Osteoblastomas of the spine: a comprehensive review.

Osteoblastomas are primary bone tumors with an affinity for the spine. They typically involve the posterior elements, although extension through the pedicles into the vertebral body is not uncommon. Histologically, they are usually indistinguishable from osteoid osteomas. However, there are different variants of osteoblastomas, with the more aggressive type causing more pronounced bone destruction, soft-tissue infiltration, and epidural extension. A bone scan is the most sensitive radiographic examination used to evaluate osteoblastomas. These osseous neoplasms usually present in the 2nd decade of life with dull aching pain, which is difficult to localize. At times, they can present with a painful scoliosis, which usually resolves if the osteoblastoma is resected in a timely fashion. Neurological manifestations such as radiculopathy or myelopathy do occur as well, most commonly when there is mass effect on nerve roots or the spinal cord itself. The mainstay of treatment involves surgical intervention. Curettage has been a surgical option, although marginal excision or wide en bloc resection are preferred options. Adjuvant radiotherapy and chemotherapy are generally not undertaken, although some have advocated their use after less aggressive surgical maneuvers or with residual tumor. In this manuscript, the authors have aimed to systematically review the literature and to put forth an extensive, comprehensive overview of this rare osseous tumor.

Intramedullary Spinal Cord Abscess Management: Case Series, Operative Video, and Systematic Review.

BACKGROUND: Intramedullary spinal cord abscess (ISCA) is an extremely rare disease, which has had fewer than 250 reported cases since its initial description in 1830. The condition is limited to level V evidence, limiting the ability for surgeons to characterize and treat it. OBJECTIVE: To report the cases of 2 patients with ISCA and their surgical management: a 59-year-old woman who presented with progressive right hemiparesis and a 69-old man who presented with acute gait instability and significant bilateral shoulder pain. In addition, to report findings from a systematic literature review and associated logistic regression analysis. METHODS: A MEDLINE and Embase search was conducted using the keywords "intramedullary," "spinal cord," "abscess," and "tuberculoma" and the results were screened for case reports. A logistic regression model was fit 100 times on data to retrieve predictor odds ratios. RESULTS: Two hundred case reports of ISCA were identified between 1965 and 2022. Logistic regression determined that the only variables of significance were age (P < 0.01) and antibiotics (P < 0.05). CONCLUSIONS: Treatment of ISCAs has significantly improved over the years. However, ISCAs are still poorly understood. Our recommendations can be used to guide diagnosis and treatment.

Educational impact of early COVID-19 operating room restrictions on neurosurgery resident training in the United States: A multicenter study.

BACKGROUND: The coronavirus (COVID-19) pandemic has caused unprecedented suspensions of neurosurgical elective surgeries, a large proportion of which involve spine procedures. The goal of this study is to report granular data on the impact of early COVID-19 pandemic operating room restrictions upon neurosurgical case volume in academic institutions, with attention to its secondary impact upon neurosurgery resident training. This is the first multicenter quantitative study examining these early effects upon neurosurgery residents caseloads. METHODS: A retrospective review of neurosurgical caseloads among seven residency programs between March 2019 and April 2020 was conducted. Cases were grouped by ACGME Neurosurgery Case Categories, subspecialty, and urgency (elective vs. emergent). Residents caseloads were stratified into junior (PGY1-3) and senior (PGY4-7) levels. Descriptive statistics are reported for individual programs and pooled across institutions. RESULTS: When pooling across programs, the 2019 monthly mean (SD) case volume was 214 (123) cases compared to 217 (129) in January 2020, 210 (115) in February 2020, 157 (81), in March 2020 and 82 (39) cases April 2020. There was a 60% reduction in caseload between April 2019 (207 [101]) and April 2020 (82 [39]). Adult spine cases were impacted the most in the pooled analysis, with a 66% decrease in the mean number of cases between March 2020 and April 2020. Both junior and senior residents experienced a similar steady decrease in caseloads, with the largest decreases occurring between March and April 2020 (48% downtrend). CONCLUSIONS: Results from our multicenter study reveal considerable decreases in caseloads in the neurosurgical specialty with elective adult spine cases experiencing the most severe decline. Both junior and senior neurosurgical residents experienced dramatic decreases in case volumes during this period. With the steep decline in elective spine cases, it is possible that fellowship directors may see a disproportionate increase in spine fellowships in the coming years. In the face of the emerging Delta and Omicron variants, programs should pay attention toward identifying institution-specific deficiencies and developing plans to mitigate the negative educational effects secondary to such caseloads reduction.

Bullet retrieval from the cauda equina after penetrating spinal injury: A case report and review of the literature.

BACKGROUND: When gunshot injuries occur to the spine, bullet fragments may be retained within the spinal canal. Indications for bullet removal include incomplete spinal cord injury, progressive loss of neurologic function including injury to the cauda equina, and dural leaks with impending risk of meningitis. CASE DESCRIPTION: Here, we present a 34-year-old male with a missile penetrating spinal injury to the cauda equina. In addition to the computed tomography scan demonstrating retention of a bullet in the left L1/2 disc space, the scan suggested likely dural injury. The patient underwent a decompression/instrumented fusion with retrieval of the retained bullet fragment. A laminectomy was performed from T12 to L3, and at L1 and L2, a large traumatic durotomy was identified and repaired. The patient, unfortunately, continued to have bilateral lower extremity plegia with neurogenic bladder/bowel dysfunction at 1-year follow-up. CONCLUSION: We discuss the operative management and provide an intraoperative video showing the bullet extraction and dural closure.

Follow-up Brain Imaging Within 30 Days of Gamma-Knife Surgery for New Symptoms: Retrospective Analysis.

OBJECTIVE: Gamma Knife surgery is a complementary procedure to open microsurgery for several indications. However, posttreatment symptomatic complaints are common and often result in short-term follow-up imaging. Here we evaluate the efficacy of repeat brain imaging within 30 days of a Gamma Knife procedure by analyzing the frequency with which that imaging reveals addressable pathology. METHODS: All patients who underwent Gamma Knife treatments at our institution between January 2013 and August 2019 were retrospectively analyzed, and any patient who received imaging of the brain within 30 days for a symptomatic complaint was evaluated. RESULTS: Of the 956 Gamma Knife cases performed, 78 (8.2%) scans were performed within a 30-day time frame for symptomatic complaints. Of these, the most common complaint was headache (25%). Most images demonstrated no changes when compared with the treatment scan (68%) and there were no hemorrhages and only 1 stroke (<1%). Univariate analysis revealed that sex (P = 0.046), treatment volume (P < 0.001), and treatments for metastasis (P < 0.001) or glioma (P < 0.001) were associated with symptomatic complaints leading to imaging, but no factors were associated with higher rates of abnormal imaging. CONCLUSIONS: Gamma Knife therapy remains a safe treatment for multiple indications, but it is not risk free and acute symptomatic complaints are common. However, our data suggest that the need for reimaging within 30 days for symptomatic complaints is likely overestimated as obtained imaging does not usually show any change and the rate of significant complication is exceedingly low.

Utilizing vertebral body autograft for anterior cervical corpectomy/fusion.

BACKGROUND: There are numerous ways to reconstruct cervical vertebral bodies and achieve arthrodesis following anterior cervical corpectomy and fusion (ACF). However, device and donor site complications abound. Here, we describe a novel technique for performing ACF using the vertebral body itself as a structural autograft. METHODS: The anterior cervical spine was accessed and discectomies were performed rostral and caudal to the corpectomy. Five millimeter troughs were drilled on the lateral borders of the vertebral body, and it was removed en bloc. The autograft was rotated 90°, and an anterior cervical plate was selected to span the length of the graft, allowing for fixation to the adjacent vertebral bodies. The plate was secured to the graft, the graft was placed in the bony defect, and the plate was secured to the adjacent levels. RESULTS: This corpectomy reconstructive technique was successfully applied in a 57-year-old female with cervical myelopathy due to a C5-C6 disc herniation with caudal migration. The C6 vertebral body was used as a structural autograft. Postoperatively, the patient experienced satisfactory improvement in her myelopathy, and the construct appeared stable 8 months later. CONCLUSION: This corpectomy reconstructive technique takes advantage of the favorable osteogenic properties of autograft, while avoiding donor site morbidity as well as the cost and complications of other devices, such as cages. Further cases are required to verify the safety, efficacy, and biomechanical stability of this technique.

Resection of a large presacral schwannoma from an all-posterior trans-sacral approach.

BACKGROUND: Presacral schwannomas vary greatly in size, and symptomatology. Resections may utilize anterior, posterior, or combined 360-degree approaches. CASE DESCRIPTION: A 67-year-old female presented with a progressively enlarging presacral schwannoma originating from the S1 nerve root. Here, we utilized a unique all-posterior, trans-sacral tumor resection technique that did not result in any increased neurological deficit, or warrant fusion (e.g., including operative video). Further, we avoided potential urogenital, vascular, and bowel injuries that are associated with anterior approaches to such lesions. CONCLUSION: Here, we described and demonstrated successful resection of a large presacral schwannoma originating from the S1 nerve root that was safely resected utilizing an all-posterior resection without fusion.

Tandem Thoracic Spinal Cord Lesions of Differing Pathologies: Concurrent Metastatic Lung Adenocarcinoma Lesion in Close Proximity to a Intradural Meningioma.

Simultaneously having two pathologically distinct neoplastic lesions causing critical spinal stenosis is exceedingly rare. When such lesions are near one another but occupy different spinal compartments, significant challenges arise. We present the case of a patient with metastatic non-small cell carcinoma to the thoracic spine and an intradural meningioma occurring two spinal segments from each other. A 66-year-old female presented with one month of progressive mechanical back pain and two days of lower extremity weakness and urinary retention. She was found to have a left upper lobe lung mass. An urgent biopsy demonstrated non-small cell lung carcinoma. MRI of her thoracic spine demonstrated a T9 intradural-extramedullary enhancing lesion simultaneously with a destructive lesion of the T11 vertebral body extending into the anterior epidural space with significant cord compression at T9 and T11. The patient was taken for an urgent posterior decompression from T9 to T11, T9 left-sided pediculectomy with resection of intradural tumor, T11 corpectomy with anterior cage reconstruction, and instrumented fixation from T7 to L2. The pathology from the T9 lesion demonstrated findings consistent with a meningioma while the T11 lesion confirmed metastatic non-small cell lung adenocarcinoma. The patient improved neurologically postoperatively and regained the ability to ambulate within one week of surgery. Pathologically distinct spinal lesions in close anatomic proximity, but in two separate compartments are exceptionally rare. We performed a simultaneous posterior approach for resection of the T9 meningioma and a T11 corpectomy for the metastatic lesion with rapid neurologic recovery.

Dorsal migration of lumbar disc fragments causing cauda equina syndromes: A three case series and literature review.

BACKGROUND: Dorsal migration of an intervertebral lumbar disc fragment is exceedingly rare and may result in spinal cord or cauda equina compression. Radiologically, these lesions may be misdiagnosed as extradural masses or epidural hematomas. CASE DESCRIPTION: We present three cases involving dorsal migration of sequestered lumbar disc fragments resulting in cauda equina syndromes. A 31-year-old male, 79-year-old female, and 47-year-old female presented with cauda equina syndromes attributed to the migration of dorsal sequestered lumbar disc fragments. Prompt surgical decompression resulted in adequate outcomes. Here, we review the three cases and the current literature for such lesions. CONCLUSION: Dorsal migration of sequestered lumbar disc fragments is exceedingly rare, and these lesions are frequently misdiagnosed as extradural masses of other origin or epidural hematomas. Here and in the literature, prompt epidural decompression both confirmed the correct diagnosis and resulted in excellent outcomes.

Rapid Development of Spinal Epidural Lipomatosis after Treatment of Metastatic Castration-Resistant Prostate Cancer with Second-Generation Androgen Receptor Antagonists.

BACKGROUND: Previous studies have described the association of spinal epidural lipomatosis with several conditions including chronic steroid therapy, Cushing's syndrome, obesity, Paget disease, and hypothyroidism. We present a report of rapid development of spinal epidural lipomatosis after treatment with second-generation anti-androgen therapy, a new strategy for treatment of metastatic castration-resistant prostate cancer that has been increasingly employed in the past few years. A comprehensive discussion of the underlying molecular networks involving androgen receptor blockage and adipocyte differentiation, as well as the clinical implications of such a phenomenon, are provided. CASE DESCRIPTION: We describe the clinical and radiological evolution of a 58-year-old male patient with metastatic prostate cancer, who developed new onset of rapidly progressing lumbosacral epidural lipomatosis with significant compression of the nerve roots of the cauda equina a few months after initiation of treatment with second-generation androgen receptor antagonists. CONCLUSIONS: The underlying pathophysiology of adipose tissue growth following the administration of anti-androgen therapy is discussed, with emphasis on both the canonical Wnt/ß-catenin pathway as well as in the Wnt-independent pathway involving direct activation of downstream transcription factors from the T-cell factor family by the androgen receptor. As second-generation androgen receptor antagonists have been increasingly used for treatment of castration-resistant stage metastatic prostate cancer, new onset of symptomatic epidural lipomatosis should be considered as a possible differential diagnosis, especially because the urinary symptoms of cauda equina compression may be improperly attributed to the primary prostate neoplasm.

Rapid-Onset Thoracic Myelopathy due to an Epidural Sarcoid-Like Lesion in a Pediatric Patient.

BACKGROUND: Isolated intraspinal neurosarcoidosis is a rare clinical entity, with most reports describing intramedullary involvement in adults. CASE DESCRIPTION: We detail the case of a 9-year-old girl with rapid-onset compressive myelopathy secondary to a thoracic epidural lesion. Although pathologic diagnosis was challenging, a presumptive diagnosis of isolated extradural neurosarcoidosis was made in light of the patient's investigations and dramatic response to corticosteroids. CONCLUSIONS: Although less likely than neoplasia, rheumatologic processes such as inflammatory granulomatous disease warrant consideration in similar cases.

Anatomical nuances of the internal carotid artery in relation to the quadrangular space.

OBJECTIVE The aim of this study was to evaluate the anatomical variations of the internal carotid artery (ICA) in relation to the quadrangular space (QS) and to propose a classification system based on the results. METHODS A total of 44 human cadaveric specimens were dissected endonasally under direct endoscopic visualization. During the dissection, the anatomical variations of the ICA and their relationship with the QS were noted. RESULTS The space between the paraclival ICAs (i.e., intercarotid space) can be classified as 1 of 3 different shapes (i.e., trapezoid, square, or hourglass) based on the trajectory of the ICAs. The ICA trajectories also directly influence the volumetric area of the QS. Based on its geometry, the QS was classified as one of the following: 1) Type A has the smallest QS area and is associated with a trapezoid intercarotid space, 2) Type B corresponds to the expected QS area (not minimized or enlarged) and is associated with a square intercarotid space, and 3) Type C has the largest QS area and is associated with an hourglass intercarotid space. CONCLUSIONS The different trajectories of the ICAs can modify the area of the QS and may be an essential parameter to consider for preoperative planning and defining the most appropriate corridor to reach Meckel's cave. In addition, ICA trajectories should be considered prior to surgery to avoid injuring the vessels.

Newly Diagnosed Sellar Tumors in Patients with Cancer: A Diagnostic Challenge and Management Dilemma.

BACKGROUND: The use of combined positron emission tomography/computed tomography for staging in patients with cancer and the widespread use of magnetic resonance imaging has led to increased detection of incidental sellar masses. The imaging findings can be suggestive of a benign pituitary tumor, but metastasis can never be completely ruled out with noninvasive work-up. Appropriate diagnosis of sellar masses is critical, as the treatment paradigm might change in the presence of a pituitary metastasis. Definitive tissue diagnosis might prevent unnecessary radiotherapy to the skull base or the need for systemic treatment when benign pituitary disease is confirmed. METHODS: A retrospective chart review from 2010 to 2015 of all patients with recently diagnosed cancer and undergoing surgery for sellar region masses was performed. RESULTS: There were 9 patients (3 female and 6 male) identified. Lung cancer was the primary condition in 4 patients; the remaining 5 patients had breast cancer, follicular thyroid cancer, cutaneous melanoma, colorectal carcinoma, and renal cell carcinoma. On final pathology, the sellar mass was a benign pituitary adenoma in 5 patients, metastatic cancer in 3 patients, and a granular cell tumor in 1 patient. CONCLUSIONS: Surgical resection of a sellar mass in patients with known cancer helps in the definitive diagnosis, relieves compressive symptoms, and avoids unnecessary empiric radiotherapy in cases of confirmed benign pituitary disease.

Photoradiation and orthodontic movement: experimental study with canines.

OBJECTIVE: The aim of this study was to evaluate, through a double-blind study, the effect of gallinium-aluminium- arsenic (GaAlAs) laser irradiation on the speed of orthodontic movement in canine premolars. METHODS: Eighteen dogs were divided into two groups, and their third molars were extracted. An orthodontic device was placed between the first molar and the second premolar for stabilization purpose. Group I was irradiated with a dosage of 5.25 J/cm(2) on the right side, whereas the left side was used as the control group. Group II was submitted to the same procedure, but was irradiated with a dosage of 35.0 J/cm(2). Irradiations were done every 7 days, for a total of nine irradiations. The orthodontic space was measured every 21 days. RESULTS: The 5.25 J/cm(2) dosage accelerated orthodontic movement during the first observation period, from 0 to 21 days (p < 0.05), whereas the 35.0 J/cm(2) dosage retarded the orthodontic movement in the treated group when compared with the control group, during both the first and second observation periods, from 0 to 42 days (p < 0.05). CONCLUSION: The results suggets that photoradiation may accelerate orthodontic movement at a dosage of 5.25 J/cm(2), whereas a higher dosage, 35.0 J/cm(2), may retard it.

Retropharyngeal abscess with secondary osteomyelitis and epidural abscess: proposed pathophysiological mechanism of an underrecognized complication of unstable craniocervical injuries: case report.

Because of the proximity of the oropharynx (a naturally contaminated region) to the spinal structures of the craniocervical junction, it is possible that small mucosal lacerations in the oropharynx caused by unstable traumatic craniocervical injuries may become contaminated and lead to secondary infection and osteomyelitis. In this report, the authors describe the case of a previously healthy and immunocompetent patient who developed a large retropharyngeal abscess with spinal osteomyelitis after a high-energy craniocervical injury. This unusual report of osteomyelitis with a delayed presentation after a high-energy traumatic injury of the craniocervical junction highlights the possibility of direct injury to a specific area in the oropharyngeal mucosa adjacent to the osteoligamentous structures of the craniocervical junction, an overall underrecognized complication of unstable craniocervical injuries.

Successful outcome after endovascular thrombolysis for acute ischemic stroke with basis on perfusion-diffusion mismatch after 24 h of symptoms onset.

BACKGROUND: Although intravenous thrombolysis is the Food and Drug Administration-approved treatment for acute ischemic stroke (AIS) within 3 h, combined intravenous and intra-arterial thrombolysis with endovascular techniques may be able to extend this traditional time window. CASE DESCRIPTION: We present the clinical evolution of a 45-year-old male presenting with acute left hemiparesis. Magnetic resonance imaging revealed a small diffusion restriction at the right basal ganglia with perfusion compromise in the entire right middle cerebral artery (MCA) territory. Angiography revealed a complete occlusion of MCA at its M1 segment. The patient underwent endovascular mechanical thrombectomy with additional intra-arterial thrombolysis more than 24 hours after the onset of the initial symptoms and experienced complete vessel recanalization. At 1 year, the patient had global independence with minor residual motor impairment in the left arm. CONCLUSIONS: We report the case of a successful thrombolytic therapy following AIS performed more than 24 h after the initial symptoms based on the presence of a perfusion-diffusion mismatch. This report is expected to stimulate the development of future prospective studies with special focus on the role of perfusion-diffusion mismatch in patient selection for treatment of AIS, especially in those presenting outside the traditional time window.

Epidemiological profile of pregnant women with syphilis in the city of Macaé, Rio de Janeiro

Introduction: Gestational and congenital syphilis are diseases that can be prevented. Practices routinely carried out in prenatal care are effective for the prevention of cases. The prevalence of syphilis in pregnant women is considered an indicator of prenatal care quality. The objective is to define the epidemiological profile of pregnant women diagnosed with syphilis in the city of Macaé ­ Rio de Janeiro from 2010 to 2018. Methods: A cross-sectional retrospective study covering from 2010 to 2018 was conducted to assess the general prevalence in the period and annual incidence rates in records and database from the Care Center of Women and Children and from the Macaé Public Hospital. Results: A total of 535 cases of syphilis were reported in pregnant women. The highest number of reported cases was observed in 2018 (n = 151), with a detection rate of 38.4% per 1000 live births, meaning an increase of 37% compared to 2010. Most cases were diagnosed in the third trimester of pregnancy (n = 194 cases). The majority of women were aged 20-29 years (n = 322) and were housewives (n = 248). The predominant skin color was brown, accounting for 32.4% (n = 180) of the cases, followed by black skin (16.9%; n = 124). The majority of patients (n = 124) had incomplete elementary school education. The annual incidence rate of congenital syphilis increased from 1.4 to 17.2 cases per 1,000 live births between 2010 and 2018. Conclusions: There was an increased prevalence of syphilis in the city of Macaé, especially after 2015, with a peak of cases in 2018. (AU)

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 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.