Stem cell therapy for traumatic brachial plexus injury.

Stem cell therapy is rapidly evolving, with preclinical studies showing various stem cell types successfully promoting peripheral nerve regeneration. Despite the lack of clinical studies demonstrating efficacy and safety, the number of commercial entities marketing and promoting this treatment direct to patients is also increasing. We describe three adult traumatic brachial plexus injury (BPI) patients who had stem cell therapies prior to consultation in a multidisciplinary brachial plexus clinic. No functional improvement was noted at long-term follow-up despite claims reported by the commercial entities. Considerations and implications of stem cell application in BPI patients are reviewed.

Large infratentorial cystic oligodendroglioma in a pregnant patient: A case report of a rare presentation and literature review.

Oligodendrogliomas (ODGs) are rare brain tumors in adults, mostly presenting as a supratentorial solid mass, while less than 10% occur infratentorially. Infratentorial cystic ODGs are extremely rare. We reported a large partially cystic cerebellar ODG in a 31-week pregnant patient with an unusual presentation and discussed the challenging management.

Detethering the superficial temporal artery: Application to tension free superficial temporal artery-middle cerebral artery bypasses.

Extracranial-intracranial bypass has been shown to be effective in the surgical treatment of moyamoya disease, complex aneurysms, and tumors that involve proximal vasculature in carefully selected patients. Branches of the superficial temporal artery (STA) are used commonly for the bypass surgery; however, an appropriate length of the donor vessel must be harvested to avoid failure secondary to anastomotic tension. The goal of this cadaveric study was to investigate quantitatively operative techniques that can increase the STA length available to facilitate tension-free STA-middle cerebral artery (MCA) bypass. We conducted a cadaveric study using a total of 16 sides in eight cadavers. Measurements of the STA trunk with its frontal branch (STAfb) were taken before and after skeletonization and detethering of the STA with the STAfb and mobilization of the parietal branch of the STA. A final measurement of the STA with the STAfb was taken for the free length gained toward visible proximal cortical branches of the MCA. Paired student's t-tests were used to compare the mean length before and after mobilization and unpaired t-tests to analyze according to laterality. The mean length of the STA with the STAfb was 9.0 cm prior to modification. After skeletonization and mobilization, the mean lengths increased significantly to 10.5 and 11.3 cm, respectively (p < 0.05). Especially in the cases that had the coiled and tortuous STA, skeletonization was considerably effective to increase the length of the STA with the STAfb. After simulating a bypass by bringing the STAfb to the recipient MCA site, the mean extended length of the STA with the STAfb was 3.0 cm. There were no statistically significant differences between sides in all measurements. We report a significant increase in the mean STA length available (3.0 cm) following skeletonization and mobilization. Clinical applications of the extended length of the STA with the STAfb may facilitate tension-free STA-MCA bypasses and improve outcomes. Further studies are needed in a clinical context.

The Reproducibility of Cerebrovascular Randomized Controlled Trials.

BACKGROUND: Numerous randomized controlled trials (RCTs) relevant to the cerebrovascular field have been performed. The fragility index was recently developed to complement the P value and measure the robustness and reproducibility of clinical findings of RCTs. OBJECTIVE: In this study, we evaluate the fragility index for key surgical and endovascular cerebrovascular RCTs and propose a novel RCT classification system based on the fragility index. METHODS: Cerebrovascular RCTs reported between 2000 and 2018 were reviewed. Six key areas were specifically targeted in relation to stroke, carotid stenosis, cerebral aneurysms, and subarachnoid hemorrhage. The correlation between fragility index, number of patients lost to follow-up, and fragility quotient were evaluated to propose a classification system for the robustness of the studies. RESULTS: A total of 20 RCTs that reported significant differences between both study groups in terms of the primary outcome were included. The median fragility index for the trials was 5.5. An additional 30 randomly selected RCTs were added to propose a classification system with high reliability. The difference between the number of patients lost to follow-up and fragility index inversely correlated with the fragility quotient and was used to divide the robustness of the RCTs into 3 classes reflecting the reproducibility of the trial. CONCLUSIONS: Neurosurgeons and neurointerventionalists should exercise caution with interpreting the results of cerebrovascular RCTs, especially when the sample size and events numbers are small and there is a high number of patients who were lost to follow-up, as quantitatively identified using the proposed classification system.

Fulminant and Diffuse Cerebral Toxoplasmosis as the First Manifestation of HIV Infection: A Case Presentation and Review of the Literature.

BACKGROUND One of the most common causes of central nervous system (CNS) opportunistic infections in immunocompromised patients is toxoplasmosis. It can cause focal or disseminated brain lesions leading to neurological deficit, coma, and death. Prompt management with optimal antibiotics is vital. However, the diagnosis of cerebral toxoplasmosis is challenging in infected individuals with human immunodeficiency virus (HIV). The possible diagnosis is based on clinical presentation, imaging, and specific serologic investigations. The diagnosis can be confirmed by histopathological examination and/or by finding nucleic material in the spinal cerebrospinal fluid (CSF) examination. CASE REPORT We present a review of the literature with a rare illustrative case of diffuse CNS toxoplasmosis as the first manifestation of HIV infection in a young patient. Brain MRI showed diffuse, ring-enhancing lesions, and significant midline shift. Decompressive hemicraniectomy for control of intracranial pressure and anti-infectious therapy were performed. CONCLUSIONS This should raise awareness that cerebral toxoplasmosis can occur in pediatric patients with HIV infection, and, more importantly, as the first manifestation of AIDS. Although the prognosis is often poor, early diagnosis and immediate treatment of this life-threatening opportunistic infection can improve outcomes.

Recent update on basic mechanisms of spinal cord injury.

Spinal cord injury (SCI) is a life-shattering neurological condition that affects between 250,000 and 500,000 individuals each year with an estimated two to three million people worldwide living with an SCI-related disability. The incidence in the USA and Canada is more than that in other countries with motor vehicle accidents being the most common cause, while violence being most common in the developing nations. Its incidence is two- to fivefold higher in males, with a peak in younger adults. Apart from the economic burden associated with medical care costs, SCI predominantly affects a younger adult population. Therefore, the psychological impact of adaptation of an average healthy individual as a paraplegic or quadriplegic with bladder, bowel, or sexual dysfunction in their early life can be devastating. People with SCI are two to five times more likely to die prematurely, with worse survival rates in low- and middle-income countries. This devastating disorder has a complex and multifaceted mechanism. Recently, a lot of research has been published on the restoration of locomotor activity and the therapeutic strategies. Therefore, it is imperative for the treating physicians to understand the complex underlying pathophysiological mechanisms of SCI.

Gliomas: survival differences between metropolitan and non-metropolitan counties.

BACKGROUND: For gliomas, metropolitan status has not been heavily explored in the context of short-term mortality or long-term observed survival. Larger populations are associated with proximity to academic universities/high-volume hospitals. METHODS: The SEER-18 registry was queried for patients with gliomas. The patients were further classified into two population groups based on rural-urban continuum codes: metropolitan or non-metropolitan. Demographics and clinical factors were compared between both groups. For observed survival, univariate and multivariate analyses occurred with Cox proportional hazards model. RESULTS: The non-metropolitan group constituted approximately 10.8% of all patients. Age at diagnosis of glioma was older for the non-metropolitan group compared to metropolitan group (51.60 years vs. 49.06 years). Relative to the metropolitan group, the non-metropolitan group exhibited a larger proportion of Caucasian, married, grade I and IV gliomas, no surgery, no GTR (for those who had surgery), and temporal/parietal/occipital locations. Other covariates (sex, tumor size, laterality, and radiation status) did not exhibit significant differences in proportions. From analysis of observed survival, independent predictors include population group, as well as age, gender, marital status, tumor location, tumor grade, laterality, GTR, and receipt of radiation. Short-term mortality was 11.68% and 13.04% for Metropolitan and non-metropolitan groups, respectively. Median survival was 15 months and 12 months for Metropolitan and non-metropolitan groups, respectively. CONCLUSIONS: About one-tenth of gliomas are treated at non-metropolitan sites. Key differences exist among patient/glioma characteristics based on metropolitan status. Overall, metropolitan status appears to influence short-term mortality and long-term observed survival for gliomas.

Causes of death in glioblastoma: insights from the SEER database.

BACKGROUND: Glioblastoma (GB) and its variants portend a poor prognosis. The predominant cause of death (COD) is related to the cancer diagnosis, but a significant subset is related to other causes. As GB is a systemic disease requiring systemic treatment, focus regarding all COD provides a comprehensive illustration of the disease. METHODS: The SEER-18 was queried for patients with cranial GB and its variants. Age, gender, race, marital status, tumor characteristics, treatment details, and follow-up data were acquired. The patients were classified into group A (death attributed to this cancer diagnosis) or group B (death attributed to causes other than this cancer diagnosis). RESULTS: From 1973 to 2013, 36,632 deaths (94%) constituted group A, and 2,324 deaths (5.9%) constituted group B. The latter significantly exhibited lower proportions of age <60, Caucasians, married status, frontal/brain stem/ventricle tumor locations, and receipt of radiation. From logistic regression, age >60, male gender, race, not married, tumor location, and no radiation were significant independent predictors for group B. The top known CODs in group B are diseases of heart, pneumonia and influenza, cerebrovascular diseases, accidents and adverse effects, and infections. CONCLUSIONS: CODs not attributed to GB remains a significant subset of all CODs. Many of these, particularly diseases of heart, are frequent comorbidities. Moreover, infection-related CODs after GB diagnosis appear more salient compared to CODs in the general population. Consideration of these CODs, and vigilant treatment aimed at these CODs, may improve overall care for GB patients.

Ideal sedation for stroke thrombectomy: a prospective pilot single-center observational study.

OBJECTIVESeveral retrospective studies have supported the use of conscious sedation (CS) over general anesthesia (GA) as the preferred methods of sedation for stroke thrombectomy, but a recent randomized controlled trial showed no difference in outcomes after CS or GA. The purpose of the Ideal Sedation for Stroke Thrombectomy (ISST) study was to evaluate the difference in time and outcomes in the reperfusion of anterior circulation in ischemic stroke using GA and monitored anesthesia care (MAC).METHODSThe ISST study was a prospective, open-label registry. A total of 40 patients who underwent mechanical thrombectomy for anterior circulation ischemic stroke were enrolled. Informed consent was obtained from each patient before enrollment. The primary endpoint included the interval between the patient's arrival to the interventional radiology room and reperfusion time. Secondary endpoints were evaluated to estimate the effects on the outcome of patients between the 2 sedation methods.RESULTSOf the 40 patients, 32 received thrombectomy under MAC and 8 patients under GA. The male-to-female ratio was 18:14 in the MAC group and 4:4 in the GA group. The mean time from interventional radiology room arrival to reperfusion in the GA group was 2 times higher than that in the MAC group. Complete reperfusion (TICI grade 3) was achieved in more than 50% of patients in both groups. The mean modified Rankin Scale score at 3 months was < 2 in the MAC group and > 3 in the GA group (p = 0.021).CONCLUSIONSThe findings from the pilot study showed a significantly shorter time interval between IR arrival and reperfusion and better outcomes in patients undergoing reperfusion for ischemic stroke in the anterior circulation using MAC compared with GA.Clinical trial registration no.: NCT03036631 (clinicaltrials.gov).

MRI-Guided High-Intensity Focused Ultrasound as an Emerging Therapy for Stroke: A Review.

Stroke, either ischemic or hemorrhagic, accounts for significantly high morbidity and mortality rates around the globe effecting millions of lives annually. For the past few decades, ultrasound has been extensively investigated to promote clot lysis for the treatment of stroke, myocardial infarction, and acute peripheral arterial occlusions, with or without the use of tPA or contrast agents. In the age of modern minimal invasive techniques, magnetic resonance imaging-guided high-intensity focused ultrasound is a new emerging modality that seems to promise therapeutic utilities for both ischemic and hemorrhagic stroke. High-intensity focused ultrasound causes thermal heating as the tissue absorbs the mechanical energy transmitted by the ultrasonic waves leading to tissue denaturation and coagulation. Several in-vitro and in-vivo studies have demonstrated the viability of this technology for sonothrombolysis in both types of stroke and have warranted clinical trials. Apart from safety and efficacy, initiation of trials would further enable answers regarding its practical application in a clinical setup. Though this technology has been under study for treatment of various brain diseases for some decades now, relatively very few neurologists and even neurosurgeons seem to be acquainted with it. The aim of this review is to provide basic understanding of this powerful technology and discuss its clinical application and potential role as an emerging viable therapeutic option for the future management of stroke.

Modern operative nuances for the management of eloquent high-grade gliomas.

INTRODUCTION: Despite advancements in the treatment of high-grade gliomas (HGG), the rate of tumor recurrence is high and survival rate for the patient is low. Gross total resection has shown increased survival but the location of the tumor in the eloquent brain poses significant risk of morbidity. In this report, we focus on modern surgical nuances for resection of tumors located in the eloquent brain. EVIDENCE ACQUISITION: Research of the literature was conducted using the following search terms: surgical resection of gliomas, high-grade gliomas, and the role of vascular encasement - from 1986-2018. An institutional experience from the first author of this paper was also reviewed for selection of our illustrative cases. EVIDENCE SYNTHESIS: Gross total resection remains the mainstay of therapy for high-grade gliomas. The resection of the peritumoral FLAIR, when possible, has been associated with increased survival but also has the potential to cause increased morbidity. In the eloquent brain, the resection of the tumor itself is possible if attention is given to the interface of the tumor and brain, or if a safe pseudo-interface is created by the surgeon. Tumor-seeding to the ventricular system needs to be avoided. Devascularization, dissection away from the brain, and retractorless brain surgery are key to successful surgical outcomes. Management of the venous and arterial invasion/encasement are also outlined in this report. Technical aspects are discussed with corresponding videos. CONCLUSIONS: High-grade gliomas involving eloquent brain areas require a tailored treatment plan. While the medical treatment is undergoing quick evolution, gross total resection still remains one of the key milestones of treatment for improved survival. Surgical techniques play key role. We propose that encasement and/or the invasion of arteries and veins, should be considered equally as important as the eloquent brain when contemplating the resection of gliomas.

Management and survival trends for adult patients with malignant gliomas in the setting of multiple primary tumors: a population based analysis.

INTRODUCTION: The impact of multiple primary tumors, in the setting of malignant glioma (MG), has not been heavily explored. METHODS: We extracted demographics and clinical data from the SEER-18 registry for adult patients with MGs. The cases were separated based on the sequence of MG diagnosis relative to the other primary tumors: Group (A) One primary only or first primary of multiple primaries and Group (B) second primary or subsequent primary tumor. Incidences, frequencies, and glioma-related survivals were analyzed. RESULTS: Group B constituted 12.8% of new MG. The incidences of group B, relative to those of all new MG, range from 0.14 to 0.18. Compared to group A, group B exhibited an older age. Moreover, group B exhibited a higher proportion of females, Caucasians, smaller tumors, non-operative cases, and those receiving radiation (p < 0.05); the proportion with GTR remained comparable. Multiple groupings (oral cavity, digestive system, respiratory system, skin, breast, genital systems, urinary system, lymphoma) exhibited lower glioma-related observed survival (p < 0.05) compared to Group A. An active diagnosis of "leukemia" appears to confer longer glioma-related survival while a history of "breast" or "digestive system" malignancies portends a shorter glioma-related survival. CONCLUSION: For newly diagnosed MG, a high proportion does have history of extra-CNS primary tumors. Generally, these patients appear to have worse glioma-related observed survival compare to those with malignant glioma as the only primary or the first of multiple primary tumors. Knowledge regarding epidemiology, clinical factors, and observed survival can help guide clinical management/consultation for this subset of patients.

Design, Application and Infield Validation of a Pre-Hospital Emergent Large Vessel Occlusion Screening Tool: Ventura Emergent Large Vessel Occlusion Score.

BACKGROUND: The outcome of endovascular treatment for emergent large vessel occlusion (ELVO) is dependent on timely recanalization. To identify ELVO in the field, we present a simplified score, which has been applied and validated in the field by emergency medical services (EMS). Methods and Analysis: Ventura ELVO Scale (VES) comprise of 4 components: Eye Deviation, Aphasia, Neglect, and Obtundation with score range 0-4. The score of greater than or equal to 1 will be considered as ELVO positive. A positive VES along with positive Cincinnati scale prompts ELVO activation. EMS then notify to neurointervention protocol at the receiving stroke center. The performance of VES was evaluated retrospectively. For statistical analysis, SAS version 9.4 was used and Fisher's modelling was used for the comparative analysis. RESULTS: Total 184 patients were included in the final analysis, 62 (33.7%) patients were called VES positive from the field. Out of 62, 36 (58%) patients had ELVO. The mean NIHSS on arrival was 16 in VES positive and 5 in VES negative patients. VES was 94.7% sensitive and 82.4% specific while the PPV and NPV of VES were 58.1% and 98.4%, respectively. It showed 84.9% accuracy. CONCLUSIONS: VES is an effective and simplified prehospital screening tool for detection of ELVO in the field. Its implementation can beat the target door to groin time to improve outcomes and in future it can be used for rerouting of ELVO patients to comprehensive stroke center.

Glioblastoma in the setting of prior lower grade gliomas - insights from SEER database.

INTRODUCTION: Secondary glioblastomas (GBs) constitute a small subset of all GBs and tend to arise after a lower grade glioma. Though knowledge regarding this subset has gained traction in recent years, its definition continues to evolve, complicating its clinical management. Investigation of epidemiology and survival patterns may help provide needed insights. RESULTS: The age at GB diagnosis is significantly lower (46.22 vs 60.25 years) for group B. The distribution among type of GB (glioblastoma, giant cell glioblastoma, or gliosarcoma) was significantly different, with no diagnosis of giant cell GB in Group B. Compared to Group A, Group B exhibited a higher proportion of females, not married, smaller tumors, no GTR, and no radiation (all p < 0.05). GB-related observed survivals were comparable. Cox regression with inclusion of co-variates reveal no significant influence of GB group on observed survival. Regarding group B, mean age was 40.197 for diagnosis of initial lower grade glioma. The most common initial ICD-O-3 pathology was oligodendroglioma, NOS; astrocytoma, NOS; astrocytoma, anaplastic; and mixed glioma. METHODS: The SEER-18 registry was queried for patients with GBs. Patients were further classified into two GB groups: Group A - those with GB as the only primary tumor, and Group B - those with GB as a 2nd primary or subsequent tumor and with history of lower grade gliomas. Demographics and clinical factors were compared between group A and B. Appropriate statistics were employed to calculate incidences and differences among factors and GB-related survivals between the groups. CONCLUSIONS: Overall, Group B develops GBs at an earlier age, but observed survival remains similar to those with GBs as the only primary. Moreover, this subset also exhibit different proportions of the types of GBs, and well as differences in other key clinical factors (namely, gender and tumor size at presentation). Prior treatments for lower grade gliomas likely explain some of the differences noted regarding management course after diagnosis of GB.

Subependymal Giant Cell Astrocytoma: A Surveillance, Epidemiology, and End Results Program-Based Analysis from 2004 to 2013.

BACKGROUND: Subependymal giant cell astrocytoma (SEGA) is a rare, benign neoplasm predominantly associated with tuberous sclerosis complex. Clinical outcomes have largely been conveyed via small- and medium-sized case series. METHODS: With the Surveillance, Epidemiology, and End Results Program (SEER)-18 registry database, information from all patients diagnosed with SEGA from 2004 to 2013 was obtained (age, sex, race, marital status, tumor size, tumor location, occurrence of surgery, receipt of radiation, and follow-up data). Age-adjusted incidence rates and overall survival (OS) were determined. Cox proportional hazards model was used for both univariate and multivariate analyses. RESULTS: The overall incidence of SEGA within the SEER-18 database is 0.027 per 100,000 person-years (95% confidence interval, 0.024-0.031). A total of 226 cases were identified. For OS, univariate analysis revealed age younger than 18 years (hazard ratio [HR], 0.214; P = 0.004) and occurrence of surgery (HR, 0.328; P = 0.039) were significant positive prognostic factors. Sex, marital status, race, tumor size, tumor location, and receipt of radiation did not exhibit significant relationships. Interestingly, subanalysis for extent of resection to gross total resection did not show benefit. Multivariate analysis revealed that both age younger than 18 years (HR, 0.193; P = 0.002) and occurrence of surgery (HR, 0.286; P = 0.021) remained significant. CONCLUSIONS: Based on our analysis, younger age and occurrence of surgery are significant independent factors associated with better OS. There was no support for radiation.

Intracranial hemangioblastoma - A SEER-based analysis 2004-2013.

INTRODUCTION: Intracranial hemangioblastoma (HB) is a rare pathology. Limited data exist regarding its epidemiology. METHODS: With the SEER-18 registry database, information from all patients diagnosed with intracranial HB from 2004 to 2013 were extracted, including age, gender, race, marital status, presence of surgery, extent of surgery, receipt of radiation, tumor size, tumor location, and follow-up data. Age-adjusted incidence rates and overall survival (OS). Cox proportional hazards model was employed for both univariate and multivariate analyses. RESULTS: A total of 1307 cases were identified. The overall incidence of intracranial hemangioblastoma is 0.153 per 100,000 person-years [95% confidence interval (CI)=0.145-0.162]. Through univariate analysis, age < 40 [hazard ratio (HR)=0.277, p<0.001], no radiation [HR=0.56, p=0.047], and presence of surgery [HR=0.576, p=0.012] are significant positive prognostic factors. Caucasian race [HR=1.42, p=0.071] and female gender [HR=0.744, p=0.087] exhibit noticeable trends towards positive prognosis. Through multivariate analysis, younger age [HR=1.053, p < 0.01], race [HR=1.916, p<0.01], and presence of surgery [HR=0.463, p<0.01 were significant independent prognostic factors. CONCLUSION: Clinical factors such as younger age, Caucasian race, and presence of surgery are significant independent factors for overall survival in patients with HBs. Though analysis regarding extent of surgery did not produce a meaningful relationship, this may be related to surgical bias / expertise. Moreover, no validation for radiation therapy was identified, but this may be related to short follow up intervals and the variable growth patterns of HBs.

A comprehensive review of the clivus: anatomy, embryology, variants, pathology, and surgical approaches.

INTRODUCTION: The clivus is a bony structure formed by the fusion of the basioccipital and basispheniod bone at the sphenooccipital synchondrosis. This downward sloping structure from the dorsum sellae to the foramen magnum is derived from mesoderm and ectoderm properties. METHODS: This comprehensive review of the clivus will discuss its basic anatomy, embryology, pathological findings, and surgical implications. The clivus is an endochondral bone, formed under two processes; first, a cartilaginous base is developed, and it is secondly reabsorbed and replaced with bone. Knowledge of its embryological structure and growth of development will clarify the pathogenesis of anatomical variants and pathological findings of the clivus. CONCLUSIONS: Understanding the anatomy including proximity to anatomical structures, adjacent neurovasculature properties, and anatomical variants will aid neurosurgeons in their surgical management when treating pathological findings around the clivus.

Imaging Characteristics of Dural Arteriovenous Fistulas Involving the Vein of Galen: A Comprehensive Review.

Vein of Galen aneurysmal malformation (VGAM) is a rare angiopathy, which most commonly presents in infancy. Although very rare, it is associated with high morbidity and mortality rates. In order to minimize such morbid rates, a prompt diagnosis followed by a timely initiation of management is crucial. Multiple antenatal and postnatal imaging techniques for the diagnosis have been described and discussed in the literature. However, to our knowledge, a comprehensive review exploring such a list of imaging options for VGAM has never been established. We aim to review the diagnostic tools to aid in better understanding of the investigative modalities physicians may choose from when treating patients with a VGAM.

The superior petrosal sinus: a review of anatomy, embryology, pathology, and neurosurgical relevance.

The superior petrosal sinus is located between the middle and posterior cranial fossae and is important during many neurosurgical approaches to the skull base. Using standard search engines, the anatomical and clinical importance of the superior petrosal sinus was investigated. The superior petrosal sinus is important in many neurosurgical approaches and pathological entities. Therefore, it is important for those who operate at the skull base or interpret imaging here to have a good working knowledge of its anatomy, development, and pathological involvement.

Subarachnoid Trabeculae: A Comprehensive Review of Their Embryology, Histology, Morphology, and Surgical Significance.

INTRODUCTION: Brain is suspended in cerebrospinal fluid (CSF)-filled subarachnoid space by subarachnoid trabeculae (SAT), which are collagen-reinforced columns stretching between the arachnoid and pia maters. Much neuroanatomic research has been focused on the subarachnoid cisterns and arachnoid matter but reported data on the SAT are limited. This study provides a comprehensive review of subarachnoid trabeculae, including their embryology, histology, morphologic variations, and surgical significance. METHODS: A literature search was conducted with no date restrictions in PubMed, Medline, EMBASE, Wiley Online Library, Cochrane, and Research Gate. Terms for the search included but were not limited to subarachnoid trabeculae, subarachnoid trabecular membrane, arachnoid mater, subarachnoid trabeculae embryology, subarachnoid trabeculae histology, and morphology. Articles with a high likelihood of bias, any study published in nonpopular journals (not indexed in PubMed or MEDLINE), and studies with conflicting data were excluded. RESULTS: A total of 1113 articles were retrieved. Of these, 110 articles including 19 book chapters, 58 original articles, 31 review articles, and 2 case reports met our inclusion criteria. CONCLUSIONS: SAT provide mechanical support to neurovascular structures through cell-to-cell interconnections and specific junctions between the pia and arachnoid maters. They vary widely in appearance and configuration among different parts of the brain. The complex network of SAT is inhomogeneous and mainly located in the vicinity of blood vessels. Microsurgical procedures should be performed with great care, and sharp rather than blunt trabecular dissection is recommended because of the close relationship to neurovascular structures. The significance of SAT for cerebrospinal fluid flow and hydrocephalus is to be determined.