Dynamic interaction between cerebrospinal fluid and sinovenous pressure in idiopathic intracranial hypertension: a case report.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a common neurosurgical condition, and the exact pathophysiology remains elusive. Cerebral sinovenous stenosis (CSS) and the resultant decreased venous outflow have been labelled as a potential contributors to the pathophysiology of IIH. We describe the effect of cerebrospinal fluid (CSF) drainage on sinovenous pressure in a patient with IIH and a radiographic evidence of CSS. CASE DESCRIPTION: A patient in their 40s with a diagnoses of IIH and imaging finding of focal stenosis of the distal left transverse sinus. To assess the nature of the stenosis, we performed venous sinus pressure monitoring with concurrent CSF drainage (5 ml at one minute intervals) through a lumbar drain with continuous mean sinovenous pressures recording. We observed a progressive decline in the pressure recording while draining CSF, after draining 40 ml of CSF, the final pressure gradient recording of the TS-SS trans-stenotic was (7 mm Hg from 27 mm Hg), mean SSS pressure (37 mm Hg from 60 mm Hg), and mean TS pressure (35 mm Hg from 56 mm Hg). The mean SS pressure remained relatively unperturbed. CONCLUSION: Our findings indicate that the cerebral sinovenous pressure response to CSF removal generally conforms to a monophasic exponential decay model.

Early ambulation after transfemoral diagnostic cerebral angiography: a pilot study.

BACKGROUND: A significant proportion of transfemoral cerebral angiography complications are related to the access site, with no clear consensus concerning the optimal closure technique. In this study, we examined the usefulness of a shortened closure protocol for transfemoral diagnostic cerebral angiography. METHODS: We performed a retrospective review of patients who underwent transfemoral (4Fr sheath) diagnostic cerebral angiography procedures at our institution. We included patients > 18 years old who underwent the shortened closure protocol to achieve hemostasis at the access site. The shortened protocol entailed the use of nonocclusive manual compression for 15 min followed by 2 h of bed rest, with additional 10-15 min of compression for new hematoma. We collected and analyzed the patients' demographics, use of antiplatelet and anticoagulation medications, sheath size, and others. RESULTS: The study cohort comprised 119 patients with a mean age was 54 years with (88%) females. Forty-one patients (34%) were on antiplatelet medications, with 12 (10%) on dual antiplatelet therapy (DAPT). Four patients (3%) (two on DAPT, one on Aspirin alone, and one was not on any antiplatelet medication) had access site hematoma that required additional compression. Subgroup analysis showed that within the DAPT, Aspirin alone, and no antiplatelet medications groups, (17%), (3%), and (1%) of patients developed access site hematoma, respectively. CONCLUSION: This pilot study demonstrates that our closure protocol for transfemoral angiograms is safe and effective. There was a trend toward higher access-site complications in patients on DAPT. Further studies are required to expand on and validate our results.

Thoracic ganglioneuroma with extension into the epidural space.

A patient in their 30s presented with chronic right upper quadrant abdominal pain, nausea, bloating, and constipation. Her clinical exam was unremarkable, and computed tomography (CT) of the chest and abdomen which showed a large right-sided thoracic mass with extension into the thoracic spinal canal. A needle biopsy revealed a diagnosis of ganglioneuroma, the patient then underwent a combined approach for excision the tumor. Ganglioneuroma is a neuroblastic tumor of a neural crest origin, it originates from paravertebral sympathetic chain ganglia of the posterior mediastinum or retroperitoneum. They usually extend through neuroforamina to involve the epidural space and surgical excision can be curative.

Economics of the Management of Craniospinal Chordoma and Chondrosarcoma and the feasibility of the bundled payment model.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) created a new reimbursement model "Bundled Payment for Care Improvement (BPCI)" which reimburses providers a predetermined payment in advance to cover all possible services rendered within a certain time window. Chordoma and Chondrosarcoma are locally aggressive malignant primary bony tumors. Treatment includes surgical resection and radiotherapy with substantial risk for recurrence which necessitates monitoring and further treatment. We assessed the feasibility of the BPCI model in these neurosurgical diseases. METHODS: We selected patients with chordoma/chondrosarcoma from inpatient admission table using the International Classification of Disease, 9th (ICD-9), and 10th (ICD-10) revision codes. We collected the patients' demographics and insurance type at the index hospitalization. We recorded the following outcomes length of stay, total payment, discharge disposition, and complications for the index hospitalization. For post-discharge, we collected the 30 days and 3/6/12 months inpatient admission, outpatient service, and medication refills. Continuous variables were summarized by means with standard deviations, median with interquartile and full ranges (minimum-maximum); Continuous outcomes were compared by nonparametric Wilcoxson rank-sum test. All tests were 2-sided with a significance level of 0.05. Statistical data analysis was performed in SAS 9.4 (SAS Institute, Inc, Cary, NC). RESULTS: The population size was 2041 patients which included 1412 patients with cranial (group1), 343 patients with a mobile spine (group 2), and 286 patients with sacrococcygeal (group 3) chordoma and chondrosarcoma. For index hospitalization, the median length of stay (days) was 4, 6, and 7 for groups 1, 2, and 3 respectively (P<.001). The mean payments were ($58,130), ($84,854), and ($82,440), for groups 1, 2, and 3 respectively (P=.02). The complication rates were 30%, 35%, and 43% for groups 1, 2, and 3 respectively (P<.001). Twelve months post-discharge, the hospital readmission rates were 44%, 53%, and 65% for groups 1, 2, and 3, respectively (P<.001). The median payments for this period were ($72,294), ($76,827), and ($101,474), for groups 1, 2, and 3, respectively (P <.001). CONCLUSION: The management of craniospinal chordoma and chondrosarcoma is costly and may extend over a prolonged period. The success of BPCI requires a joint effort between insurers and hospitals. Also, it should consider patients' comorbidities, the complexity of the disease. Finally, the adoptionof quality improvement programs by hospitals can help with cost reduction.

Defining recovery neurobiology of injured spinal cord by synthetic matrix-assisted hMSC implantation.

Mesenchymal stromal stem cells (MSCs) isolated from adult tissues offer tangible potential for regenerative medicine, given their feasibility for autologous transplantation. MSC research shows encouraging results in experimental stroke, amyotrophic lateral sclerosis, and neurotrauma models. However, further translational progress has been hampered by poor MSC graft survival, jeopardizing cellular and molecular bases for neural repair in vivo. We have devised an adult human bone marrow MSC (hMSC) delivery formula by investigating molecular events involving hMSCs incorporated in a uniquely designed poly(lactic-co-glycolic) acid scaffold, a clinically safe polymer, following inflammatory exposures in a dorsal root ganglion organotypic coculture system. Also, in rat T9-T10 hemisection spinal cord injury (SCI), we demonstrated that the tailored scaffolding maintained hMSC stemness, engraftment, and led to robust motosensory improvement, neuropathic pain and tissue damage mitigation, and myelin preservation. The scaffolded nontransdifferentiated hMSCs exerted multimodal effects of neurotrophism, angiogenesis, neurogenesis, antiautoimmunity, and antiinflammation. Hindlimb locomotion was restored by reestablished integrity of submidbrain circuits of serotonergic reticulospinal innervation at lumbar levels, the propriospinal projection network, neuromuscular junction, and central pattern generator, providing a platform for investigating molecular events underlying the repair impact of nondifferentiated hMSCs. Our approach enabled investigation of recovery neurobiology components for injured adult mammalian spinal cord that are different from those involved in normal neural function. The uncovered neural circuits and their molecular and cellular targets offer a biological underpinning for development of clinical rehabilitation therapies to treat disabilities and complications of SCI.

Management trends for anaplastic meningioma with adjuvant radiotherapy and predictors of long-term survival.

OBJECTIVEThe purpose of this study was to describe effects of adjuvant radiotherapy (RT) for anaplastic meningiomas (AMs) on long-term survival, and to analyze patient and RT characteristics associated with long-term survival.METHODSThe authors queried a retrospective cohort of patients with AM from the National Cancer Database (NCDB) diagnosed between 2004 and 2015 to describe treatment trends. For outcome analysis, patients with at least 10 years of follow-up were included, and they were stratified based on adjuvant RT status and propensity matched to controls for covariates. Survival curves were compared. A data-driven approach was used to find a biologically effective dose (BED) of RT with the largest difference between survival curves. Factors associated with long-term survival were quantified.RESULTSThe authors identified 2170 cases of AM in the NCDB between 2004 and 2015. They observed increased use of adjuvant RT in patients treated with higher doses. A total of 178 cases met the inclusion criteria for outcome analysis. Forty-five percent (n = 80) received adjuvant RT. Patients received a BED of 80.23 ± 16.6 Gy (mean ± IQR). The median survival time was not significantly different (32.8 months for adjuvant RT vs 38.5 months for no RT; p = 0.57, log-rank test). Dichotomizing the patients at a BED of 81 Gy showed maximal difference in survival distribution with a decrease in median survival in favor of no adjuvant RT (31.2 months for adjuvant RT vs 49.7 months for no RT; p = 0.03, log-rank test), but this difference was not significant after false discovery rate correction. Age was a significant predictor for long-term survival.CONCLUSIONSAMs are aggressive tumors that carry a poor prognosis. Conventional adjuvant RT improves local control. However, the effect of adjuvant radiation on overall survival is unclear. Further investigation into this area is warranted.

An elderly patient presenting with a primary spinal multifocal intradural extramedullary pilocytic astrocytoma: a case report and review of the literature.

BACKGROUND: Pilocytic astrocytoma is a low-grade central nervous system tumor most commonly seen in children. Dissemination from a primary intracranial tumor along the neuroaxis has been described at both presentation and disease progression. However, the development of an intradural extramedullary pilocytic astrocytoma independent of a primary intraparenchymal tumor in an adult patient with no history of pilocytic astrocytoma has rarely been reported. CASE PRESENTATION: A 69-year-old woman presented with progressive myelopathic symptoms and thoracic radicular pain. MRI imaging of the whole spine showed an enhancing intradural extramedullary lesion extending from the cervical cord to T11 causing cord compression. Laminectomies were performed for surgical decompression and histopathology was consistent with pilocytic astrocytoma. Complete staging was done that included imaging of the brain and cerebrospinal fluid cytology. No other tumor was found by these methods. Postoperatively the patient was treated with large field spinal radiation and concurrent chemotherapy followed by adjuvant chemotherapy. She has thus far been clinically and radiographically stable. CONCLUSION: This is a rare case of an adult with multiple spinal pilocytic astrocytomas in an intradural extramedullary location, typically the result of cerebrospinal fluid dissemination of neoplastic cells from a primary intracranial tumor site (i.e. drop metastasis). No conventional primary tumor was identified in this patient, suggesting these tumors may arise from heterotopic gliomas.

Health care utilization and overall costs based on opioid dependence in patients undergoing surgery for degenerative spondylolisthesis.

OBJECTIVE Opioid abuse is highly prevalent in patients with back pain. The aim of this study was to identify health care utilization and overall costs associated with opioid dependence in patients undergoing surgery for degenerative spondylolisthesis (DS). METHODS The authors queried the MarketScan database using ICD-9 and CPT-4 codes from 2000 to 2012. Opioid dependency was defined as having a diagnosis of opioid use disorder, having a prescription for opioid use disorder, or having 10 or more opioid prescriptions. Opioid dependency was evaluated in 12-month period leading to surgery and in the period 3-15 months following the procedure. Patients were segregated into 4 groups based on opioid dependence before and after surgery: group NDND (prior nondependent who remain nondependent), group NDD (prior nondependent who become dependent), group DND (prior dependent who become nondependent), and group DD (prior dependent who remain dependent). The outcomes of interest were discharge disposition, hospital length of stay (LOS), complications, and health care resource costs. The 4 groups were compared using the Kruskal-Wallis test and linear contrasts built from generalized regression models. RESULTS A total of 10,708 patients were identified, with 81.57%, 3.58%, 8.54%, and 6.32% of patients in groups NDND, NDD, DND, and DD, respectively. In group DD, 96.31% of patients had decompression with fusion, compared with 93.59% in group NDND. Patients in group NDD, DND, and DD had longer hospital LOS compared with those in group NDND. Patients in group DD were less likely to be discharged home compared with those in group NDND (odds ratio 0.639, 95% confidence interval 0.52-0.785). At 3-15 months postdischarge, patients in group DD incurred 21% higher hospital readmission costs compared with those in group NDND. However, patients in groups NDD and DD were likely to incur 2.8 times the overall costs compared with patients in group NDND (p < 0.001) at 3-15 months after surgery (median overall payments: group NDD $20,033 and group DD $19,654, vs group NDND $7994). CONCLUSIONS Patients who continued to be opioid dependent or became opioid dependent following surgery for DS incurred significantly higher health care utilization and costs within 3 months and in the period 3-15 months after discharge from surgery.

T12-L3 Nerve Transfer-Induced Locomotor Recovery in Rats with Thoracolumbar Contusion: Essential Roles of Sensory Input Rerouting and Central Neuroplasticity.

Locomotor recovery after spinal cord injury (SCI) remains an unmet challenge. Nerve transfer (NT), the connection of a functional/expendable peripheral nerve to a paralyzed nerve root, has long been clinically applied, aiming to restore motor control. However, outcomes have been inconsistent, suggesting that NT-induced neurological reinstatement may require activation of mechanisms beyond motor axon reinnervation (our hypothesis). We previously reported that to enhance rat locomotion following T13-L1 hemisection, T12-L3 NT must be performed within timeframes optimal for sensory nerve regrowth. Here, T12-L3 NT was performed for adult female rats with subacute (7-9 days) or chronic (8 weeks) mild (SCImi: 10 g × 12.5 mm) or moderate (SCImo: 10 g × 25 mm) T13-L1 thoracolumbar contusion. For chronic injuries, T11-12 implantation of adult hMSCs (1-week before NT), post-NT intramuscular delivery of FGF2, and environmentally enriched/enlarged (EEE) housing were provided. NT, not control procedures, qualitatively improved locomotion in both SCImi groups and animals with subacute SCImo. However, delayed NT did not produce neurological scale upgrading conversion for SCImo rats. Ablation of the T12 ventral/motor or dorsal/sensory root determined that the T12-L3 sensory input played a key role in hindlimb reanimation. Pharmacological, electrophysiological, and trans-synaptic tracing assays revealed that NT strengthened integrity of the propriospinal network, serotonergic neuromodulation, and the neuromuscular junction. Besides key outcomes of thoracolumbar contusion modeling, the data provides the first evidence that mixed NT-induced locomotor efficacy may rely pivotally on sensory rerouting and pro-repair neuroplasticity to reactivate neurocircuits/central pattern generators. The finding describes a novel neurobiology mechanism underlying NT, which can be targeted for development of innovative neurotization therapies.

Outcome measures in neurosurgery: Is a unified approach better? A literature review.

Background: Accurate assessment and evaluation of health interventions are crucial to evidence-based care. The use of outcome measures in neurosurgery grew with the introduction of the Glasgow Coma Scale. Since then, various outcome measures have appeared, some of which are disease-specific and others more generally. This article aims to address the most widely used outcome measures in three major neurosurgery subspecialties, "vascular, traumatic, and oncologic," focusing on the potential, advantages, and drawbacks of a unified approach to these outcome measures. Methods: A literature review search was conducted by using PubMed MEDLINE and Google scholar Databases. Data for the three most common outcome measures, The Modified Rankin Scale (mRS), The Glasgow Outcome Scale (GOS), and The Karnofsky Performance Scale (KPS), were extracted and analyzed. Results: The original objective of establishing a standardized, common language for the accurate categorization, quantification, and evaluation of patients' outcomes has been eroded. The KPS, in particular, may provide a common ground for initiating a unified approach to outcome measures. With clinical testing and modification, it may offer a simple, internationally standardized approach to outcome measures in neurosurgery and elsewhere. Based on our analysis, Karnofsky's Performance Scale may provide a basis of reaching a unified global outcome measure. Conclusion: Outcome measures in neurosurgery, including mRS, GOS, and KPS, are widely utilized assessment tools for patients' outcomes in various neurosurgical specialties. A unified global measure may offer solutions with ease of use and application; however, there are limitations.

Persistent Stapedial Artery Resulting in Direct Communication Between the Middle Meningeal and Basilar Arteries: Clinical Image.

A persistent stapedial artery originates from the petrous segment of the internal carotid artery due to failure of the regression of the embryonic stapedial artery. During embryologic development, the stapedial artery supplies the middle meningeal artery through the ventral pharyngeal artery. The presence of a persistent stapedial artery can result in direct communication between the basilar and middle meningeal arteries. We present a cerebral angiogram image of an adult patient that shows a right-sided persistent stapedial artery with communication between the right middle meningeal and basilar arteries. It is important to recognize such rare anatomic variants during endovascular interventions to avoid catastrophic complications such as nontarget embolization of the posterior circulation.

Predictors of the Size and Surgical Freedom of the Trans-Cribriform and Trans-Clival Corridors, a Radiographic Analysis.

Introduction The transcribriform and transclival corridors are endoscopic endonasal approaches used to treat pathologies of the skull base. We present a predictive model that uses the clival length and ethmoidal width to predict the size and surgical freedom (SF) of these corridors. Methods Adult facial computed tomography scans were reviewed. Exclusion criteria included patients <18 years of age or radiographic evidence of trauma, neoplasm, or congenital deformities of the skull base. The images were analyzed using OsiriX MD (Bernex, Switzerland). Patients' demographics, clival length, ethmoidal width, surface area, and others were collected. Linear regression was used to create prediction models for the size and SF of the transclival and transcribriform corridors. Results A total of 103 patients were included with an average age of 44.9 years and 47% males. Females had a smaller clival surface area (8 vs. 9.2 cm 2 , p = 0.001). For transclival corridor, clival length correlated positively with SF in the sagittal plane (rho = 0.44, p < 0.05) and negatively with SF in the coronal plane (rho = - 0.2, p < 0.05). For transcribriform corridor, ethmoidal width correlated positively with SF in the coronal plane (rho = 0.74, p < 0.05), and negatively with SF in the sagittal plane (rho = - 0.2, p < 0.05). Conclusion A significant variability of the bony anatomy of the anterior and central skull base was found. The use of clival length and ethmoidal width as part of preoperative surgical planning might help to overcome the anatomical variability which could affect the adequacy of surgical corridors.

Incidence and Long-Term Health Care Utilization Associated With Pseudomeningocele Repair Following Vestibular Schwannoma Resection: A National Database Analysis.

Introduction To compare the healthcare utilization in patients who presented with no pseudomeningocele (PSM) following vestibular schwannoma (VS) surgery (nd-PSM), PSM following VS surgery and required surgical repair (s-PSM) and those who presented with PSM and did not require surgical repair (ns-PSM). Methods MarketScan database was queried using the International Classification of Diseases, ninth and tenth revisions, and current procedural terminology four, from 2000 to 2018. We included patients ≥18 years of age with a PSM diagnosis with at least two years of continuous enrollment. The hospital admissions, outpatient services, medication refills, and associated payments were analyzed. Results Of 1,460 patients, 96.6% (n=1,411) had no PSM following surgery for VS, 2.4% (n=35) were in s-PSM and only 0.95% (n=14) were in ns-PSM cohorts. Patients in the s-PSM cohort incurred higher hospital readmission rate, outpatient payments compared to those in the nd-PSM and ns-PSM cohorts at six months, one-year, and two-years following the following VS resection. At one-year following VS resection, the median combined payments for the s-PSM cohort were $74,683 compared to $42,664 for the ns-PSM and $9,476 for the nd-PSM cohort, p<0.0001. Similarly, at two-years, median combined payments for s-PSM cohort were $83,351 compared to $63,942 for ns-PSM and $18,839 for the nd-PSM cohort, p<0.0001. Conclusion  Patients in the s-PSM cohort incurred eight times and 4.4 times the combined payments at one- and two-years, respectively, compared to the nd-PSM cohort. Also, patients in the ns-PSM cohort incurred 4.5 times and 3.4 times the payments compared to the nd-PSM cohort.

Morphometric Study of the Posterior Fossa: Identification of Practical Parameters for Tailored Selection of Surgical Routes to the Petroclival Region.

Introduction The petroclival region is an integral part of the skull base. It can harbor different pathologies and provides access to the petroclival junction and cerebellopontine angle. We present the results of the morphometric analysis of the posterior fossa and a prediction model to enable skull base surgeons to choose an optimal surgical corridor considering patient's bony anatomy. Methods Ninety patients (14 to assess interobserver reliability) with temporal bone computed tomography were selected. Exclusion criteria included patients <18 years of age, radiographic evidence of trauma, infection, or previous surgery. The images were analyzed using OsiriX MD (Bernex, Switzerland). We recorded clival length, vertical angle, and surface area, and petroclival angle, petrous apex, and translabyrinthine corridors volume. Results The average age was 49.5 years (55%) for males. The mean clival length and surface areas were 44.2 mm (standard deviation [SD] ± 4.1) and 8.1 cm 2 (SD ± 1.3). The mean petrous apex and translabyrinthine corridors volumes were 2.2 cm 3 (SD ± 0.6) and 10.1 cm 3 (SD ± 3.7). The mean petroclival angle at the internal auditory canal (IAC) was 154.9 degrees (SD ± 9). The clival length correlated positively with clival surface area (rho = 0.6, p <0.05), petrous apex volume (rho = 0.3, p < 0.05), and translabyrinthine volume (rho = 0.3, p < 0.05). Conclusion The petroclival region is complex and with high variability of surgical significance. The use of preoperative measurements of the clival length and petroclival angle as part of surgical planning that could help the surgeon to choose an optimal surgical corridor by overcoming the anatomical variability elements.

A case series of crossbow injury to the head highlighting the importance of an interdisciplinary management approach.

BACKGROUND: Penetrating crossbow head injuries are rare with no clear consensus regarding the optimal management paradigm for such injuries. We present three cases of crossbow injury to the head, with emphasis on the need for a comprehensive multidisciplinary management plan. CASE DESCRIPTION: Three cases are presented of patients presenting with self-inflicted penetrating crossbow to head injuries. All three patients presented with intact neurological exam. A comprehensive multidisciplinary plan was created for all three cases with subsequent successful removal of the arrows. All three patients were discharged home with modified Rankin scale score of <2. CONCLUSION: Penetrating crossbow brain injuries are rare and require complex management. A comprehensive management strategy is necessary to manage these injuries. Moreover, careful consideration of factors such as the arrow trajectory, complexity of the injuries, and availability of the required expertise is important to increase the chances of success.

Complications associated with early cranioplasty for patients with traumatic brain injury: a 25-year single-center analysis.

OBJECTIVE: Cranioplasty is a technically simple procedure, although one with potentially high rates of complications. The ideal timing of cranioplasty should minimize the risk of complications, but research investigating cranioplasty timing and risk of complications has generated diverse findings. Previous studies have included mixed populations of patients undergoing cranioplasty following decompression for traumatic, vascular, and other cerebral insults, making results challenging to interpret. The objective of the current study was to examine rates of complications associated with cranioplasty, specifically for patients with traumatic brain injury (TBI) receiving this procedure at the authors' high-volume level 1 trauma center over a 25-year time period. METHODS: A single-institution retrospective review was conducted of patients undergoing cranioplasty after decompression for trauma. Patients were identified and clinical and demographic variables obtained from 2 neurotrauma databases. Patients were categorized into 3 groups based on timing of cranioplasty: early (≤ 90 days after craniectomy), intermediate (91-180 days after craniectomy), and late (> 180 days after craniectomy). In addition, a subgroup analysis of complications in patients with TBI associated with ultra-early cranioplasty (< 42 days, or 6 weeks, after craniectomy) was performed. RESULTS: Of 435 patients identified, 141 patients underwent early cranioplasty, 187 patients received intermediate cranioplasty, and 107 patients underwent late cranioplasty. A total of 54 patients underwent ultra-early cranioplasty. Among the total cohort, the mean rate of postoperative hydrocephalus was 2.8%, the rate of seizure was 4.6%, the rate of postoperative hematoma was 3.4%, and the rate of infection was 6.0%. The total complication rate for the entire population was 16.8%. There was no significant difference in complications between any of the 3 groups. No significant differences in postoperative complications were found comparing the ultra-early cranioplasty group with all other patients combined. CONCLUSIONS: In this cohort of patients with TBI, early cranioplasty, including ultra-early procedures, was not associated with higher rates of complications. Early cranioplasty may confer benefits such as shorter or fewer hospitalizations, decreased financial burden, and overall improved recovery, and should be considered based on patient-specific factors.

Rectus gyrus hematoma: An overview.

Background: Rectus gyrus hematoma (RGH) is a localized intracerebral hemorrhage involving the most medial part of the orbital surface of the frontal lobe. It can be an imaging finding in the setting of a ruptured anterior communicating artery aneurysm; however, other differentials are rarely reported in the literature. In this paper, we opt to present for the 1st time an overview of RGH regarding its history, anatomical correlation, and related neuroimaging with particular emphasis on the potential differential diagnosis for underlying pathologies. Methods: A literature review was conducted in PubMed, Medline, and Google scholar databases to review the existing literature highlighting the history, pertinent anatomy, and clinical characteristics of RGH. Results: The literature review yielded papers targeting the RGH neither as a radiological sign nor as a surgical correlate to the cerebrovascular lesion. We used the available indirectly related articles to formulate an overview to serve the aim of this paper and to highlight the potential value of studying the RGH. Conclusion: The RGH may represent an overlooked radiological finding that has potential significance through its relation to a set of vascular lesions affecting the brain. Further studies into the topic are needed to expand the utility of this sign.

Failure of tandem flow diversion for intracranial aneurysms: Literature review and illustrative case.

Background: Flow diverters are becoming one of the main endovascular procedures used to treat aneurysms. Flow diverter devices (FDDs) have multiple types approved for endovascular procedure use. Although their indications are not well described, they are usually used for large or giant, wide-necked, and recurrent aneurysms. Multiple FDDs can be deployed to treat giant aneurysms to ensure and accelerate aneurysm occlusion and mitigate complications. We report a case of endovascular treatment of an intracranial aneurysm using three silk FDDs complicated by a delayed migration of the stents along the parent artery, along with a literature review of the related cases. Methods: We conducted a PubMed Medline database search by the following combined formula of subjects headings: ((((((intracranial aneurysm[MeSH Terms]) AND (endovascular procedure[MeSH Terms])) OR (endovascular technique[MeSH Terms])) AND (endovascular[Title/Abstract]) AND (Flow diverter[Title/ Abstract])) OR (flow diversion[Title/Abstract])) OR (Pipeline[Title/Abstract])) AND (Multiple[Title/Abstract]). Results: The result was eight cases of endovascular treatment of intracranial aneurysms with multiple FDD. The male-to-female ratio in these cases was 5:3, and there is a wide age range from 22 months to 69 years old. The cases differed in the type and number of FDDs used, yet, they all had similar results with aneurysm occlusion and recovery of the patient with no observed complications. Conclusion: Tandem flow diverter deployment has technical challenges and complications such as complete obstruction can occur. Planning and learning from experience with those new technologies are the typical way to overcome such complications in the future.

Overview of the modeling of complex biological systems and its role in neurosurgery.

Biological systems are complex with distinct characteristics such as nonlinearity, adaptability, and self-organization. Biomedical research has helped in advancing our understanding of certain components the human biology but failed to illustrate the behavior of the biological systems within. This failure can be attributed to the use of the linear approach, which reduces the system to its components then study each component in isolation. This approach assumes that the behavior of complex systems is the result of the sum of the function of its components. The complex systems approach requires the identification of the components of the system and their interactions with each other and with the environment. Within neurosurgery, this approach has the potential to advance our understanding of the human nervous system and its subsystems.