Thomas J. Buell

Radiosurgery for Cerebral Arteriovenous Malformations with Associated Arterial Aneurysms

OBJECTIVE The radiosurgical outcomes for cerebral arteriovenous malformations (AVM) with AVM-associated arterial aneurysms (AAA) are poorly understood, because many AAAs are embolized before nidal intervention. The aim of this retrospective case-control study is to determine the effect of AAAs on AVM radiosurgery outcomes. METHODS We evaluated an institutional AVM radiosurgery database from 1989 to 2013. AAAs were classified as intranidal (type I) or prenidal (type II). The case cohort comprised AVMs with patent type I or II AAAs. The control cohort comprised AVMs without AAAs and matched 2:1 to the case cohort. RESULTS The case cohort comprised 51 AVMs, including 23 with type I and 28 with type II AAAs. The control cohort comprised 102 AVMs without AAAs. The cumulative AVM obliteration, annual postradiosurgery hemorrhage, and radiologically evident radiation-induced changes rates were 67%, 3.3%, and 28%, respectively, for the case cohort, compared with 70%, 2.0%, and 35%, respectively, for the control cohort. The presence of an AAA was not significantly associated with obliteration (P = 0.293), postradiosurgery hemorrhage (P = 0.209), or radiation-induced changes (P = 0.323). The rates of type II AAA occlusion at 3, 5, and 10 years were 46%, 77%, and 95%, respectively. The type II AAA occlusion rate was significantly higher in obliterated AVMs (P = 0.002). CONCLUSIONS Patent intranidal or prenidal AAAs do not significantly affect AVM radiosurgical outcomes. Occlusion of distal prenidal AAAs commonly occurs after radiosurgery. These findings may support a more conservative stance for embolization before radiosurgery for AVMs with AAAs.

Endovascular mechanical thrombectomy for cerebral venous sinus thrombosis: a systematic review

Background Cerebral venous sinus thrombosis (CVST) is an uncommon form of stroke that, when severe, can be a therapeutic challenge. Endovascular mechanical thrombectomy (EMT) techniques have significantly evolved over the past decade, but data regarding the efficacy and safety of EMT for CVST are poorly defined. Objective To summarize the large number of case series on this relatively rare condition and establish trends in the outcomes of EMT for CVST. Methods A literature review was performed using PubMed and Medline to identify reports of three or more patients with CVST treated with EMT. Baseline and outcomes data, including radiographic resolution, neurological outcome, recurrence, and treatment-related complications, were extracted for analysis. Results A total of 17 studies comprising 235 patients treated with EMT were included for analysis. Based on pooled data, 40.2% of patients presented with encephalopathy or coma. Concurrent endovascular thrombolysis was employed in 87.6% of patients. Complete radiographic resolution of CVST was achieved in 69.0% of patients. At follow-up (range 0.5–3.5 years), 34.7% of patients were neurologically intact and the mortality rate was 14.3%. CVST recurrence was evident in 1.2%. Worsening or new intracranial hemorrhage (ICH) occurred in 8.7% of cases. ORs of good outcome (modified Rankin Scale score 0–2) and development of ICH with sole EMT versus concurrent thrombolytic therapy were 1.51 (95% CI 0.29 to 8.15, p=0.61) and 1.15 (95% CI 0.12 to 10.80, p=0.90), respectively. Conclusions EMT is an effective salvage therapy for refractory CVST, with a reasonable safety profile. Chemical thrombolysis, in conjunction with EMT, did not appear to result in additional harm or benefit. Further analysis is warranted to determine predictors of success after EMT for CVST.

Pathogenesis and Cerebrospinal Fluid Hydrodynamics of the Chiari I Malformation

This article summarizes the current understanding of the pathophysiology of the Chiari I malformation that is based on observations of the anatomy visualized by modern imaging with MRI and prospective studies of the physiology of patients before and after surgery. The pathogenesis of a Chiari I malformation of the cerebellar tonsils is grouped into 4 general mechanisms.

Endoport-Assisted Microsurgical Treatment of a Ruptured Periventricular Aneurysm

Background and Importance. Ruptured periventricular aneurysms in patients with moyamoya disease represent challenging pathologies. The most common methods of treatment include endovascular embolization and microsurgical clipping. However, rare cases arise in which the location and anatomy of the aneurysm make these treatment modalities particularly challenging. Clinical Presentation. We report a case of a 34-year-old female with moyamoya disease who presented with intraventricular hemorrhage. CT angiography and digital subtraction angiography revealed an aneurysm located in the wall of the atrium of the right lateral ventricle. Distal endovascular access was not possible, and embolization risked the sacrifice of arteries supplying critical brain parenchyma. Using the BrainPath endoport system, the aneurysm was able to be accessed. Since the fusiform architecture of the aneurysm prevented clip placement, the aneurysm was ligated with electrocautery. Conclusion. We demonstrate the feasibility of endoport-assisted approach for minimally invasive access and treatment of uncommon, distally located aneurysms.

Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology

We describe an 80-year-old woman with intraventricular silicone oil mimicking traumatic pathology upon presentation to the emergency department after a ground-level fall. Intraventricular migration of silicone oil from prior intraocular endotamponade is rare having only been described in a handful of case reports. While it has a unique and characteristic appearance on imaging, intraventricular silicone oil can be confused with intraventricular hemorrhage or calcified ventricular neoplasms. Recognition and differentiation of intraventricular silicone oil from more sinister pathology is essential for the radiologist, neurologist and neurosurgeon and can be done with routine head CT scan. We discuss the imaging findings of intraventricular silicone oil and review the current understanding of this unusual phenomenon.

A pilot study and novel angiographic classification for superior sagittal sinus stenting in patients with non-thrombotic intracranial venous occlusive disease

Objective Safety and efficacy of superior sagittal sinus (SSS) stenting for non-thrombotic intracranial venous occlusive disease (VOD) is unknown. The aim of this retrospective cohort study is to evaluate outcomes after SSS stenting. Methods We evaluated an institutional database to identify patients who underwent SSS stenting. Radiographic and clinical outcomes were analyzed and a novel angiographic classification of the SSS was proposed. Results We identified 19 patients; 42% developed SSS stenosis after transverse sinus stenting. Pre-stent maximum mean venous pressure (MVP) in the SSS of 16.2 mm Hg decreased to 13.1 mm Hg after stenting (p=0.037). Preoperative trans-stenosis pressure gradient of 4.2 mm Hg decreased to 1.5 mm Hg after stenting (p<0.001). No intraprocedural complication or junctional SSS stenosis distal to the stent construct was noted. Improvement in headache, tinnitus, and visual obscurations was reported by 66.7%, 63.6%, and 50% of affected patients, respectively, at mean follow-up of 5.2 months. We divided the SSS into four anatomically equal segments, numbered S1–S4, from the torcula to frontal pole. SSS stenosis typically occurs in the S1 segment, and the anterior extent of SSS stents was deployed at the S1–S2 junction in all but one case. Conclusions SSS stenting is reasonably safe, may improve clinical symptoms, and significantly reduces maximum MVP and trans-stenosis pressure gradients in patients with VOD with SSS stenosis. The S1 segment is most commonly stenotic, and minimum pressure gradients for symptomatic SSS stenosis may be lower than for transverse or sigmoid stenosis. Additional studies and follow-up are necessary to better elucidate appropriate clinical indications and long-term efficacy of SSS stenting.

Intracranial venous pressures under conscious sedation and general anesthesia

Introduction Venous outflow obstruction has been implicated in the pathophysiology of a subset of patients with idiopathic intracranial hypertension (IIH), and venous sinus stenting (VSS) has emerged as an effective treatment. However, the effect of anesthesia on venous sinus pressure measurements is unpredictable. A more thorough understanding of the effect of the level of anesthesia on intracranial venous pressures might help to better define patients who might benefit most from stent placement. Objective To compare, in a retrospective cohort study, intracranial venous pressures measured under conscious (CS) sedation versus general anesthesia (GA) and to assess the relationship between anesthetic-dependent venous pressures and outcomes after VSS. Methods We performed a retrospective review of a prospectively maintained database to identify patients undergoing angiographic evaluation and VSS for intracranial venous stenosis. Mean venous pressures (MVPs) and trans-stenosis pressure gradients obtained under CS were compared with those measured under GA. Results The maximal MVP was significantly lower under GA (19.8 mm Hg) than CS (21.9 mm Hg; p=0.029). The MVPs in the superior sagittal sinus, torcula, and transverse sinus were lower under GA, but were significantly higher in the sigmoid sinus and jugular bulb under GA (p<0.001). The mean trans-stenosis pressure gradient was also significantly lower under GA (8.6 mm Hg) than CS (12.1 mm Hg; p<0.001). Patients with a larger difference between maximum MVP under GA versus CS were more likely to have normalization of the MVP after VSS (p=0.0008). Conclusions Intracranial venous pressures are markedly affected by GA. In order to obtain an accurate measurement of MVPs and trans-stenosis gradients, patients undergoing investigation for IIH should undergo cerebral angiography and venous manometry under CS, which provides more reliable data for outcomes after VSS.

Endovascular Mechanical Thrombectomy for Acute Middle Cerebral Artery M2 Segment Occlusion: A Systematic Review

INTRODUCTION The benefit of endovascular mechanical thrombectomy (EMT) for acute distal occlusions of the middle cerebral artery M2 segment is incompletely defined. The aim of this systematic review is to analyze the recent literature regarding EMT for acute M2 occlusions. METHODS We reviewed the literature to identify all studies of patients with acute M2 occlusions who underwent EMT that were published after January 1, 2015. Excellent and good outcomes were defined as modified Rankin Scale score of 0-1 and 0-2, respectively, at 3 months. Successful reperfusion was defined as modified Thrombolysis In Cerebral Infarction (mTICI) score of 2b-3. RESULTS Eight studies, comprising 630 EMT-treated patients with acute M2 occlusions, were included in the analysis. The median National Institute of Health Stroke Scale score ranged from 10 to 16, and the median Alberta Stroke Program Computed Tomography Score ranged from 9 to 10. Excellent and good outcomes at 3-month follow-up were observed in 40% and 62%, respectively, of patients with acute M2 occlusion who underwent EMT, with a mortality of 11%. Successful reperfusion was achieved in 78% of cases. Postprocedural intracerebral hemorrhage (ICH) occurred in 14% of patients, including a symptomatic ICH rate of 5%. CONCLUSIONS EMT for acute M2 occlusion affords functional independence to most patients, with a modest rate of symptomatic ICH. However, compared with the natural history of distal MCA occlusions, the benefit of M2 thrombectomy using stent retriever or direct aspiration techniques remains unclear.

Transient resolution of venous sinus stenosis after high-volume lumbar puncture in a patient with idiopathic intracranial hypertension

Stenosis of the transverse sinus (TS) and sigmoid sinus (SS), with a trans-stenosis pressure gradient, has been implicated in the pathophysiology of idiopathic intracranial hypertension (IIH). MRI has shown improvement in TS and SS stenosis after high-volume lumbar puncture (HVLP) in a subset of patients with IIH. The authors present the first report of an IIH patient with immediate post-HVLP TS and SS trans-stenosis pressure gradient reduction and an attendant increase in TS and SS cross-sectional area confirmed using intravascular ultrasonography (IVUS). Recurrence of the patients TS-SS stenosis coincided with elevated HVLP opening pressure, and venous sinus stent placement resulted in clinical improvement. This report suggests that TS and SS stenosis may be a downstream effect of elevated intracranial pressure in IIH, rather than its principal etiological mechanism. However, the authors hypothesize that endovascular stenting may obliterate a positive feedback loop involving trans-stenosis pressure gradients, and still benefit appropriately selected patients.

Endovascular treatment for cerebral vasospasm following aneurysmal subarachnoid hemorrhage: predictors of outcome and retreatment

Objective Although endovascular therapy has been widely adopted for the treatment of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH), its effect on clinical outcomes remains incompletely understood. The aims of this retrospective cohort study are to evaluate the outcomes of endovascular intervention for post-aSAH vasospasm and identify predictors of functional independence at discharge and repeat endovascular vasospasm treatment. Methods We assessed the baseline and outcomes data for patients with aSAH who underwent endovascular vasospasm treatment at our institution, including intra-arterial (IA) vasodilator infusion and angioplasty. Statistical analyses were performed to determine factors associated with good outcome at discharge (modified Rankin Scale 0–2) and repeat endovascular vasospasm treatment. Results The study cohort comprised 159 patients with a mean age of 52 years. Good outcome was achieved in 17% of patients at discharge (26/150 patients), with an in-hospital mortality rate of 22% (33/150 patients). In the multivariate analysis, age (OR 0.895; p=0.009) and positive smoking status (OR 0.206; p=0.040) were negative independent predictors of good outcome. Endovascular retreatment was performed in 34% (53/156 patients). In the multivariate analysis, older age (OR 0.950; p=0.004), symptomatic vasospasm (OR 0.441; p=0.046), initial treatment with angioplasty alone (OR 0.096; p=0.039), and initial treatment with combined IA vasodilator infusion and angioplasty (OR 0.342; p=0.026) were negative independent predictors of retreatment. Conclusion We found a modest rate of functional independence at discharge in patients with aSAH who underwent endovascular vasospasm treatment. Older patients and smokers had worse functional outcomes at discharge. Initial use of angioplasty appears to decrease the need for subsequent retreatment.