Long-term follow up data on difficult to treat intracranial arteriovenous malformations treated with the CyberKnife

INTRODUCTION

The CyberKnife, a frameless, robotic, stereotactic device, has been developed to radiosurgically treat arteriovenous malformations (AVMs). While most AVMs are obliterated within two-to-three years, a subset remain recalcitrant; long-term data on these difficult to treat AVMs are limited in the neurosurgical literature.

MATERIALS AND METHODS

A retrospective analysis of all patients who underwent CyberKnife treatment for intracranial AVMs at a single U.S. institution between 2002 and 2012, whose AVMs had failed to obliterate within 48 months or longer from the treatment start date, were eligible for inclusion.

RESULTS

Eleven patients (9 AVMs; 7 males, 2 females) were followed for an average of 85.2 months (range 56.2-119.4). The median lesion size was 3.5 cm (range: 2.8-8.0 cm) and median Spetzler-Martin grade was 3 (range: 2-5). All AVMs were treated with one radiation dose (median prescribed dose was 18.0 Gy; median D_max: 23.7 Gy). Six (66.7%) were obliterated in a median time of 84 months (range: 52-94 months), while 3 (33.3%) remained active after a median of 90.8 months (range 69.7-119.4). Transient, post-radiosurgery adverse radiation effects occurred in 5 (55.6%) cases. One (11.1%) patient had an acute hemorrhage from the AVM after radiosurgery. Four (44.4%) patients underwent repeat radiosurgery and/or embolization. Three of these lesions eventually obliterated, while 1 did not.

CONCLUSION

The median time to obliteration was 84 months. Two-thirds of AVMs which persisted for over 4 years following initial radiosurgery treatment eventually obliterated. Transient post-radiosurgery adverse effects were common; delayed hemorrhages were rare in our case series.

Milestones in stereotactic radiosurgery for the central nervous system

INTRODUCTION

Since Lars Leksell developed the first stereotactic radiosurgery (SRS) device in 1951, there has been growth in the technologies available and clinical indications for SRS. This expansion has been reflected in the medical literature, which is built upon key articles and institutions that have significantly impacted SRS applications. Our aim was to identify these prominent works and provide an educational tool for training and further inquiry.

METHOD

A list of search phrases relating to central nervous system applications of stereotactic radiosurgery was compiled. A topic search was performed using PubMed and Scopus databases. The journal, year of publication, authors, treatment technology, clinical subject, study design and level of evidence for each article were documented. Influence was proposed by citation count and rate.

RESULTS

Our search identified a total of 10,211 articles with the top 10 publications overall on the study of SRS spanning 443-1313 total citations. Four articles reported on randomized controlled trials, all of which evaluated intracranial metastases. The most prominent subtopics included SRS for arteriovenous malformation, glioblastoma, and acoustic neuroma. Greatest representation by treatment modality included Gamma Knife, LINAC, and TomoTherapy.

CONCLUSIONS

This systematic reporting of the influential literature on SRS for intracranial and spinal pathologies underscores the technology's rapid and wide reaching clinical applications. Moreover the findings provide an academic guide to future health practitioners and engineers in their study of SRS for neurosurgery.

Patterns of Stroke Transfers and Identification of Predictors for Thrombectomy

BACKGROUND

Interhospital transfers for endovascular thrombectomy (EVT) evaluation have increased since the publication of landmark neuroendovascular stroke trials in 2015. The lack of guidelines to select potential EVT candidates prior to transfer can lead to instances where, despite considerable costs and transport risks, transferred patients do not ultimately undergo EVT. Our aim was to characterize the patterns and identify predictors for EVT on transfer.

METHODS

In this observational cohort study, we retrospectively analyzed patients with acute ischemic stroke (AIS) transferred to our institution for EVT evaluation from January 2015 to March 2016. Clinical and radiographic predictors for EVT on transfer were determined with multivariable logistic regression analysis.

RESULTS

A total of 103 transfer patients with AIS were included in the study, and 52% were women. A higher collateral score (P < 0.01), a higher National Institutes of Health Stroke Scale (NIHSS) score (P < 0.01), computed tomography angiography (CTA) at referring hospital (P < 0.01), and large vessel occlusion on arrival CTA (P < 0.01) were significant in patients who underwent EVT on univariable analysis. More than half (61.1%) of transfers were futile and primarily related to absence of large vessel occlusion on arrival. A higher collateral score (P = 0.02), a higher NIHSS score (P = 0.006), and having undergone a CTA at the referring center (P = 0.002) remained the independent predictors of EVT. The C statistic for the model was 0.94.

CONCLUSIONS

A higher collateral score, the acquisition of CTA imaging at the referring centers, and a higher NIHSS score independently predicted EVT on transfer.

Direct endovascular thrombectomy and bridging strategies for acute ischemic stroke: a network meta-analysis

OBJECTIVES

The present Bayesian network meta-analysis aimed to compare the various strategies for acute ischemic stroke: direct endovascular thrombectomy within the thrombolysis window in patients with no contraindications to thrombolysis (DEVT); (2) direct endovascular thrombectomy secondary to contraindications to thrombolysis (DEVTc); (3) endovascular thrombectomy in addition to thrombolysis (IVEVT); and (4) thrombolysis without thrombectomy (IVT).

METHODS

Six electronic databases were searched from their dates of inception to May 2017 to identify randomized controlled trials (RCTs) comparing IVT versus IVEVT, and prospective registry studies comparing IVEVT versus DEVT or IVEVT versus DEVTc. Network meta-analyses were performed using ORs and 95% CIs as the summary statistic.

RESULTS

We identified 12 studies (5 RCTs, 7 prospective cohort) with a total of 3161 patients for analysis. There was no significant difference in good functional outcome at 90 days (modified Rankin Scale score ≤2) between DEVT and IVEVT. There was no significant difference in mortality between all treatment groups. DEVT was associated with a 49% reduction in intracranial hemorrhage (ICH) compared with IVEVT (OR 0.51; 95% CI 0.33 to 0.79), due to reduction in rates of asymptomatic ICH (OR 0.47; 95% CI 0.29 to 0.76). Patients treated with DEVT had higher rates of reperfusion compared with IVEVT (OR 1.73; 95% CI 1.04 to 2.94).

CONCLUSIONS

To our knowledge, this is the first network meta-analysis to be performed in the era of contemporary mechanical thrombectomy comparing DEVT and DEVTc. Our analysis suggests the addition of thrombolysis prior to thrombectomy for large vessel occlusions may not be associated with improved outcomes.

Type I Spinal Arteriovenous Fistula with Ventral Intradural Venous Drainage: A Proposal of a Modified Classification

Objectives:

Spinal arteriovenous fistula (AVF) is the most common spinal vascular lesion and constitutes an abnormal communication between a feeder artery and a draining vein. Arterialization of the venous plexus leads to venous hypertension; consequent edema and congestion of the spinal cord are associated with progressive neurological decline.

Patients and Methods:

In this report, we describe two unique cases of type I cervical spinal AVF, in which a radiculomeningeal artery forms an intradural fistula that drains into the ventral venous plexus.

Results:

Both patients underwent surgical obliteration of the fistula with complete occlusion confirmed on postoperative angiography.

Conclusion:

Both cases do not fit into the current classification scheme. A modified classification is proposed.

Proposal of a Grading System for Predicting Discharge Mortality and Functional Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Several outcome prediction systems have been developed to evaluate aneurysmal subarachnoid hemorrhage (aSAH). However, they can be difficult to use and can contain subjective elements. We sought to identify the predictors of aSAH outcomes at discharge to provide an accurate and reliable scoring system.

METHODS

A retrospective cohort study of patients with aSAH at an academic institution from 2007 to 2016 was conducted. The primary outcome measure was the modified Rankin scale (mRS) score at discharge, with mRS scores of 0-2 considered favorable and mRS scores of 3-6 considered unfavorable. Factors significant on multivariate regression were used to develop a scale, which was compared with other established grading systems using receiver operating characteristic curves.

RESULTS

We identified 279 patients with aSAH, 37.3% of whom had unfavorable outcomes. The proposed scale assigns 2 points for postresuscitation Glasgow coma scale score of ≤8, 1 point for age ≥70 years, 1 for antiplatelet therapy on admission, and 1 for SAH thickness of ≥10 mm, with a total score of 0-5. The proposed, Subarachnoid Hemorrhage International Trialists, and Hunt and Hess scales had similar areas under the curve (85.2%, 84.8%, and 80.6%, respectively; P > 0.05) but were significantly better than the World Federation of Neurological Surgeons (78.5%; P = 0.001) and modified Fisher (60.8%; P < 0.001) scales.

CONCLUSION

We propose a grading scale to predict discharge mortality and functional outcomes in patients with aSAH. The proposed scale outperformed most other outcome prediction scales. The proposed scale contains objective elements, is easy to apply by memory, and can be a useful and effective measure to predict aSAH outcomes.

Statin Therapy and Diabetes Do Not Affect Aneurysm Occlusion or Clinical Outcomes After Pipeline Embolization Device Treatment: A Preliminary Study

BACKGROUND

The effect of statins and diabetes on angiographic and clinical outcomes in aneurysms treated with pipelines has not been adequately reported. Our aim is to assess the effect of concurrent statin medications and diabetes mellitus (DM) on aneurysm occlusion status and outcomes in patients treated with the pipeline embolization device.

METHODS

A retrospective review of our institution's database of aneurysms treated with the pipeline embolization device between 2013 and 2017 was conducted. We collected data about statin therapy status and intensity, and identified patients with a documented history of DM. Our primary outcome was aneurysm obliteration seen on digital subtracted angiography or magnetic resonance angiography at last follow-up.

RESULTS

We identified 151 patients with 182 aneurysms for this cohort, with a median radiographic follow-up time of 7.2 months (6.1-14.5). Thirty-nine patients were taking statins, and 112 patients did not receive statins. Log-rank tests revealed no statistically significant difference in occlusion rates between patients with and without statin therapy (P = 0.30). A history of DM was documented in 11 patients, with 14 aneurysms in total; 140 patients with 168 aneurysms had no history of DM. Similarly, there were no differences in occlusion rates between the diabetic and nondiabetic groups in multivariate analysis (P = 0.24). Only 2 patients showed significant in-stent stenosis on angiographic follow up, and both were diabetic.

CONCLUSIONS

Our analysis did not identify a statistically significant association between statin therapy or DM and higher occlusion rates or better outcomes after pipeline embolization. Diabetic patients may have a theoretic risk of significant in-stent stenosis.

Natural history of Rathke's cleft cysts: A retrospective analysis of a two centres experience

OBJECTIVE

Rathke's cleft cyst (RCC) is a common sellar lesion which may cause visual impairment, hypopituitarism and headaches from mass effect. The natural history of these lesions is currently unclear. We investigated the natural history of RCCs and compared surgically treated patients with those treated conservatively.

METHODS

We performed a retrospective cohort study of patients diagnosed with a RCC between 1996 and 2016 at Stanford University and Ospedale Maggiore Policlinico di Milano.

RESULTS

Patients were divided into 2 cohorts: Group A, 72 subjects who underwent surgical resection of a symptomatic RCC, and Group B, 62 subjects managed conservatively. Compared to Group B, Group A subjects had larger RCCs (79% vs 22% had a largest diameter >10 mm, P < .001) and were more likely (41.5% vs 16%, P < .001) to present with hypopituitarism and diabetes insipidus (DI) (18% vs 1.6%, P = .002). In Group A, after a mean follow-up of 53.7 months, 12.5% of patients had recurrence and a second surgery. After surgery, 35% of patients recovered pituitary function. Hyperprolactinemia (26.6%) and hypogonadism (66.6%) resolved more commonly that did DI (20.1%). New pituitary deficits appeared in 16.6% of patients after surgery. In Group B, with a mean follow-up of 41 months, only 6.4% had cyst enlargement, none underwent surgery, and none developed a pituitary deficit.

CONCLUSION

Our data offer guidance in decision-making regarding the management of RCC patients and confirm the safety of conservative treatment in asymptomatic patients.

Use of Flow Diversion for the Treatment of Distal Circulation Aneurysms: A Multicohort Study

OBJECTIVE

The safety and efficacy of flow diversion for distal circulation aneurysms of the cerebral vasculature has not been well evaluated. The objective of this study was to assess the use of flow diversion for distal circulation aneurysms (defined as at or beyond the M1, P1, and A1 segments of the middle cerebral artery, posterior cerebral artery, and anterior cerebral artery, respectively) in an international multicenter cohort.

METHODS

Clinical and radiologic records from all patients undergoing flow diversion treatment of distal circulation aneurysms at 3 academic centers (2 in the USA and 1 in Europe) from 2014 until 2017 were retrospectively reviewed.

RESULTS

Forty-six patients (mean age, 58.2 years; 33 women) harboring 46 aneurysms who underwent treatment with either the Pipeline Embolization Device (Medtronic Inc., Dublin, Ireland) or the Flow Re-Direction Endoluminal Device (MicroVention, Tustin, California, USA) were included in these analyses. Thirty-four aneurysms (74%) were located in the anterior circulation and 12 (26%) were located in the posterior circulation. With a mean follow-up of 13.0 months, complete (100%) and near-complete (90%-99%) occlusion was noted in 36 aneurysms (78.2%). Angiographic evidence of side branch or perforator vessel coverage was present in 35 aneurysms (76.1%) but was not associated with failure to occlude at follow-up (P = 0.06). All patients had good functional outcomes after treatment (modified Rankin Scale score 0-2). There were 2 cases (4.3%) of perforator vessel stroke and no hemorrhagic complications.

CONCLUSIONS

Flow diversion for aneurysms beyond the circle of Willis has occlusion rates comparable to alternative treatments and low morbidity. The clinical significance of flow limitation through covered side branches requires further investigation.

Relationship between external ventricular drain clamp trials and ventriculoperitoneal shunt insertion following nontraumatic subarachnoid hemorrhage: a single-center study

OBJECTIVE

Currently, there is no established standard regarding the ideal number of external ventricular drain (EVD) clamp trials performed before ventriculoperitoneal (VP) shunt insertion following nontraumatic subarachnoid hemorrhage (SAH). In this study, the authors aimed to evaluate this relationship.

METHODS

A retrospective review of all patients presenting with SAH between July 2007 and December 2016 was performed. Patients with SAH who had received an EVD within the first 24 hours of hospital admission and had undergone at least 1 clamp trial prior to EVD removal were eligible for inclusion in the study. Patient demographics, clinical presentations, SAH etiologies and grades, clamp trial data, hospital lengths of stay, and functional outcomes were recorded.

RESULTS

One hundred fourteen patients with nontraumatic SAH complicated by posthemorrhagic hydrocephalus were included in the study. The median patient age was 57 years (range 28-90 years), with a male/female ratio of 1:1.7. A ruptured aneurysm was the underlying etiology of SAH in 79.8% of patients. A majority of patients (69.4%) had a Hunt and Hess grade III-V on admission. The median number of clamp trials performed was 2 (range 1-6). A VP shunt was required in 40.4% of patients. In those who underwent 2 and 3 clamp trials, 60% and 38.9%, respectively, did not require subsequent VP shunt placement.

CONCLUSIONS

Surgical placement of a VP shunt is associated with complications. Clamp trials are routinely performed before making the decision to insert a shunt. In the present study, the authors found that a significant percentage of patients passed their second and third clamp trials without requiring subsequent shunt insertion. These data support performing multiple clamp trials prior to shunt placement.

CyberKnife robotic radiosurgery in the multimodal management of acromegaly patients with invasive macroadenoma: a single center's experience

Surgery is the primary treatment for acromegaly. However, surgery may not be curative of some tumors, particularly invasive macroadenomas. Adjuvant radiation, specifically robotic stereotactic radiosurgery (rSRS), may improve the endocrine outcome. We retrospectively reviewed hormonal and radiological data of 22 acromegalic patients with invasive macroadenomas treated with rSRS at Stanford University Medical Center between 2000 and 2016. Prior to treatment, the tumor's median maximal diameter was 19 mm (2.5-50 mm). Cavernous sinus invasion occurred in 19 patients (86.3%) and compression of the optic chiasm in 2 (9.0%). At last follow up, with an average follow up of 43.2 months, all patients had a reduction in their IGF-1 levels (median IGF-1% upper limit of normal (ULN) baseline: 136% vs last follow up: 97%; p = 0.05); 9 patients (40.9%) were cured, and 4 (18.1%) others demonstrated biochemical control of acromegaly. The median time to cure was 50 months and the mean interval to cure or biochemical control was 30.3 months (± 24 months, range 6-84 months). Hypopituitarism was present in 8 patients (36.3%) and new pituitary deficits occurred in 6 patients with a median latency of 31.6 ± 14.5 months. At final radiologic follow-up, 3 tumors (13.6%) were smaller and 19 were stable in size. The mean biologically effective dose (BED) was higher in subjects cured compared to those with persistent disease, 163 Gy3 (± 47) versus 111 Gy3 (± 43), respectively (p = 0.01). No patient suffered visual deterioration. Robotic SRS is a safe and effective treatment for acromegaly: radiation-induced visual complications and hypopituitarism is rare.

A National WestlawNext Database Analysis of Malpractice Litigation in Radiation Oncology

Although litigation involving radiation oncologists was infrequent and most verdicts were in favor of defendants, many cases resulted from claims of excessive radiation, unnecessary radiation, and a failure to refer and/or order appropriate tests.

Predictors of Incomplete Occlusion following Pipeline Embolization of Intracranial Aneurysms: Is It Less Effective in Older Patients?

BACKGROUND AND PURPOSE

Flow diversion with the Pipeline Embolization Device (PED) for the treatment of intracranial aneurysms is associated with a high rate of aneurysm occlusion. However, clinical and radiographic predictors of incomplete aneurysm occlusion are poorly defined. In this study, predictors of incomplete occlusion at last angiographic follow-up after PED treatment were assessed.

MATERIALS AND METHODS

A retrospective analysis of consecutive aneurysms treated with the PED between 2009 and 2016, at 3 academic institutions in the United States, was performed. Cases with angiographic follow-up were selected to evaluate factors predictive of incomplete aneurysm occlusion at last follow-up.

RESULTS

We identified 465 aneurysms treated with the PED; 380 (81.7%) aneurysms (329 procedures; median age, 58 years; female/male ratio, 4.8:1) had angiographic follow-up, and were included. Complete occlusion (100%) was achieved in 78.2% of aneurysms. Near-complete (90%-99%) and partial (<90%) occlusion were collectively achieved in 21.8% of aneurysms and defined as incomplete occlusion. Of aneurysms followed for at least 12 months (211 of 380), complete occlusion was achieved in 83.9%. Older age (older than 70 years), nonsmoking status, aneurysm location within the posterior communicating artery or posterior circulation, greater aneurysm maximal diameter (≥21 mm), and shorter follow-up time (<12 months) were significantly associated with incomplete aneurysm occlusion at last angiographic follow-up on univariable analysis. However, on multivariable logistic regression, only age, smoking status, and duration of follow-up were independently associated with occlusion status.

CONCLUSIONS

Complete occlusion following PED treatment of intracranial aneurysms can be influenced by several factors related to the patient, aneurysm, and treatment. Of these factors, older age (older than 70 years) and nonsmoking status were independent predictors of incomplete occlusion. While the physiologic explanation for these findings remains unknown, identification of factors predictive of incomplete aneurysm occlusion following PED placement can assist in patient selection and counseling and might provide insight into the biologic factors affecting endothelialization.