Category: Vascular

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The presigmoid approach to anterolateral pontine cavernomas

J Neurosurg 113:701–708, 2010. DOI: 10.3171/2010.1.JNS08413

Anterolateral cavernomas of the pons have been surgically removed via a variety of approaches, commonly retrosigmoid or transventricular. The goal in this study was to evaluate the presigmoid approach as an alternative.

Methods. Clinical data were reviewed in 9 patients presenting with anterolateral pontine cavernomas between 1999 and 2007.

Results. All patients were treated via a presigmoid approach, which provided a nearly perpendicular trajectory to the anterolateral pons. The brainstem was entered through a “safe zone” between the trigeminal nerve and the facial/ vestibulocochlear nerve complex. Complete resection was achieved in all cases. No patient experienced recurrent events during follow-up (1–24 months). The patients’ modified Rankin Scale score improved within 1 year of surgery (1.7 ± 0.4) compared with baseline (2.6 ± 0.2; p < 0.05). Only one patient experienced a new deficit (decreased hearing), which was corrected with a hearing aid.

Conclusions. The presigmoid approach is recommended for the resection of anterolateral pontine cavernomas. With this approach, the need for cerebellar retraction is nearly eliminated. The lateral “presigmoid” entry point creates a trajectory that allows complete resection of even deep lesions at this level, or anterior to the internal acoustic meatus.

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A prospective, multicenter, randomized trial of the Onyx liquid embolic system and N-butyl cyanoacrylate embolization of cerebral arteriovenous malformations

J Neurosurg 113:733–741, 2010. DOI: 10.3171/2010.3.JNS09370

The Onyx liquid embolic system (Onyx) was approved in the European Union in 1999 for embolization of lesions in the intracranial and peripheral vasculature, including brain arteriovenous malformations (AVMs) and hypervascular tumors. In 2001 a prospective, equivalence, multicenter, randomized controlled trial was initiated to support a submission for FDA approval. The objective of this study was to verify the safety and efficacy of Onyx compared with N-butyl cyanoacrylate (NBCA) for the presurgical treatment of brain AVMs.

Methods. One hundred seventeen patients with brain AVMs were treated with either Onyx (54 patients) or NBCA (63 patients) for presurgical endovascular embolization between May 2001 and April 2003. The primary end point was technical success in achieving ≥ 50% reduction in AVM volume. Secondary end points were operative blood loss and resection time. All adverse events (AEs) were reported and assigned a relationship to the Onyx or NBCA system, treatment, disease, surgery, or other/unknown. The Data Safety Monitoring Board adjudicated AEs, and a blinded, independent core lab assessed volume measurements. Patients were monitored through discharge after the final surgery or through a 3- and/or 12-month follow-up if resection had not been performed or was incomplete.

Results. The use of Onyx led to ≥ 50% AVM volume reduction in 96% of cases versus 85% for NBCA (p = not significant). The secondary end points of resection time and blood loss were similar. Serious AEs were also similar between the 2 treatment groups.

Conclusions. Onyx is equivalent to NBCA in safety and efficacy as a preoperative embolic agent in reducing brain AVM volume by at least 50%.

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Epileptogenicity of Cavernomas Depends on (Archi-) Cortical Localization

Neurosurgery 67:918–924, 2010 DOI: 10.1227/NEU.0b013e3181eb5032

Patients with cerebral cavernomas have an estimated risk of the development of epilepsy of 1.5% to 2.4% per patient-year.

OBJECTIVE: To clarify the predictive value of different risk factors for epilepsy in patients with supratentorial cavernomas.

METHODS: We retrospectively analyzed data of 109 patients with supratentorial cavernomas. The correlation of epilepsy with the variables of single or multiple cavernomas, sex, age, side, cortical involvement, mesiotemporal archicortical vs neocortical involvement, lobar location of neocortical cavernomas, the presence of a hemosiderin rim and of edema, and the maximal diameters of cavernoma, hemosiderin rim, and edema, if present, were calculated using univariate and multivariate penalized likelihood logistic regression models.

RESULTS: Cortical involvement was the most relevant risk factor for epilepsy (P , .0001). No patient with a subcortical cavernoma presented with epilepsy. Epilepsy was more common in patients with mesiotemporal archicortical cavernomas than in patients with neocortical cavernomas (P = .02), whereas the lobar location of neocortical cavernomas was not significantly associated with the risk of the development of epilepsy. In the multivariate analysis, a greater diameter of the cavernoma, the absence of edema, and localization in the left hemisphere were also associated with the occurrence of epilepsy (P , .05).

CONCLUSION: The epileptogenicity of supratentorial cavernomas depends on cortical, especially mesiotemporal archicortical, involvement. Exclusively subcortical cavernomas are highly unlikely to cause epilepsy. This information is helpful in counseling patients with cavernomas regarding their risk of epileptic seizures and in patients with multiple cavernomas and epilepsy to generate a valid hypothesis of which cavernoma may cause epilepsy.

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Radiosurgery for deep-seated cavernous malformations: a move toward more active, early intervention

J Neurosurg 113:691–699, 2010. DOI: 10.3171/2010.3.JNS091156

The role of radiosurgery in the treatment of cavernous malformations (CMs) remains controversial. It is frequently recommended only for inoperable lesions that have bled at least twice. Rehemorrhage can carry a substantial risk of morbidity, however. The authors reviewed their practice of treating deep-seated inoperable CMs to assess the complication rate of radiosurgery, the impact that radiosurgery might have on rebleeding, and whether a more active, earlier intervention is justified in managing this condition.

Methods. The authors performed a retrospective analysis of 113 patients with 79 brainstem and 39 thalamic/ basal ganglia CMs treated with Gamma Knife surgery. Lesions were stratified into 2 groups: those that might be lower risk with no more than 1 symptomatic bleed before radiosurgical treatment and those deemed high risk with multiple symptomatic hemorrhages before treatment.

Results. Forty-one CMs had multiple symptomatic hemorrhages before radiosurgery with a first-ever bleed rate of 2.9% per lesion per year, a rebleed rate of 30.5% per lesion per year, and a median time of 1.5 years between the first and second bleeds. In this group the rebleed rate decreased to 15% for the first 2 years after radiosurgery and declined further to 2.4% thereafter. Pretreatment multiple bleeds led to persistent deficits in 72% of the patients. Seventy-seven CMs had no more than 1 symptomatic bleed before radiosurgery, making for a lifetime bleed rate of 2.2% per lesion per year. The short period between the presenting bleed and treatment (median 1 year) makes the natural history in this group uncertain. The rate of hemorrhage in the first 2 years after treatment was 5.1%, and 1.3% thereafter. Pretreatment hemorrhages resulted in permanent deficits in 43% of the patients in this group, a rate significantly lower than in the multiple-bleeds group (p < 0.001). Posttreatment hemorrhages led to persistent deficits in only 7.3% of the patients. Permanent adverse radiation effects were rare (7.3%) and minor in both groups.

Conclusions. Stereotactic radiosurgery is a safe management strategy for CMs in eloquent sites with the marked advantage of reducing rebleed risks in patients with repeated pretreatment hemorrhages. The benefit in treating CMs with a single bleed is less clear. Note, however, that repeated hemorrhage carries a significant risk of increased morbidity far in excess of any radiosurgery-related morbidity, and the authors assert that this finding justifies the early active management of deep-seated CMs.

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Thromboembolic Complications of Elective Coil Embolization of Unruptured Aneurysms: The Effect of Oral Antiplatelet Preparation on Periprocedural Thromboembolic Complication

Neurosurgery 67:743-748, 2010 DOI: 10.1227/01.NEU.0000374770.09140.FB

We retrospectively evaluated whether antiplatelet preparation lowered the thromboembolic complication rate during the perioperative period.

METHODS:We reviewed 328 elective coil embolization procedures in which only microcatheters were used for coiling. No antiplatelet medication was prescribed before the procedure in 95 cases (29%, group 1), whereas antiplatelet therapy was used in 233 cases (71%, group 2; 61 [18.6%] with a single agent [aspirin or clopidogrel] and 172 [52.4%] with both agents). Antiplatelet agents were not given after coiling unless atherosclerosis, severe coil protrusion, or a thromboembolic complication occurred during the procedure. A thromboembolic complication was defined as a procedural thromboembolic event or transient ischemic attack or stroke occurring within 2 days of embolization.

RESULTS: Thromboembolic complications occurred in 11 cases (3.4%): 6 (6.3%) in group 1 and 5 (2.1%) in group 2 (P = .085). In 195 cases (59.5%) treated by the single microcatheter technique, the risk of thromboembolic complications was low and not affected by antiplatelet preparation (1.8% [no preparation] vs 2.2% [preparation]; P = 1.000). However, in 133 cases (40.5%) treated by the multiple microcatheter technique, antiplatelet preparation significantly reduced the thromboembolic complication risk by 85.2% (12.8% [no preparation] vs 2.1% [preparation]; odds ratio, 0.148; 95% confidence interval, 0.027-0.798; P = .023). The aneurysms treated by the multiple microcatheter technique had more complex configurations for coiling (P < .001). The risk of hemorrhage was not increased by antiplatelet preparation (P = .171).

CONCLUSION: Antiplatelet preparation lowered the periprocedural thromboembolic complication rate in unruptured aneurysms treated by the multiple microcatheter technique and did not increase the risk of hemorrhage. Therefore, antiplatelet preparation can help to reduce complications in patients in whom technical difficulties are expected without the risk of hemorrhage.

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Small Unruptured Intracranial Aneurysm Verification Study SUAVe Study, Japan

Stroke. 2010;41:1969-1977.DOI: 10.1161/STROKEAHA.110.585059

The natural history and optimal management of incidentally found small unruptured aneurysms 5 mm in size remain unclear. A prospective study was conducted to determine the optimal management for incidentally found small unruptured aneurysms.

Methods—From September 2000 to January, 2004, 540 aneurysms (446 patients) were registered. Four hundred forty-eight unruptured aneurysms 5 mm in size (374 patients) have been followed up for a mean of 41.0 months (1306.5 person-years) to date. We calculated the average annual rupture rate of small unruptured aneurysms and also investigated risk factors that contribute to rupture and enlargement of these aneurysms.

Results—The average annual risks of rupture associated with small unruptured aneurysms were 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms. Patient 50 years of age (P=0.046; hazard ratio, 5.23; 95% CI, 1.03 to 26.52), aneurysm diameter of 4.0 mm (P=0.023; hazard ratio, 5.86; 95% CI, 1.27 to 26.95), hypertension (P=0.023; hazard ratio, 7.93; 95% CI, 1.33 to 47.42), and aneurysm multiplicity (P=0.0048; hazard ratio, 4.87; 95% CI, 1.62 to 14.65) were found to be significant predictive factors for rupture of small aneurysms.

Conclusions—The annual rupture rate associated with small unruptured aneurysms is quite low. Careful attention should be paid to the treatment indications for single-type unruptured aneurysms 5 mm. If the patient is 50 years of age, has hypertension, and multiple aneurysms with diameters of 4 mm, treatment should be considered to prevent future aneurysmal rupture.

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Guidelines for the Management of Spontaneous Intracerebral Hemorrhage

Stroke. 2010;41:2108-2129. DOI: 10.1161/STR.0b013e3181ec611b

Purpose—The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of acute spontaneous intracerebral hemorrhage.

Methods—A formal literature search of MEDLINE was performed. Data were synthesized with the use of evidence tables. Writing committee members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council’s Levels of Evidence grading algorithm was used to grade each recommendation. Prerelease review of the draft guideline was performed by 6 expert peer reviewers and by the members of the Stroke Council Scientific Statements Oversight Committee and Stroke Council Leadership Committee. It is intended that this guideline be fully updated in 3 years’ time.

Results—Evidence-based guidelines are presented for the care of patients presenting with intracerebral hemorrhage. The focus was subdivided into diagnosis, hemostasis, blood pressure management, inpatient and nursing management, preventing medical comorbidities, surgical treatment, outcome prediction, rehabilitation, prevention of recurrence, and future considerations.

Conclusions—Intracerebral hemorrhage is a serious medical condition for which outcome can be impacted by early, aggressive care. The guidelines offer a framework for goal-directed treatment of the patient with intracerebral hemorrhage.

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Endovascular Treatment of Side Wall Aneurysms Using a Liquid Embolic Agent: A US Single-Center Prospective Trial

Neurosurgery 67:855-860, 2010 DOI: 10.1227/01.NEU.0000374772.22745.C3

Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms.

CLINICAL PRESENTATION:We present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths.

CONCLUSION: This is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

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Surgical approaches to brainstem cavernous malformations

Neurosurg Focus 29 (3):E8, 2010. DOI: 10.3171/2010.6.FOCUS10128

Brainstem cavernous malformations (CMs) are low-flow vascular lesions in eloquent locations. Their presentation is often marked with symptomatic hemorrhages that appear to occur more frequently than hemorrhage from supratentorial cavernomas.

Brainstem CMs can be removed using 1 of the 5 standard skull-base approaches: retrosigmoid, suboccipital (with or without telovelar approach), supracerebellar infratentorial, orbitozygomatic, and far lateral.

Patients being referred to a tertiary institution often have lesions that are aggressive with respect to bleeding rates. Nonetheless, the indications for surgery, in the authors’ opinion, are the same for all lesions: those that are symptomatic, those that cause mass effect, or those that abut a pial surface. Patients often have relapsing and remitting courses of symptoms, with each hemorrhage causing a progressive and stepwise decline.

Many patients experience new postoperative deficits, most of which are transient and resolve fully. Despite the risks associated with operating in this highly eloquent tissue, most patients have had favorable outcomes in the authors’ experience. Surgical treatment of brainstem CMs protects patients from the potentially devastating effects of rehemorrhage, and the authors believe that the benefits of intervention outweigh the risks in patients with the appropriate indications.

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Utility and the Limit of Motor Evoked Potential Monitoring for Preventing Complications in Surgery for Cerebral Arteriovenous Malformation

Neurosurgery 67[ONS Suppl 1]:ons222-ons228, 2010 DOI: 10.1227/01.NEU.0000374696.84827.22

OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring andmapping in arteriovenous malformation surgery.

METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area.

RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus.

CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

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Choosing the best operation for chronic subdural hematoma: a decision analysis

J Neurosurg 113:615–621, 2010.DOI: 10.3171/2009.9.JNS08825

Chronic subdural hematoma (CSDH), a condition much more common in the elderly, presents an increasing challenge as the population ages. Treatment strategies for CSDH include bur-hole craniostomy (BHC), twist-drill craniostomy (TDC), and craniotomy. Decision analysis was used to organize existing data and develop recommendations for effective treatment.

Methods. A Medline search was used to identify articles about treatment of CSDH. Direct assessment by health care professionals of the relative health impact of common complications and recurrences was used to generate utility values for treatment outcomes. Monte Carlo simulation and sensitivity analyses allowed comparisons across treatment strategies. A second simulation examined whether intraoperative irrigation or postoperative drainage affect the outcomes following BHC.

Results. On a scale from 0 to 1, the utility of BHC was found to be 0.9608, compared with 0.9202 for TDC (p = 0.001) and 0.9169 for craniotomy (p = 0.006). Sensitivity analysis confirmed the robustness of these values. Craniotomy yielded fewer recurrences, but more frequent and more serious complications than did BHC. There were no significant differences for BHC with or without irrigation or postoperative drainage.

Conclusions. Bur-hole craniostomy is the most efficient choice for surgical drainage of uncomplicated CSDH. Bur-hole craniostomy balances a low recurrence rate with a low incidence of highly morbid complications. Decision analysis provides statistical and empirical guidance in the absence of well-controlled large trials and despite a confusing range of previously reported morbidity and recurrence.

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Gamma Knife Surgery for Cavernous Hemangiomas in the Cavernous Sinus

Neurosurgery 67:611-616, 2010 DOI: 10.1227/01.NEU.0000378026.23116.E6

Cavernous hemangioma in the cavernous sinus (CS) is a rare vascular tumor. Direct microsurgical approach usually results in massive hemorrhage. Radiosurgery has emerged as a treatment alternative to microsurgery.

OBJECTIVE: To further investigate the role of Gamma Knife surgery (GKS) in treating CS hemangiomas.

METHODS: This was a retrospective analysis of 7 patients with CS hemangiomas treated by GKS between 1993 and 2008. Data from 84 CS meningiomas treated during the same period were also analyzed for comparison. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Data on clinical and imaging changes after radiosurgery were analyzed.

RESULTS: Six months after GKS, magnetic resonance imaging revealed an average of 72% tumor volume reduction (range, 56%-83%). After 1 year, tumor volume decreased 80% (range, 69%-90%) compared with the pre-GKS volume. Three patients had > 5 years of follow- up, which showed the tumor volume further decreased by 90% of the original size. The average tumor volume reduction was 82%. In contrast, tumor volume reduction of the 84 cavernous sinus meningiomas after GKS was only 29% (P < .001 by Mann-Whitney U test). Before treatment, 6 patients had various degrees of ophthalmoplegia. After GKS, 5 improved markedly within 6 months. Two patients who suffered from poor vision improved after radiosurgery.

CONCLUSION: GKS is an effective and safe treatment modality for CS hemangiomas with long-term treatment effect. Considering the high risks involved in microsurgery, GKS may serve as the primary treatment choice for CS hemangiomas.

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Postoperative Assessment of Clipped Aneurysms With 64-Slice Computerized Tomography Angiography

Neurosurgery 67:844-854, 2010 DOI: 10.1227/01.NEU.0000374684.10920.A2

Multidetector computerized tomography angiography (MDCTA) is now a widely accepted technique for the management of intracranial aneurysms.

OBJECTIVE: To evaluate its accuracy for the postoperative assessment of clipped intracranial aneurysms.

METHODS:We analyzed a consecutive series of 31 patients that underwent direct surgical clipping procedures of 38 aneurysms. A 64 slice MDCT scanner (Aquilion 64, Toshiba) was used and results were compared with digital subtraction angiographies (DSA). Two independent neuroradiologists analyzed the following data: examination quality, artifacts, aneurysm remnant, and patency of collateral branches. Interobserver agreement, sensitivity, and specificity were calculated.

RESULTS: Seventy-nine percent of the aneurysms were located in the anterior circulation. Significant artifacts were found with multiple and cobalt-alloy clips. According to DSA, remnants >2 mm were found in 21% of the cases, and 2 patients had one collateral branch occluded. Sensitivity and specificity of 64-MDCTA for the detection of aneurysm remnants were 50% and 100%, respectively. Sensitivity and specificity of 64-MDCTA for the detection of a significant remnant (>2 mm) and the detection of the occlusion of a collateral branch were, respectively, 67% and 100% and 50% and 100%. No relationship was found with the location, type, shape, size, or number of clips, but missed remnants tended to be larger with cobalt-alloy clips.

CONCLUSIONS: 64-MDCTA is a valuable technique to assess the presence of a significant postoperative remnant in single titanium clip application cases and might be useful for longterm follow-up. DSA remains the most accurate postoperative radiological examination.

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Near-infrared indocyanine green videoangiography versus microvascular Doppler sonography in aneurysm surgery

Acta Neurochir (2010) 152:1519–1525.DOI 10.1007/s00701-010-0723-5

The quality of surgical treatment of intracranial aneurysms is determined by complete aneurysm occlusion and restoration of flow in the parent, branching and perforating vessels. In postoperative digital subtraction angiography (DSA), unexpected aneurysm residuals and vessel occlusions are frequently detected. Here, the value of two nearly noninvasive and cost-effective techniques for intraoperative flow evaluation (near-infrared indocyanine green video angiography (ICG-VA) and microvascular Doppler sonography (mDs)) is investigated in a prospective study.

Patients and methods Over a period of 10months, the authors surgically clipped 50 aneurysms under intraoperative pre- and post-clipping evaluation of flow in the parent, branching and perforating vessels and the aneurysm sack by the two techniques. Intraoperative applicability of each technique was compared to each other and to postoperative digital subtraction angiography as standard evaluation technique.

Results Forty-five aneurysms were totally occluded without vessel compromise (90%). Intraoperatively, ICG-VA was considered useful in 43 cases (86%) and mDs in 44 cases (88%), respectively. Both techniques could compensate each other’s weak points to a certain degree; but two branch occlusions (4%) and three neck remnants (6%) were revealed by postoperative DSA.

Conclusion Both techniques have specific drawbacks that could be compensated by each other, to a certain extent. Intraoperatively, ICG-VA and mDs should not be considered competitive, but complementary. This study implicates that the combination of both applications on a routine basis assures the quality of aneurysm surgery by nearly noninvasive and cost-effective techniques. However, DSA remains the gold standard for evaluation of aneurysm occlusion.

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Postoperative Assessment of Clipped Aneurysms With 64-Slice Computerized Tomography Angiography

Neurosurgery 00:000-000, 2010 DOI: 10.1227/01.NEU.0000374684.10920.A2

Multidetector computerized tomography angiography (MDCTA) is now a widely accepted technique for the management of intracranial aneurysms.

OBJECTIVE: To evaluate its accuracy for the postoperative assessment of clipped intracranial aneurysms.

METHODS:We analyzed a consecutive series of 31 patients that underwent direct surgical clipping procedures of 38 aneurysms. A 64 slice MDCT scanner (Aquilion 64, Toshiba) was used and results were compared with digital subtraction angiographies (DSA). Two independent neuroradiologists analyzed the following data: examination quality, artifacts, aneurysm remnant, and patency of collateral branches. Interobserver agreement, sensitivity, and specificity were calculated.

RESULTS: Seventy-nine percent of the aneurysms were located in the anterior circulation. Significant artifacts were found with multiple and cobalt-alloy clips. According to DSA, remnants >2 mm were found in 21% of the cases, and 2 patients had one collateral branch occluded. Sensitivity and specificity of 64-MDCTA for the detection of aneurysm remnants were 50% and 100%, respectively. Sensitivity and specificity of 64-MDCTA for the detection of a significant remnant (>2 mm) and the detection of the occlusion of a collateral branch were, respectively, 67% and 100% and 50% and 100%. No relationship was found with the location, type, shape, size, or number of clips, but missed remnants tended to be larger with cobalt-alloy clips.

CONCLUSIONS: 64-MDCTA is a valuable technique to assess the presence of a significant postoperative remnant in single titanium clip application cases and might be useful for longterm follow-up. DSA remains the most accurate postoperative radiological examination.

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Contrast-Enhanced Magnetic Resonance Characteristics of Arteriovenous Malformations After Gamma Knife Radiosurgery: Predictors of Post-Angiographic Obliteration Hemorrhage

Neurosurgery 67:101-109, 2010 DOI: 10.1227/01.NEU.0000370601.17570.4

The reported cumulative risk of post-angiographic obliteration (post-AO) hemorrhage from arteriovenous malformations (AVMs) following gamma knife radiosurgery (GKRS) over 10 years is 2.2%.

OBJECTIVE: To identify the warning signs of post-AO hemorrhage by analyzing the characteristics of enhancement on contrast-enhanced MRI magnetic resonance imaging (MRI) of AVMs with post-AO hemorrhage.

METHODS:We performed a retrospective analysis of 121 patients whose AVMs were angiographically obliterated within 5 years of GKRS without hemorrhage and who received at least 1 contrast-enhanced MRI after GKRS (group 1), and 7 patients who experienced post- AO hemorrhage (group 2). We analyzed the enhancement persistence ratio (the percentage of AVMs with persisting enhancement on contrast-enhanced T1-weighted image after obliteration) and the change in size of the enhanced region over time in each patient.

RESULTS: The enhancement persistence ratio showed no significant difference between the 2 groups (89.4% vs 100% for groups 1 and 2, respectively; P = .401). While most cases in group 1 showed a tendency to decrease in size and gradually stabilize following GKRS, there were significantly more cases in group 2 with obvious increment of the enhanced regions within 1 year of angiographic obliteration compared with the previous measurement (4.96% vs 71.4% for groups 1 and 2, respectively; P < .0001).

CONCLUSION: Our results suggest that AVMs that show an increase in the size of the enhanced region within 1 year of angiographic obliteration should be followed up with caution for post-AO hemorrhage. Persisting enhancement itself is not positively associated with subsequent hemorrhage.

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Treatment of Intracranial Aneurysms by Functional Reconstruction of the Parent Artery: The Budapest Experience with the Pipeline Embolization Device

Am J Neuroradiol 31:1139–47. DOI 10.3174/ajnr.A2023

Aneurysm treatment by intrasacular packing has been associated with a relatively high rate of recurrence. The use of mesh tubes has recently gained traction as an alternative therapy. This article summarizes the midterm results of using an endoluminal sleeve, the PED, in the treatment of aneurysms.

MATERIALS AND METHODS: A total of 19 wide-neck aneurysms were treated in 18 patients: 10 by implantation of PEDs alone and 9 by a combination of PED and coils. Angiographic and clinical results were recorded immediately and at 6 months following treatment.

RESULTS: Immediate angiographic occlusion was achieved in 4 and flow reduction, in another 15 aneurysms. Angiography at 6 months demonstrated complete occlusion in 17 and partial filling in 1 of 18 patients. There was no difference between coil-packed and unpacked aneurysms. Of 28 side branches covered by 1 device, the ophthalmic artery was absent immediately in 1 and at 6 months in another 2 cases. One patient experienced abrupt in-stent thrombosis resulting in a transient neurologic deficit, and 1 patient died due to rupture of a coexisting aneurysm. All giant aneurysms treated with PED alone were demonstrated by follow-up cross-sectional imaging to have involuted by 6 months.

CONCLUSIONS: Treatment of large, wide-neck, or otherwise untreatable aneurysms with functional reconstruction of the parent artery may be achieved with relative safety using dedicated flowmodifying devices with or without adjunctive use of intrasaccular coil packing.

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Early infarction detected by diffusion-weighted imaging in patients with subarachnoid hemorrhage

Acta Neurochir (2010) 152:1197–1205. DOI 10.1007/s00701-010-0640-7

Early infarction that occurs at the time of initial subarachnoid hemorrhage (SAH) due to rupture of an aneurysm is a poorly understood phenomenon. We investigate the frequency of early infarction using diffusion-weighted images (DWI) at the time of admission. We then discuss the pathogenesis of infarction.

Materials and methods This study included 85 SAH patients who underwent serial DWI on admission. Early infarction detected by DWI and clinical features were investigated retrospectively.

Results The overall incidence of DWI-detected early infarction at the time of SAH onset was 8% (7 of 85 cases). In all seven patients, early infarctions were asymptomatic on admission. Types of early infarction seen on DWI included infarcts occurring in the territory of the vessel harboring a ruptured aneurysm (solitary, three cases) and infarcts occurring outside the territory of the vessel (multiple, two cases; solitary, two cases). Six of seven patients eventually developed delayed ischemic neurological deficit (DIND) and computed tomography (CT)-detected and DWI-detected delayed extensive infarction. Four of seven patients with early infarction had an unfavorable outcome. The occurrence of DWI-detected early infarction on admission was significantly correlated with delayed angiographic vasospasm, DIND, CT-detected delayed infarction, DWI-detected delayed infarction, and unfavorable outcome.

Conclusions In the present study, DWI-detected early infarction at the time of SAH onset was correlated with the occurrence of delayed extensive ischemic lesions. We believe that performing DWI at the time of admission is useful for evaluating the primary ischemic insult, which might play an important role in the pathogenesis of early brain injury and delayed vasospasm-related complications.

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Repeat Gamma Knife Surgery for Incompletely Obliterated Cerebral Arteriovenous Malformations

Neurosurgery 67:55-64, 2010 DOI: 10.1227/01.NEU.0000370204.68711.AC

The causes of failure after an initial Gamma procedure were studied, along with imaging and clinical outcomes, in a series of 140 patients with cerebral arteriovenous malformations (AVMs) treated with repeat Gamma Knife surgery (GKS).

METHODS: Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6, and suboptimal dose (< 20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm3 (mean, 1.4 cm3), and the mean prescription dose was 20.3 Gy.

RESULTS: Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiationinduced changes).

CONCLUSION: By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

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Stereotactic radiosurgery for symptomatic solitary cerebral cavernous malformations considered high risk for resection

J Neurosurg 113:23–29, 2010. DOI: 10.3171/2010.1.JNS081626

A retrospective study was conducted to reassess the benefit and safety of stereotactic radiosurgery (SRS) in patients with solitary cerebral cavernous malformations (CCMs) that bleed repeatedly and are poor candidates for surgical removal.

Methods. Between 1988 and 2005 at the University of Pittsburgh, the authors performed SRS in 103 evaluable patients (57 males and 46 females) with solitary symptomatic CCMs. The mean patient age was 39.3 years. Ninetyeight percent of these patients had experienced 2 or more hemorrhages associated with new neurological deficits. Seventeen patients (16.5%) had undergone attempted resection before radiosurgery. Ninety-three CCMs were located in deep brain structures and 10 were in subcortical lobar areas of functional brain importance. The median malformation volume was 1.31 ml, and the median tumor margin dose was 16 Gy.

Results. The follow-up ranged from 2 to 20 years. The annual hemorrhage rate—that is, a new neurological deficit associated with imaging evidence of a new hemorrhage—before SRS was 32.5%. After SRS 22 hemorrhages were observed within 2 years (10.8% annual hemorrhage rate) and 4 hemorrhages were observed after 2 years (1.06% annual hemorrhage rate). The risk of hemorrhage from a CCM was significantly reduced after radiosurgery (p < 0.0001). Overall, new neurological deficits due to adverse radiation effects following SRS developed in 14 patients (13.5%), with most occurring early in our experience. Modifications in technique (treatment volume within the T2- weighted MR imaging–defined margin, use of MR imaging, and dose reduction for CCM in critical brainstem locations) further reduced risks after SRS.

Conclusions. Data in this study provide further evidence that SRS is a relatively safe procedure that reduces the rebleeding rate for CCMs located in high-surgical-risk areas of the brain.

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