We Tabulated and Organized American Board of Neurological Surgeons Primary Exam Keywords (2015-2023) so You Don't Have to.

Background Passing the American Board of Neurological Surgeons (ABNS) Primary Exam is required for residents in training. Both the program directors and residents are given keywords of the exam afterward in the hope to help program directors determine their relative strengths and weakness. We have organized and tabulated these keywords for neurosurgery residents' benefit. Methodology We collected and analyzed ABNS Primary Exam keywords (2015-2023) in each of the exam's main categories for trends and recurrences. We examined the overall passing rates among first-time credit test takers. The frequency of each subcategory was calculated as a percentage within its corresponding category. Recurrent keywords were grouped together with their corresponding years and categorized as once, twice, or thrice and greater occurrences; the last category was considered to be high-yield keywords. Results The number of questions in Neurosciences and Neurology has decreased over the years while Neurosurgery and Critical Care questions have increased. Similarly, there are fewer keyword repeats in Neurosciences and Neurology. The most repeated keywords are in Neuroimaging. The most common keywords are presented and listed along with the years of occurrences. Overall, the passing rate among first-time credit test takers is over 90%. Conclusions Neurosurgery residents can consider the common keywords as a guide in preparation for the ABNS Primary Exam.

Medulloblastoma Presenting As Isolated Leptomeningeal Enhancement With No Primary Mass.

Medulloblastoma presenting with diffuse leptomeningeal enhancement and no identified intra-parenchymal primary mass is extremely rare. A 14-year-old previously healthy boy presented with a three-week history of symptoms consistent with increased intracranial pressure (ICP). Magnetic resonance imaging (MRI) revealed diffuse leptomeningeal enhancement which prompted consideration of infectious, inflammatory, and neoplastic etiologies. The patient became rapidly unstable requiring the placement of an external ventricular drain (EVD) and induction of a phenobarbital coma for refractory seizures. The "sugar-coated" appearance of the abnormal enhancement and thickened tissues raised concern specifically for malignancy. The patient remained extremely unstable and ultimately required surgical decompression for increased ICP at which time a biopsy was obtained. Despite attempting bridging intra-ventricular chemotherapy, the patient, unfortunately, passed away, just 14 days from the initial presentation. Final pathology later confirmed the diagnosis of medulloblastoma. Awareness of medulloblastoma in the differential of diffuse leptomeningeal enhancement is crucial for early identification and treatment of this rare presentation. This case is the first pediatric report of primary leptomeningeal medulloblastoma without a primary mass involving the large cell/anaplastic variant.

A Rare Neonatal Intramedullary Immature Teratoma Undiagnosed in utero: A Case Report.

BACKGROUND AND IMPORTANCE: Immature teratoma is a known pediatric tumor. However, spinal variants are rare and can present both a diagnostic and therapeutic challenge, particularly regarding aggression as it pertains to extent of resection, likelihood of recurrence and concordant prognosis, and the need and efficacy of adjuvant therapies. CLINICAL PRESENTATION: The patient is a 27-day-old female who presented with 10 days of poor feeding, irritability, and progressive hypotonia. Although upon immediate presentation emergency providers' differential diagnoses included meningitis, inborn error of metabolism, and genetic neurodegenerative disease, a subsequent magnetic resonance (MR) imaging of the total spine revealed a large intradural intramedullary mass extending from the medulla to the thoracic cord at T12. The patient underwent multilevel cervical and thoracic laminectomies/laminoplasty for maximal safe resection. Histopathology revealed mostly mature tissue elements originating from all 3 germ layers, interspersed with foci of immature neuroepithelium, consistent with grade 1 immature teratoma. Following surgical intervention, the patient regained strength and spontaneous movement and underwent physical therapy. Follow-up MR imaging of the total spine was obtained every 3 months, and at 9 months, recurrence was demonstrated, which was successfully treated with chemotherapy. Further surveillance MR imaging of the total spine has demonstrated cystic myelomalacia changes without definite tumor recurrence, at 5-year follow-up. Clinically, the patient has developed scoliosis without weakness, pain, or urinary symptoms. CONCLUSION: This case demonstrates an exceptionally rare and unusual variant neoplasm in a neonate and highlights the difficulty of diagnosis and the important role of MR imaging. It also illustrates the importance of gross total resection, the risk of recurrence, and the need for close radiographic follow-up of these lesions. It also provides a useful example of the efficacy of adjuvant chemotherapy in treating recurrence.

Neurosurgical management of a rare congenital supratentorial neurenteric cyst with associated nasal dermal sinus: case report.

The authors describe the case of a patient with the classic clinical presentation and radiographic features of a nasal dermal sinus with an associated intracranial cyst; however, histopathology revealed that the intracranial cyst was neurenteric instead of the typical epidermoid or dermoid cyst. Preoperative assessment included CT and MRI, which revealed a direct communication between the patient's nasal polypoid lesion and the anterior skull base via the foramen cecum. At the hands of a multidisciplinary plastic surgery and neurosurgery team, the patient underwent concurrent gross-total resection of the nasal polypoid lesion, the intracranial intradural cystic lesion, and their interconnecting tract.

Germinoma with Diffuse Subependymal Spread: A Case Report.

A 19-year-old Caucasian male presented with complaints of headaches and syncope. Suspicion of hydrocephalus prompted computed tomography (CT) and magnetic resonance imaging (MRI), which revealed pineal and suprasellar prominences with diffuse, thick, nodular subependymal enhancement of the lateral and third ventricles. Based on imaging, the differential diagnosis consisted primarily of malignancy, such as lymphoma, with inflammatory and infectious etiologies not excluded. Cerebrospinal fluid (CSF) samples were non-specific, and neuroendoscopic tissue biopsy histologically confirmed the diagnosis of pure germinoma. The patient was treated with radiation, and follow-up MRIs at one, three, six, and 12 months demonstrated progressive resolution of tumor burden with marked clinical improvement. Germinomas are rare germ cell tumors that are more frequently diagnosed in Asian countries. They uncommonly seed into the lateral ventricles, and only two other cases have been described with diffuse subependymal involvement. Unlike other malignant germ cell tumors, germinomas have marker negative CSF samples that are important in the normal diagnostic workup of diffuse subependymal lesions. Histopathologic correlation is required for definitive diagnosis in the United States and can be achieved with endoscopic tissue sampling. Germinomas are highly radio- and chemotherapy sensitive and have a fair prognosis with modern therapeutic techniques. Germinoma should be considered with simultaneous midline and diffuse ventricular lesions.

Benign extracerebral fluid collection in infancy as a risk factor for the development of de novo intracranial arachnoid cysts.

OBJECT: Intracranial arachnoid cysts are a relatively common benign intracranial pathology, accounting for as many as 0.75%-1% of nontraumatic CNS lesions. Although it has already been demonstrated that rupture of arachnoid cysts may lead to subdural hematomas/hygromas, no study to date has investigated benign extracerebral collection in infancy as a possible predisposing factor for further development of arachnoid cysts. METHODS: The authors performed a retrospective imaging and chart review of macrocephalic infants 12 months old or younger who were referred to neurosurgical care at OSF St. Francis Medical Center from 2003 to 2010, and who were diagnosed with benign extracerebral fluid collection in infancy on thin-slice (1-mm) head CT scans. Special attention was given to the investigation of risk factors for further development of de novo arachnoid cysts. Several epidemiological factors in the infants and mothers were analyzed, including gestational age at delivery, mode of delivery, mother's age at delivery, delivery complications, birth weight, age of macrocephaly development, degree of macrocephaly, family history of macrocephaly, prenatal and postnatal history of infection, fontanel status, presence of papilledema, previous history of head trauma, and smoking status. Imaging characteristics of the initial scans, such as location of subdural collection (frontal vs frontoparietal and frontotemporal) and presence of ventriculomegaly, were also evaluated. For those patients in whom arachnoid cysts were identified on subsequent CT scans, the size and location of the cysts were also analyzed. RESULTS: The authors identified 44 children with benign extracerebral fluid collection in infancy. From this group, over a mean follow-up of 13 months (range 6-13 months), 18 children developed intracranial arachnoid cysts (a 40.9% incidence of de novo development of arachnoid cysts), with 27.8% presenting with bilateral cysts. In the multiple logistic regression analysis, infants who presented with an extracerebral collection restricted to the bilateral frontal region were more likely to develop intracranial arachnoid cysts (p = 0.035) than those with collections involving the frontotemporal and frontoparietal regions (odds ratio [OR] = 5.73). Additionally, children with benign extracerebral fluid collections and plagiocephaly were more likely to develop intracranial arachnoid cysts (p = 0.043) than those without plagiocephaly (OR = 4.96). CONCLUSIONS: This is the first report in the neurosurgical literature demonstrating that benign extracerebral fluid collections in infancy may constitute a significant risk factor for development of de novo arachnoid cysts. These findings support a 2-hit hypothesis for the development of arachnoid cysts, in which the combination of an embryological defect in arachnoid development followed by a second event leading to impairment of CSF fluid absorption in early childhood could lead to abnormal CSF dynamics and the consequent expansion of fluid collections in the intraarachnoid spaces.

Design of a synthetic simulator for pediatric lumbar spine pathologies.

OBJECT: Simulation has become an important tool in neurosurgical education as part of the complex process of improving residents' technical expertise while preserving patient safety. Although different simulators have already been designed for a variety of neurosurgical procedures, spine simulators are still in their infancy and, at present, there is no available simulator for lumbar spine pathologies in pediatric neurosurgery. In this paper the authors describe the peculiarities and challenges involved in developing a synthetic simulator for pediatric lumbar spine pathologies, including tethered spinal cord syndrome and open neural tube defects. METHODS: The Department of Neurosurgery of the University of Illinois at Peoria, in a joint program with the Mechanical Engineering Department of Bradley University, designed and developed a general synthetic model for simulating pediatric neurosurgical interventions on the lumbar spine. The model was designed to be composed of several sequential layers, so that each layer might closely mimic the tensile properties of the natural tissues under simulation. Additionally, a system for pressure monitoring was developed to enable precise measurements of the degree of manipulation of the spinal cord. RESULTS: The designed prototype successfully simulated several scenarios commonly found in pediatric neurosurgery, such as tethered spinal cord, retethered spinal cord, and fatty terminal filum, as well as meningocele, myelomeningocele, and lipomyelomeningocele. Additionally, the formulated grading system was able to account for several variables involved in the qualitative evaluation of the technical performance during the training sessions and, in association with an expert qualitative analysis of the recorded sessions, proved to be a useful feedback tool for the trainees. CONCLUSIONS: Designing and building a synthetic simulator for pediatric lumbar spine pathologies poses a wide variety of unique challenges. According to the authors' experience, a modular system composed of separable layers that can be independently replaced significantly enhances the applicability of such a model, enabling its individualization to distinctive but interrelated pathologies. Moreover, the design of a system for pressure monitoring (as well as a general score that may be able to account for the overall technical quality of the trainee's performance) may further enhance the educational applications of a simulator of this kind so that it can be further incorporated into the neurosurgical residency curriculum for training and evaluation purposes.

Design and benchmark testing of a bicorporal pump for the treatment of normal-pressure hydrocephalus and idiopathic intracranial hypertension.

OBJECT: Addressing overdrainage and its associated complications is still one of the greatest challenges for future shunt designs for normal-pressure hydrocephalus and idiopathic intracranial hypertension. Nevertheless, as evidenced by tap test procedures, a small amount of CSF drainage seems to be enough to relieve patients' symptoms in most cases and, therefore, in opposition to other types of hydrocephalus, continuous CSF drainage may not be absolutely warranted. In such a clinical scenario, intermittent controlled drainage of a small amount of CSF during specific periods of the day through a 2-system pump may provide several advantages over continuous drainage of current single-system shunts. The goal in this study was to design and test an innovative concept of a bicorporal pump composed of a 2-part system. The first component was designed to be implanted in the patient and act as a pump connected to standard catheter tubing. The second component was designed to be used as an external device outside of the body and function as a power supply and control system. Ultimately, flow will only occur when the system is powered by the external device. METHODS: Testing and comparisons were performed to evaluate free fluid flow and the maximal flow after pumping in the standing and supine positions. After this, the authors compared the hydrodynamic effects of 2 different housing systems (2- and 3-in systems). An attenuation test was performed to show the effects of electromagnetic forces at progressively increasing distances. Finally, a biocompatibility report of the raw material used in the pilot design was completed. RESULTS: In the supine position, the effect of pumping was observed to increase the volumetric flow at a rate similar to or higher than that yielded in the free-flow tests. In relation to the attenuation test, it was observed that the volume drops off fairly quickly as the air gap distance was increased until ultimately reaching zero, with approximately 15 mm between the 2 components. In relation to the testing force, the 2-in housing model showed a considerable increase in the required electromagnetic force over the 3-in housing. CONCLUSIONS: The authors successfully designed and tested a new intermittent drainage system through a bicorporal shunt, which provides several advantages over current single-system continuous drainage pumps. According to the authors' benchmark results, the 3-in housing model seems to be a better choice as it requires less force from the external electromagnet control. Moreover, attenuation tests demonstrated that, for proper functioning, the gap distance between the external and implanted devices should not be greater than 15 mm. Such initial benchmark results confirm the feasibility of such innovative design and provide support for future testing of the system in in vivo animal models and in future clinical series.

Addressing the siphoning effect in new shunt designs by decoupling the activation pressure and the pressure gradient across the valve.

OBJECT: Although several improvements have been observed in the past few years in shunt technology, currently available systems still present several associated problems. Among these, overdrainage along with its complications remains one of the great challenges for new shunt designs. To address the so-called siphoning effect, the authors provide a practical example of how it is possible to decouple the activation pressure and the pressure gradient across the valve through a 3-key component system. In this new shunt design, the flow is expected to depend only on the intracranial pressure and not on the pressure gradient across the valve, thus avoiding the so-called siphoning effect. METHODS: The authors used computer models to theoretically evaluate the mechanical variables involved in the operation of the newly designed valve, such as the fluid's Reynolds number, proximal pressure, distal pressure, pressure gradient, actual flow rate, and expected flow rate. After fabrication of the first superscaled model, the authors performed benchmark tests to analyze the performance of the new shunt prototype, and the obtained data were compared with the results predicted by the previous mathematical models. RESULTS: The final design of the new paddle wheel valve with the 3-key component antisiphoning system was tested in the hydrodynamics laboratory to prove that the siphoning effect did not occur. According to the calculations obtained using the LabVIEW program during the experiments, each time the distal pressure decreased without an increase in the proximal pressure (despite the range of the pressure gradient), the pin blocked the spinning of the paddle wheels, and the calculated fluid velocity through the system tended to zero. Such a situation was significantly different from the expected flow rate for such a pressure gradient in a siphoning situation without the new antisiphon system. CONCLUSIONS: The design of this new prototype with a 3-key component antisiphoning system demonstrated that it is possible to decouple the activation pressure and the pressure gradient across the valve, avoiding the siphoning effect. Although further developments are necessary to provide a model compatible to clinical use, the authors believe that this new prototype illustrates the possibility of successfully addressing the siphoning effect by using a simple 3-key component system that is able to decouple the activation pressure and the pressure gradient across the valve by using a separate pressure chamber. It is expected that such proof of concept may significantly contribute to future shunt designs attempting to address the problem of overdrainage due to the siphoning effect.

Performance analysis of the protective effects of bicycle helmets during impact and crush tests in pediatric skull models.

OBJECT: Bicycle accidents are a very important cause of clinically important traumatic brain injury (TBI) in children. One factor that has been shown to mitigate the severity of lesions associated with TBI in such scenarios is the proper use of a helmet. The object of this study was to test and evaluate the protection afforded by a children's bicycle helmet to human cadaver skulls with a child's anthropometry in both "impact" and "crushing" situations. METHODS: The authors tested human skulls with and without bicycle helmets in drop tests in a monorail-guided free-fall impact apparatus from heights of 6 to 48 in onto a flat steel anvil. Unhelmeted skulls were dropped at 6 in, with progressive height increases until failure (fracture). The maximum resultant acceleration rates experienced by helmeted and unhelmeted skulls on impact were recorded by an accelerometer attached to the skulls. In addition, compressive forces were applied to both helmeted and unhelmeted skulls in progressive amounts. The tolerance in each circumstance was recorded and compared between the two groups. RESULTS: Helmets conferred up to an 87% reduction in so-called mean maximum resultant acceleration over unhelmeted skulls. In compression testing, helmeted skulls were unable to be crushed in the compression fixture up to 470 pound-force (approximately 230 kgf), whereas both skull and helmet alone failed in testing. CONCLUSIONS: Children's bicycle helmets provide measurable protection in terms of attenuating the acceleration experienced by a skull on the introduction of an impact force. Moreover, such helmets have the durability to mitigate the effects of a more rare but catastrophic direct compressive force. Therefore, the use of bicycle helmets is an important preventive tool to reduce the incidence of severe associated TBI in children as well as to minimize the morbidity of its neurological consequences.

Definition and measurement of rider-intrinsic physical attributes influencing all-terrain vehicle safety.

OBJECT: All-terrain vehicle (ATV) usage has grown tremendously over the years, reaching 9.5 million vehicles in use in 2007. Accompanying this growth has been a concomitant increase in rider morbidity (including traumatic brain and spine injuries) and death, especially in children. The purpose of this study was to define and measure, through field testing, those physical attributes intrinsic to riders, such as height, weight, and wingspan, which may have implications for ATV riders' safety. METHODS: Three field tests (J-hook, brake, and bump) were developed and performed to allow direct measurement of the lateral, longitudinal, and vertical dynamics in 5 riders of varying heights, weights, and wingspans. Two ATVs, a utility and a sport model, were tested for further comparisons. Data were acquired using a comprehensive data acquisition system attached to the ATVs. Assignment of individual rider/ATV test safety ratings and a rider/ATV Total Safety Rating were made from the results of these field tests. RESULTS: The J-hook test results demonstrated that larger rider wingspans positively influence ATV rider safety and mitigate against lateral instability. From the brake test it was determined that a 10-in (25.4-cm) longitudinal displacement, such as that experienced during a sharp deceleration, for a rider of any height or weight, breached the level of defined safety. As rider weight increased, displacement decreased. The bump test provided evidence that increased rider weight also mitigates against vertical displacement. CONCLUSIONS: Individuals with light weights and small wingspans, such as those in the pediatric population, are under considerable risk of injury when operating an ATV due to lateral, longitudinal, and vertical operational instability.