Use of global sagittal flexibility to predict proximal junctional kyphosis after spinal deformity surgery.

OBJECTIVE: Sagittal alignment is an important predictor of functional outcomes after surgery for adult spinal deformity (ASD). A rigid spinal column may create a large lever arm that may impact the rate of proximal junctional kyphosis (PJK) after ASD surgery. In this study, the authors sought to determine whether relatively low preoperative global spinal flexibility (i.e., rigid spine) predicts increased incidence of PJK at 1 year after ASD surgery. METHODS: The authors retrospectively reviewed long-segment thoracolumbar fusions with pelvic fixation performed at a single tertiary care center between October 2015 and September 2020 in patients with a minimum of 1-year radiographic and clinical follow-up. Two cohorts were established on the basis of the optimal value for spinal flexibility, as defined by the absolute difference between the preoperative standing and supine C7 sagittal vertical axes, which the authors termed global sagittal flexibility (GSF). Demographic information, radiographs, various associated complications, and patient-reported outcome measures (PROMs) were analyzed. RESULTS: Eighty-five patients met the inclusion criteria. Receiver operating characteristic (ROC) analysis using GSF to predict an increase in the proximal junctional sagittal Cobb angle (PJCA) greater than or equal to 10° at 1-year follow-up provided an area under the curve of 0.64 and identified an optimal GSF threshold value of 3.7 cm. Patients with GSF > 3.7 cm were considered globally flexible (48 patients), and those with GSF ≤ 3.7 cm were classified as rigid (37 patients). Rigid patients were noted to have a significantly higher risk of ΔPJCA ≥ 10° at 1-year follow-up (51.4% vs 29.3%, p = 0.049). No changes in the reoperation rates or PROMs based on GSF were observed in the 1- or 2-year postoperative window. CONCLUSIONS: Based on these retrospective data, preoperative global spinal rigidity portends an independently elevated risk for the development of PJK after ASD surgery. No differences in other complication rates or PROMs data were observed between groups. Data collection was limited to a 2-year postoperative window; therefore, longer follow-up is required to further elucidate the relationship between rigidity and reoperation rates. Based on these retrospective data, flexibility may influence the outcomes of patients with ASD.

Demineralized Bone Matrix and Fibers in Spinal Fusion.

Formation of bony fusion after arthrodesis depends on osteoinduction, osteoconduction, and osteogenesis. Traditionally, the patient's own bone, or autograft, has been used to provide biological material necessary for these steps. However, the amount of autograft obtainable is often inadequate. Modern spine surgery has adopted the use of many autograft extenders or replacements, such as demineralized bone matrix or fibers. The present article covers the history of bone grafting, the production and technical details of demineralized bone matrix, and the evidence supporting its use in spine fusions.

Surgical Management of Recurrent Brain Metastasis: A Systematic Review of Laser Interstitial Thermal Therapy.

The incidence of recurrent metastatic brain tumors is increasing due to advances in local therapy, including surgical and radiosurgical management, as well as improved systemic disease control. The management of recurrent brain metastases was previously limited to open resection and/or irradiation. In recent years, laser interstitial thermal therapy (LITT) has become a promising treatment modality. As systemic and intracranial disease burden increases in a patient, patients may no longer be candidates for surgical resection. LITT offers a relatively minimally invasive option for patients that cannot tolerate or do not want open surgery, as well as an option for accessing deep-seated tumors that may be difficult to access via craniotomy. This manuscript aims to critically review the available data regarding the use of LITT for recurrent intracranial brain metastasis. Ten of seventy-two studies met the criteria for review. Generally, the available literature suggests that LITT is a safe and feasible option for the treatment of recurrent brain metastases involving supratentorial and cortical brain, as well as posterior fossa and deep-seated locations. Among all studies, only one directly compared craniotomy to LITT in the setting of recurrent brain metastasis. Prospective studies are needed to better elucidate the role of LITT in the management of recurrent brain metastases.

Viral therapies for glioblastoma and high-grade gliomas in adults: a systematic review.

OBJECTIVE: High-grade gliomas (HGGs) inevitably recur and progress despite resection and standard chemotherapies and radiation. Viral therapies have emerged as a theoretically favorable adjuvant modality that might overcome intrinsic factors of HGGs that confer treatment resistance. METHODS: The authors present the results of systematic searches of the MEDLINE and ClinicalTrials.gov databases that were performed for clinical trials published or registered up to July 15, 2020. RESULTS: Fifty-one completed clinical trials were identified that made use of a virus-based therapeutic strategy to treat HGG. The two main types of viral therapies were oncolytic viruses and viral vectors for gene therapy. Among clinical trials that met inclusion criteria, 20 related to oncolytic viruses and 31 to gene therapy trials. No oncolytic viruses have progressed to phase III clinical trial testing, although there have been many promising early-phase results and no reported cases of encephalitis or death due to viral therapy. Three phase III trials in which viral gene therapy was used have been completed but have not resulted in any FDA-approved therapy. Recent efforts in this area have been focused on the delivery of suicide genes such as herpes simplex virus thymidine kinase and cytosine deaminase. CONCLUSIONS: Decades of research efforts and an improving understanding of the immunomodulatory effects of viral therapies for gliomas are informing ongoing clinical efforts aimed at improving outcomes in patients with HGG. The available clinical data reveal varied efficacy among different virus-based treatment strategies.

Phase I trial of intracerebral convection-enhanced delivery of carboplatin for treatment of recurrent high-grade gliomas.

BACKGROUND: Carboplatin is a potent cytoreductive agent for a variety of solid tumors. However, when delivered systemically, clinical efficacy for the treatment of high grade gliomas is poor due to limited penetration across the blood-brain barrier (BBB). Direct intracerebral (IC) convection-enhanced delivery (CED) of carboplatin has been used to bypass the BBB and successfully treat the F98 rat glioma. Based on these studies, we initiated a Phase I clinical trial. OBJECTIVE: This Phase I clinical trial was conducted to establish the maximum tolerated dose and define the toxicity profile of carboplatin delivered intracerebrally via convection enhanced delivery (CED) for patients with high grade glial neoplasms. METHODS: Cohorts of 3 patients with recurrent WHO grade III or IV gliomas were treated with escalating doses of CED carboplatin (1-4 µg in 54mL over 72 hours) delivered via catheters placed at the time of recurrent tumor resection. The primary outcome measure was determination of the maximum tolerated dose (MTD). Secondary outcome measures included overall survival (OS), progression-free survival (PFS), and radiographic correlation. RESULTS: A total of 10 patients have completed treatment with infusion doses of carboplatin of 1µg, 2µg, and 4µg. The total planned volume of infusion was 54mL for each patient. All patients had previously received surgery and chemoradiation. Histology at treatment include GBM (n = 9) and anaplastic oligodendroglioma (n = 1). Median KPS was 90 (range, 70 to 100) at time of treatment. Median PFS and OS were 2.1 and 9.6 months after completion of CED, respectively. A single adverse event possibly related to treatment was noted (generalized seizure). CONCLUSIONS: IC CED of carboplatin as a potential therapy for recurrent malignant glioma is feasible and safe at doses up to 4µg in 54mL over 72 hours. Further studies are needed to determine the maximum tolerated dose and potential efficacy.

Techniques for Open Surgical Resection of Brain Metastases.

Brain metastases are the most common intracranial tumor and a leading cause of morbidity and mortality for patients with systemic cancer. En bloc surgical resection of brain metastases improves survival, local recurrence rates, and functional independence in patients with up to three metastases and controlled extracranial disease. Modern techniques and technologies provide the neurosurgeon with minimally invasive approaches, such as keyhole craniotomies and tubular retractors. Preoperative planning for tumors located in eloquent regions includes mapping with functional MRI and diffusion tensor imaging, and intraoperative mapping and monitoring with electrophysiologic techniques under general or awake anesthesia to preserve normal neurologic function.

One and Done: Multimodal Treatment of Pediatric Cerebral Arteriovenous Malformations in a Single Anesthesia Event.

BACKGROUND: Brain arteriovenous malformations (AVMs) are complex vascular lesions composed of abnormal arteries directly connected to veins without the typical intervening angioarchitecture. Rupture rates range from 2% to 4%, with that risk increasing to 4.5% per year for those presenting with hemorrhage. Mortality ranges from 12% to 66.7% after rupture, and up to 40% of survivors suffer from permanent neurologic sequelae. Treatment commonly includes a multimodality approach consisting of a combination of microsurgery, embolization, and radiosurgery. Typically, preoperative embolization is undertaken in a staged manner several days to weeks prior to microsurgical resection. METHODS: We describe a series of 5 pediatric patients harboring intracranial AVMs who underwent embolization and resection in the same anesthetic event, an approach that has not yet been described in the literature. RESULTS: Three patients presented symptomatically, whereas 2 AVMs were discovered incidentally, and average Spetzler-Martin grade was 1.6. Average anesthesia length was 580.8 minutes, and intraoperative angiography revealed complete resection in all cases. All patients were extubated at the end of the case and were discharged and followed up with a modified Rankin Scale score of 0. CONCLUSIONS: We describe a novel approach to treatment of pediatric intracranial AVMs that is shown to be safe and feasible. A single anesthesia event allows for aggressive preoperative embolization without increasing the risk of hemorrhage in the waiting period until resection. A single anesthesia event also prevents the patients from undergoing another intubation and anesthesia and decreases the risk associated with another anesthesia in a relatively short time frame.

Accelerated growth of hemangioblastoma in pregnancy: the role of proangiogenic factors and upregulation of hypoxia-inducible factor (HIF) in a non-oxygen-dependent pathway.

Hemangioblastomas (HBs) are benign, highly vascular tumors, often characterized by loss of function of the von Hippel-Lindau (vHL) gene. They are the most common central nervous system tumor observed in vHL syndrome. Loss of function of the vHL gene creates a "pseudo-hypoxic" state, causing overactivation of hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF)-related pathways. In some cases, HBs can rapidly increase in size during pregnancy to then present acutely, which most frequently occurs after the 20th gestational week. These changes in size usually occur from enlargement of the cystic component of the HB. Due to their preferred location in the posterior fossa near critical structures as well as along the spinal cord, such cases can present with severe neurological deficits, requiring urgent surgical intervention in a multidisciplinary setting. However, the reasons for this acute flare-up during pregnancy remain poorly understood, as are the reasons why this occurs in only a subset of tumors. Unveiling the etiology for this clinical scenario can affect the treatment of HBs, as it will contribute to the understanding of the pathophysiology of such a transformation from a quiescent lesion to a symptomatic one, not only in the setting of pregnancy. Identifying the correct triggers and the conditions initiating and mediating this switch will enable us to develop preventive medications which should allow us to keep the tumor in its quiescent phase. In this pathophysiological review, we investigate the association between HB growth and pregnancy based on an analysis > 40 such published cases. We suggest that the proangiogenic state of pregnancy is the leading etiology for this striking association, and to support the argument, we discuss its potential impact on HIF overexpression in a non-hypoxic manner through activation of the PI3K/Akt/mTOR pathway by proangiogenic factors. Specifically, we discuss the involvement of placental growth factor (PlGF) and its receptor vascular endothelial growth factor receptor 1 (VEGFR-1) in various pathologic processes that can lead to the formation and growth of peritumoral edema and cysts, which are the primary causes for the development of any symptoms in HB. Both PlGF and VEGFR-1 are expressed at increased levels during pregnancy, and both have been reported as part of various pathological processes, including angiogenesis and tumorigenesis. The unique feature that both do essentially not show any significant negative impact on regular physiological processes makes them attractive therapeutic targets since very little side effects are expected. Further research into the effects of anti-PlGF or anti-VEGFR-1 therapy in HB is therefore recommended.

A hypothalamic circuit for the circadian control of aggression.

'Sundowning' in dementia and Alzheimer's disease is characterized by early-evening agitation and aggression. While such periodicity suggests a circadian origin, whether the circadian clock directly regulates aggressive behavior is unknown. We demonstrate that a daily rhythm in aggression propensity in male mice is gated by GABAergic subparaventricular zone (SPZGABA) neurons, the major postsynaptic targets of the central circadian clock, the suprachiasmatic nucleus. Optogenetic mapping revealed that SPZGABA neurons receive input from vasoactive intestinal polypeptide suprachiasmatic nucleus neurons and innervate neurons in the ventrolateral part of the ventromedial hypothalamus (VMH), which is known to regulate aggression. Additionally, VMH-projecting dorsal SPZ neurons are more active during early day than early night, and acute chemogenetic inhibition of SPZGABA transmission phase-dependently increases aggression. Finally, SPZGABA-recipient central VMH neurons directly innervate ventrolateral VMH neurons, and activation of this intra-VMH circuit drove attack behavior. Altogether, we reveal a functional polysynaptic circuit by which the suprachiasmatic nucleus clock regulates aggression.

A Genetically Defined Circuit for Arousal from Sleep during Hypercapnia.

The precise neural circuitry that mediates arousal during sleep apnea is not known. We previously found that glutamatergic neurons in the external lateral parabrachial nucleus (PBel) play a critical role in arousal to elevated CO2 or hypoxia. Because many of the PBel neurons that respond to CO2 express calcitonin gene-related peptide (CGRP), we hypothesized that CGRP may provide a molecular identifier of the CO2 arousal circuit. Here, we report that selective chemogenetic and optogenetic activation of PBelCGRP neurons caused wakefulness, whereas optogenetic inhibition of PBelCGRP neurons prevented arousal to CO2, but not to an acoustic tone or shaking. Optogenetic inhibition of PBelCGRP terminals identified a network of forebrain sites under the control of a PBelCGRP switch that is necessary to arouse animals from hypercapnia. Our findings define a novel cellular target for interventions that may prevent sleep fragmentation and the attendant cardiovascular and cognitive consequences seen in obstructive sleep apnea. VIDEO ABSTRACT.

Supramammillary glutamate neurons are a key node of the arousal system.

Basic and clinical observations suggest that the caudal hypothalamus comprises a key node of the ascending arousal system, but the cell types underlying this are not fully understood. Here we report that glutamate-releasing neurons of the supramammillary region (SuMvglut2) produce sustained behavioral and EEG arousal when chemogenetically activated. This effect is nearly abolished following selective genetic disruption of glutamate release from SuMvglut2 neurons. Inhibition of SuMvglut2 neurons decreases and fragments wake, also suppressing theta and gamma frequency EEG activity. SuMvglut2 neurons include a subpopulation containing both glutamate and GABA (SuMvgat/vglut2) and another also expressing nitric oxide synthase (SuMNos1/Vglut2). Activation of SuMvgat/vglut2 neurons produces minimal wake and optogenetic stimulation of SuMvgat/vglut2 terminals elicits monosynaptic release of both glutamate and GABA onto dentate granule cells. Activation of SuMNos1/Vglut2 neurons potently drives wakefulness, whereas inhibition reduces REM sleep theta activity. These results identify SuMvglut2 neurons as a key node of the wake-sleep regulatory system.

Successful coil embolization of a ruptured mycotic aneurysm that developed three days after septic embolic infarction: Case report and review of the literature.

BACKGROUND: Infectious intracranial aneurysms (IIAs) are rare entities and are often associated with septic embolus from infectious endocarditis. They may develop rapidly and carry a higher risk of rupture and mortality compared to noninfectious aneurysms. However, the development and rupture of an IIA within 48h in a patient with septic infarction patient is exceedingly rare. CASE DESCRIPTION: In this report, we describe a 25-year-old male who presented with left-sided hemiparesis and dysarthria from septic embolus to the right middle cerebral artery. Thirty-nine hours after presentation, he became encephalopathic following a witnessed seizure. Angiography demonstrated a new, ruptured aneurysm, which was successfully treated with endovascular coil embolization. Our study documents the first report of coil embolization in a rapidly developed infectious aneurysm. CONCLUSIONS: Importantly, this case demonstrates that septic infarction may precede and herald IIA development and rupture. If IIA is detected due to rupture, coil embolization can be a safe and effective therapy.

BRAF-Mutated Pleomorphic Xanthoastrocytoma of the Spinal Cord with Eventual Anaplastic Transformation.

BACKGROUND: Pleomorphic xanthoastrocytoma (PXA) is an uncommon, primary neoplasm of the central nervous system with a relatively favorable prognosis. Most patients are managed with surgery alone and experience significant long-term survival. PXAs occur most commonly along the superficial surfaces of the temporal lobes. Although these tumors may occur in other regions of the brain, their origin within the spinal cord is rare, and it is unclear whether spinal cord PXAs should be managed differently from their intracranial counterparts. CASE DESCRIPTION: We describe a 31-year-old patient with a PXA of spinal cord origin who despite surgery, radiation, and multiple chemotherapy regimens experienced anaplastic transformation of his tumor and died of extensive leptomeningeal progression. CONCLUSIONS: To our knowledge, our patient represents the seventh reported case of PXA of the spinal cord but is the first described to have a BRAF mutation. Specifically, both the initial and recurrent tumors of the patient showed the same BRAF V600E mutation, which refutes previous suggestions that BRAF mutations may be limited to intracranial PXAs and also shows that BRAF mutations may occur earlier in PXA tumorigenesis.

Genetic Characterization of a Multifocal Ganglioglioma Originating Within the Spinal Cord.

BACKGROUND: Gangliogliomas are rare, low-grade intra-axial tumors that exhibit both neuronal and glial components. Although the vast majority present as an intracranial lesion, a rare subset exist as isolated lesions of the spinal cord. Gangliogliomas have also been shown to harbor mutations in the p53 tumor suppressor gene and BRAF oncogene. Previous studies in ganglioglioma have correlated p53 mutations with histologic transformation and BRAF mutations with worse prognosis. CASE DESCRIPTION: In this report, we describe a 35-year-old female who presented with multifocal ganglioglioma, involving both the conus medullaris and filum terminale. The dominant lesion in the filum terminale was resected, which revealed World Health Organization I grade, p53 mutant, and BRAF wildtype status. Our study documents the first report of a multifocal ganglioglioma, originating within the spinal cord. CONCLUSIONS: Importantly, this case contradicts previous reports of p53 and BRAF mutations portending worsened tumor behavior and prognosis and demonstrates that further studies are needed to delineate the role of genetic characterization in the biologic understanding and management of gangliogliomas.

Suprachiasmatic neuron numbers and rest-activity circadian rhythms in older humans.

The suprachiasmatic nucleus (SCN) of the hypothalamus, the master mammalian circadian pacemaker, synchronizes endogenous rhythms with the external day-night cycle. Older humans, particularly those with Alzheimer disease (AD), often have difficulty maintaining normal circadian rhythms compared to younger adults, but the basis of this change is unknown. We report that the circadian rhythm amplitude of motor activity in both AD subjects and age-matched controls is correlated with the number of vasoactive intestinal peptide-expressing SCN neurons. AD was additionally associated with delayed circadian phase compared to cognitively healthy subjects, suggesting distinct pathologies and strategies for treating aging- and AD-related circadian disturbances.

Sleep is related to neuron numbers in the ventrolateral preoptic/intermediate nucleus in older adults with and without Alzheimer's disease.

Fragmented sleep is a common and troubling symptom in ageing and Alzheimer's disease; however, its neurobiological basis in many patients is unknown. In rodents, lesions of the hypothalamic ventrolateral preoptic nucleus cause fragmented sleep. We previously proposed that the intermediate nucleus in the human hypothalamus, which has a similar location and neurotransmitter profile, is the homologue of the ventrolateral preoptic nucleus, but physiological data in humans were lacking. We hypothesized that if the intermediate nucleus is important for human sleep, then intermediate nucleus cell loss may contribute to fragmentation and loss of sleep in ageing and Alzheimer's disease. We studied 45 older adults (mean age at death 89.2 years; 71% female; 12 with Alzheimer's disease) from the Rush Memory and Aging Project, a community-based study of ageing and dementia, who had at least 1 week of wrist actigraphy proximate to death. Upon death a median of 15.5 months later, we used immunohistochemistry and stereology to quantify the number of galanin-immunoreactive intermediate nucleus neurons in each individual, and related this to ante-mortem sleep fragmentation. Individuals with Alzheimer's disease had fewer galaninergic intermediate nucleus neurons than those without (estimate -2872, standard error = 829, P = 0.001). Individuals with more galanin-immunoreactive intermediate nucleus neurons had less fragmented sleep, after adjusting for age and sex, and this association was strongest in those for whom the lag between actigraphy and death was <1 year (estimate -0.0013, standard error = 0.0005, P = 0.023). This association did not differ between individuals with and without Alzheimer's disease, and similar associations were not seen for two other cell populations near the intermediate nucleus. These data are consistent with the intermediate nucleus being the human homologue of the ventrolateral preoptic nucleus. Moreover, they demonstrate that a paucity of galanin-immunoreactive intermediate nucleus neurons is accompanied by sleep fragmentation in older adults with and without Alzheimer's disease.