Endovascular embolization versus surgical clipping in a single surgeon series of basilar artery aneurysms: a complementary approach in the endovascular era.

BACKGROUND: Currently, most basilar artery aneurysms (BAAs) are treated endovascularly. Surgery remains an appropriate therapy for a subset of all intracranial aneurysms. Whether open microsurgery would be required or utilized, and to what extent, for BAAs treated by a surgeon who performs both endovascular and open procedures has not been reported. METHODS: Retrospective analysis of prospectively maintained, single-surgeon series of BAAs treated with endovascular or open surgery from the first 5 years of practice. RESULTS: Forty-two procedures were performed in 34 patients to treat BAAs-including aneurysms arising from basilar artery apex, trunk, and perforators. Unruptured BAAs accounted for 35/42 cases (83.3%), and the mean aneurysm diameter was 8.4 ± 5.4 mm. Endovascular coiling-including stent-assisted coiling-accounted for 26/42 (61.9%) treatments and led to complete obliteration in 76.9% of cases. Four patients in the endovascular cohort required re-treatment. Surgical clip reconstruction accounted for 16/42 (38.1%) treatments and led to complete obliteration in 88.5% of cases. Good neurologic outcome (mRS ≤ 2) was achieved in 88.5% and 75.0% of patients in endovascular and open surgical cohorts, respectively (p = 0.40). Univariate logistic regression analysis demonstrated that advanced age (OR 1.11[95% CI 1.01-1.23]) or peri-procedural adverse event (OR 85.0 [95% CI 6.5-118.9]), but not treatment modality (OR 0.39[95% CI 0.08-2.04]), was the predictor of poor neurologic outcome. CONCLUSIONS: Complementary implementation of both endovascular and open surgery facilitates individualized treatment planning of BAAs. By leveraging strengths of both techniques, equivalent clinical outcomes and technical proficiency may be achieved with both modalities.

The natural history of AVM hemorrhage in the posterior fossa: comparison of hematoma volumes and neurological outcomes in patients with ruptured infra- and supratentorial AVMs.

OBJECT: Patients with posterior fossa arteriovenous malformations (AVMs) are more likely to present with hemorrhage than those with supratentorial AVMs. Observed patients subject to the AVM natural history should be informed of the individualized effects of AVM characteristics on the clinical course following a new, first-time hemorrhage. The authors hypothesize that the debilitating effects of first-time bleeding from an AVM in a previously intact patient with an unruptured AVM are more pronounced when AVMs are located in the posterior fossa. METHODS: The University of California, San Francisco prospective registry of brain AVMs was searched for patients with a ruptured AVM who had a pre-hemorrhage modified Rankin Scale (mRS) score of 0 and a post-hemorrhage mRS score obtained within 2 days of the hemorrhagic event. A total of 154 patients met the inclusion criteria for this study. Immediate post-hemorrhage presentation mRS scores were dichotomized into nonsevere outcome (mRS ≤ 3) and severe outcome (mRS > 3). There were 77 patients in each group. Univariate and multivariate logistic regression analyses using severe outcome as the binary response were run. The authors also performed a logistic regression analysis to measure the effects of hematoma volume and AVM location on severe outcome. RESULTS: Posterior fossa location was a significant predictor of severe outcome (OR 2.60, 95% CI 1.20-5.67, p = 0.016) and the results were strengthened in a multivariate model (OR 4.96, 95% CI 1.73-14.17, p = 0.003). Eloquent location (OR 3.47, 95% CI 1.37-8.80, p = 0.009) and associated arterial aneurysms (OR 2.58, 95% CI 1.09, 6.10; p = 0.031) were also significant predictors of poor outcome. Hematoma volume for patients with a posterior fossa AVM was 10.1 ± 10.1 cm(3) compared with 25.6 ±28.0 cm(3) in supratentorial locations (p = 0.003). A logistic analysis (based on imputed hemorrhage volume values) found that posterior fossa location was a significant predictor of severe outcome (OR 8.03, 95% CI 1.20-53.77, p = 0.033) and logarithmic hematoma volume showed a positive, but not statistically significant, association in the model (p = 0.079). CONCLUSIONS: Patients with posterior fossa AVMs are more likely to have severe outcomes than those with supratentorial AVMs based on this natural history study. Age, sex, and ethnicity were not associated with an increased risk of severe outcome after AVM rupture, but posterior fossa location, associated aneurysms, and eloquent location were associated with poor post-hemorrhage mRS scores. Posterior fossa hematomas are poorly tolerated, with severe outcomes observed even with smaller hematoma volumes. These findings support an aggressive surgical posture with respect to posterior fossa AVMs, both before and after rupture.

Treatment and outcomes of ARUBA-eligible patients with unruptured brain arteriovenous malformations at a single institution.

OBJECT: Management of unruptured arteriovenous malformations (AVMs) is controversial. In the first randomized trial of unruptured AVMs (A Randomized Trial of Unruptured Brain Arteriovenous Malformations [ARUBA]), medically managed patients had a significantly lower risk of death or stroke and had better outcomes. The University of California, San Francisco (UCSF) was one of the participating ARUBA sites. While 473 patients were screened for eligibility, only 4 patients were enrolled in ARUBA. The purpose of this study is to report the treatment and outcomes of all ARUBA-eligible patients at UCSF. METHODS: The authors compared the treatment and outcomes of ARUBA-eligible patients using prospectively collected data from the UCSF brain AVM registry. Similar to ARUBA, they compared the rate of stroke or death in observed and treated patients and used the modified Rankin Scale to grade outcomes. RESULTS: Of 74 patients, 61 received an intervention and 13 were observed. Most treated patients had resection with or without preoperative embolization (43 [70.5%] of 61 patients). One of the 13 observed patients died after AVM hemorrhage. Nine of the 61 treated patients had a stroke or died. There was no significant difference in the rate of stroke or death (HR 1.34, 95% CI 0.12-14.53, p = 0.81) or clinical impairment (Fisher's exact test, p > 0.99) between observed and treated patients. CONCLUSIONS: The risk of stroke or death and degree of clinical impairment among treated patients was lower than reported in ARUBA. The authors found no significant difference in outcomes between observed and treated ARUBA-eligible patients at UCSF. Results in ARUBA-eligible patients managed outside that trial led to an entirely different conclusion about AVM intervention, due to the primary role of surgery, judicious surgical selection with established outcome predictors, and technical expertise developed at high-volume AVM centers.

"Open-window" craniectomy for the removal of frontal sinus mucosa to prevent a delayed mucocele: illustrative case.

BACKGROUND: Frontal craniotomies for a medial subfrontal approach necessitate crossing the frontal sinus. Large superior extensions of the frontal sinus into frontal bone can result in mucosal retention in a free craniotomy bone flap, leading to a delayed mucocele with significant associated morbidity. The authors describe an "open-window" craniectomy technique that permits mucosal removal under direct vision and maintains the inner table on the bone flap's inferior side, helping to seal off the sinus opening with a pericranial flap. OBSERVATIONS: An illustrative case involving a medial right frontal craniotomy for a third ventricle mass in a patient with a large superior extension of the frontal sinus into frontal bone is presented. After creating a free frontal bone flap, the inner table was drilled out to the margins of the frontal sinus cavity and any remaining mucosa was cleared. A portion of the inner table above the bone flap's inferior margin was left in place, resembling an open window when viewed from the inner table side. The remaining anterior and posterior wall of the flap inferiorly provided a matched surface for the opening into the remaining frontal sinus, which was covered by pericranium. Long-term follow-up indicated no major complications or delayed mucocele. LESSONS: The open-window craniectomy technique can be considered for frontal sinus violations in patients with large superior frontal bone extension.

Factors Associated with Unfavorable Clinical Presentations in Patients with Ruptured BrainArteriovenous Malformations.

BACKGROUND: Rupture of brain arteriovenous malformations (bAVMs) carries potentially devastating consequences. For patients presenting with ruptured bAVMs, several clinical grading systems have been shown to predict long-term patient morbidity and may be taken into consideration when making clinical decisions. Unfortunately, use of these scoring systems is typically limited to their prognostic value and offer little to patients in therapeutic benefit. Tools are needed not only to predict prognosis for patients experiencing ruptured bAVMs but to gain insight into what characteristics predispose patients to poor long-term outcomes before they rupture. Our objective was to find clinical, morphologic, and demographic variables that correlate with unfavorable clinical grades on presentation in patients with ruptured bAVMs. METHODS: We retrospectively reviewed a cohort of patients with ruptured bAVMs. Linear regression models were used to test whether Glasgow Coma Scale (GCS) and Hunt-Hess scores on presentation(outcomes) were associated with patient and arteriovenous malformation (AVM) characteristics (predictors) individually. RESULTS: GCS and Hunt-Hess were assessed following bAVM rupture for 121 brain cases. The median age at rupture was 28.5 years, and 62 (51%) were female. Smoking history was associated with worse GCS; current and past smokers had GCS scores 1.33 points lower on average than nonsmokers (95% confidence interval [CI] -2.59 to -0.07, P = 0.039) and had worse Hunt-Hess scores (0.42, 95% CI 0.07-0.77, P = 0.019). Associated aneurysms were associated with worse GCS (-1.60, 95% CI -3.16 to -0.05, P = 0.043) and trended towards worse Hunt-Hess scores (0.42 points, 95% CI -0.01 to 0.86, P = 0.057). CONCLUSIONS: Patient smoking status and presence of an AVM associated aneurysm were shown to have modest correlations with unfavorable clinical grades (Hunt-Hess, GCS) on presentation, with unfavorable clinical grades being associated with long-term patient prognosis following bAVM rupture. Further investigation using AVM-specific grading scales and external data are needed to determine the utility of these and other variables in clinical practice for patients with bAVM.

Subarachnoid haemorrhage associated with an intrathecal catheter.

Although 15 to 20 percent of patients with subarachnoid haemorrhage (SAH) do not have a vascular lesion on four-vessel cerebral angiography, venous injury is a potential cause. This case describes an intracranial catheter associated with nonaneurysmal SAH. It suggests that intrathecal catheters can cause vascular injury, and that nonaneurysmal perimesencephalic SAH may be due to injury of small blood vessels.

Measurement of both the equilibrium constant and rate constant for electronic energy transfer by control of the limiting kinetic regimes.

Electronic energy transfer can fall into two limiting cases. When the rate of the energy transfer back reaction is much faster than relaxation of the acceptor excited state, equilibrium between the donor and acceptor excited states is achieved and only the equilibrium constant for the energy transfer can be measured. When the rate of the back reaction is much slower than relaxation of the acceptor, the energy transfer is irreversible and only the forward rate constant can be measured. Herein, we demonstrate that with trans-[Cr(d(4)-cyclam)(CN)(2)](+) as the donor and either trans-[Cr([15]ane-ane-N(4))(CN)(2)](+) or trans-[Cr(cyclam)(CN)(2)](+) as the acceptor, both limits can be obtained by control of the donor concentration. The equilibrium constant and rate constant for the case in which trans-[Cr([15]ane-ane-N(4))(CN)(2)](+) is the acceptor are 0.66 and 1.7 x 10(7) M(-1) s(-1), respectively. The equilibrium constant is in good agreement with the value of 0.60 determined using the excited state energy gap between the donor and acceptor species. For the thermoneutral case in which trans-[Cr(cyclam)(CN)(2)](+) is the acceptor, an experimental equilibrium constant of 0.99 was reported previously, and the rate constant has now been measured as 4.0 x 10(7) M(-1) s(-1).

Combined Pterional Transsylvian and Bifrontal Interhemispheric Approach to Ruptured Subcallosal and Pericallosal Brain Arteriovenous Malformation with Skeletonization of the Entire A2 ACA Segment.

A 39-year-old man presented with a large left paramedian frontal lobe intracerebral hemorrhage. Computed tomography angiography and magnetic resonance imaging revealed a tangle of vessels arising from the anterior cerebral arteries (ACAs) and dilated draining veins entering the superior sagittal sinus. Angiography confirmed a Spetzler-Martin grade 3, supplemented 2 arteriovenous malformation (AVM) with predominant supply from branches of the left ACA with superficial and deep drainage (Video 1). The case illustrates an unusual cerebrovascular pathology involving the entire A2 ACA segment. The AVM extended from the A1/2 junction along the entire A2 segment past the genu of the corpus callosum (A3 segment). A combined pterional transsylvian and bifrontal interhemispheric approach was performed. The proximal sylvian fissure and opticocarotid cistern were opened to expose the A1/2 junction. Once proximal control was obtained, the hematoma was evacuated to define the lateral border of the AVM. The interhemispheric fissure was then opened to identify the draining vein and the distal pericallosal arteries. The interhemispheric approach also defined the medial border of the AVM. The A2 ACAs were then skeletonized from the AVM from the A1/2 junction to the pericallosal arteries. Aneurysm clips were used to interrupt large AVM feeders from the A2 arteries, which avoids cautery and heat transmission to the parent vessel. Once the AVM was disconnected and skeletonized from the A2s, the draining vein was clipped and the nidus was removed. Indocyanine green angiography confirmed patency of the A2s and pericallosal arteries. Postoperative angiography demonstrated no residual shunting, and the patient was discharged in good condition.

Y-Stent Technique for Treatment of Wide-Necked Posterior Communicating Artery Aneurysm Associated with Fetal Posterior Cerebral Artery: Technical Report.

BACKGROUND: Despite a variety of technologies that are available for treatment of complex intracranial aneurysms, certain anatomic configurations remain challenging to address endovascularly. CASE DESCRIPTION: A patient was found to have an incidental 12 mm × 11 mm × 10 mm, wide-necked right posterior communicating artery aneurysm with a fetal origin of the posterior cerebral artery arising directly from the aneurysm dome. After multidisciplinary discussion, a staged endovascular treatment approach was undertaken in 2 stages. First, a Y-stent construct using 2 overlapping Neuroform Atlas stents was placed into the M1 and fetal posterior cerebral artery segments. Two months later, after endothelialization of the stent construct, coil embolization of the aneurysm was performed. The patient tolerated both stages of the procedure well and was discharged the following day in each case. She remained neurologically intact, and at follow-up 5 months later had no evidence of residual or recurrent aneurysm. CONCLUSIONS: This case illustrates a number of important considerations in the management approach for wide-necked intracranial aneurysms.

Spontaneous Perforation of Anterior Choroidal Artery with Resultant Pseudoaneurysm Formation: Unusual Cause of Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage resulting from spontaneous perforation of a small intracranial vessel, with resultant pseudoaneurysm formation, has not been widely reported in the literature. CASE DESCRIPTION: We present the case of a 71-year-old patient with rupture of a small aneurysm of a duplicated left anterior choroidal artery causing an acute third nerve palsy. The aneurysm was not able to be treated endovascularly without sacrifice of the parent vessel. At surgery, a pseudoaneurysm was seen completely separate from the parent vessel, which was actively bleeding through a hole in the vessel. The pseudoaneurysm was indenting the oculomotor nerve. After confirmation of adequate collateral flow, the abnormal segment of vessel was trapped and the pseudoaneurysm removed with surrounding clot. The patient's cranial nerve palsy resolved. CONCLUSIONS: This case illustrates an unusual sequela of subarachnoid hemorrhage presenting a unique challenge in surgical management.

An Update on Medications for Brain Arteriovenous Malformations.

Despite a variety of treatment options for brain arteriovenous malformations (bAVMs), many lesions remain challenging to treat and present significant ongoing risk for hemorrhage. In Vitro investigations have recently led to a greater understanding of the formation, growth, and rupture of bAVMs. This has, in turn, led to the development of therapeutic targets for medications for bAVMs, some of which have begun testing in clinical trials in humans. These include bevacizumab, targeting the vascular endothelial growth factor driven angiogenic pathway; thalidomide or lenalidomide, targeting blood-brain barrier impairment; and doxycycline, targeting matrix metalloproteinase overexpression. A variety of other medications appear promising but either requires adaptation from other disease states or development from early bench studies into the clinical realm. This review aims to provide an overview of the current state of development of medications targeting bAVMs and to highlight their likely applications in the future.

Interhemispheric Surgical Approaches for Ruptured Intraventricular Arteriovenous Malformation-Associated Aneurysms: Technical Report and Case Series.

BACKGROUND: Aneurysms associated with brain arteriovenous malformations (AVMs) represent a hemorrhage risk in addition to that of the AVM nidus. In high-risk or unresectable cases, targeted treatment of an aneurysm causing hemorrhage may effectively decrease future hemorrhage risk. The objective of this report is to describe our series of patients with intraventricular AVM-associated aneurysms treated surgically. We highlight technical nuances of the surgical approaches to aneurysms in the lateral and third ventricles. METHODS: A retrospective review was performed of patients in whom an intraventricular aneurysm rupture was responsible for hemorrhage. In each patient, the aneurysm was excluded surgically via an interhemispheric approach, including transcallosal, transchoroidal, or transcingulate corridors. Aneurysm, AVM characteristics, surgical approach, and outcomes were reviewed. RESULTS: Six patients were included in the series. In 5 patients, the disease was located on the left and approached from the right. Aneurysms were located in, or projecting into, the lateral ventricle in 4 patients (transcingulate approach) and in the third ventricle in 2 patients (transchoroidal fissure approach). The aneurysm was clipped in 1 patient and resected in 5 patients. The associated AVM was resected in 2 patients. In all patients, the surgical approach allowed adequate treatment of the aneurysm without new neurologic morbidity. No patients experienced recurrent intraventricular hemorrhage during follow-up. CONCLUSIONS: Ruptured intraventricular aneurysms associated with brain AVMs can be treated surgically to reduce the risk of rebleeding in patients in whom the aneurysms are not accessible to endovascular treatment and in which the AVM nidus may not be safely resected.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020.

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Bringing high-grade arteriovenous malformations under control: clinical outcomes following multimodality treatment in children.

OBJECTIVE: Brain arteriovenous malformations (AVMs) consist of dysplastic blood vessels with direct arteriovenous shunts that can hemorrhage spontaneously. In children, a higher lifetime hemorrhage risk must be balanced with treatment-related morbidity. The authors describe a collaborative, multimodal strategy resulting in effective and safe treatment of pediatric AVMs. METHODS: A retrospective analysis of a prospectively maintained database was performed in children with treated and nontreated pediatric AVMs at the University of California, San Francisco, from 1998 to 2017. Inclusion criteria were age ≤ 18 years at time of diagnosis and an AVM confirmed by a catheter angiogram. RESULTS: The authors evaluated 189 pediatric patients with AVMs over the study period, including 119 ruptured (63%) and 70 unruptured (37%) AVMs. The mean age at diagnosis was 11.6 ± 4.3 years. With respect to Spetzler-Martin (SM) grade, there were 38 (20.1%) grade I, 40 (21.2%) grade II, 62 (32.8%) grade III, 40 (21.2%) grade IV, and 9 (4.8%) grade V lesions. Six patients were managed conservatively, and 183 patients underwent treatment, including 120 resections, 82 stereotactic radiosurgery (SRS), and 37 endovascular embolizations. Forty-four of 49 (89.8%) high-grade AVMs (SM grade IV or V) were treated. Multiple treatment modalities were used in 29.5% of low-grade and 27.3% of high-grade AVMs. Complete angiographic obliteration was obtained in 73.4% of low-grade lesions (SM grade I-III) and in 45.2% of high-grade lesions. A periprocedural stroke occurred in a single patient (0.5%), and there was 1 treatment-related death. The mean clinical follow-up for the cohort was 4.1 ± 4.6 years, and 96.6% and 84.3% of patients neurologically improved or remained unchanged in the ruptured and unruptured AVM groups following treatment, respectively. There were 16 bleeding events following initiation of AVM treatment (annual rate: 0.02 events per person-year). CONCLUSIONS: Coordinated multidisciplinary evaluation and individualized planning can result in safe and effective treatment of children with AVMs. In particular, it is possible to treat the majority of high-grade AVMs with an acceptable safety profile. Judicious use of multimodality therapy should be limited to appropriately selected patients after thorough team-based discussions to avoid additive morbidity. Future multicenter studies are required to better design predictive models to aid with patient selection for multimodal pediatric care, especially with high-grade AVMs.

Clipping of High-Risk Dural Arteriovenous Fistula of the Posterior Fossa: 3-Dimensional Operative Video.

Dural arteriovenous fistulas (DAVFs) represent 10%-15% of all intracranial arteriovenous malformations.1 DAVFs located in the posterior cranial fossa are rare and often present with intracranial hemorrhage and myelopathy.2 Arterial supply could be provided by the meningeal branches of the vertebral artery and external and internal carotid arteries.3 A 68-year-old man presented with progressive lower-extremity weakness (Video 1). Magnetic resonance imaging revealed a patchy longitudinal cord signal abnormality extending from the cervicomedullary junction to C7. A tentorial DAVF supplied by the right posterior meningeal artery with drainage via dorsal and ventral perimedullary veins was identified on angiography. According to the Cognard classification, the patient's DAVF was determined to be high risk as a type V lesion with spinal venous drainage and progressive myelopathy.4 The fistula was embolized with 50% ethanol resulting in near-complete occlusion. However, follow-up angiography revealed a persistent arteriovenous shunt and slightly worsening symptoms for the patient. He underwent a sitting supracerebellar approach with a torcular craniotomy for successful clip ligation of the dural arteriovenous fistula. The patient was discharged with improvements in lower-extremity strength and no residual arteriovenous shunting in postoperative imaging.

Incidence, classification, and treatment of angiographically occult intracranial aneurysms found during microsurgical aneurysm clipping of known aneurysms.

OBJECTIVE: During the microsurgical clipping of known aneurysms, angiographically occult (AO) aneurysms are sometimes found and treated simultaneously to prevent their growth and protect the patient from future rupture or reoperation. The authors analyzed the incidence, treatment, and outcomes associated with AO aneurysms to determine whether limited surgical exploration around the known aneurysm was safe and justified given the known limitations of diagnostic angiography. METHODS: An AO aneurysm was defined as a saccular aneurysm detected using the operative microscope during dissection of a known aneurysm, and not detected on preoperative catheter angiography. A prospective database was retrospectively reviewed to identify patients with AO aneurysms treated microsurgically over a 20-year period. RESULTS: One hundred fifteen AO aneurysms (4.0%) were identified during 2867 distinct craniotomies for aneurysm clipping. The most common locations for AO aneurysms were the middle cerebral artery (60 aneurysms, 54.1%) and the anterior cerebral artery (20 aneurysms, 18.0%). Fifty-six AO aneurysms (50.5%) were located on the same artery as the known saccular aneurysm. Most AO aneurysms (95.5%) were clipped and there was no attributed morbidity. The most common causes of failed angiographic detection were superimposition of a large aneurysm (type 1, 30.6%), a small aneurysm (type 2, 18.9%), or an adjacent normal artery (type 3, 36.9%). Multivariate analysis identified multiple known aneurysms (odds ratio [OR] 3.45, 95% confidence interval [CI] 2.16-5.49, p < 0.0001) and young age (OR 0.981, 95% CI 0.965-0.997, p = 0.0226) as independent predictors of AO aneurysms. CONCLUSIONS: Meticulous inspection of common aneurysm sites within the surgical field will identify AO aneurysms during microsurgical dissection of another known aneurysm. Simultaneous identification and treatment of these additional undiagnosed aneurysms can spare patients later rupture or reoperation, particularly in those with multiple known aneurysms and a history of subarachnoid hemorrhage. Limited microsurgical exploration around a known aneurysm can be performed safely without additional morbidity.

Microsurgical Clipping of Anterior Choroidal Artery Aneurysms: A Systematic Approach to Reducing Ischemic Complications in an Experience with 146 Patients.

BACKGROUND: Aneurysms of the anterior choroidal artery (AChA) have been associated with high treatment-associated morbidity due to ischemic complications. OBJECTIVE: To report a large clinical experience of microsurgically treated AChA aneurysms and describe a systematic approach to reduce ischemic complications. METHODS: One hundred forty-six patients with AChA aneurysms were retrospectively reviewed from a prospectively maintained database. Clinical characteristics, surgical techniques, clinical outcomes, arterial infarction, and use of intraoperative adjuncts (ie, ultrasonography, indocyanine green videoangiography, and neuromonitoring) were analyzed. RESULTS: In total, one hundred forty-three aneurysms (97.9%) were clipped. Temporary clipping was utilized in 47 cases (32.2%) with mean occlusion time of 5.6 min. Arterial infarction occurred in 12 patients (8.2%). In clipped aneurysms, 90.5% were completely obliterated, 8.8% had minimal residual (<5% of original), and 0.7% were incompletely occluded (>5% of original). Mortality (2.7%) was limited to patients with high-grade subarachnoid hemorrhage. Indocyanine green videoangiography and neuromonitoring altered operative technique in ∼20% of cases. Multivariate logistic regression identified intraoperative rupture as the sole predictor for arterial infarction. CONCLUSION: Open microsurgical clipping remains a safe, effective treatment for AChA aneurysms. Microsurgical technique is paramount in preserving AChA patency and reducing ischemic complications. Despite increasing reliance on qualitative measures of AChA blood flow (videoangiography and ultrasonography) and neurophysiological monitoring, these technologies aid us infrequently. However, these adjuncts provide important safety checks for AChA patency. Temporary clipping must be used judiciously to lower the risk of intraoperative rupture while limiting possible ischemia in the AChA territory.

Defective vascular signaling & prospective therapeutic targets in brain arteriovenous malformations.

The neurovascular unit is composed of endothelial cells, vascular smooth muscle cells, pericytes, astrocytes and neurons. Through tightly regulated multi-directional cell signaling, the neurovascular unit is responsible for the numerous functionalities of the cerebrovasculature - including the regulation of molecular and cellular transport across the blood-brain barrier, angiogenesis, blood flow responses to brain activation and neuroinflammation. Historically, the study of the brain vasculature focused on endothelial cells; however, recent work has demonstrated that pericytes and vascular smooth muscle cells - collectively known as mural cells - play critical roles in many of these functions. Given this emerging data, a more complete mechanistic understanding of the cellular basis of brain vascular malformations is needed. In this review, we examine the integrated functions and signaling within the neurovascular unit necessary for normal cerebrovascular structure and function. We then describe the role of aberrant cell signaling within the neurovascular unit in brain arteriovenous malformations and identify how these pathways may be targeted therapeutically to eradicate or stabilize these lesions.

A mini-open transspinous approach for resection of intramedullary spinal cavernous malformations.

BACKGROUND AND IMPORTANCE: Advances in minimally invasive (MIS) and mini-open surgical approaches have led to reductions in perioperative morbidity without compromising rates of resection of non-degenerative intradural spinal pathologies. Whether these approaches may be adapted for the surgical resection for intramedullary vascular malformations - such as cavernous malformations (CMs) - has yet to be reported. The authors describe a mini-open transspinous approach to resect a ruptured intramedullary CM of the conus medullaris. CLINICAL PRESENTATION: A 28-year-old man presented with sudden onset of bilateral lower extremity weakness, urinary retention and saddle anesthesia. Magnetic resonance imaging demonstrated a ruptured CM within the conus medullaris with pronounced extralesional hemorrhage. A mini-open transspinous approach with an expandable tubular retractor was successfully applied to facilitate microsurgical resection of the CM and evacuation of the associated hematoma. The patient made a good neurologic recovery, and postoperative imaging confirmed a gross total resection of the CM. CONCLUSION: A mini-open transspinous approach utilizing an expandable tubular retractor offers feasible less invasive alternative to provide dorsal midline access for the microsurgical resection of intramedullary spinal CMs. Larger case series or future randomized prospective trials are warranted to fully explore suitability of MIS techniques for the surgical management of intradural spinal cord vascular pathologies - such as CMs.

Reduction of shunt dependency rates following aneurysmal subarachnoid hemorrhage by tandem fenestration of the lamina terminalis and membrane of Liliequist during microsurgical aneurysm repair.

OBJECTIVEShunt-dependent hydrocephalus is an important cause of morbidity following aneurysmal subarachnoid hemorrhage (aSAH) in excess of 20% of cases. Hydrocephalus leads to prolonged hospital and ICU stays, well as to repeated surgical interventions, readmissions, and complications associated with ventriculoperitoneal (VP) shunts, including shunt failure and infection. Whether variations in surgical technique at the time of aneurysm treatment may modify rates of shunt dependency remains a matter of debate. Here, the authors report on their experience with tandem fenestration of the lamina terminalis (LT) and membrane of Liliequist (MoL) at the time of open microsurgical repair of the ruptured aneurysm.METHODSThe authors conducted a retrospective review of 663 consecutive patients with aSAH treated from 2005 to 2015 by open microsurgery via a pterional or orbitozygomatic craniotomy by the senior author (M.T.L.). Data collected from review of the electronic medical record included age, Hunt and Hess grade, Fisher grade, need for an external ventricular drain, and opening pressure. Patients were stratified into those undergoing no fenestration and those undergoing tandem fenestration of the LT and MoL at the time of surgical repair. Outcome variables, including VP shunt placement and timing of shunt placement, were recorded and statistically analyzed.RESULTSIn total, shunt-dependent hydrocephalus was observed in 15.8% of patients undergoing open surgical repair following aSAH. Tandem microsurgical fenestration of the LT and MoL was associated with a statistically significant reduction in shunt dependency (17.9% vs 3.2%, p < 0.01). This effect was confirmed with multivariate analysis of collected variables (multivariate OR 0.09, 95% CI 0.03-0.30). Number-needed-to-treat analysis demonstrated that tandem fenestration was required in approximately 6.8 patients to prevent a single VP shunt placement. A statistically significant prolongation in days to VP shunt surgery was also observed in patients treated with tandem fenestration (26.6 ± 19.4 days vs 54.0 ± 36.5 days, p < 0.05).CONCLUSIONSTandem fenestration of the LT and MoL at the time of open microsurgical clipping and/or bypass to secure ruptured anterior and posterior circulation aneurysms is associated with reductions in shunt-dependent hydrocephalus following aSAH. Future prospective randomized multicenter studies are needed to confirm this result.