Eric Marvin

Proposed clinical internal carotid artery classification system.

Introduction: Numerical classification systems for the internal carotid artery (ICA) are available, but modifications have added confusion to the numerical systems. Furthermore, previous classifications may not be applicable uniformly to microsurgical and endoscopic procedures. The purpose of this study was to develop a clinically useful classification system. Materials and Methods: We performed cadaver dissections of the ICA in 5 heads (10 sides) and evaluated 648 internal carotid arteries with computed tomography angiography. We identified specific anatomic landmarks to define the beginning and end of each ICA segment. Results: The ICA was classified into eight segments based on the cadaver and imaging findings: (1) Cervical segment; (2) cochlear segment (ascending segment of the ICA in the temporal bone) (relation of the start of this segment to the base of the styloid process: Above, 425 sides [80%]; below, 2 sides [0.4%]; at same level, 107 sides [20%];P< 0.0001) (relation of cochlea to ICA: Posterior, 501 sides [85%]; posteromedial, 84 sides [14%];P< 0.0001); (3) petrous segment (horizontal segment of ICA in the temporal bone) starting at the crossing of the eustachian tube superolateral to the ICA turn in all 10 samples; (4) Gasserian-Clival segment (ascending segment of ICA in the cavernous sinus) starting at the petrolingual ligament (PLL) (relation to vidian canal on imaging: At same level, 360 sides [63%]; below, 154 sides [27%]; above, 53 sides [9%];P< 0.0001); in this segment, the ICA projected medially toward the clivus in 275 sides (52%) or parallel to the clivus with no deviation in 256 sides (48%;P< 0.0001); (5) sellar segment (medial loop of ICA in the cavernous sinus) starting at the takeoff of the meningeal hypophyseal trunk (ICA was medial into the sella in 271 cases [46%], lateral without touching the sella in 127 cases [23%], and abutting the sella in 182 cases [31%];P< 0.0001); (6) sphenoid segment (lateral loop of ICA within the cavernous sinus) starting at the crossing of the fourth cranial nerve on the lateral aspect of the cavernous ICA and located directly lateral to the sphenoid sinus; (7) ring segment (ICA between the 2 dural rings) starting at the crossing of the third cranial nerve on the lateral aspect of the ICA; (8) cisternal segment starting at the distal dural ring. Conclusions: The classification may be applied uniformly to all skull base surgical approaches including lateral microsurgical and ventral endoscopic approaches, obviating the need for 2 separate classification systems. The classification allows extrapolation of relevant clinical information because each named segment may indicate potential surgical risk to specific structures.

Microsurgical Clipping of a Giant Middle Cerebral Artery Aneurysm with Successful Postoperative Endovascular Mechanical Thrombectomy for Emergent Treatment of Large Vessel Occlusion

BACKGROUND Giant intracranial aneurysms (>25 mm) are uncommon. These lesions typically manifest clinically due to mass effect, acute hemorrhage, or thromboembolic events. To minimize the risk of poor clinical outcome, detailed operative planning and a consideration of all neurosurgical and endovascular techniques are essential before proceeding with microsurgical clipping of ruptured giant aneurysms. CASE DESCRIPTION We describe a case involving a 15-year-old male with a ruptured giant middle cerebral artery aneurysm treated with microsurgical clipping. After clip application, poor distal flow was demonstrated intraoperatively, and emergent angiography demonstrated an M1 occlusion with thrombus. A salvage procedure using endovascular mechanical thrombectomy reestablished distal flow resulting in a good neurologic outcome. CONCLUSIONS To our knowledge, this is the first case report to describe microsurgical clipping of an aneurysm followed by successful postoperative endovascular mechanical thrombectomy.

Rapidly Expanding Lateral Ventricular Meningioma Presenting with Intraventricular Hemorrhage following Remote Whole Brain Radiation and Stereotactic Radiosurgery

Intraventricular meningiomas are uncommon intracranial tumors and infrequently present with hemorrhage. With only 10 reported cases in the literature, it is exceedingly rare for meningiomas of the ventricular system to present with hemorrhage. To our knowledge, this is the first report of a patient presenting with an acute intraventricular hemorrhage in relation to a ventricular meningioma suspected to be radiation induced. In addition, we review the current literature on hemorrhagic intraventricular meningiomas and review the natural history of radiation-induced meningiomas.

Tumor cerebri: Metastatic renal cell carcinoma with dural venous sinus compression leading to intracranial hypertension; a case report

Background: Pseudotumor cerebri (PTC), also known as idiopathic intracranial hypertension (IIH), is a condition associated with increased intracranial pressure (ICP) in the absence of radiographic findings such as mass lesions or cerebral edema. Case Description: We describe a case of progressive headache and visual disturbances attributed to PTC that resulted from subacute superior sagittal sinus (SSS) stenosis by a metastatic tumor. Conclusions: Venous outflow obstruction often presents with an acute symptomatology including infarcts, hemorrhages, and seizures, but only rarely does it cause the progressive development of raised ICP. The sinister presentation of our patients pathology stemmed from local mass effect caused by a tumor that has hitherto not been reported to cause intracranial hypertension (IH) and was best elucidated using magnetic resonance venography (MRV).

Ruptured pseudoaneurysm of the middle meningeal artery presenting with a temporal lobe hematoma and a contralateral subdural hematoma.

Background: Traumatic pseudoaneurysms of the middle meningeal artery (MMA) are rare, associated with skull fractures, and have a high mortality rate. When they rupture, MMA pseudoaneurysms frequently cause epidural hematomas and occasionally ipsilateral subdural or subarachnoid hemorrhage. Isolated intraparenchymal hemorrhage has also been reported. Case Description: A 54-year-old female who suffered a loss of consciousness resulting in a fall presented with a Glasgow Coma Scale of 7t. Imaging demonstrated a right subdural hematoma (SDH) with midline shift, left skull fracture overlying the left MMA, and left temporal lobe intraparenchymal hematoma extending to the surface. The patient underwent a right craniectomy with evacuation of the SDH, and the preoperative computed tomographic angiography revealed abnormal dilation of the left MMA consistent with a pseudoaneurysm. The pseudoaneurysm was treated with endovascular treatment, and the intraparenchymal hematoma was treated conservatively. Her recovery was uneventful, and she received a cranioplasty 3 months after the decompression. Conclusions: The presence of a fracture over the MMA and intraparenchymal hematoma should prompt suspicion for a traumatic pseudoaneurysm. Pseudoaneurysms of the MMA can cause catastrophic bleeding, and prompt treatment is necessary. Endovascular embolization is an effective method that decreases the hemorrhage risk of MMA pseudoaneurysms.

Vaccine-Based Immunotherapeutics for the Treatment of Glioblastoma: Advances, Challenges, and Future Perspectives

Glioblastoma is a highly aggressive neoplasm with an extremely poor prognosis. Despite maximal gross resection and chemoradiotherapy, these grade IV astrocytomas consistently recur. Glioblastoma cells exhibit numerous pathogenic mechanisms to decrease tumor immunogenicity while promoting gliomagenesis, which manifests clinically as a median survival of less than 2 years and few long-term survivors. Recent clinical trials of vaccine-based immunotherapeutics against glioblastoma have demonstrated encouraging results in prolonging progression-free survival and overall survival. Several vaccine-based treatments have been trialed, such as peptide and heat-shock proteins, dendritic cell-based vaccines, and viral-based immunotherapy. In this literature review, we discuss the immunobiology of glioblastoma, significant current and completed vaccine-based immunotherapy clinical trials, and broad clinical challenges and future directions of glioblastoma vaccine-based immunotherapeutics.

Meckel’s Cave Epidermoid Cyst Presenting as Multiple Cranial Nerve Deficits Due to Indirect Tumoral Compression of the Cavernous Sinus: A Case Report and Literature Review

BACKGROUND Epidermoid cysts in Meckel cave are exceedingly rare. Since 1971, only 17 cases have been reported in the literature, with most patients presenting with trigeminal hypesthesia. However, outgrowth of these lesions from Meckel cave can rarely lead to compression of the proximate cavernous sinus and the neurovascular structures contained within. To date, 2 cases have reported a Meckel cave epidermoid cyst presenting clinically as an intracavernous cranial nerve palsy, presumably a clinical manifestation of cavernous sinus compression from the lesion. CASE DESCRIPTION We describe a case involving a 51-year-old woman presenting with unilateral refractory trigeminal neuralgia, facial hypesthesia, abducens palsy, plus new-onset partial ptosis. Magnetic resonance imaging revealed a mass in the left Meckel cave that was T1 hypointense, T2 hyperintense, peripherally enhancing, and restricting diffusion. A stereotactic left subtemporal extradural approach was used to resect the lesion, which alleviated most of the patients symptomatology except for minimal intermittent left-sided facial hypesthesia that remained at her 1-year postoperative visit. CONCLUSIONS This is a unique report depicting an epidermoid cyst in the Meckel cave causing numerous cranial nerve deficits because of indirect tumoral compression of cranial nerves within the cavernous sinus.

Quantitative Description of Osteopathic Physician Authorship in Prominent Neurosurgery Journals Since 1944: Coming of Age?

Background The Accreditation Council for Graduate Medical Education and the American Osteopathic Association recently agreed to establish a single graduate medical education system for the United States allopathic and osteopathic resident physicians by 2020. Consequential to this merger, new standards will be implemented for academic and research requirements within medical schools as well as residency programs. In the United States, osteopathic medicine is considered to be a parallel profession to allopathic medicine. However, recent studies have revealed that the percentages of United States osteopathic physicians currently in practice are not proportional to the percentages of editorial board member positions they hold in several high-profile medical journals as well as neurosurgical journals. To our knowledge, there is currently no published literature examining osteopathic physician author representation of any neurosurgical journal. In the present study, we analyze the number of osteopathic physicians and osteopathic neurosurgeons serving as authors in prominent neurosurgical journals. Methods American neurosurgical journals with the highest number of citations plus an affiliation with a neurosurgical society open to osteopathic neurosurgeons were used as criteria for journal selection. The Journal of Neurosurgery Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Spine, Journal of Neurosurgery: Pediatrics, and Neurosurgical Focus) fulfilled these criteria. The number of allopathic and osteopathic physicians who have published at least one manuscript in a Journal of Neurosurgery Publishing Group journal was counted. The specialty of each osteopathic author was examined. Results Our analysis found that allopathic physicians represented 105,157 (99.68%) and osteopathic physicians represented 335 (0.32%) of the 105,492 authorship positions held by these physicians in these journals since 1944. Statistical significance was found comparing the number of allopathic authors versus the number of osteopathic authors (p < 0.0001). The most common specialty represented by osteopathic authors in all journals was neurosurgery (45%). Osteopathic neurosurgeons represented 153 (0.15%) of the total number of allopathic and osteopathic authors. Conclusions These data establish that the percentages of the United States osteopathic physicians and osteopathic neurosurgeons currently in practice are not proportional to the percentages of authorship positions they hold in Journal of Neurosurgery Publishing Group journals. We postulate that this apparent disproportionality may originate from significant differences between allopathic and osteopathic medical school research funding, research opportunities, scholarly activities, and dual-degree programs.

ACTA2 Cerebral Arteriopathy: Not Just a Puff of Smoke

Background: Missense mutations in the gene that codes for smooth muscle actin, ACTA2, cause diffuse smooth muscle dysfunction and a distinct cerebral arteriopathy collectively known as multisystemic smooth muscle dysfunction syndrome (MSMDS). Until recently, ACTA2 cerebral arteriopathy was considered to be a variant of moyamoya disease. However, recent basic science and clinical data have demonstrated that the cerebral arteriopathy caused by mutant ACTA2 exhibits genetic loci, histopathology, neurological sequelae, and radiographic findings unique from moyamoya disease. We conducted a literature review to provide insight into the history, clinical significance, and neurosurgical management of this recently described novel cerebral arteriopathy. Summary: We performed a literature search using PubMed with the key words “ACTA2 mutation,” “ACTA2 cerebral arteriopathy,” and “multisystemic smooth muscle dysfunction syndrome.” Case reports with confirmed ACTA2 mutations and cerebral arteriopathy were included in our review. Our literature search revealed 15 articles (58 cases) of confirmed ACTA2 cerebral arteriopathy. Distinctive features of this arteriopathy included an aberrant internal carotid circulation with dilatation of the proximal segments, occlusive disease at the distal segments, and dolichoectasia. As such, mutant ACTA2 predisposed patients to ischemic strokes as children. Direct and indirect cerebral revascularization procedures are the mainstay treatment options with varying degrees of success. Key Messages: ACTA2 cerebral arteriopathy is a recently described novel cerebrovascular disease seen in patients with MSMDS. Patients currently diagnosed with moyamoya disease who also have dysfunction of smooth muscle organs may benefit from reevaluation by a medical geneticist and ACTA2 genotyping.

Recurrent hemorrhage in hemangioblastoma involving the posterior fossa: Case report

Background: Hemangioblastomas (HGBs) are the most common primary intra-axial posterior fossa tumor in adults. Although spontaneous hemorrhage of these tumors is exceedingly rare, despite their vascular nature, we describe a case of recurrent hemorrhage with associated tonsillar herniation, and demonstrate that a surgical approach can provide a suitable outcome. Case Description: A 54-year-old female with von Hippel-Lindau (VHL) syndrome presented with acute loss of consciousness and Glasgow Coma Scale (GCS) was 4. Computed tomographic (CT) images demonstrated large volume subarachnoid hemorrhage of the posterior fossa with intraventricular extension and intraparenchymal hemorrhage involving the right cerebellar tonsil. Magnetic resonance imaging (MRI) displayed three lesions in the posterior fossa, two near the hemorrhage site. Patient underwent suboccipital craniectomy with a decent recovery followed by radiosurgery as she refused resection. A second hemorrhage occurred ultimately prompting surgical resection of the three posterior fossa lesions, with a reasonable postoperative course. Conclusion: Hemorrhage of HGBs of the posterior fossa can present in conjunction of tonsillar herniation. Re-hemorrhage appears to be likely if prior acute hemorrhage has occurred. A stepwise approach of surgical decompression and resection may provide the best outcome.