Neurosurgery Blog

J Neurosurg 118:923–934, 2013

Management of dural arteriovenous fistulas (DAVFs) has changed during the last decades due to increased knowledge of their pathophysiology and natural history as well as advances in treatment modalities. The authors describe the characteristics and long-term outcome of a large consecutive series of patients with DAVFs.

Methods. Altogether 251 patients with 261 DAVFs were treated in 2 of the 5 neurosurgery departments at Helsinki and Kuopio University Hospitals between 1944 and 2006. Clinical data and radiological examinations were reviewed to assess patients’ overall long-term clinical outcome.

Results. The detection rate of DAVFs increased markedly in the 1970s and again in the 1990s when digital subtraction angiography was introduced. The incidence of DAVFs in a defined southern Finnish population was 0.51 per 100,000 individuals per year, which represents 32% of all the brain arteriovenous malformations. In the early part of the series, DAVFs were treated by proximal ligation of the feeding arteries. Later, most of the patients underwent preoperative embolization and subsequent craniotomy, and since 2000 stereotactic radiosurgery has been increasingly used in the treatment of DAVFs. Fifty-nine percent of the 261 fistulas were totally occluded. Treatment-related major complications were seen in 21 patients.

Conclusions. The advances in diagnostic methods (digital subtraction angiography, CT, and MRI) increased the detection rate of DAVFs, and as treatment modalities developed, the results of treatment and outcome of patients markedly improved with the introduction of endovascular techniques and stereotactic radiosurgery. Microsurgery is of limited use in DAVFs resistant to other treatment modalities.

Neurosurgery 72:25–32, 2013

The natural history and treatment results for spinal glomus (type II) arteriovenous malformations (AVMs) remain relatively obscure.

OBJECTIVE: To calculate spinal glomus (type II) AVM hemorrhages rates and amalgamate results of intervention.

METHODS: We performed a pooled analysis via the PubMed database through May 2012, including studies with at least 3 cases. Data on individual patients were extracted and analyzed using a Cox proportional hazards regression model to obtain hazard ratios for hemorrhage risk factors.

RESULTS: The annual hemorrhage rate before treatment was 4% (95% confidence interval [confidence interval]: 3%-6%), increasing to 10% (95% CI: 7%-16%) for AVMs with previous hemorrhage. The hazard ratio for hemorrhage after hemorrhagic presentation was 2.25 (95% CI: 0.71-7.07), increasing to 13.0 within the first 10 years (95% CI: 1.44-118). The overall rates of complete obliteration were 78% (95% CI: 72%-83%) for surgery and 33% (95% CI: 24%-43%) for endovascular treatment. Long-term clinical worsening occurred in 12% of patients after surgical treatment (95% CI: 8%-16%) and in 13% after endovascular treatment (95% CI: 7%-21%). No hemorrhages occurred after complete obliteration. After partial surgical treatment, the annual hemorrhage rate was 3% (95% CI: 1%-6%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment.

CONCLUSION: Spinal glomus (type II) AVMs with previous hemorrhage, particularly within 10 years, demonstrated a greater risk of hemorrhage. Complete obliteration and even partial endovascular treatment significantly decreased their hemorrhage rate.

KEY WORDS:

J Neurosurg 117:265–275, 2012

In this paper the authors’ goal was to define the long-term benefits and risks of stereotactic radiosurgery (SRS) for patients with arteriovenous malformations (AVMs) who underwent prior embolization.

Methods. Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 120 patients underwent embolization followed by SRS. In this series, 64 patients (53%) had at least one prior hemorrhage. The median number of embolizations varied from 1 to 5. The median target volume was 6.6 cm3 (range 0.2–26.3 cm3). The median margin dose was 18 Gy (range 13.5–25 Gy).

Results. After embolization, 25 patients (21%) developed symptomatic neurological deficits. The overall rates of total obliteration documented by either angiography or MRI were 35%, 53%, 55%, and 59% at 3, 4, 5, and 10 years, respectively. Factors associated with a higher rate of AVM obliteration were smaller target volume, smaller maximum diameter, higher margin dose, timing of embolization during the most recent 10-year period (1997–2006), and lower Pollock-Flickinger score. Nine patients (8%) had a hemorrhage during the latency period, and 7 patients died of hemorrhage. The actuarial rates of AVM hemorrhage after SRS were 0.8%, 3.5%, 5.4%, 7.7%, and 7.7% at 1, 2, 3, 5, and 10 years, respectively. The overall annual hemorrhage rate was 2.7%. Factors associated with a higher risk of hemorrhage after SRS were a larger target volume and a larger number of prior hemorrhages. Permanent neurological deficits due to adverse radiation effects (AREs) developed in 3 patients (2.5%) after SRS, and 1 patient had delayed cyst formation 210 months after SRS. No patient died of AREs. A larger 12-Gy volume was associated with higher risk of symptomatic AREs. Using a case-control matched approach, the authors found that patients who underwent embolization prior to SRS had a lower rate of total obliteration (p = 0.028) than patients who had not undergone embolization.

Conclusions. In this 20-year experience, the authors found that prior embolization reduced the rate of total obliteration after SRS, and that the risks of hemorrhage during the latency period were not affected by prior embolization. For patients who underwent embolization to volumes smaller than 8 cm3, success was significantly improved. A margin dose of 18 Gy or more also improved success. In the future, the role of embolization after SRS should be explored.

Neuroradiology (2012) 54:719–726 DOI 10.1007/s00234-011-0950-3

The authors present a series of patients in whom early rebleeding occurred after coiling for ruptured aneurysms. We investigated the incidence and possible mechanisms of early rebleeding.

Methods This study consisted of 1,167 consecutive patients who underwent coiling for a ruptured saccular aneurysm. Clinical and radiological data were collected retrospectively from three institutions. Early rebleeding was defined as occurrence of further bleeding within 30 days after coiling with worsening of the patient’s condition. We divided early rebleeding into hyperacute, subacute, and delay groups depending on the timing of rebleeding after coil embolization.

Results Incidence of early rebleeding after coiling of a ruptured saccular aneurysm was 1.1% (13 of 1,167), and mortality was 31% (4 of 13) in our series. Out of ten patients in hyperacute group, three (30%) had incomplete occlusion result and six patients (60%) underwent intraarterial (IA) infusion of abciximab or tirofiban during the procedures. Seven patients (70%) had an intracerebral hemorrhage (ICH) on initial computed tomography. Four patients died, another four sustained severe disabilities, and the others had good recovery. All three patients in subacute and delay group showed recanalization on post-rebleeding angiography and made an excellent recovery.

Conclusion Early rebleeding was associated with high mortality and morbidity. IA abciximab infusion or thrombolytic interventions during the procedure, maintenance of anticoagulation after the procedure, incomplete treatment of the aneurysms, and presence of ICH seemed to be related to hyperacute early rebleeding after coiling. Increased aneurysmal size and coil compaction could induce subacute and delayed early rebleeding.

J Neurosurg Spine 16:523–531, 2012 .DOI: 10.3171/2012.3.SPINE11982

Intramedullary, or glomus, spinal arteriovenous malformations (AVMs) are rare vascular lesions amenable to resection with or without adjuvant embolization. The authors retrospectively reviewed the senior author’s (R.F.S.’s) surgical series of intramedullary spinal AVMs to evaluate clinical and radiographic outcomes.

METHODS
Detailed chart and radiographic reviews were performed for all patients with intramedullary spinal AVMs who underwent surgical treatment between 1994 and 2011. Presenting and follow-up neurological examination results were obtained and graded using the modified Rankin Scale (mRS) and McCormick Scale. Surgical technique, outcomes, complications, and long-term angiographic studies were reviewed.

RESULTS
During the study period, 20 patients (10 males and 10 females) underwent resection of glomus spinal AVMs. The mean age at presentation was 30 ± 17 years (range 7–62 years). The location of the AVMs was as follows: cervical spine (n = 10), thoracic spine (n = 9), and cervicothoracic junction (n = 1). The most common presenting signs and symptoms included paresis or paralysis (65%), paresthesias (40%), and myelopathy (40%). Perioperative embolization was performed in the majority (60%) of patients. Pial AVM resection was performed in 17 cases (85%). Angiographically verified AVM obliteration was achieved in 15 patients (75%). At a mean follow-up duration of 45.4 ± 52.4 months (range 2–176 months), 14 patients (70%) remained functionally independent (mRS and McCormick Scale scores ≤ 2). One perioperative complication occurred, yielding a surgical morbidity rate of 5%. Three symptomatic spinal cord tetherings occurred at a mean of 5.7 years after AVM resection. No neurological decline was observed after endovascular and surgical interventions. No deaths occurred. Long-term angiographic follow-up data were available for 9 patients (40%) at a mean of 67.6 ± 60.3 months (range 5–176 months) following AVM resection. Durable AVM obliteration was documented in 5 (83%) of 6 patients.

CONCLUSIONS
Intramedullary AVMs may be safely resected with satisfactory clinical and angiographic results. The pial resection technique, which provides subtotal AVM nidus resection, effectively devascularized these lesions, as confirmed on postoperative angiography, without violating the spinal cord parenchyma, thereby potentially reducing iatrogenic injury.

Spine 2012 ; 37 : 482 – 488. DOI: 10.1097/BRS.0b013e31822670df

This study was a case series study using a prospective single-institute database for the treatment of spinal dural arteriovenous fi stulas (SDAVFs).

Objective. To evaluate clinical factors that infl uence the neurological outcomes of treatment for SDAVFs, which were obtained from the analysis of 21 patients treated in our institution, and to provide management recommendations based on the review of former major clinical studies including our own reported over the past 2 decades.

Summary of Background Data. Since 1977, when Kendall and Logue described the etiology of SDAVFs as hyperpressure of intrathecal veins due to an abnormal shunting from the arteries, treatment strategies have improved dramatically along with developments in neuroimaging, endovascular techniques and materials, and microsurgery based on the underlying pathophysiological process. However, therapeutic guidelines remain controversial.

Methods. Patients treated for SDAVFs from 2000 to 2008 were eligible. Age, sex, level of shunting, initial symptom, duration of symptom, the treatment method, and clinical symptoms before and 6 months after treatment were investigated.

Results. There were a total of 30 patients (18 male and 12 female), with a mean age of 59 years; 21 of them underwent treatment for the fi rst time. We conducted a univariate analysis using a logistic regression model, on age, sex, the level of SDAVFs, duration of symptoms, symptom (sensory or paralysis), and gait function and micturition before treatment, and the intervention method were set as variables to investigate the risk factors for motor deficit 6 months after the treatment. Only gait function before treatment was correlated with the motor deficit 6 months after treatment (odds ratio = 10.0; 95% confidence interval = 1.28–78.11, P = 0.03). From these results, intervention at an early stage would be the key to a preferable outcome of the treatment for SDAVFs.

Conclusion. The clinical status before treatment significantly influenced the clinical outcome after the treatment.

Neurosurgery 70:141–149, 2012 DOI: 10.1227/NEU.0b013e31822ec19e

Giant perimedullary arteriovenous fistulas (GPMAVFs) located in the cervical region are a rare pathology with distinctive characteristics.

OBJECTIVE: To evaluate clinical presentation and different endovascular treatment options of cervical GPMAVFs and review previously published data in the literature regarding cervical GPMAVFs.

METHODS: Six patients with cervical GPMAVFs were found in the spinal vascular malformations database of our group collected between 1990 and 2009. Endovascular techniques and treatment outcomes were evaluated and compared with other published series.

RESULTS: Clinical presentations were progressive motor deficit (5 patients), hematomyelia (1 patient), meningeal syndrome (1 patient), and respiratory arrest and gait apraxia (1 patient). Three patients were treated by the transarterial approach. One patient was treated by the transvenous approach due to previous embolizations resulting in a proximal occlusion and preventing a safe transarterial approach. A transvenous approach was used in another patient due to complex arterial anatomy. In 1 patient, direct percutaneous puncture of the venous pouch was necessary because of previous proximal occlusion of the arteries. All embolizations resulted in complete occlusions with clinical improvement, and there was no recanalization during a mean follow-up of 21 months.

CONCLUSION: Transarterial embolization of cervical GPMAVFs is safe and effective when it is done in highly experienced centers. Cervical GPMAVFs that cannot be accessed by the transarterial technique due to their complex angioarchitecture can be treated by transvenous embolization or direct puncture of the venous pouch.

Neurosurg Focus 31 (6):E4, 2011. DOI: 10.3171/2011.9.FOCUS11237

The management of incidental small unruptured intracranial aneurysms (UIAs) is controversial and many factors need to be considered in the decision-making process. The authors describe a large consecutive series of patients harboring small incidental intracranial aneurysms. Treatment strategy, natural history, complications, and short-term outcomes are presented.

Methods. Between January 2008 and May 2011, the authors prospectively evaluated 212 patients with 272 small (< 10-mm) incidental aneurysms. Treatment recommendations (observation, endovascular treatment, or surgery), complications of treatment, and short-term outcomes were assessed.

Results. Recommended treatment consisted of observation in 125 patients, endovascular embolization in 64, and surgery in 18. Six patients were excluded from further analysis because they underwent treatment elsewhere. In the observation group, at a mean follow-up of 16.7 months, only 1 patient was moved to the embolization group. Seven (6%) of the 125 patients in the observation group died of causes unrelated to aneurysm. Sixty-five patients underwent 69 embolization procedures. The periprocedural permanent morbidity and mortality rates in patients undergoing endovascular treatment were 1.5% and 1.5%, respectively (overall morbidity and mortality rate 3.0%). In the surgery group no periprocedural complications were observed, although 1 patient did not return to her previous occupation. No aneurysmal rupture was documented in any of the 3 treatment groups during the follow-up period.

Conclusions. A cautious and individualized approach to incidental UIAs is of utmost importance for formulation of a safe and effective treatment algorithm. Invasive treatment (either endovascular or surgery) can be considered in selected younger patients, certain “higher-risk” locations, expanding aneurysms, patients with a family history of aneurysmal hemorrhage, and in those who cannot live their lives knowing that they harbor the UIA. Although the complication rate of invasive treatment is very low, it is not negligible. The study confirms that small incidental UIAs deemed to be not in need of treatment have a very benign short-term natural history, which makes observation a reasonable approach in selected patients.

Acta Neurochir (2011) 153:869–878. DOI 10.1007/s00701-010-0848-6

Onyx has emerged in recent years for the endovascular treatment of brain arteriovenous malformations (AVMs). However, the role of Onyx embolization is still under discussion. We report our initial experiences in the treatment of brain AVMs with Onyx embolization.

Methods Between January 2004 and December 2007, 86 patients with brain AVMs were embolized with Onyx. Clinical presentation included intracerebral hemorrhage in 32 patients, seizures in 25 patients, headaches in 20 patients, neurologic deficits in 3 patients, and in 6 patients the AVM was an incidental finding. According to the Spetzler–Martin scale, three AVMs were grade I, 13 were grade II, 45 were grade III, 19 were grade IV, and 6 were grade V. Seventy-four AVMs were located in eloquent regions.

Results Initial complete obliteration after final embolization was achieved in 16 patients (18.6%), with an average of 80.5% (range, 30–100%) volume reduction. Partial embolization was followed by surgery in 18 patients, whereas 17 AVMs were cured. In 48 patients treated by embolization and radiosurgery, four patients were lost to follow-up. Three-year follow-up angiography was performed on 30 patients and showed complete obliteration after radiosurgery in 23 patients. The remaining 14 patients are awaiting 3-year postradiosurgery results. Embolization-related permanent morbidity was 3.5%, whereas mortality was 1.2%.

Conclusions Although Onyx allows moderate obliteration rates, combined management, such as adjunctive embolization with microsurgery or radiosurgery, may be effective for selected large AVMs.

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.

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.

Neurosurgery 66:714-721, 2010 DOI: 10.1227/01.NEU.0000367451.59090.D7

More elderly patients are presenting with intracranial aneurysms. Many are poor surgical candidates and often undergo endovascular treatment.

OBJECTIVE: We present our experience with embolization in elderly patients.

METHODS:We performed a retrospective review of a prospective database of elderly patients treated with coil embolization for intracranial aneurysms.

RESULTS: In a period of 16 years, 205 aneurysms were treated in 196 individuals (age range, 70–96 years; mean age, 77.3 years), including 159 females (average follow-up, 16.2 months). Ninety-seven patients presented with unruptured aneurysms, and 99 patients presented after subarachnoid hemorrhage; the diagnosis was confirmed by computed tomographic scan or lumbar puncture. Complete occlusion was achieved in 53 aneurysms (26%), with a neck remnant in 127 (62%), incomplete occlusion in 13 (6%), and 12 unsuccessful attempts. Postembolization, 89.3% of patients were neurologically intact or unchanged, whereas 8.7% had new deficits. Four patients died. By modified Rankin Scale score, at last clinical evaluation, 128 patients (65%) had a good outcome. Follow-up angiograms were available for 113 aneurysms; they revealed that 62% were unchanged, 21% were further thrombosed, and 17% had recanalized. Three aneurysms ruptured after treatment during follow-up. Rupture was not associated with incomplete occlusion or neck remnant results (P = .6). Twenty-five aneurysms required reembolization. Reembolization was not associated with new deficits or death (odds ratio, 0.56; 95% confidence interval, 0.19–1.58; P = .27).

CONCLUSION: Coil embolization of intracranial aneurysms is safe and effective in the elderly. Preembolization clinical condition strongly correlates with clinical outcome. Incomplete embolizations are not associated with a higher rerupture risk. Additional embolization does not affect the clinical results.

Surgical Neurology 72 (2009) 612–619. DOI:10.1016/j.surneu.2009.03.038

Background: Stent-assisted coiling is an accepted endovascular treatment (EVT) for wide-necked intracranial aneurysms. The Neuroform stent (Target Therapeutics, Fremont, Calif) is a flexible nitinol self-expandable stent that was designed to potentially overcome the limitations of balloon expandable coronary stents in the intracranial circulation. The aim of this study was to reenforce the use of this stent for EVT of wide-necked cerebral aneurysms.

Methods: Between March 2005 and March 2008, 24 patients harboring wide-necked cerebral aneurysms were treated with stent reconstruction of the aneurysm neck. Inclusion criteria restricted the group to adult patients with wide-necked intracranial aneurysms (ruptured and unruptured lesions). Immediate postprocedure angiography studies were performed to determine successful coil occlusion of the aneurysm as well as patency of the parent vessel. We assessed the clinical history, aneurysm dimensions, and technical detail of the procedures, including any difficulties with stent placement and deployment, degree of aneurysm occlusion, and complications. Clinical outcome was assessed with the Glasgow Outcome Scale (GOS).

Results: The stent was easily navigated and precisely positioned in 24 of 26 cases. However, technical difficulties occurred in 9 patients, including difficulties in crossing the stents interstice in 6 cases, inadvertent stent delivery (n = 1), and incapacity of stent delivery (n = 1) and incapacity of crossing the neck (n = 1). These latter 2 cases were classified as failures of the stent-assisted technique. A single procedural complication occurred, involving transient nonocclusive intrastent thrombus formation, which was treated uneventfully with abciximab. Seventeen patients experienced excellent clinical outcomes (GOS 5), with good outcomes (GOS 4) in 5 patients and a poor outcome (GOS 3) in 2 patients. There were no treatment-related deaths or neurologic complications (mean clinical follow-up, 12 months). Angiographic results consisted of 17 complete occlusions, 4 neck remnants, and 3 incomplete occlusions.

Conclusions: The Neuroform stent is very useful for EVT of wide-necked intracranial aneurysms because it is easy to navigate and to deploy accurately. In most cases, the stent can be deployed precisely, even in very tortuous carotid siphons. Although in some cases delivery and deployment was challenging, clinically significant complications were not observed.

Journal of Neuroradiology (36) 3: 147 – 152 (01/06/2009)

Background and purpose. – To evaluate the safety and efficacy of onyx for embolization of brain arteriovenous malformations (BAVM). Methods. – A prospective, multicenter study was conducted in France to evaluate embolization of BAVM with onyx. From May 2003 to March 2005, 50 patients (26 females, 24 mates; mean age: 34.8 years, range: 16-64 years) were included. Clinical. Presentation was haemorrhage in 22 patients (44.0%), seizures in 16 patients (32.0%), headaches in six patients (12.0%) and progressive neurological. Deficit in two cases (4.0%). Four patients were asymptomatic (8.0%). Results. – One hundred and forty-nine sessions of embolization were performed: one to eight sessions/patient with a mean of 3.0 sessions. One hundred and sixteen sessions (77.9%) were performed with onyx, 20 sessions (13.4%) with glue and 13 sessions (8.7%) with onyx and glue. Symptomatic acute postembolization haemorrhage (APEH) was observed in four cases (8.0% per patient). At 1 month, morbidity and mortality related to the treatment were of 8% and 2%, respectively. Complete BAVM occlusion was obtained in 8.3% of cases. In the remaining cases, occlusion rate was between 99 and 80% in 56.3% of patients, 79 and 60% in 16.7%, and less than 60 in 18.7%. In case of incomplete occlusion, complementary treatment was performed by radiosurgery. Conclusion. – Onyx is suitable for BAVM embolization with acceptable morbidity and mortality.