmission after transsphenoidal surgery, with a reported incidence of 9% to 30.7%. Studies have failed to identify consistent predictive factors for postoperative hyponatremia; thus, it is difficult to determine patients that are at a high risk. Fluid restriction is one approach for the prevention of hyponatremia. We have performed a meta-analysis and systematic review of the literature to evaluate the impact of fluid restriction on hyponatremia and hospital readmissions. METHODS: Ovid EMBASE, PubMed, Scopus, and Cochrane were searched from inception to May 2021, using the Population, Intervention, Comparison, Outcome, and Study question format: Do patients who underwent transsphenoidal surgery and followed a postoperative fluid restriction regimen differ in terms of hyponatremia and readmission rates? Studies that implemented fluid restriction and reported hyponatremia and/or readmission rates were included for analysis. Data were pooled by meta-analysis and analyzed using fixed effect and random effect models. RESULTS: A total of 143 manuscripts representing 103 unique studies were identified, with 5 studies included for analysis, yielding a pooled cohort of 1586 patients: 594 on fluid restriction protocols and 992 control patients. Fluid restriction protocols ranged from 1.0 to 2.5 L and varied in the length time between postoperative days 1 to 15. Patients on fluid restriction had a decreased risk of hyponatremia (risk ratio: 0.34; 95% CI, 0.21-0.57; P < .00001) and readmission due to hyponatremia (risk ratio: 0.24; 95% CI, 0.09-0.63; P = .0038). CONCLUSION: Postoperative fluid restriction after transsphenoidal surgery represents an effective method for the prevention of hyponatremia and hospital readmission and has the potential to decrease health care costs.

Single-neuron correlate of epilepsy-related cognitive deficits in visual recognition memory in right mesial temporal lobe.

OBJECTIVE: Impaired memory is a common comorbidity of refractory temporal lobe epilepsy (TLE) and often perceived by patients as more problematic than the seizures themselves. The objective of this study is to understand what the relationship of these behavioral impairments is to the underlying pathophysiology, as there are currently no treatments for these deficits, and it remains unknown what circuits are affected. METHODS: We recorded single neurons in the medial temporal lobes (MTLs) of 62 patients (37 with refractory TLE) who performed a visual recognition memory task to characterize the relationship between behavior, tuning, and anatomical location of memory selective and visually selective neurons. RESULTS: Subjects with a seizure onset zone (SOZ) in the right but not left MTL demonstrated impaired ability to recollect as indicated by the degree of asymmetry of the receiver operating characteristic curve. Of the 1973 recorded neurons, 159 were memory selective (MS) and 366 were visually selective (VS) category cells. The responses of MS neurons located within right but not left MTL SOZs were impaired during high-confidence retrieval trials, mirroring the behavioral deficit seen both in our task and in standardized neuropsychological tests. In contrast, responses of VS neurons were unimpaired in both left and right MTL SOZs. Our findings show that neuronal dysfunction within SOZs in the MTL was specific to a functional cell type and behavior, whereas other cell types respond normally even within the SOZ. We show behavioral metrics that detect right MTL SOZ-related deficits and identify a neuronal correlate of this impairment. SIGNIFICANCE: Together, these findings show that single-cell responses can be used to assess the causal effects of local circuit disruption by an SOZ in the MTL, and establish a neural correlate of cognitive impairment due to epilepsy that can be used as a biomarker to assess the efficacy of novel treatments.

Infectious Complications of Expanded Endoscopic Transsphenoidal Surgery: A Retrospective Cohort Analysis of 100 Cases.

Objective To identify perioperative factors that may predict postoperative cerebrospinal fluid (CSF) leak and meningitis following expanded endoscopic transsphenoidal surgery (EETS). Study Design This is a retrospective study. This study was set at the Cedars-Sinai Medical Center, Los Angeles. A total of 78 patients who underwent EETS between January 2007 and November 2018 were participated. The main outcome measures were CSF leak and meningitis. Results A total of 78 patients underwent a total of 100 EETS procedures; 17.9 and 10.3% of patients developed postoperative CSF leaks and meningitis, respectively. Out of eight, three patients with meningitis did not develop an observable CSF leak. The risk of developing meningitis in patients with a CSF leak was significantly higher than those without a leak, with an odds ratio (OR) of 11.48 (95% confidence interval, 2.33-56.47; p = 0.004). Pituicytomas were significantly associated with meningitis compared with other pathologies. No other patient-specific factors were identified as risks for leak or meningitis, including method of skull base repair, sex, tumor volume, or body mass index, although there was a strong trend toward reduced CSF leak rates in patient with nasoseptal flaps used for skull base repair, compared with those without (9.5 vs. 25%). CSF protein was consistently elevated on the first CSF values obtained when meningitis was suspected. Conclusion CSF leak and meningitis are common complications of expanded endonasal surgery No statistically significant risk factors for developing a postoperative leak other than the pathology of pituicytoma were identified, including method of skull base repair, although the use of a vascularized nasoseptal flap did trend toward a reduced CSF leak rate. CSF protein is the most sensitive marker for the presumptive diagnosis and timely treatment of meningitis.

BRAF V600E Mutations Occur in a Subset of Glomus Tumors, and Are Associated With Malignant Histologic Characteristics.

Glomus tumors are rare mesenchymal neoplasms with a phenotype akin to the modified smooth muscle cells of the glomus body. Most are benign, but rare examples show malignant histologic characteristics and aggressive behavior. We recently encountered a malignant glomus tumor with BRAF V600E mutation. We sought to study a large cohort for this mutation, with particular attention to associated malignant histologic characteristics. Tumors were classified based on WHO criteria as benign, uncertain malignant potential (glomus tumors of uncertain malignant potential-GT-UMP), or malignant. Tumors were screened for BRAF V600E by immunohistochemistry, and positive staining was evaluated further by Sanger sequencing. A total of 102 glomus tumors were included and classified as benign (57, 56%), GT-UMP (15, 15%) and malignant (30, 29%). Tumors occurred in patients aged 8 to 89.9 years (median: 50.2), without sex predilection (55% men). Most occurred in the superficial soft tissue (84%) and upper extremities (55%). Six of 95 tested cases had BRAF V600E mutation (6%), including 0 of 57 benign tumors, 3 of 14 GT-UMP (21%), and 3 of 24 malignant tumors (12%). Follow-up was obtained for 59 cases (median: 75.7 mo, range: 7.8 to 268.5). Three of 11 malignant tumors (27%) had progressive disease: 1 with metastasis to brain and heart, 1 with enlarging residual disease, and 1 with recurrence. Two of 4 GT-UMP (50%) had progressive disease: 1 with metastasis to lung, and 1 with local recurrence (50%). Three of 44 benign tumors (7%) had local recurrence. Two of 5 patients with BRAF V600E had progression, including 1 GT-UMP with local recurrence and 1 malignant tumor with enlarging residual disease. In summary, BRAF V600E mutation was detected in 6% of glomus tumors, all of which were malignant or GT-UMP. This mutation may be associated with a malignant phenotype, although study of additional cases is needed. In patients with progressive disease, BRAF could be a promising therapeutic target.

Overlooked diagnosis of infected paratracheal air cysts in patients with respiratory symptoms: Case report.

RATIONALE: Infected paratracheal air cysts as the focus of respiratory symptoms can be overlooked in practice because of nonspecific symptoms and physician's scant knowledge for this entity. We report 2 cases of infected paratracheal air cyst diagnosed at chest computed tomography (CT) and bronchoscopy/endobronchial ultrasound. PATIENT CONCERN: Two patients visited our hospital with respiratory symptoms, including cough, sputum, and fever. DIAGNOSES: Chest CT showed paratracheal cystic lesions with air-fluid level in the thoracic inlet. In the first patient, endobronchial ultrasound revealed a right paratracheal hypoechoic mass corresponding to the lesion on CT scan. In the second patient, bronchoscopy revealed purulent discharge from a dimpling at posterolateral wall of trachea, which was the opening of communication between the trachea and infected paratracheal air cyst. INTERVENTIONS: Both patients received antibiotic treatment. OUTCOME: After medical treatment, the patients' symptoms were improved. Follow-up chest CT scans showed air-filled paratracheal air cysts without internal fluid or rim enhancement. LESSONS: A physician should pay attention to paratracheal air cyst in patients with respiratory symptoms when their lungs are clear on CT scan.

Corpora amylacea mimicking low-grade glioma and manifesting as a seizure: Case report.

BACKGROUND: Corpora amylacea (CA) are accumulations of polyglucosan bodies typically found in astrocytic foot processes, and rarely, can mimic neoplasm. CA accumulation has also been associated with seizure disorders. We report the first case of a histologically confirmed intracranial, intraparenchymal CA lesion mimicking a low-grade glioma and manifesting as a seizure. CASE DESCRIPTION: A 43-year-old man presented after a general tonic-clonic (GTC) seizure. Brain magnetic resonance imaging (MRI) revealed a small lesion in the right mesial temporal lobe with radiologic features of a low-grade glioma. The patient underwent a right pteronial craniotomy for resection of the lesion. Histology demonstrated abundant polyglucosan bodies without neoplastic features. The patient tolerated the procedure well, was free from seizures without antiepileptic drugs at 2-week follow-up, and is undergoing serial surveillance. CONCLUSION: The clinical manifestation of CA as a seizure in the context of an identified brain mass is extraordinarily rare. Nevertheless, CA should be considered in the differential diagnosis for patients with seizures and a radiologically identifiable low-grade lesion. Symptomatic CA lesions Mimicking a low-grade glioma should be surgically pursued with a goal of safe, maximal resection to confirm the diagnosis and to provide the patient with prognosis, which can significantly impact patient quality of life.

Analyzing the efficacy of frequent sodium checks during hypertonic saline infusion after elective brain tumor surgery.

OBJECTIVE: To assess the utility of frequent sodium checks (every 6h) in patients receiving hypertonic saline (HS) after elective brain tumor surgeries. PATIENTS AND METHODS: A single-institution retrospective review of patients having undergone elective craniotomies for brain tumors and treated with postoperative continuous intravenous infusions of 3% HS was performed. Changes in serum sodium values were analyzed at different time points. The rates of <12.5, 25, and 50cc/h infusions were also examined. Healthcare cost analysis was performed by extrapolating our cohort to the total number of craniotomies performed in the United States. RESULTS: No significant differences among sodium values checked between 0 to 4, 4-6, 6-8, 8-10, and >10h were observed (P=.64). In addition, no differences in serum sodium values among the rates of <12.5, 25, and 50cc/h were found (P=.30). No patients developed symptoms of acute hypernatremia. CONCLUSIONS: Serum sodium values did not significantly change more than 10h after infusion of HS. Further studies are needed to determine the optimal frequency of routine sodium checks to increase the quality of care and decrease healthcare costs.

Computerized Assessment of Superior Semicircular Canal Dehiscence Size using Advanced Morphological Imaging Operators.

Superior semicircular canal dehiscence (SSCD) describes a pathological aperture at the level of the arcuate eminence. Techniques for quantifying defect size are described with most studies using two-dimensional lengths that underestimate the pathology. The objective of this study is to describe a novel method of measurement that combines manual segmentation of high-resolution computed tomography (HRCT) images of the temporal bone and a morphological skeletonization transform to calculate dehiscence volume. Images were imported into a freely available image segmentation tool: ITK-SNAP (version 3.4.0; available at: http://www.itksnap.org/) software. Coronal and sagittal planes were used to outline the dehiscence in all slices demonstrating the defect using the paintbrush tool. A morphological skeletonization transform derived a single-pixel thick representation of the original delineation. This "sheet" of voxels overlaid the dehiscence. Volume was calculated by counting the number of nonzero image voxels within this "sheet" and multiplying this number by the volume (mm3) of each voxel. A total of 70 cases of SSCD were identified. Overall, mean volume was 0.88 mm3 (standard deviation: 0.57, range: 0.11-2.27). We present a novel technique for measuring SSCD, which we believe provides a more accurate representation of the pathology, and has the potential to standardize measurement of SSCD.

Pineal germ cell tumors: Two cases with review of histopathologies and biomarkers.

Pineal germ cell tumors (GCTs) are primarily seen in pediatric and Asian populations. These tumors are divided into germinomatous and non-germinomatous GCTs (NGGCTs). GCTs are thought to arise by misplacement of totipotent stem cells en route to gonads during embryogenesis. Intracranial GCTs display an affinity to develop along the pineal-suprasellar axis and have variable manifestations dependent upon the location of the tumor. Management and outcomes are driven by histopathologies. In this study, we highlight two cases of pineal GCTs and present a review of the literature with an emphasis on histopathologies and biomarkers.

Utilizing virtual and augmented reality for educational and clinical enhancements in neurosurgery.

Neurosurgery has undergone a technological revolution over the past several decades, from trephination to image-guided navigation. Advancements in virtual reality (VR) and augmented reality (AR) represent some of the newest modalities being integrated into neurosurgical practice and resident education. In this review, we present a historical perspective of the development of VR and AR technologies, analyze its current uses, and discuss its emerging applications in the field of neurosurgery.

Evaluating the utility of a scoring system for lipomas of the cerebellopontine angle.

BACKGROUND: Cerebellopontine angle (CPA) lipomas are rare, benign, slow-growing masses. Resections are considered in symptomatic patients who are refractory to targeted medical therapies, but at those stages the lipomas have often reached considerable sizes and encompass critical neurovascular structures. The objective of this study is to develop and to evaluate the utility of a scoring system for CPA lipomas. The hypothesis is that CPA lipomas with lower scores are probably best managed with early surgery. METHODS: The PubMed database was searched using relevant terms. Data on patient and lipoma characteristics were extracted and used to design a scoring system. CPA lipomas were stratified by scores with corresponding managements and outcomes analyzed. RESULTS: One hundred and seventeen patients with CPA lipomas were identified and 40 CPA lipomas were scored. The remaining CPA lipomas were deficient in data and not scored. No lipomas were scored as 1. Score 2 lipomas (n = 12; 30%) most often underwent serial surveillances (n = 5; 41.6%), with the majority of symptoms remaining unimproved (n = 2; 40%). Patients with score 2 CPA lipomas treated with medical therapies (n = 3; 25%) often experienced symptom resolution (n = 2; 66.6%) (p = 0.0499). Patients with score 2 CPA lipomas undergoing surgical resections (n = 3; 25%) all experienced symptom resolution (n = 3; 100%) (p = 0.0499). Score 3 was most common (n = 16; 40%) and these lipomas were often surgically resected (n = 10; 62.5%). The majority of patients with score 3 CPA lipomas having undergone surgical resections (n = 10; 62.5%) experienced symptom improvement (n = 1; 10%) or resolution (n = 4; 40%). CONCLUSIONS: Score 2 CPA lipomas are smaller and would be deemed non-surgical in general practice. However, our data suggest that these lipomas may benefit from either medical therapies or early surgical resections. The advantages of early surgery are maximal resection, decreased surgical morbidity, and improved symptom relief.

Isolated Transverse Process Fractures: A Systematic Analysis.

OBJECTIVE: To review the literature on isolated transverse process fractures (ITPFs) and provide evidence for the current practice of conservative management. METHODS: The PubMed database was searched for published literature related to ITPFs. Baseline patient (age, sex, presentation, and mechanism of injury) and fracture (number of fractures, level, and single or multisegmental) characteristics were extracted. Management and outcomes were also recorded. Statistical comparisons were ascertained through n-1 Pearson χ2 tests. RESULTS: A total of 4 studies comprised of 398 patients with 819 ITPFs were evaluated. Mean age was 33.5 years (69% men and 31% women). No patients presented with neurologic deficits. The most common mechanism of injury was motor vehicle accident (MVA), followed by fall. MVAs were more commonly the cause of ITPFs in pediatric versus adult patients (88% vs. 65%, respectively; P = 0.0001). Falls were more commonly the cause of ITPFs in adults than in children (18% vs. 9%, respectively; P = 0.05). Management strategies involved unrestricted movement, bracing, and orthotics. Radiologic evidence of spinal instability or deformity was not reported in any of the cases. Mean follow-up was 20.5 months. CONCLUSIONS: Our data suggests that nonsurgical management of ITPFs leads to complete resolution of the fracture without evidence of permanent neurologic deficit or spinal instability. However, interpretation of our results is limited by the paucity of meaningful literature reporting on long-term outcomes. Nevertheless, the results provide support for conservative management and highlight the existing need to identify markers or scenarios where the diagnosis of ITPF is actually likely to be erroneous.

Laser neurosurgery: A systematic analysis of magnetic resonance-guided laser interstitial thermal therapies.

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel minimally invasive modality that uses heat from laser probes to destroy tissue. Advances in probe design, cooling mechanisms, and real-time MR thermography have increased laser utilization in neurosurgery. The authors perform a systematic analysis of two commercially available MRgLITT systems used in neurosurgery: the Visualase® thermal therapy and NeuroBlate® Systems. Data extraction was performed in a blinded fashion. Twenty-two articles were included in the quantitative synthesis. A total of 223 patients were identified with the majority having undergone treatment with Visualase (n=154, 69%). Epilepsy was the most common indication for Visualase therapy (n=8 studies, 47%). Brain mass was the most common indication for NeuroBlate therapy (n=3 studies, 60%). There were no significant differences, except in age, wherein the NeuroBlate group was nearly twice as old as the Visualase group (p<0.001). Frame, total complications, and length-of-stay (LOS) were non-significant when adjusted for age and number of patients. Laser neurosurgery has evolved over recent decades. Clinical indications are currently being defined and will continue to emerge as laser technologies become more sophisticated. Head-to-head comparison of these systems was difficult given the variance in indications (and therefore patient population) and disparate literature.