Predictive Model Evaluating Risk of Hemorrhage in Intracranial Aneurysms: Analysis from Prospectively Collected HEAT Trial Database.

OBJECTIVE: We analyzed the data of patients enrolled in the Hydrogel Endovascular Aneurysm Treatment (HEAT) trial to develop and validate a model to predict the risk of aneurysmal hemorrhage. METHODS: Analysis included data from 600 patients enrolled for the HEAT trial and included single saccular aneurysms of 3-14 mm size. Baseline characteristics were compared between patients with ruptured and unruptured aneurysms. Regression analysis was performed in the training set to identify significant risk factors and was validated in the validation dataset. The complete dataset was used to formulate a scoring model in which positive and negative predictors were assigned 1 and -1 points, respectively. RESULTS: Data from 593 patients were analyzed in which 169 (28.5%) patients had ruptured aneurysms. The training (n = 297) and validation dataset (n = 296) had a comparable proportion of ruptured aneurysms (29.3% and 27.7%). Dome-to-neck ratio >2.5 (odds ratio [OR] 3.66), irregular shape (OR 3.79), daughter sac (OR 5.89), and anterior and posterior communicating artery locations (OR 3.32 and 3.56, respectively) had a higher rupture rate. Use of aspirin was associated with lower risk of hemorrhage (OR 0.16). The area under the curve from the receiver operating curve analysis was 0.88, 0.87, and 0.87 in the training, validation, and combined data set, respectively. The scoring model created a score of -1 to 2, yielding an of aneurysmal hemorrhage probability from 1.5% (score -1) to 70% (score 2). CONCLUSIONS: This prospective study identifies dome-to-neck ratio >2.5, irregular shape, presence of daughter sac, absence of aspirin use, and aneurysm location at anterior communicating and posterior communicating artery as factors associated with increased risk of hemorrhagic presentation in small- to medium-sized intracranial aneurysms. Our model provides an estimate of rupture risk based on the presence or absence of these factors.

Direct puncture of the superior ophthalmic vein for carotid cavernous fistulas: a 21-year experience.

BACKGROUND: Direct puncture of the superior ophthalmic vein (SOV) is an alternative approach to traversing the inferior petrosal sinus for embolization of carotid cavernous fistulas (CCFs). OBJECTIVE: To analyze direct SOV puncture for the treatment of CCFs and review the literature. METHODS: All patients at a single center, treated for a CCF with direct SOV cannulation between January 1, 2000, and December 31, 2020, were retrospectively analyzed. An additional review of the literature for all case series for direct puncture of the SOV for treatment of CCF was performed. RESULTS: During the 21-year study period, direct cannulation of the SOV for treatment of a CCF was attempted for 19 patients, with the procedure aborted for one patient because of an inability to navigate the wire into the distal aspect of the cavernous sinus. In 18 patients with direct SOV CCF treatment, 1 experienced a minor complication with an asymptomatic postoperative hemorrhage. Angiographic cure and improvement of symptoms were achieved in 17 patients with a mean (SD) follow-up of 6 (5.2) months. In the review of the literature, an additional 45 patients were reported to have direct cannulation of the SOV for CCF treatment, with angiographic cure in 43 (96%) and decreased objective visual acuity in 1 (2%). CONCLUSION: Direct SOV cannulation to treat CCFs is safe and effective. Although it is typically used after other endovascular approaches have failed, SOV access for CCF treatment may be warranted as a first-line treatment for select patients.

High-Dose Frameless Stereotactic Radiosurgery for Trigeminal Neuralgia: A Single-Institution Experience and Systematic Review.

OBJECTIVE: Stereotactic radiosurgery is an effective treatment option for trigeminal neuralgia (TN), with frameless stereotactic radiosurgery (fSRS) allowing for a less invasive experience. A single-institutional series and systematic review of the literature were performed for cases of TN treated with fSRS. METHODS: Patients at our institution with TN that were treated with fSRS from the years 2012-2021 were included. Similarly, multiple databases were searched for studies regarding TN treated with fSRS where patient-level data was included from 2004-2020. Pain levels, via the Barrow Neurological Institute (BNI) scale, before and after treatment were analyzed. Pooled analysis was performed to compare treatment outcomes between studies using CyberKnife and LINAC modalities. RESULTS: Twenty-three patients at our institution were treated with LINAC fSRS (median treatment dose: 85 Gy). Most patients had TN refractory to previous procedural treatments. Eight (35%) patients had an excellent posttreatment response (BNI I-II), while 11 (48%) patients had a good result (BNI IIIa/b). Eight patients had recurrence of pain. A total of 30 articles were included in the systematic review, encompassing 1705 patients. At last follow-up, 63.1% (774/1227) of patients endorsed an excellent response, while 16.1% (197/1227) had a good response, and 22.5% (215/957) of patients had recurrence. Pain response, facial numbness rates, and pain recurrence rates were not significantly different between CyberKnife and LINAC modalities. CONCLUSIONS: Frameless SRS for TN appears to be an efficacious noninvasive option for patients with substantial comorbidities, who have failed other treatment methods, although it can be limited by higher recurrence rates.

A mentorship model for neurosurgical training: the Mayo Clinic experience.

Neurosurgical education is a continually developing field with an aim of training competent and compassionate surgeons who can care for the needs of their patients. The Mayo Clinic utilizes a unique mentorship model for neurosurgical training. In this paper, the authors detail the historical roots as well as the logistical and experiential characteristics of this teaching model. This model was first established in the late 1890s by the Mayo brothers and then adopted by the Mayo Clinic Department of Neurological Surgery at its inception in 1919. It has since been implemented enterprise-wide at the Minnesota, Florida, and Arizona residency programs. The mentorship model is focused on honing resident skills through individualized attention and guidance from an attending physician. Each resident is closely mentored by a consultant during a 2- or 3-month rotation, which allows for exposure to more complex cases early in their training. In this model, residents take ownership of their patients' care, following them longitudinally during their hospital course with guided oversight from their mentors. During the chief year, residents have their own clinic, operating room (OR) schedule, and OR team and service nurse. In this model, chief residents conduct themselves more in the manner of an attending physician than a trainee but continue to have oversight from staff to provide a "safety net." The longitudinal care of patients provided by the residents under the mentorship model is not only beneficial for the trainee and the hospital, but also has a positive impact on patient satisfaction and safety. The Mayo Clinic Mentorship Model is one of many educational models that has demonstrated itself to be an excellent approach for resident education.

Does complete regression of intraneural ganglion cysts occur without surgery?

PURPOSE: The dynamic nature of intraneural ganglion cysts, including spontaneous expansion and regression, has been described. However, whether these cysts can regress completely in the absence of surgical management has important therapeutic implications. Therefore, we aim to review the literature for cyst regression without surgical intervention. METHODS: We reviewed our database of 970 intraneural ganglion cysts in the literature to search for evidence of complete regression based on strict radiologic confirmation, either spontaneously, or after percutaneous cyst aspiration or steroid injection. RESULTS: We did not find any examples of complete regression without surgical treatment that met inclusion criteria. Spontaneous regression was reported in four cases; however, only two cases had follow-up imaging, both of which demonstrated residual cysts. Nineteen cases of percutaneous intervention were found in the literature, 13 of which reported clinical improvement following aspiration/steroid injection; however, only seven cases had available imaging. Only two cases reported complete resolution of cyst on MR imaging at follow-up, but reinterpretation found residual intraneural cyst in both cases. CONCLUSION: We believe that pathology (structural abnormalities and/or increased joint fluid) always exists at the joint origin of intraneural ganglion cysts which persist even with regression of the cyst. The persistence of a capsular abnormality or defect can lead to recurrence of the cyst in the future, and while imaging may show dramatic decreases in cyst size, truly focused assessment of images will show a tiny focus of persistent intraneural cyst at the joint origin. Thus, expectant management or percutaneous intervention may lead to regression, but not complete resolution, of intraneural ganglion cysts.

Research advances in the diagnosis and treatment of moyamoya disease: a bibliometric analysis.

Moyamoya disease is a rare cerebrovascular condition involving stenotic carotid arteries and the formation of abnormal blood vessels. In this study, we aimed to characterize the key players involved in moyamoya research at the individual and institutional level and to identify the critical publications that have advanced our understanding of this disease. We performed a title-specific search of the Web of Science database using the search term "moyamoya" for publications dating from 1900 to April 2020. The 100 most frequently cited articles were obtained, screened for duplicates, and reviewed by 2 independent reviewers. These 100 articles were cited an average of 150 times each (range, 74 to 1,360 citations per article). Publication dates ranged from 1969 to 2016, with the largest number of publications (n=40) cited between 2000 and 2009. The article with the greatest number of citations (1,360 citations) was "Cerebrovascular 'moyamoya' disease: disease showing abnormal net-like vessels in base of brain," by Suzuki and Takaku, published in the Archives of Neurology, 1969. Stroke published the greatest number of the most frequently cited articles (23 of 100). The institution that contributed the most articles was Tohoku University (16%); the majority of the most frequently cited articles originated in Japan (62%). We identified the 100 most cited articles on moyamoya disease over the past 51 years to recognize significant and impactful works. These results can be used as a guide to evaluate our current understanding of moyamoya disease and to direct future efforts.

Trends in the Neurosurgical Workforce and Implications in Providing for an Aging Population.

BACKGROUND: The United States is projected to face increasing physician-workforce shortages. However, the shortage in the neurosurgical workforce has not yet been characterized. In the present study, we outlined the current state of the neurosurgical workforce by quantifying the divide between the number of practicing neurosurgeons and the U.S. METHODS: The Medicare Physician National Medicare database was queried from 2014 to 2019 to obtain the numbers of practicing neurosurgeons, which were compared with the population counts from the U.S. Census data. RESULTS: From 2014 to 2019, the total increase in neurosurgeons per capita was 9.4%. The Northeast neurosurgeons per capita rate (NPCR) increased by 17.1%, the South NPCR by 3.4%, the Midwest NPCR by 13.3%, and the West NPCR by 12.5%. In all regions, except for the West, the surgeon per capita ratio had decreased from 2017 to 2019. The greatest increase in the number of surgeons was 2018 to 2019 (n = 214). In 2014, the states with the lowest NPCRs were Vermont, Arkansas, and New Mexico. In 2019, these included Nevada, New Mexico, and Vermont. As of 2020, 56.6% of the neurosurgeons had practiced for >20 years. CONCLUSIONS: Although the national NPCR has slowly increased during the past 5 years, a more recent decrease occurred within the last 3 years. Additionally, with almost 57% of surgeons having been practicing for >20 years, concern exists regarding whether current practices can sustain increasing patient needs. The results from the present study indicate that further investigation is warranted regarding the factors contributing to this shortage and the steps that can be taken to increase the production of well-trained neurosurgeons.

Craniofacial Chondromyxoid Fibromas: A Systematic Review and Analysis Based on Anatomic Locations.

BACKGROUND: Craniofacial chondromyxoid fibromas (CMFs) are a rare benign tumor of cartilaginous origin. They are commonly misdiagnosed due to the paucity of information on tumor characteristics. We performed a systematic review to characterize CMFs located in different regions of the craniofacial skeleton. METHODS: A search of the literature was executed using the search phrase "chondromyxoid fibroma" and included articles from 1990-2020. Sixty-eight articles met the inclusion criteria, with a total of 91 patients with analyzable data (22 with calvarial and 69 with sinonasal tumor locations). Descriptive analyses were performed to compare pre-selected characteristics between the 2 groups. RESULTS: Sinonasal CMF frequently presented with cranial nerve palsy and expectedly had a high rate of nasal symptoms. Calvarial tumors frequently presented with an external mass and headache. Gross total resection (GTR) was achieved in a higher proportion of cases in the calvarial group versus the sinonasal group (83.3% vs. 53.1%). Overall recurrence rate at 17.7% was higher in sinonasal CMF compared with the calvarial tumors at 8.3%. Recurrences after GTR were similar in the sinonasal and calvarial groups (9.7% vs. 9.1%). In patients who did not achieve GTR, recurrence was higher in the sinonasal compared with the calvarial group (27.6% vs. 0%). CONCLUSIONS: Craniofacial CMF in calvarial and sinonasal locations have distinct clinical characteristics and response to treatment. Sinonasal lesions tend to have higher recurrence compared to calvarial CMF. Performance of GTR is associated with decreased recurrence in all CMFs.

Totally Cystic Schwannoma: A Misnomer.

BACKGROUND: Although partial cystic degeneration is commonly observed in schwannoma, cases of totally cystic forms have also been reported. A literature review of cases describing totally cystic schwannoma was performed to assess their imaging characteristics. METHODS: PubMed was queried with the phrases "totally cystic schwannoma," "purely cystic schwannoma," and "completely cystic schwannoma." A total of 19 papers encompassing 22 cases of reported totally cystic schwannoma were included. Patient characteristics, clinical presentation, and reported imaging characteristics were recorded. Computed tomography and magnetic resonance images from the papers were collected and reviewed by a senior musculoskeletal radiologist. RESULTS: The most frequent presenting location of these lesions was in spinal nerve roots. The interpretations of imaging reported in the papers described a homogeneous lesion that was isointense to slightly hyperintense to cerebrospinal fluid (CSF) on T1-weighted images. On contrast administration, the studies described a thin rim of "ring-like" enhancement around the lesion. Our reinterpretation of the imaging revealed heterogeneous lesions that were hyperintense to CSF on T1-weighted images. Post-contrast images typically demonstrated an irregularly thickened enhancing rim. Most images showed evidence of solid components in the lesion, with many containing enhancing soft tissue elements. The observed imaging features were not consistent with simple cystic lesions. CONCLUSIONS: Review of the imaging studies of the reported cases of completely cystic schwannoma did not produce any convincing examples of purely cystic lesions. The description of these lesions as "totally cystic" appears to be a misnomer and has diagnostic and therapeutic implications.

Timing of Restarting Anticoagulation and Antiplatelet Therapies After Traumatic Subdural Hematoma-A Single Institution Experience.

BACKGROUND: There is a paucity of information regarding the optimal timing of restarting antiplatelet therapy (APT) and anticoagulation therapy (ACT) after traumatic subdural hematoma (tSDH). Therefore, we sought to report our experience at a single level 1 trauma center with regard to restarting APT and/or ACT after tSDH. METHODS: A total of 456 consecutive records were reviewed for unplanned hematoma evacuation within 90 days of discharge and thrombotic/thromboembolic events before restarting APT and/or ACT. RESULTS: There was no difference in unplanned hematoma evacuation rate in patients not receiving APT or ACT (control) compared with those necessitating APT and/or ACT (6.4% control, 6.9% APT alone, 5.8% ACT alone, 5.4% APT and ACT). There was an increase in post-tSDH thrombosis/thromboembolism in patients needing to restart ACT (1.9% APT alone, P = 0.53 vs. control; 5.8% ACT alone, P = 0.04 vs. control; 16% APT and ACT; P < 0.001 vs. control). Subgroup analysis revealed that patients with coronary artery disease necessitating APT and patients with atrial fibrillation necessitating ACT had higher thrombosis/thromboembolism rates compared with controls (1.0% control vs. 6.1% coronary artery disease, P = 0.02; 1.0% control vs. 10.1% atrial fibrillation, P < 0.001). The median restart time of ACT was approximately 1 month after trauma; APT was restarted 2-4 weeks after trauma depending on clinical indication. CONCLUSIONS: Patients requiring reinitiation of APT and/or ACT after tSDH were at elevated risk of thrombotic/thromboembolic events but not unplanned hematoma evacuation. Therefore, patients should be followed closely until APT and/or ACT are restarted, and consideration for earlier reinitiation of blood thinners should be given on a case-by-case basis.

Differences by Practice Year in Numbers of U.S. Female Neurosurgeons.

OBJECTIVE: We sought to determine the proportion and number of female neurosurgeons in the workforce at different stages of practice. METHODS: The Physician Compare National Downloadable File data set was obtained from the Centers for Medicare & Medicaid Services for physicians who indicated "neurosurgery" as their primary specialty. Physician duplicates, physicians with no listed medical school graduation year, and physicians expected to be in residency (graduation years 2013-2019) were removed, yielding 4956 neurosurgeons. Five-year intervals were used to measure the number of male and female neurosurgeons by different stages of their careers. For example, graduates from years 2008-2012 were expected to be in their first 1-5 years of practice. RESULTS: There were 405 female (8.2%) and 4551 male (91.8%) neurosurgeons. At 1-5 years of practice, 13.8% (105/760) were women; 6-10 years, 11.5% (94/820) women; 11-15 years, 8.9% (64/720) women; 16-20 years, 8.7% (59/682) women; 21-25 years, 7.4% (46/619) women; 26-30 years, 3.8% (20/520) women; 31-35 years, 3.6% (15/413) women; and 36 years or more, 0.5% women (2/422). The number of female neurosurgeons varied among states, ranging from 0 in Hawaii to 53 in California. The states with the lowest percentage of female neurosurgeons were Hawaii (0%), Oklahoma (3.1%), and Nevada (3.6%). The states with the highest percentage of female neurosurgeons were New Hampshire (20.0%), Vermont (16.7%), and Rhode Island (15.8%). CONCLUSIONS: The number of practicing female neurosurgeons within the United States is increasing, as shown by the growing percentage of women who are earlier in their surgical careers.

Auditory and Visual System White Matter Is Differentially Impacted by Normative Aging in Macaques.

Deficits in auditory and visual processing are commonly encountered by older individuals. In addition to the relatively well described age-associated pathologies that reduce sensory processing at the level of the cochlea and eye, multiple changes occur along the ascending auditory and visual pathways that further reduce sensory function in each domain. One fundamental question that remains to be directly addressed is whether the structure and function of the central auditory and visual systems follow similar trajectories across the lifespan or sustain the impacts of brain aging independently. The present study used diffusion magnetic resonance imaging and electrophysiological assessments of auditory and visual system function in adult and aged macaques to better understand how age-related changes in white matter connectivity at multiple levels of each sensory system might impact auditory and visual function. In particular, the fractional anisotropy (FA) of auditory and visual system thalamocortical and interhemispheric corticocortical connections was estimated using probabilistic tractography analyses. Sensory processing and sensory system FA were both reduced in older animals compared with younger adults. Corticocortical FA was significantly reduced only in white matter of the auditory system of aged monkeys, while thalamocortical FA was lower only in visual system white matter of the same animals. Importantly, these structural alterations were significantly associated with sensory function within each domain. Together, these results indicate that age-associated deficits in auditory and visual processing emerge in part from microstructural alterations to specific sensory white matter tracts, and not from general differences in white matter condition across the aging brain.SIGNIFICANCE STATEMENT Age-associated deficits in sensory processing arise from structural and functional alterations to both peripheral sensory organs and central brain regions. It remains unclear whether different sensory systems undergo similar or distinct trajectories in function across the lifespan. To provide novel insights into this question, this study combines electrophysiological assessments of auditory and visual function with diffusion MRI in aged macaques. The results suggest that age-related sensory processing deficits in part result from factors that impact the condition of specific white matter tracts, and not from general decreases in connectivity between sensory brain regions. Such anatomic specificity argues for a framework aimed at understanding vulnerabilities with relatively local influence and brain region specificity.

Auditory Processing Deficits Are Selectively Associated with Medial Temporal Lobe Mnemonic Function and White Matter Integrity in Aging Macaques.

Deficits in auditory function and cognition are hallmarks of normative aging. Recent evidence suggests that hearing-impaired individuals have greater risks of developing cognitive impairment and dementia compared to people with intact auditory function, although the neurobiological bases underlying these associations are poorly understood. Here, a colony of aging macaques completed a battery of behavioral tests designed to probe frontal and temporal lobe-dependent cognition. Auditory brainstem responses (ABRs) and visual evoked potentials were measured to assess auditory and visual system function. Structural and diffusion magnetic resonance imaging were then performed to evaluate the microstructural condition of multiple white matter tracts associated with cognition. Animals showing higher cognitive function had significantly better auditory processing capacities, and these associations were selectively observed with tasks that primarily depend on temporal lobe brain structures. Tractography analyses revealed that the fractional anisotropy (FA) of the fimbria-fornix and hippocampal commissure were associated with temporal lobe-dependent visual discrimination performance and auditory sensory function. Conversely, FA of frontal cortex-associated white matter was not associated with auditory processing. Visual sensory function was not associated with frontal or temporal lobe FA, nor with behavior. This study demonstrates significant and selective relationships between ABRs, white matter connectivity, and higher-order cognitive ability.