Treatment of pediatric intracranial aneurysms: institutional case series and systematic literature review

INTRODUCTION

Pediatric intracranial aneurysms (IAs) are rare and have distinct clinical profiles compared to adult IAs. They differ in location, size, morphology, presentation, and treatment strategies. We present our experience with pediatric IAs over an 18-year period using surgical and endovascular treatments and review the literature to identify commonalities in epidemiology, treatment, and outcomes.

METHODS

We identified all patients < 20 years old who underwent treatment for IAs at our institution between 2005 and 2020. Medical records and imaging were examined for demographic, clinical, and operative data. A systematic review was performed to identify studies reporting primary outcomes of surgical and endovascular treatment of pediatric IAs. Demographic information, aneurysm characteristics, treatment strategies, and outcomes were collected.

RESULTS

Thirty-three patients underwent treatment for 37 aneurysms over 18 years. The mean age was 11.4 years, ranging from one month to 19 years. There were 21 males (63.6%) and 12 females (36.4%), yielding a male: female ratio of 1.75:1. Twenty-six (70.3%) aneurysms arose from the anterior circulation and 11 (29.7%) arose from the posterior circulation. Aneurysmal rupture occurred in 19 (57.5%) patients, of which 8 (24.2%) were categorized as Hunt-Hess grades IV or V. Aneurysm recurrence or rerupture occurred in five (15.2%) patients, and 5 patients (15.2%) died due to sequelae of their aneurysms. Twenty-one patients (63.6%) had a good outcome (modified Rankin Scale score 0-2) on last follow up. The systematic literature review yielded 48 studies which included 1,482 total aneurysms (611 with endovascular treatment; 656 treated surgically; 215 treated conservatively). Mean aneurysm recurrence rates in the literature were 12.7% and 3.9% for endovascular and surgical treatment, respectively.

CONCLUSIONS

Our study provides data on the natural history and longitudinal outcomes for children treated for IAs at a single institution, in addition to our treatment strategies for various aneurysmal morphologies. Despite the high proportion of patients presenting with rupture, good functional outcomes can be achieved for most patients.

Identification and management of low-risk isolated traumatic brain injury patients initially treated at a rural level IV trauma center

STUDY OBJECTIVE

Our goal was to determine if low-risk, isolated mild traumatic brain injury (TBI) patients who were initially treated at a rural emergency department may have been safely managed without transfer to the tertiary referral trauma center.

METHODS

This was a retrospective observational analysis of isolated mild TBI patients who were transferred from a rural Level IV Trauma Center to a regional Level I Trauma Center between 2018 and 2022. Patients were risk-stratified according to the modified Brain Injury Guidelines (mBIG). Data abstracted from the electronic medical record included patient presentation, management, and outcomes.

RESULTS

250 patients with isolated mild TBI were transferred out to the Level I Trauma Center. Fall was the most common mechanism of injury (69.2%). 28 patients (11.2%) were categorized as low-risk (mBIG1). No mBIG1 patients suffered a progression of neurological injury, had worsening of intracranial hemorrhage on repeat head CT, or required neurosurgical intervention. 12/28 (42.9%) of mBIG1 patients had a hospital length of stay of 2 days or less, typically for observation. Those with longer lengths of stay were due to medical complications, such as sepsis, or difficulty in arranging disposition.

CONCLUSION

We propose that patients who meet mBIG1 criteria may be safely observed without transfer to a referral Level I Trauma Center. This would be of considerable benefit to patients, who would not need to leave their community, and would improve resource utilization in the region.

Reducing frame rate and pulse rate for routine diagnostic cerebral angiography: ALARA principles in practice

OBJECTIVE

Diagnostic cerebral angiograms (DCAs) are widely used in neurosurgery due to their high sensitivity and specificity to diagnose and characterize pathology using ionizing radiation. Eliminating unnecessary radiation is critical to reduce risk to patients, providers, and health care staff. We investigated if reducing pulse and frame rates during routine DCAs would decrease radiation burden without compromising image quality.

METHODS

We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. Radiation doses and exposures were calculated. Two endovascular neurosurgeons reviewed randomly selected angiograms of both doses and blindly assessed their quality.

RESULTS

A total of 40 consecutive angiograms were retrospectively analyzed, 20 prior to the protocol change and 20 after. After the intervention, radiation dose, radiation per run, total exposure, and exposure per run were all significantly decreased even after adjustment for BMI (all p<0.05). On multivariable analysis, we identified a 46% decrease in total radiation dose and 39% decrease in exposure without compromising image quality or procedure time.

CONCLUSIONS

We demonstrated that for routine DCAs, pulse rate of 7.5 with a frame rate of 4.0 is sufficient to obtain diagnostic information without compromising image quality or elongating procedure time. In the interest of patient, provider, and health care staff safety, we strongly encourage all interventionalists to be cognizant of radiation usage to avoid unnecessary radiation exposure and consequential health risks.

Optimizing suction force in mechanical thrombectomy: Priming the aspiration tubing with air versus saline

Objective

We sought to investigate how priming the tube between air versus air mixed with saline ex vivo influenced suction force. We examined how priming the tube influenced peak suction force and time to achieve peak suction force between both modalities.

Methods

Using a Dwyer Instruments (Dwyer Instruments Inc., Michigan City, IN, USA), INC Digitial Pressure Gauge, we were able to connect a .072 inch aspiration catheter to a rotating hemostatic valve and to aspiration tubing. We recorded suction force measured in negative inches of Mercury (inHg) over 10 iterations between having the aspiration tube primed with air alone versus air mixed with saline. A test was used to compare results between both modalities.

Results

Priming the tube with air alone compared to air mixed with saline was found to have an increased average max suction force (-28.60 versus -28.20 in HG, p<0.01). We also identified a logarithmic curve of suction force across time in which time to maximal suction force was more prompt with air compared with air mixed with saline (13.8 seconds versus 21.60 seconds, p<0.01).

Conclusions

Priming the tube with air compared to air mixed with saline suggests that not only is increased maximal suction force achieved, but also the time required to achieve maximal suction force is less. This data suggests against priming the aspiration tubing with saline and suggests that the first pass aspiration primed with air may have the greatest suction force.

Safety of middle meningeal artery embolization for treatment of subdural hematoma: A nationwide propensity score matched analysis

OBJECTIVE

Middle meningeal artery embolization (MMAe) has burgeoned as a treatment for chronic subdural hematoma (cSDH). This study evaluates the safety and short-term outcomes of MMAe patients relative to traditional treatment approaches.

METHODS

In this retrospective large database study, adult patients in the National Inpatient Sample from 2012-2019 with a diagnosis of cSDH were identified. Cost of admission, length of stay (LOS), discharge disposition, and complications were analyzed. Propensity score matching (PSM) was utilized.

RESULTS

A total of 123,350 patients with cSDH were identified: 63,450 without intervention, 59,435 surgery only, 295 MMAe only, and 170 surgery plus MMAe. On PSM analysis, MMAe did not increase the risk of inpatient complications or prolong the length of stay compared to conservative management (p>0.05); MMAe had higher cost ($31,170 vs. $10,768, p<0.001) than conservative management, and a lower rate of nonroutine discharge (53.8% vs. 64.3%, p=0.024). Compared to surgery, MMAe had shorter LOS (5 vs. 7 days, p<0.001), and lower rates of neurological complications (2.7% vs. 7.1%, p=0.029) and nonroutine discharge (53.8% vs. 71.7%, p<0.001). There was no significant difference in cost (p>0.05).

CONCLUSIONS

MMAe had similar LOS and decreased odds of adverse discharge with a modest cost increase compared to conservative management. There was no difference in inpatient complications. Compared to surgery, MMAe treatment was associated with decreased LOS and rates of neurological complications and nonroutine discharge. This nationwide analysis supports the safety of MMAe to treat cSDH.

Custom 3D-Printed External Cranial Orthotic for Prevention and Treatment of Syndrome of the Trephined

Syndrome of the Trephined (SoT) is a frequently misunderstood and underdiagnosed outcome of decompressive craniectomy, especially in cases of trauma. The pressure gradient between atmospheric pressure and the sub-atmospheric intracranial pressure results in a sinking of the scalp overlying the craniectomy site. This gradually compresses the underlying brain parenchyma. This parenchymal compression can disrupt normal autoregulation and subsequent metabolism, yielding symptoms ranging from headaches, dizziness, altered behavior to changes in sensation, and difficulty with ambulation, coordination, and activities of daily living. We present a case of SoT treated with a 3D-printed custom polycarbonate external cranial orthotic that allowed us to re-establish this pressure gradient by returning the cranium to a closed system. The patient demonstrated subjective improvement in quality of life and his symptoms. This was consistent with the re-expanded brain parenchyma on CT imaging.

Direct Transorbital Approach for Treatment of Carotid Cavernous Fistula: An Illustrative Case Series

BACKGROUND AND OBJECTIVES

Endovascular techniques have become the first-line treatment for carotid-cavernous fistulas (CCFs). Direct transorbital venous access may be used if anatomic constraints limit standard transarterial or transvenous access. We describe our institutional experience with the transorbital approach for Barrow Type A-D CCFs.

METHODS

Patients with CCFs undergoing transorbital endovascular treatment at our institution between 2017 and 2019 were retrospectively reviewed. Demographic, treatment, and outcome data were collected.

RESULTS

Eight patients met inclusion criteria, 4 female and 4 male patients. The mean age was 43 years, with 6 right-sided CCF and 2 left-sided CCFs. Symptoms were present for an average of 1.5 months before treatment. All patients presented with eye pain and subjective visual changes. Seven (87.5%) patients presented with proptosis, 6 (75%) patients had elevated intraocular pressure (IOP), and 3 (37.5%) patients had ophthalmoplegia. Six CCFs (75%) were spontaneous, and 2 CCFs (25%) were traumatic. Barrow types were A (n = 1), B (n = 1), C (n = 1), and D (n = 5). All patients underwent direct percutaneous transorbital embolization with coils followed by Onyx. Three patients had undergone prior transarterial and/or transvenous treatment. A radiographic cure was obtained in all patients after direct transorbital embolization. After CCF cure, cranial nerve palsies resolved in 66.7% of patients, visual acuity in the affected eye was improved or stable in 75% of patients, and IOP had normalized in 85.7% of patients. Proptosis improved in all patients, with complete resolution in 75%.

CONCLUSION

Direct transorbital embolization is a safe and potentially curative treatment for all 4 Barrow types of CCFs.

The Cost of Operating: Analysis of Single-Use Instrument Costs for Craniotomies

Introduction All-cause craniotomies comprise a significant portion of neurosurgical practice as well as hospital costs. While some instruments are reusable with a fixed cost, price variability for similar single-use instruments exists. A better understanding of these cost variations within cranial procedures can better inform operating physicians to be cost-sensitive stewards. Objective In this study, we examine how single-use items contribute to the overall cost of cranial procedures.  Methods A de-identified institutional database containing records of all single-use items from craniotomies between July 1, 2019, and June 30, 2020, was subject to a longitudinal analysis by three independent parties (one senior surgeon, one resident, and one medical student). Four hundred and sixty-nine unique single-use items were identified and classified by function. Similar items were combined, and a range of costs was provided. Three sample cases with sum costs were reviewed for cost division and primary contributors. Results  The category with the highest median cost across all cases was non-specialty implants comprising dural onlays, mesh, aneurysm clips, and plates. The category with the lowest median cost was personal protective equipment. The items with the most cost variability were sterile surgical patties due to the variety of sizes and preset multipacks. The proportion of cost generators varies from craniotomy indication.  Conclusion While institution dependent, awareness of cost generators in cranial cases is important for economic stewardship. For single-use items, costs are highly variable and not insignificant. Surgeons and neurosurgical departments are responsible for allocating single-use items in a responsible and efficient manner.

Enlarging symptomatic arachnoid cyst in an elderly patient: illustrative case

BACKGROUND

Arachnoid cysts are congenital or acquired structures found within the brain and are rarely symptomatic for adults. The literature documenting enlarging arachnoid cysts in adults is also discussed.

OBSERVATIONS

An elderly woman presented with acutely worsening headaches, photophobia, cognitive function, and a seizure-like episode. The patient had a known arachnoid cyst with a decade of radiographic stability, which was now idiopathically enlarging. The patient had a previous history of traumatic brain injuries but no reported trauma around the time of presentation. Due to the severity of midline shift and symptomatology, the decision was made to treat the patient surgically with fenestration and shunting. She recovered well postoperatively.

LESSONS

During the workup for a symptomatic elderly patient, enlargement of a previously asymptomatic arachnoid cyst should remain on the differential until specifically ruled out, even in the absence of recent trauma. While rare, enlarging arachnoid cysts result in neurological findings and impact the quality of life for patients.

Robotics and Artificial Intelligence in Endovascular Neurosurgery

The use of artificial intelligence (AI) and robotics in endovascular neurosurgery promises to transform neurovascular care. We present a review of the recently published neurosurgical literature on artificial intelligence and robotics in endovascular neurosurgery to provide insights into the current advances and applications of this technology.

The PubMed database was searched for "neurosurgery" OR "endovascular" OR "interventional" AND "robotics" OR "artificial intelligence" between January 2016 and August 2021. A total of 1296 articles were identified, and after applying the inclusion and exclusion criteria, 38 manuscripts were selected for review and analysis. These manuscripts were divided into four categories: 1) robotics and AI for the diagnosis of cerebrovascular pathology, 2) robotics and AI for the treatment of cerebrovascular pathology, 3) robotics and AI for training in neuroendovascular procedures, and 4) robotics and AI for clinical outcome optimization.

The 38 articles presented include 23 articles on AI-based diagnosis of cerebrovascular disease, 10 articles on AI-based treatment of cerebrovascular disease, two articles on AI-based training techniques for neuroendovascular procedures, and three articles reporting AI prediction models of clinical outcomes in vascular disorders of the brain. Innovation with robotics and AI focus on diagnostic efficiency, optimizing treatment and interventional procedures, improving physician procedural performance, and predicting clinical outcomes with the use of artificial intelligence and robotics. Experimental studies with robotic systems have demonstrated safety and efficacy in treating cerebrovascular disorders, and novel microcatheterization techniques may permit access to deeper brain regions. Other studies show that pre-procedural simulations increase overall physician performance. Artificial intelligence also shows superiority over existing statistical tools in predicting clinical outcomes.

The recent advances and current usage of robotics and AI in the endovascular neurosurgery field suggest that the collaboration between physicians and machines has a bright future for the improvement of patient care. The aim of this work is to equip the medical readership, in particular the neurosurgical specialty, with tools to better understand and apply findings from research on artificial intelligence and robotics in endovascular neurosurgery.

Maturation of the sella turcica and parasellar region: Surgical relevance for anterior skull base approaches in pediatric patients

OBJECTIVE

Traditional and extended transnasal transsphenoidal approaches provide direct access to a variety of anterior skull base pathologies. Despite increased utilization of transnasal approaches in children, anatomic studies on pediatric skull base maturation are limited. We herein perform a surgically relevant morphometric analysis of the sella and parasellar regions during pediatric maturation.

METHODS

Measurements of sellar length (SL), sellar depth (SDp), sellar diameter (SDm), interclinoid distance (ID), intercavernous distance (ICD), and the presence of sphenoid sinus pneumatization (SSP), and sphenoid sinus type (SST) were made on thin-cut CT scans from 60 patients (evenly grouped by ages 0-3, 4-7, 8-11 12-15, 16-18, and >18 years) for analysis. Data were analyzed by sex and age groups using t-tests and linear regression.

RESULTS

Sella and parasellar parameters did not differ by sex. SL steadily increased from 8.5 ± 1.2 mm to 11.5 ± 1.6 mm throughout development. SDp and SDm increased from 6.0 ± 0.9 mm to 9.3 ± 1.4 mm and 9.0 ± 1.6 mm to 14.4 ± 1.8 mm during maturation, with significant interval growth from ages 16-18 to adult (p < 0.01). ID displayed significant growth from ages 0-3 to 4-7 (18.0 ± 2.4 mm to 20.7 ± 1.9 mm; p = 0.002) and ICD from ages 0-3 to 8-11 (12.0 ± 1.8 mm to 13.5 ± 2.1 mm; p < 0.001), without further significant interval growth. SSP was not seen in patients < 3, but was 100% by ages 8-11. SSTs progressed from conchal/presellar (60% at ages 4-7) to sellar/postsellar (80% at adulthood).

CONCLUSION

The sella and parasellar regions have varied growth patterns with development. Knowledge of the expected maturation of key anterior skull base structures may augment surgical planning in younger patients.

Microsurgical Resection of a Giant Posterior Fossa Aneurysmal Malformation in a 21-Month-Old

Pediatric aneurysms commonly occur in the vertebrobasilar circulation with complex morphologies.¹ "Aneurysmal malformations," or fistulous vessel dilations without a nidus, have also been described.² Vessel friability and sensitivity to blood loss can complicate surgery. A 21-month-old male with motor and speech delay was found to have a giant posterior fossa aneurysmal malformation. He was lethargic, with minimal speech, and moved all extremities with mild hypotonia. Imaging demonstrated a 6.9 × 5.1 × 4.6 cm aneurysm arising from a fenestrated right V4 segment. This communicated via a single connection with the deep venous system, draining through the superior vermian cistern veins, posterior mesencephalic vein, basal vein of Galen, and inferior sagittal sinus, consistent with an arteriovenous fistula with secondary aneurysmal dilatation. Endovascular sacrifice was not feasible, in addition to concern for swelling after embolization. Three-dimensional modeling confirmed close proximity of the single inflow and outflow tracts. A suboccipital and left far lateral craniotomy for clip trapping and excision of the aneurysmal arteriovenous malformation was performed in a lateral position to completely decompress the brainstem (Video 1). Angiography before closure and postoperative vascular imaging demonstrated complete aneurysmal resection and fistula disconnection, with patency of normal vasculature. The postoperative course was notable for transient swallowing difficulties likely from lower cranial nerve irritation and refractory hydrocephalus requiring a shunt. The patient was meeting all developmental milestones at 2-year follow-up. This case highlights the complex vascular pathology often seen in pediatric patients, as well as the importance of presurgical planning and careful microsurgical technique in achieving a successful outcome.

Maturation of the anterior petrous apex: surgical relevance for performance of the middle fossa transpetrosal approach in pediatric patients

OBJECTIVE

The middle fossa transpetrosal approach to the petroclival and posterior cavernous sinus regions includes removal of the anterior petrous apex (APA), an area well studied in adults but not in children. To this end, the authors performed a morphometric analysis of the APA region during pediatric maturation.

METHODS

Measurements of the distance from the clivus to the internal auditory canal (IAC; C-IAC), the distance of the petrous segment of the internal carotid artery (petrous carotid; PC) to the mesial petrous bone (MPB; PC-MPB), the distance of the PC to the mesial petrous apex (MPA; PC-MPA), and the IAC depth from the middle fossa floor (IAC-D) were made on thin-cut CT scans from 60 patients (distributed across ages 0-3, 4-7, 8-11, 12-15, 16-18, and > 18 years). The APA volume was calculated as a cylinder using C-IAC (length) and PC-MPB (diameter). APA pneumatization was noted. Data were analyzed by laterality, sex, and age.

RESULTS

APA parameters did not differ by laterality or sex. APA pneumatization was seen on 20 of 60 scans (33.3%) in patients ≥ 4 years. The majority of the APA region growth occurred by ages 8-11 years, with PC-MPA and PC-MPB increasing 15.9% (from 9.4 to 10.9 mm, p = 0.08) and 23.5% (from 8.9 to 11.0 mm, p < 0.01) between ages 0-3 and 8-11 years, and C-IAC increasing 20.7% (from 13.0 to 15.7 mm, p < 0.01) between ages 0-3 and 4-7 years. APA volume increased 79.6% from ages 0-3 to 8-11 years (from 834.3 to 1499.2 mm3, p < 0.01). None of these parameters displayed further significant growth. Finally, IAC-D increased 51.1% (from 4.3 to 6.5 mm, p < 0.01) between ages 0-3 and adult, without significant differences between successive age groups.

CONCLUSIONS

APA development is largely complete by the ages of 8-11 years. Knowledge of APA growth patterns may aid approach selection and APA removal in pediatric patients.

Surgical Relevance of Pediatric Anterior Clinoid Process Maturation for Anterior Skull Base Approaches

BACKGROUND

Removal of the anterior clinoid process (ACP) can expand anterior skull base surgical corridors. ACP development and anatomical variations are poorly defined in children.

OBJECTIVE

To perform a morphometric analysis of the ACP during pediatric maturation.

METHODS

Measurements of ACP base thickness (ACP-BT), midpoint thickness (ACP-MT), length (ACP-L), length from optic strut to ACP tip (ACP-OS), pneumatization (ACP-pneumo), and the presence of an ossified carotico-clinoid ligament (OCCL) or interclinoid ligament (OIL) were made from high-resolution computed-tomography scans from 60 patients (ages 0-3, 4-7, 8-11 12-15, 16-18, and >18 yr). Data were analyzed by laterality, sex, and age groups using t-tests and linear regression.

RESULTS

There were no significant differences in ACP parameters by laterality or sex, and no significant growth in ACP-BT or ACP-MT during development. From ages 0-3 yr to adult, mean ACP-L increased 49%, from 7.7 to 11.5 mm. The majority of ACP-L growth occurred in 2 phases between ages 0-3 to 8-11 and ages 16-18 to adult. Conversely, ACP-OS was stable from ages 0-3 to 8-11 but increased by 63% between ages 8-11 to adult. Variations in ACP morphology (OCCL/OIL/ACP-pneumo) were found in 15% (9/60) of scans. OCCL and OIL occurred in patients as young as 3 yrs, whereas ACP-pneumo was not seen in patients younger than 11 yrs.

CONCLUSION

The ACP demonstrates stable thickness and a complex triphasic elongation and remodeling pattern with development, the understanding of which may facilitate removal in patients <12. Clinically relevant ACP anatomic variations can occur at any age.

Arteriovenous malformation surgery in children: the Rady Children's Hospital experience (2002-2019)

PURPOSE

Compared to adult AVMs, there is a paucity of data on the microsurgical treatment of pediatric AVMs. We report our institutional experience with pediatric AVMs treated by microsurgical resection with or without endovascular embolization and radiation therapy.

METHODS

We retrospectively reviewed all patients ≤ 18 years of age with cerebral AVMs that underwent microsurgical resection at Rady Children's Hospital 2002-2019.

RESULTS

Eighty-nine patients met inclusion criteria. The mean age was 10.3 ± 5.0 years, and 56% of patients were male. In total, 72 (81%) patients presented with rupture. Patients with unruptured AVMs presented with headache (n = 5, 29.4%), seizure (n = 9, 52.9%), or incidental finding (n = 3, 17.7%). The mean presenting mRS was 2.8 ± 1.8. AVM location was lobar in 78%, cerebellar/brainstem in 15%, and deep supratentorial in 8%. Spetzler-Martin grade was I in 28%, II in 45%, III in 20%, IV in 6%, and V in 1%. Preoperative embolization was utilized in 38% of patients and more frequently in unruptured than ruptured AVMs (62% vs. 32%, p = 0.022). Radiographic obliteration was achieved in 76/89 (85.4%) patients. Complications occurred in 7 (8%) patients. Annualized rates of delayed rebleeding and recurrence were 1.2% and 0.9%, respectively. The mean follow-up was 2.8 ± 3.1 years. A good neurological outcome (mRS score ≤ 2) was obtained in 80.9% of patients at last follow-up and was improved relative to presentation for 75% of patients.

CONCLUSIONS

Our case series demonstrates high rates of radiographic obliteration and relatively low incidence of neurologic complications of treatment or AVM recurrence.

Surgical revascularization for Moyamoya disease in the United States: A cost-effectiveness analysis

Objective

Moyamoya disease (MMD) is a vasculopathy of the internal carotid arteries with ischemic and hemorrhagic sequelae. Surgical revascularization confers upfront peri-procedural risk and costs in exchange for long-term protective benefit against hemorrhagic disease. The authors present a cost-effectiveness analysis (CEA) of surgical versus non-surgical management of MMD.

Methods

A Markov Model was used to simulate a 41-year-old suffering a transient ischemic attack (TIA) secondary to MMD and now faced with operative versus nonoperative treatment options. Health utilities, costs, and outcome probabilities were obtained from the CEA registry and the published literature. The primary outcome was incremental cost-effectiveness ratio which compared the quality adjusted life years (QALYs) and costs of surgical and nonsurgical treatments. Base-case, one-way sensitivity, two-way sensitivity, and probabilistic sensitivity analyses were performed with a willingness to pay threshold of $50,000.

Results

The base case model yielded 3.81 QALYs with a cost of $99,500 for surgery, and 3.76 QALYs with a cost of $106,500 for nonsurgical management. One-way sensitivity analysis demonstrated the greatest sensitivity in assumptions to cost of surgery and cost of admission for hemorrhagic stroke, and probabilities of stroke with no surgery, stroke after surgery, poor surgical outcome, and death after surgery. Probabilistic sensitivity analyses demonstrated that surgical revascularization was the cost-effective strategy in over 87.4% of simulations.

Conclusions

Considering both direct and indirect costs and the postoperative QALY, surgery is considerably more cost-effective than non-surgical management for adults with MMD.

Hydrophilic polymer embolism identified in brain tumor specimens following Wada testing: A report of 2 cases

Hydrophilic polymers are commonly used as coatings on intravascular medical devices. As intravascular procedures continue to increase in frequency, the risk of embolization of this material throughout the body has become evident. These emboli may be discovered incidentally but can result in serious complications including death. Here, we report the first two cases of hydrophilic polymer embolism (HPE) identified on brain tumor resection following Wada testing. One patient experienced multifocal vascular complications and diffuse cerebral edema, while the other had an uneventful postoperative course. Wada testing is frequently performed during preoperative planning prior to epilepsy surgery or the resection of tumors in eloquent brain regions. These cases demonstrate the need for increased recognition of this histologic finding to enable further correlation with clinical outcomes.

First-in-Man Clinical Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery

BACKGROUND

During its development and preclinical assessment, a novel, 3-dimensional (3D), high-definition (4K-HD) exoscope system was formerly shown to provide an immersive surgical experience, while maintaining a portable, low-profile design.

OBJECTIVE

To assess the clinical applicability of this 3D 4K-HD exoscope via first-in-man surgical use.

METHODS

The operative workflow, functionality, and visual haptics of the 3D 4K-HD exoscope were assessed in a variety of microneurosurgical cases at 2 US centers.

RESULTS

Nineteen microneurosurgical procedures in 18 patients were performed exclusively using the 3D 4K-HD exoscope. Pathologies treated included 4 aneurysms, 3 cavernous malformations (1 with intraoperative electrocorticography), 2 arteriovenous malformations, 1 foramen magnum meningioma, 1 convexity meningioma, 1 glioma, 1 occipital cyst, 1 chiari malformation, 1 carotid endarterectomy, 1 subdural hematoma, 1 anterior cervical discectomy and fusion, and 2 lumbar laminectomies. All patients experienced good surgical and clinical outcomes. Similar to preclinical assessments, the 3D 4K-HD exoscope provided an immersive 3D surgical experience for the primary surgeon, assistants, and trainees. The small exoscope frame, large depth of field, and hand/foot pedal controls improved exoscope mobility, decreased need to re-focus, and provided unobstructed operative corridors. Flexible positioning of the camera allows the surgeon's posture to be kept in a neutral position with uncompromised viewing angles.

CONCLUSION

The first-in-man clinical experience with the 3D 4K-HD exoscope confirms its excellent optics and ergonomics for the entire operative team, with high workflow adaptability for a variety of microneurosurgical cases. Expanded clinical use of the 3D 4K-HD exoscope is justified.

Middle fossa approach for a pediatric facial nerve meningioma

Pediatric cerebellopontine angle (CPA) meningiomas are extremely rare and are usually treated with a retrosigmoid surgical approach or radiation. The authors present the use of a middle fossa approach for the treatment of a symptomatic CPA meningioma in a 22-month-old female. The patient initially presented at 17 months with isolated progressive, long-standing right-sided facial weakness. MRI demonstrated a 5.0 × 5.0-mm right CPA lesion just superior to the cisternal segment of cranial nerve (CN) VII, which demonstrated growth on interval imaging. At 22 months of age she underwent a successful middle fossa craniotomy, including wide exposure of the porus acusticus, allowing for a gross-total resection with preservation of CNs VII and VIII. Pathological analysis revealed a WHO grade I meningioma. The patient remained neurologically stable on follow-up. The middle fossa approach can be used to safely access the CPA in properly selected pediatric patients.

A Paramedian Supracerebellar, Infratentorial Approach for Resection of Midbrain Tumor

Brainstem tumors represent formidable lesions for neurosurgical intervention. They should be approached with a thorough understanding of the anatomy and clear sense of surgical goals. A 14-year-old previously healthy girl presented with 2 weeks of nausea, headaches, diplopia, and gait instability. Workup revealed a 3.5 x 2.5 x 2.5 cm contrast-enhancing mass within the right midbrain. The patient consented to the surgical procedure. Preoperative imaging demonstrated superior displacement of the deep venous system because of the tumor, as well as inferior displacement of the fourth cranial nerve exit zone and posterior bowing of the entire tectal region. This allowed a safe corridor from a supracerebellar infratentorial approach. The three quarters lateral position was chosen to optimize surgeon ergonomics and allow for gravity to drain blood from the operative field. Near total resection was obtained without any new neurologic deficit. Final pathology was consistent with pilocytic astrocytoma, World Health Organization grade I. The video demonstrates the surgical approach in addition to techniques for brainstem tumor resection (Video 1).

Simulator Training for Endovascular Neurosurgery

Simulation-based training has become common practice across medical specialties, especially for learning complex skills performed in high-risk environments. In the field of endovascular neurosurgery, the demand for consequence- and risk-free learning environments led to the development of simulation devices valuable for medical trainees. The goal of this protocol is to provide instructive guidelines for the use of an endovascular neurosurgery simulator in an academic setting. The simulator provides trainees with the opportunity to receive realistic feedback on their knowledge of anatomy, as well as haptic feedback indicative of their success in handling the catheter-based systems without negative consequences. The utility of this specific protocol in relation to other neuroendovascular training modalities is also discussed.

Epidemiology, Natural History, and Clinical Presentation of Large Vessel Ischemic Stroke

Large vessel occlusions (LVOs), variably defined as blockages of the proximal intracranial anterior and posterior circulation, account for approximately 24% to 46% of acute ischemic strokes. Commonly refractory to intravenous tissue plasminogen activator (tPA), LVOs place large cerebral territories at ischemic risk and cause high rates of morbidity and mortality without further treatment. Over the past few years, an abundance of high-quality data has demonstrated the efficacy of endovascular thrombectomy for improving clinical outcomes in patients with LVOs, transforming the treatment algorithm for affected patients. In this review, we discuss the epidemiology, pathophysiology, natural history, and clinical presentation of LVOs as a framework for understanding the recent clinical strides of the endovascular era.

Antiplatelet therapy within 24 hours of tPA: lessons learned from patients requiring combined thrombectomy and stenting for acute ischemic stroke

Objective

Although stroke guidelines recommend antiplatelets be started 24 hours after tissue plasminogen activator (tPA), select mechanical thrombectomy (MT) patients with luminal irregularities or underlying intracranial atherosclerotic disease may benefit from earlier antiplatelet administration.

Methods

We explore the safety of early (<24 hours) post-tPA antiplatelet use by retrospectively reviewing patients who underwent MT and stent placement for acute ischemic stroke from June 2015 to April 2018 at our institution.

Results

Six patients met inclusion criteria. Median presenting and pre-operative National Institutes of Health Stroke Scale scores were 14 (Interquartile Range [IQR] 5.5–17.3) and 16 (IQR 13.7–18.7), respectively. Five patients received standard intravenous (IV) tPA and one patient received intra-arterial tPA. Median time from symptom onset to IV tPA was 120 min (IQR 78–204 min). Median time between tPA and antiplatelet administration was 4.9 hours (IQR 3.0–6.7 hours). Clots were successfully removed from the internal carotid artery (ICA) or middle cerebral artery (MCA) in 5 patients, the anterior cerebral artery (ACA) in one patient, and the vertebrobasilar junction in one patient. All patients underwent MT before stenting and achieved thrombolysis in cerebral infarction 2B recanalization. Stents were placed in the ICA (n=4), common carotid artery (n=1), and basilar artery (n=1). The median time from stroke onset to endovascular access was 185 min (IQR 136–417 min). No patients experienced symptomatic post-procedure intracranial hemorrhage (ICH). Median modified Rankin Scale score on discharge was 3.5.

Conclusions

Antiplatelets within 24 hours of tPA did not result in symptomatic ICH in this series. The safety and efficacy of early antiplatelet administration after tPA in select patients following mechanical thrombectomy warrants further study.

The effect of hospital safety-net burden on outcomes, cost, and reportable quality metrics after emergent clipping and coiling of ruptured cerebral aneurysms

OBJECTIVE

Safety-net hospitals deliver care to a substantial share of vulnerable patient populations and are disproportionately impacted by hospital payment reform policies. Complex elective procedures performed at safety-net facilities are associated with worse outcomes and higher costs. The effects of hospital safety-net burden on highly specialized, emergent, and resource-intensive conditions are poorly understood. The authors examined the effects of hospital safety-net burden on outcomes and costs after emergent neurosurgical intervention for ruptured cerebral aneurysms.

METHODS

The authors conducted a retrospective analysis of the Nationwide Inpatient Sample (NIS) from 2002 to 2011. Patients ≥ 18 years old who underwent emergent surgical clipping and endovascular coiling for aneurysmal subarachnoid hemorrhage (SAH) were included. Safety-net burden was defined as the proportion of Medicaid and uninsured patients treated at each hospital included in the NIS database. Hospitals that performed clipping and coiling were stratified as low-burden (LBH), medium-burden (MBH), and high-burden (HBH) hospitals.

RESULTS

A total of 34,647 patients with ruptured cerebral aneurysms underwent clipping and 23,687 underwent coiling. Compared to LBHs, HBHs were more likely to treat black, Hispanic, Medicaid, and uninsured patients (p < 0.001). HBHs were also more likely to be associated with teaching hospitals (p < 0.001). No significant differences were observed among the burden groups in the severity of subarachnoid hemorrhage. After adjusting for patient demographics and hospital characteristics, treatment at an HBH did not predict in-hospital mortality, poor outcome, length of stay, costs, or likelihood of a hospital-acquired condition.

CONCLUSIONS

Despite their financial burden, safety-net hospitals provide equitable care after surgical clipping and endovascular coiling for ruptured cerebral aneurysms and do not incur higher hospital costs. Safety-net hospitals may have the capacity to provide equitable surgical care for highly specialized emergent neurosurgical conditions.

Keyhole Microsurgical Middle Fossa Arachnoid Cyst Fenestration: 2-Dimensional Operative Video

Surgical options for symptomatic intracranial arachnoid cysts include cyst shunting and microscopic or endoscopic fenestration.¹ We advocate a microsurgical keyhole approach for the durable fenestration of middle fossa arachnoid cysts, taking advantage of the superior magnification, depth perception, and illumination of the operating microscope, as well as the ability to use bimanual surgical technique and variable suction to ensure safe manipulation of arachnoid membranes and fenestration of these lesions into the deep cisterns.² Key technical aspects of this approach demonstrated in this video (Video 1) include performance of a dime-sized temporal craniotomy; strict microsurgical technique with sharp dissection via a No. 11 blade, sharp microdissectors, and microscissors; disruption of the arachnoid membranes overlying cranial nerves II/III, the internal carotid artery, and the posterior communicating artery; and fenestration of the membrane of Lilliquist through the opticocarotid, oculomotor, and/or supratrochlear triangles. The utility of this approach is illustrated by the case of a 5-year-old male with a history of headaches and interval progression of a left temporal grade 2 arachnoid cyst, who experienced symptom resolution and cyst shrinkage after keyhole microsurgical fenestration.

The Potential Impact of "Take the Volume Pledge" on Outcomes After Carotid Artery Stenting

BACKGROUND

The "Volume Pledge" aims to centralize carotid artery stenting (CAS) to hospitals and surgeons performing ≥10 and ≥5 procedures annually, respectively.

OBJECTIVE

To compare outcomes after CAS between hospitals and surgeons meeting or not meeting the Volume Pledge thresholds.

METHODS

We queried the Nationwide Inpatient Sample for CAS admissions. Hospitals and surgeons were categorized as low volume and high volume (HV) based on the Volume Pledge. Multivariable hierarchical regression models were used to examine the impact of hospital volume (2005-2011) and surgeon volume (2005-2009) on perioperative outcomes.

RESULTS

Between 2005 and 2011, 22 215 patients were identified. Most patients underwent CAS by HV hospitals (86.4%). No differences in poor outcome (composite endpoint of in-hospital mortality, postoperative neurological or cardiac complications) were observed by hospital volume but HV hospitals did decrease the likelihood of other complications, nonroutine discharge, and prolonged hospitalization. From 2005 to 2009, 9454 CAS admissions were associated with physician identifiers. Most patients received CAS by HV surgeons (79.2%). On multivariable analysis, hospital volume was not associated with improved outcomes but HV surgeons decreased odds of poor outcome (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.59-0.97; P = .028), complications (OR 0.56, 95% CI 0.46-0.71, P < .001), nonroutine discharge (OR 0.70, 95% CI 0.57-0.87; P = .001), and prolonged hospitalization (OR 0.52, 95% 0.44-0.61, P < .001).

CONCLUSION

Most patients receive CAS by hospitals and providers meeting the Volume Pledge threshold for CAS. Surgeons but not hospitals who met the policy's volume standards were associated with superior outcomes across all measured outcomes.

Histology of the vertebral artery-dural junction: relevance to posterolateral approaches to the skull base

OBJECTIVE

The far-lateral and extreme-lateral infrajugular transcondylar-transtubercular exposure (ELITE) and extreme-lateral transcondylar transodontoid (ELTO) approaches provide access to lesions of the foramen magnum, inferolateral to mid-clivus, and ventral pons and medulla. A subset of pathologies in this region require manipulation of the vertebral artery (VA)-dural interface. Although a cuff of dura is commonly left on the VA to avoid vessel injury during these approaches, there are varying descriptions of the degree of VA-dural separation that is safely achievable. In this paper the authors provide a detailed histological analysis of the VA-dural junction to guide microsurgical technique for posterolateral skull base approaches.

METHODS

An ELITE approach was performed on 6 preserved adult cadaveric specimens. The VA-dural entry site was resected, processed for histological analysis, and qualitatively assessed by a neuropathologist.

RESULTS

Histological analysis demonstrated a clear delineation between the intima and media of the VA in all specimens. No clear plane was identified between the connective tissue of the dura and the connective tissue of the VA adventitia.

CONCLUSIONS

The VA forms a contiguous plane with the connective tissue of the dura at its dural entry site. When performing posterolateral skull base approaches requiring manipulation of the VA-dural interface, maintenance of a dural cuff on the VA is critical to minimize the risk of vascular injury.

Risk Factors for Urinary Tract Infection or Pneumonia After Admission for Traumatic Subdural Hematoma at a Level I Trauma Center: Large Single-Institution Series

BACKGROUND

The development of infections such as urinary tract infections (UTIs) or pneumonia after a traumatic subdural hematoma (tSDH) can worsen patient outcomes and increase healthcare costs. We herein identify clinical parameters that influence the risk of infections after tSDH.

METHODS

This single-institution retrospective cohort study examined the incidence and risk factors for UTI and pneumonia among tSDH patients from 1990 to 2015. Multivariate logistic regression assessed the impact of various demographic and clinical variables on these outcomes.

RESULTS

3024 patients with tSDHs were identified (73.1% male); Of those, 208 (6.9%) experienced a UTI and 434 (14.4%) experienced pneumonia. Of the 559 patients (18.5%) who underwent a craniotomy and/or craniectomy for evacuation of a tSDH, 62 (11.1%) experienced a UTI and 222 (39.7%) experienced pneumonia. Risk factors for both pneumonia and UTI included length of stay (LOS) ≥7 days (odds ratio [OR] = 6.0, P < 0.001; OR = 11.2, P < 0.001), intensive care unit LOS ≥7 days (OR = 8.1, P < 0.001; OR = 1.7, P = 0.012), and mechanical ventilation ≥14 days (OR = 3.4, P < 0.001; OR = 1.8, P = 0.007). Craniotomy/craniectomy increased the risk of pneumonia (OR = 1.4, P = 0.019) but not UTI. Glasgow Coma Scale (GCS) ≥13 was associated with a decreased pneumonia risk (OR = 0.5, P = 0.003), and male gender (OR = 0.5, P < 0.001) and age <60 (OR = 0.6, P < 0.001) were associated with a decreased UTI risk.

CONCLUSIONS

Patients with prolonged hospitalizations and/or intensive care unit stays were more likely to experience UTIs and pneumonia. Male gender and younger age were protective against UTI, and higher GCS was protective against pneumonia. These data may aid the identification and treatment of at-risk populations after admission for a tSDH.

Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery

BACKGROUND

The operative microscope and endoscope have significantly advanced modern neurosurgery. These devices are nonetheless limited by high costs and suboptimal optics, ergonomics, and maneuverability. A recently developed extracorporeal telescope ("exoscope") operative system combines characteristics from both the operative microscope and endoscope and provides an affordable, portable, high-definition operative experience. Widespread use of exoscopes in neurosurgery has previously been limited by a lack of stereopsis with 2-dimensional(2-D) monitors.

OBJECTIVE

To assess the surgical potential of a novel, 3-D, high-definition (4K-HD) exoscope system.

METHODS

Assess dissection time and visualization of critical structures in a series of human cadaveric cranial neurosurgical approaches with the 3-D 4K-HD exoscope as compared to a standard operating microscope.

RESULTS

Dissection times and visualization of critical structures was comparable with the 3-D 4K-HD exoscope and a standard operating microscope. The low-profile exoscope nonetheless allowed for larger operative corridors, enhanced instrument maneuverability, and less obstruction in passing instrumentation. The large monitor also resulted in an immersive surgical experience, and gave multiple team members the same high-quality view as the primary operator. Finally, the exoscope possessed a more ergonomically favorable setup as compared to the traditional microscope, allowing the surgeon to be in a neutral position despite the operative angle.

CONCLUSION

The novel 3-D 4K-HD exoscope system possesses favorable optics, ergonomics, and maneuverability as compared to the traditional operating microscope, with the exoscope's shared surgical view possessing obvious educational and workflow advantages. Further clinical trials are justified to validate this initial cadaveric experience.

Markov modeling for the neurosurgeon: a review of the literature and an introduction to cost-effectiveness research

OBJECTIVE Markov modeling is a clinical research technique that allows competing medical strategies to be mathematically assessed in order to identify the optimal allocation of health care resources. The authors present a review of the recently published neurosurgical literature that employs Markov modeling and provide a conceptual framework with which to evaluate, critique, and apply the findings generated from health economics research. METHODS The PubMed online database was searched to identify neurosurgical literature published from January 2010 to December 2017 that had utilized Markov modeling for neurosurgical cost-effectiveness studies. Included articles were then assessed with regard to year of publication, subspecialty of neurosurgery, decision analytical techniques utilized, and source information for model inputs. RESULTS A total of 55 articles utilizing Markov models were identified across a broad range of neurosurgical subspecialties. Sixty-five percent of the papers were published within the past 3 years alone. The majority of models derived health transition probabilities, health utilities, and cost information from previously published studies or publicly available information. Only 62% of the studies incorporated indirect costs. Ninety-three percent of the studies performed a 1-way or 2-way sensitivity analysis, and 67% performed a probabilistic sensitivity analysis. A review of the conceptual framework of Markov modeling and an explanation of the different terminology and methodology are provided. CONCLUSIONS As neurosurgeons continue to innovate and identify novel treatment strategies for patients, Markov modeling will allow for better characterization of the impact of these interventions on a patient and societal level. The aim of this work is to equip the neurosurgical readership with the tools to better understand, critique, and apply findings produced from cost-effectiveness research.

Cost-effectiveness of Intraoperative MRI for Treatment of High-Grade Gliomas

Background Intraoperative MRI has been shown to improve gross-total resection of high-grade glioma. However, to the knowledge of the authors, the cost-effectiveness of intraoperative MRI has not been established. Purpose To construct a clinical decision analysis model for assessing intraoperative MRI in the treatment of high-grade glioma. Materials and Methods An integrated five-state microsimulation model was constructed to follow patients with high-grade glioma. One-hundred-thousand patients treated with intraoperative MRI were compared with 100 000 patients who were treated without intraoperative MRI from initial resection and debulking until death (median age at initial resection, 55 years). After the operation and treatment of complications, patients existed in one of three health states: progression-free survival (PFS), progressive disease, or dead. Patients with recurrence were offered up to two repeated resections. PFS, valuation of health states (utility values), probabilities, and costs were obtained from randomized controlled trials whenever possible. Otherwise, national databases, registries, and nonrandomized trials were used. Uncertainty in model inputs was assessed by using deterministic and probabilistic sensitivity analyses. A health care perspective was used for this analysis. A willingness-to-pay threshold of $100 000 per quality-adjusted life year (QALY) gained was used to determine cost efficacy. Results Intraoperative MRI yielded an incremental benefit of 0.18 QALYs (1.34 QALYs with intraoperative MRI vs 1.16 QALYs without) at an incremental cost of $13 447 ($176 460 with intraoperative MRI vs $163 013 without) in microsimulation modeling, resulting in an incremental cost-effectiveness ratio of $76 442 per QALY. Because of parameter distributions, probabilistic sensitivity analysis demonstrated that intraoperative MRI had a 99.5% chance of cost-effectiveness at a willingness-to-pay threshold of $100 000 per QALY. Conclusion Intraoperative MRI is likely to be a cost-effective modality in the treatment of high-grade glioma. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Bettmann in this issue.

Surgical relevance of pediatric skull base maturation for the far-lateral and extreme-lateral infrajugular transcondylar-transtubercular exposure approaches

OBJECTIVE

Lesions of the foramen magnum, inferolateral-to-midclival areas, and ventral pons and medulla are often treated using a far-lateral or extreme-lateral infrajugular transcondylar-transtubercular exposure (ELITE) approach. The development and surgical relevance of critical posterior skull base bony structures encountered during these approaches, including the occipital condyle (OC), hypoglossal canal (HGC), and jugular tubercle (JT), are nonetheless poorly defined in the pediatric population.

METHODS

Measurements from high-resolution CT scans were made of the relevant posterior skull base anatomy (HGC depth from posterior edge of the OC, OC and JT dimensions) from 60 patients (evenly distributed among ages 0-3, 4-7, 8-11, 12-15, 16-18, and > 18 years), and compared between laterality, sex, and age groups by using t-tests and linear regression.

RESULTS

There were no significant differences in posterior skull base parameters by laterality, and HGC depth and JT size did not differ by sex. The OC area was significantly larger in males versus females (174.3 vs 152.2 mm2; p = 0.01). From ages 0-3 years to adult, the mean HGC depth increased 27% (from 9.0 to 11.4 mm) and the OC area increased 52% (from 121.4 to 184.0 mm2). The majority of growth for these parameters occurred between the 0-3 year and 4-7 year age groups. Conversely, JT volume increased nearly 3-fold (281%) from 97.4 to 370.9 mm3 from ages 0-3 years to adult, with two periods of substantial growth seen between the 0-3 to 4-7 year and the 12-15 to 16-18 year age groups. Overall, JT growth during pediatric development was significantly greater than increases in HGC depth and OC area (p < 0.05). JT volume remained < 65% of adult size up to age 16.

CONCLUSIONS

When considering a far-lateral or ELITE approach in pediatric patients, standard OC drilling is likely to be needed due to the relative stability of OC and HGC anatomy during development. The JT significantly increases in size with development, yet is only likely to need to be drilled in older children (> 16 years) and adults.

Tentorial sling for microvascular decompression in patients with trigeminal neuralgia: a description of operative technique and clinical outcomes

OBJECTIVE

Trigeminal neuralgia is a debilitating pain disorder most often caused by arterial compression of the trigeminal nerve, although there are other etiologies. Microvascular decompression (MVD) remains the most definitive treatment for this disorder, with cure rates reported between 60% and 80%. Traditional MVD techniques involve a retrosigmoid craniotomy with placement of an inert foreign material, such as Teflon, between the nerve and compressive vessel. Recurrence of trigeminal neuralgia after MVD has been associated with vessel migration, adhesion formation, and arterial pulsation against the Teflon abutting the nerve. Additionally, foreign materials such as Teflon have been reported to trigger inflammatory responses, resulting in recurrence of trigeminal pain. An alternative method for decompression involves the use of a sling to transpose the compressive vessel away from the nerve. Results of various sling techniques as a decompressive strategy are limited to small series and case reports. In this study, the authors present their experience utilizing a tentorial sling for MVD in patients with trigeminal neuralgia.

METHODS

Institutional review board approval was obtained in order to contact patients who underwent MVD for trigeminal neuralgia via the tentorial sling technique. Clinical outcomes were assessed utilizing the Barrow Neurological Institute (BNI) pain intensity score immediately after surgery and at the time of the study.

RESULTS

The tentorial sling technique was performed in 45 patients undergoing MVD for trigeminal neuralgia. In 41 of these patients, this procedure was their first decompressive surgery. Immediate postoperative relief of pain (BNI score I) was achieved in 80% of patients undergoing their first decompressive procedure. At last follow-up, 73% of these patients remained pain free. Three patients experienced recurrent trigeminal pain, with surgical exploration demonstrating an intact tentorial sling. The complication rate was 6.6%.

CONCLUSIONS

Transposition techniques for MVD have been described previously in small series and case reports. This study represents the largest experience in which the utilization of a tentorial sling for MVD in patients with trigeminal neuralgia is described. The technique represents a novel method for decompression of the trigeminal nerve by transposition of the offending vessel without the use of foreign material. Although the authors’ preliminary results parallel the historical cure rate, further outcome data are required to assess long-term durability of this method.

Extracranial-to-Intracranial Bypass for Refractory Vertebrobasilar Insufficiency

BACKGROUND

Vertebrobasilar insufficiency (VBI) is associated with high rates of morbidity and mortality, especially after failure of first-line medical and/or endovascular therapies. Although the optimal therapeutic strategy for refractory VBI remains unclear, surgical bypass represents a potentially life-saving treatment in this patient subset.

METHODS

A multi-institution retrospective database review was performed to identify patients with symptomatic refractory VBI over a 4-year period (July 2014 to July 2018). Surgical treatments, as well as clinical and neurologic outcomes were recorded.

RESULTS

Five patients were identified with refractory VBI (average age 55 ± 11.0 years). All 5 patients had clinically significant posterior circulation strokes on presentation. Three patients underwent superficial temporal artery-to-superior cerebellar artery bypass based on significant acute perfusion mismatches or progressive strokes despite maximal medical therapy; 1 surgical patient (33%) experienced punctate perioperative strokes and there were no significant bypass related complications. Functional outcomes in the 3 surgical patients were correlated with preoperative stroke burden. The remaining 2 patients experienced rapid neurologic declines after presentation that precluded bypass, and died shortly thereafter.

CONCLUSIONS

Refractory VBI has high morbidity, with cerebral bypass representing a safe and potentially efficacious treatment for selected patients. Long-term post-bypass outcomes are dependent on the level of irreversible preoperative neurologic injuries.

The impact of traveling distance and hospital volume on post-surgical outcomes for patients with glioblastoma

BACKGROUND

High-volume hospitals are associated with improved outcomes in glioblastoma (GBM). However, the impact of travel burden to high-volume centers is poorly understood. We examined post-operative outcomes between GBM patients that underwent treatment at local, low-volume hospitals with those that traveled long distances to high-volume hospitals.

METHODS

The National Cancer Database was queried for GBM patients that underwent surgery (2010-2014). We established two cohorts: patients in the lowest quartile of travel distance and volume (Short-travel/Low-Volume: STLV) and patients in the highest quartile of travel and volume (Long-travel/High-Volume: LTHV). Outcomes analyzed were 30-day, 90-day mortality, overall survival, 30-day readmission, and hospital length of stay.

RESULTS

Of 35,529 cases, STLV patients (n = 3414) traveled a median of 3 miles (Interquartile range [IQR] 1.8-4.2) to low-volume centers (5 [3-7] annual cases) and LTHV patients (n = 3808) traveled a median of 62 miles [44.1-111.3] to high-volume centers (48 [42-71]). LTHV patients were younger, had lower Charlson scores, largely received care at academic centers (84.4% vs 11.9%), were less likely to be minorities (8.1% vs 17.1%) or underinsured (6.9% vs 12.1), and were more likely to receive trimodality therapy (75.6% vs 69.2%; all p < 0.001). On adjusted analysis, LTHV predicted improved overall survival (HR 0.87, p = 0.002), decreased 90-day mortality (OR 0.72, p = 0.019), lower 30-day readmission (OR 0.42, p < 0.001), and shorter hospitalizations (RR 0.79, p < 0.001).

CONCLUSIONS

Glioblastoma patients who travel farther to high-volume centers have superior post-operative outcomes compared to patients who receive treatment locally at low-volume centers. Strategies that facilitate patient travel to high-volume hospitals may improve outcomes.

A Practical Cadaveric Model for Intracranial Bypass Training

BACKGROUND

Intracranial bypass is technically challenging and difficult to learn owing to its relative rarity and complexity. Although multiple training models for intracranial bypass exist, a detailed depiction of the use and fidelity of cadaveric specimens for bypass training is lacking in the literature. This study describes use of preserved cadaveric specimens as a practical training model for performance of multiple intracranial bypasses and discusses the surgical setup for a cadaveric bypass laboratory.

METHODS

Using a cadaveric specimen and basic microneurosurgical instruments and supplies, 5 intracranial bypasses were performed (superficial temporal artery [STA]-to-middle cerebral artery [MCA], MCA-to-MCA, STA-to-posterior cerebral artery [PCA], anterior cerebral artery-to-anterior cerebral artery, and posterior inferior cerebellar artery-to-posterior inferior cerebellar artery) using pterional, subtemporal, interhemispheric, and suboccipital approach. Bypass integrity was assessed by direct fluid injection into the adjacent vessel segment. All procedures were recorded.

RESULTS

Procedural steps mirrored actual bypass surgery and included vessel marking, performance of arteriotomy, and completion of an end-to-end, end-to-side, or side-to-side anastomosis. Simulations included anatomically appropriate exposures of common intracranial (MCA, PCA, posterior inferior cerebellar artery, anterior cerebral artery) and extracranial (STA) vessels encountered during cerebral bypass surgery and high-fidelity recreations of the operative corridors associated with deeper anastomoses, such as STA-to-PCA bypass. Vessel diameters were 1.5-2.1 mm, and anastomosis times were 20-40 minutes. Immediate feedback on anastomotic integrity was achieved via direct fluid injection adjacent to the anastomosis site.

CONCLUSIONS

The cadaveric specimen trainee model is a relatively simple yet high-fidelity approach for learning intracranial bypass.

Impact of preoperative endovascular embolization on immediate meningioma resection outcomes

OBJECTIVE

Preoperative embolization of meningiomas can facilitate their resection when they are difficult to remove. The optimal use and timing of such a procedure remains controversial given the risk of embolization-linked morbidity in select clinical settings. In this work, the authors used a large national database to study the impact of immediate preoperative embolization on the immediate outcomes of meningioma resection.

METHODS

Meningioma patients who had undergone elective resection were identified in the National (Nationwide) Inpatient Sample (NIS) for the period 2002–2014. Patients who had undergone preoperative embolization were propensity score matched to those who had not, adjusting for patient and hospital characteristics. Associations between preoperative embolization and morbidity, mortality, and nonroutine discharge were investigated.

RESULTS

Overall, 27,008 admissions met the inclusion criteria, and 633 patients (2.34%) had undergone preoperative embolization and 26,375 (97.66%) had not. The embolization group was younger (55.17 vs 57.69 years, p < 0.001) with a lower proportion of females (63.5% vs 69.1%, p = 0.003), higher Charlson Comorbidity Index (p = 0.002), and higher disease severity (p < 0.001). Propensity score matching retained 413 embolization and 413 nonembolization patients. In the matched cohort, preoperative embolization was associated with increased rates of cerebral edema (25.2% vs 17.7%, p = 0.009), posthemorrhagic anemia or transfusion (21.8% vs 13.8%, p = 0.003), and nonroutine discharge (42.8% vs 35.7%, p = 0.039). There was no difference in mortality (≤ 2.4% vs ≤ 2.4%, p = 0.82). Among the embolization patients, the mean interval from embolization to resection was 1.49 days. On multivariate analysis, a longer interval was significantly associated with nonroutine discharge (OR 1.33, p = 0.004) but not with complications or mortality.

CONCLUSIONS

Relative to meningioma patients who do not undergo preoperative embolization in the same admission, those who do have higher rates of cerebral edema and nonroutine discharge but not higher rates of stroke or death. Thus, meningiomas requiring preoperative embolization represent a distinct clinical entity that requires prolonged, more complex care. Further, among embolization patients, the timing of resection did not affect the risk of in-hospital complications, suggesting that the timing of surgery can be determined according to surgeon discretion.

Improving Door to Groin Puncture Time for Mechanical Thrombectomy via Iterative Quality Protocol Interventions

Introduction: Delays in door to groin puncture time (DGPT) for patients with ischemic stroke caused by acute large vessel occlusions (LVO) are associated with worse clinical outcomes. We present the results of a quality improvement protocol for endovascular stroke treatment at the University of California, San Diego (UCSD) that aimed to minimize DGPT.

Materials and Methods: Our stroke team implemented a series of quality improvement measures to decrease DGPT, with a target of 90 minutes or less. Sixty-three patients treated at our center were retrospectively divided into three groups based on the date of their intervention as a proxy for the implementation of process improvement protocols: 23 patients treated from July to December 2015, 24 patients treated from January to July 2016, and 16 patients treated from July 2016 to December 2016. Multivariate log-linear and logistic regression analyses were used to assess the predictors of prolonged DGPT and compliance with target DGPT (<90 min), respectively.

Results: Date of intervention—a proxy for the implementation of process improvement protocols—was predictive of compliance with target DGPT. Patients treated from July 2016 to December 2016—after the full implementation of process improvements—were 3.2 times more likely to meet or exceed the target DGPT compared to patients treated from July 2015 to December 2015 (p=0.011). When adjusting for potential confounders in a multivariate analysis, patients in the final cohort were associated with shorter DGPT (Exp(B)=0.61, p=0.013) and remained significantly more likely to achieve the DGPT goal (OR=14.2, p=0.007).

Conclusion: An iterative quality improvement process can significantly improve DGPT. This analysis demonstrates the utility of a formal quality improvement system at an academic comprehensive stroke center.

Balloon Bridge: Novel Technique for Reaccessing Carotid Artery Stent

BACKGROUND

Crossing a nascently deployed carotid artery stent (CAS) is required to perform angioplasty and filter recapture. If the traversing balloon or filter recapture catheters are eccentric or tangentially angled to the vertical axis of the CAS, they can ensnare on the ledge of the proximal CAS step-off, potentially causing life-threatening complications secondary to deformation, displacement, or mechanical occlusion of the stent. We report a novel "balloon bridge" technique that facilitates safe entry and passage across the CAS with both a balloon catheter and a large-bore guide catheter (LBGC).

METHODS

We used the balloon bridge technique for 2 patients with >90% carotid artery stenosis and steep carotid artery angles of origin who underwent routine CAS, balloon angioplasty, and distal embolic protection. During filter recapture, the balloon was inflated across the junction of the distal LBGC tip and proximal CAS, centering the LBGC within the vessel lumen and CAS. During balloon deflation, the LBGC was sequentially advanced, successfully navigating the LBGC across the proximal stent construct without resistance or complication.

RESULTS

The balloon bridge technique was completed without complications. We believe that the mechanism of action is secondary to balloon-facilitated LBGC alignment with the true axis of the stent.

CONCLUSIONS

Traversing a CAS with an LBGC or balloon catheter can be tedious and fraught with the potential of neurologic peril should mechanical deformation and occlusion occur. The balloon bridge technique is safe and highly effective for navigating a catheter that is eccentric or tangentially angled to the long axis of a CAS.

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations

Arteriovenious malformations (AVMs) are associated with significant morbidity and mortality, and have a rupture risk of ~3% per year. Treatment of AVMs must be tailored specifically to the lesion, with surgical resection being the gold standard for small, accessible lesions. Pre-operative embolization of AVMs can reduce nidal blood flow and remove high-risk AVM features such as intranidal or venous aneurysms, thereby simplifying a challenging neurosurgical procedure. Herein, we describe our approach for the staged endovascular embolization and open resection of AVMs, and highlight the advantages of having a comprehensively trained neurovascular surgeon leading a multi-disciplinary clinical team. This includes planning the craniotomy and resection to immediately follow the final embolization stage, thereby using a single session of anesthesia for aggressive embolization, and rapid resection. Finally, we provide a representative case of a 22-year-old female with an unruptured right frontal AVM diagnosed during a seizure workup, who was successfully treated via staged embolizations followed by open surgical resection.

Spinal Shortening for Recurrent Tethered Cord Syndrome via a Lateral Retropleural Approach: A Novel Operative Technique

Spine shortening via vertebral osteotomy (SSVO) for recurrent tethered cord syndrome (TCS) is a novel surgical technique that avoids the complication profile associated with revision detethering. While SSVO has previously been described via a posterior approach, we describe a lateral retropleural approach for SSVO in recurrent TCS in a 21-year-old female.

Our patient presented with progressive lower extremity weakness, bowel and bladder incontinence, and back pain in the setting of childhood repair of myelomeningocele and two previous detethering procedures. SSVO was offered to the patient as further detethering was deemed to have significant risk. A discectomy at T11-T12 via the lateral retropleural approach was performed, followed by a T12 partial corpectomy removing the vertebral body down to the inferior aspect of the T12 pedicle, followed by the removal of the ipsilateral pedicle. The T10, T11, L1, and L2 pedicle screws were then placed in the prone position and temporary rods were placed for temporary stability, followed by a laminectomy at T12 and a facetectomy for posterior element release. The remaining pedicle was removed, permanent rods were sequentially placed, and spinal column shortening was achieved by compression against the rods. Standing lateral radiographs demonstrated 19 millimeters (mm) of shortening after the intervention. The patient remained at her neurologic baseline postoperatively. At the six-month follow-up, the patient reported decreased lower extremity radicular pain and improved bowel and bladder function.

This operative report demonstrates that SSVO via a lateral retropleural approach is a viable treatment for the recurrence of TCS. The advantages of this minimally invasive approach compared to the posterior approach are direct access to the vertebral body and disc space, avoiding the need to operate around the spinal cord. Further studies are necessary to assess this minimally invasive approach to spinal shortening and to see if a complete minimally invasive approach is possible.

Ipsilateral Pupillary Dilation Following Carotid Endarterectomy: A Temporary and Benign Phenomenon

BACKGROUND AND IMPORTANCE: Cases of post carotid endarterectomy (CEA) Horner's syndrome have been reported, with symptoms attributed to manipulation of the sympathetic plexus situated along the carotid artery; however, these patients presented with the typical constricted pupil. We report the first 3 cases to our knowledge of mydriasis following CEA.

CLINICAL PRESENTATION: We present 3 cases of CEA followed by immediate postoperative development of ipsilateral mydriasis. The patients were otherwise at their neurologic baseline and the mydriasis resolved over the ensuing few days.

CONCLUSION: We suggest that these cases are secondary to an ischemic phenomenon, specifically to parasympathetic structures such as the ciliary ganglion and/or oculomotor nerve, resulting in autonomic dysfunction manifested by pupillary dilation. A similar finding of mydriasis occurring subsequent to other carotid pathology has been reported, with ischemia to parasympathetic structures also proposed as the underlying etiology. Although pupillary dilation often represents a worrisome neurosurgical sign indicating herniation, it should be recognized that after CEA this finding may be a transient, benign occurrence.

The circle of Willis predicts the antihypertensive effects of carotid artery stenting

OBJECTIVE Carotid artery stenting (CAS) has antihypertensive effects, but the durability and degree of this response remain variable. The authors propose that this clinical variability is a function of the presence or absence of a complete circle of Willis (COW). Incomplete COWs perfuse through a higher-resistance pial collateral pathway, and therefore patients may require a higher mean arterial pressure (MAP). Carotid artery revascularization in these patients would reduce the end-organ collateral demand that has been hypothesized to drive the MAP response. METHODS Using a retrospective, nonrandomized within-subject case-control design, the authors compared the postoperative effects of CAS in patients with and without a complete COW by using changes in MAP and antihypertensive medication as end points. They recorded MAP and antihypertensive medications 3 months prior to surgery, preoperatively, immediately postoperatively, and at the 3-month follow-up. RESULTS Data were collected from 64 consecutive patients undergoing CAS. Patients without a complete COW (25%) were more likely to demonstrate a decrease in BP response to stenting (i.e., a drop in MAP of 10 mm Hg and/or a reduction or cessation of BP medications at 3 months postoperatively). Of the patients in the incomplete COW cohort, 75% had this outcome, whereas of those in the complete COW cohort, only 41% had it (p < 0.041). These findings remained statistically significant in a logistic regression analysis for possible confounders (p < 0.024). A receiver operating curve analysis of preoperative data indicated that a MAP > 96.3 mm Hg was 55.5% sensitive and 57.4% specific for predicting a complete COW and that patients with a MAP > 96.3 mm Hg were more likely to demonstrate a good MAP decrease following CAS (p < 0.0092). CONCLUSIONS CAS is associated with a significant decrease in MAP and/or a reduction/cessation in BP medications in patients in whom a complete COW is absent.

Simulator-Based Angiography and Endovascular Neurosurgery Curriculum: A Longitudinal Evaluation of Performance Following Simulator-Based Angiography Training

This study establishes performance metrics for angiography and neuroendovascular surgery procedures based on longitudinal improvement in individual trainees with differing levels of training and experience.

Over the course of 30 days, five trainees performed 10 diagnostic angiograms, coiled 10 carotid terminus aneurysms in the setting of subarachnoid hemorrhage, and performed 10 left middle cerebral artery embolectomies on a Simbionix Angio Mentor™ simulator. All procedures were nonconsecutive. Total procedure time, fluoroscopy time, contrast dose, heart rate, blood pressures, medications administered, packing densities, the number of coils used, and the number of stent-retriever passes were recorded. Image quality was rated, and the absolute value of technically unsafe events was recorded. The trainees’ device selection, macrovascular access, microvascular access, clinical management, and the overall performance of the trainee was rated during each procedure based on a traditional Likert scale score of 1=fail, 2=poor, 3=satisfactory, 4=good, and 5=excellent. These ordinal values correspond with published assessment scales on surgical technique.

After performing five diagnostic angiograms and five embolectomies, all participants demonstrated marked decreases in procedure time, fluoroscopy doses, contrast doses, and adverse technical events; marked improvements in image quality, device selection, access scores, and overall technical performance were additionally observed (p < 0.05). Similarly, trainees demonstrated marked improvement in technical performance and clinical management after five coiling procedures (p < 0.05). However, trainees with less prior experience deploying coils continued to experience intra-procedural ruptures up to the eighth embolization procedure; this observation likely corresponded with less tactile procedural experience to an exertion of greater force than appropriate for coil placement.

Trainees across all levels of training and prior experience demonstrated a significant performance improvement after completion of our simulator curriculum consisting of five diagnostic angiograms, five embolectomy cases, and 10 aneurysm coil embolizations.

Hypoplastic Internal Carotid Artery Co-Presenting with Neurofibromatosis and Intracranial Masses

Neurofibromatosis type 1 (NF1) is associated with systemic vascular disease, and it can also affect intracranial vasculature in a small percentage of patients. Very rarely, NF1 may co-present with hypoplasia of the internal carotid artery (ICA). Prior reports have documented NF1 with bilateral optic gliomas and a unilateral hypoplastic internal carotid artery; however, we report a case with the aforementioned findings in addition to a right-sided lentiform mass. This case report further suggests a common congenital pathway related to neurofibromin loss of function resulting in both nerve sheath tumors and cerebrovascular anomalies.

Ventricular Tract Hemorrhage Following Intracranial Nail Removal: Utility of Real-time Endovascular Assistance

Penetrating brain trauma commonly results in occult neurovascular injury. Detailed cerebrovascular imaging can evaluate the relationship of intracranial foreign bodies to major vascular structures, assess for traumatic pseudoaneurysms, and ensure hemostasis during surgical removal. We report a case of a self-inflicted intracranial nail gun injury causing a communicating ventricular tract hemorrhage upon removal, as well as a delayed pseudoaneurysm. Pre- and post-operative vascular imaging, as well as intra-operative endovascular assistance, was critical to successful foreign body removal in this patient. This report demonstrates the utility of endovascular techniques for the assessment and treatment of occult cerebrovascular injuries from intracranial foreign bodies.

Histologic Evidence for Arteriovenous Malformation-Like Vasculature Occurring within an Intracerebral Schwannoma: A Case Report and Review of the Literature

BACKGROUND

The phenomenon of intracerebral schwannoma is exceedingly rare, and its etiology still a matter of debate. No documented cases of intracerebral schwannoma containing vascular elements consistent with those of an arteriovenous malformation (AVM) have been reported. We describe such a case here.

CASE DESCRIPTION

A left temporal intraparenchymal lesion was discovered incidentally in a 34-year-old man after he suffered a mild trauma. The lesion was resected and found on histologic examination to be an intracerebral schwannoma with AVM-like vasculature. The patient made a full recovery after resection.

CONCLUSIONS

To our knowledge, this is the first case of an intracerebral schwannoma with AVM-like characteristics to be reported in the literature. We hypothesize that the co-occurrence of this rare pathologic entity is caused by an interrelated etiologic process, with the tumor microenvironment of the schwannoma inciting the development of the vascular malformation.