Category: Vascular

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Endovascular versus surgical treatment of cranial dural arteriovenous fistulas: a single‑center 8‑year experience

Acta Neurochirurgica (2022) 164:151–161

Cranial dural arteriovenous fistulas (dAVFs) are rare lesions managed mainly with endovascular treatment (EVT) and/or surgery. We hypothesize that there may be subtypes of dAVFs responding better to a specific treatment modality in terms of successful obliteration and cessation of symptoms and/or risks.

Methods All dAVFs treated during 2011–2018 at our hospital were analyzed retrospectively. Presenting symptoms, radiological variables, treatment modality, complications, and residual symptoms were related to dAVF type using the original Djindjian classification.

Results We treated 112 dAVFs in 107 patients (71, 66% males). They presented with hemorrhage (n = 23; 21%), nonhemorrhagic symptoms (n = 75; 70%), or were discovered incidentally (n = 9; 8%). There were 25 (22%) type I, 29 (26%) type II, 26 (23%) type III, and 32 (29%) type IV fistulas. EVT was the primary treatment modality in 72/112 (64%) dAVFs whereas 40/112 (36%) underwent primary surgery with angiographic obliteration rates of 60% and 90%, respectively. Using a secondary treatment modality in 23 dAVFs, we obtained a final obliteration rate of 93%, including all type III/IV and 26/27 (96%) type II dAVFs. Except for headache, residual symptoms were rare and minor. Permanent neurological complications consisted of five cranial nerve deficits.

Conclusions We recommend EVT as first treatment modality in types I, II, and in non-hemorrhagic type III/IV dAVFs. We recommend surgery as first treatment choice in acute hemorrhagic dAVFs and as secondary choice in type III/IV dAVFs not successfully occluded by EVT. Combining the two modalities provides obliteration in 9/10 dAVF cases at a low procedural risk.

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Intermediate-grade brain arteriovenous malformations and the boundary of operability using the supplemented Spetzler-Martin grading system

J Neurosurg 136:125–133, 2022

Supplemented Spetzler-Martin grading (Supp-SM), which is the combination of Spetzler-Martin and Lawton-Young grades, was validated as being more accurate than stand-alone Spetzler-Martin grading, but an operability cutoff was not established. In this study, the authors surgically treated intermediate-grade AVMs to provide prognostic factors for neurological outcomes and to define AVMs at the boundary of operability.

METHODS Surgically treated Supp-SM intermediate-grade (5, 6, and 7) AVMs were analyzed from 2011 to 2018 at two medical centers. Worsened neurological outcomes were defined as increased modified Rankin Scale (mRS) scores on postoperative examinations. A second analysis of 2000–2011 data for Supp-SM grade 6 and 7 AVMs was performed to determine the subtypes with improved or unchanged outcomes. Patients were separated into three groups based on nidus size (S1: < 3 cm, S2: 3–6 cm, S3: > 6 cm) and age (A1: < 20 years, A2: 20–40 years, A3: > 40 years), followed by any combination of the combined supplemented grade: low risk (S1A1, S1A2, S2A1), intermediate risk (S2A2, S1A3, S3A1, or high risk (S3A3, S3A2, S2A3).

RESULTS Two hundred forty-six patients had intermediate Supp-SM grade AVMs. Of these patients, 102 had Supp-SM grade 5 (41.5%), 99 had Supp-SM grade 6 (40.2%), and 45 had Supp-SM grade 7 (18.3%). Significant differences in the proportions of patients with worse mRS scores at follow-up were found between the groups, with 24.5% (25/102) of patients in Supp-SM grade 5, 29.3% (29/99) in Supp-SM grade 6, and 57.8% (26/45) in Supp-SM grade 7 (p < 0.001). Patients with Supp-SM grade 7 AVMs had significantly increased odds of worse postoperative mRS scores (p < 0.001; OR 3.7, 95% CI 1.9–7.3). In the expanded cohort of 349 Supp-SM grade 6 AVM patients, a significantly higher proportion of older patients with larger Supp-SM grade 6 AVMs (grade 6+, 38.6%) had neurological deterioration than the others with Supp-SM grade 6 AVMs (22.9%, p = 0.02). Conversely, in an expanded cohort of 197 Supp-SM grade 7 AVM patients, a significantly lower proportion of younger patients with smaller Supp-SM grade 7 AVMs (grade 7–, 19%) had neurological deterioration than the others with Supp-SM grade 7 AVMs (44.9%, p = 0.01).

CONCLUSIONS Patients with Supp-SM grade 7 AVMs are at increased risk of worse postoperative neurological outcomes, making Supp-SM grade 6 an appropriate operability cutoff. However, young patients with small niduses in the low-risk Supp-SM grade 7 group (grade 7−) have favorable postoperative outcomes. Outcomes in Supp-SM grade 7 patients did not improve with surgeon experience, indicating that the operability boundary is a hard limit reflecting the complexity of high-grade AVMs.

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What is the role of neurosurgeons in the current management of intracranial aneurysm in France?

Neurochirurgie 68 (2022) 16–20 

Study Design. – Retrospective observational survey-based study.

Introduction. – In France, intracranial aneurysm (IA) patients are managed by neurosurgeons and by interventional neuroradiologists. The growth of endovascular treatment led us to reflect on the role of neurosurgeons in the management of patients with IA. The present study aimed to highlight the current organization of IA management in France.

Method. – A 60-question survey was sent to the neurosurgeons in 34 hospitals managing IA patients. Thirty-three questions dealt with standards of care, follow-up procedures and the involvement of thespecific specialist.

Results. – Twenty-seven centers (79.4%) responded to the survey. A Vascular Multidisciplinary DiscussionTeam was organized, including both surgeons and neuroradiologists, in 92% of responding centers. There were department protocols in 66% of centers, a local registry in 33% and clinical trials in IA in 60%. Patients with unruptured IA were first seen by a neurosurgeon or by an interventional neuroradiologist, with different practices. For ruptured IA, the neurosurgeons were contacted first in 93% of cases, and were systematically involved in initial intensive care unit management. The patients were hospitalized in the neurosurgery department in 89% of the centers. The neurosurgeons took care of initial follow-up in 85%of the centers, and of lifetime follow-up in 36%. In most centers, radiological monitoring of IA was based on MRI angiography for patients who were embolized or under surveillance, and on CT angiography after microsurgery.

Conclusion. – Despite the growth of endovascular treatments, the present survey and the literature highlight a major role of neurosurgeons in treatment, follow-up and care coordination

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Effects of Preoperative Embolization on Spetzler– Martin Grade I and II Arteriovenous Malformations

 

Neurosurgery 90:92–98, 2022

Cerebral arteriovenous malformations (AVMs) with low Spetzler–Martin grades (I and II) are associated with good neurological outcomes after microsurgical resection; however, the use of preoperative embolization for these lesions is controversial.

OBJECTIVE: To compare the neurological outcomes of preoperative embolization with no embolization in patients with low-grade AVMs.

METHODS: Patients with a Spetzler–Martin grade I or II AVM who underwent microsurgical resection during January 1, 1997, through December 31, 2019, were analyzed. Patients undergoing preoperative embolization were compared with patients not undergoing embolization. A propensity score was constructed from baseline characteristics and used to match intervention (embolization) and control (nonembolization) groups in a 1:1 ratio. The primary outcome was poor neurological status on last follow-up examination, defined as a modified Rankin Scale score >2 and a modified Rankin Scale score worse at follow-up than at the preoperative examination.

RESULTS: Of the 603 patients analyzed, 310 (51.4%) underwent preoperative embolization and 293 (48.6%) did not. Patients in the embolization cohort compared with those in the nonembolization cohort had a higher percentage of Spetzler–Martin grade II AVMs (71.6% vs 52.6%, P < .001) and a lower percentage of hemorrhage (41% vs 55%, P = .001). After propensity score matching, no differences were found between paired cohorts (each N = 203) for baseline characteristics with a significant reduction in absolute standardized mean differences. No significant differences were found in primary outcomes between treatment groups in the matched or unmatched cohorts.

CONCLUSION: Preoperative embolization of low-grade Spetzler–Martin AVMs is not associated with improved neurological outcomes after microsurgical resection.

 

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Retrosigmoid transhorizontal fissure approach to lateral pontine cavernous malformation

J Neurosurg 136:205–214, 2022

The retrosigmoid (RS) approach is a classic route used to access deep-seated brainstem cavernous malformation (CM). The angle of access is limited, so alternatives such as the transpetrosal presigmoid retrolabyrinthine (TPPR) approach have been used to overcome this limitation. Here, the authors evaluated a modification to the RS approach, horizontal fissure dissection by using the RS transhorizontal (RSTH) approach.

METHODS Relevant clinical parameters were evaluated in 9 patients who underwent resection of lateral pontine CM. Cadaveric dissection was performed to compare the TPPR approach and the RSTH approach.

RESULTS Five patients underwent the TPPR approach, and 4 underwent the RSTH approach. Dissection of the horizontal fissure allowed for access to the infratrigeminal safe entry zone, with a direct trajectory to the middle cerebellar peduncle similar to that used in TPPR exposure. Operative time was longer in the TPPR group. All patients had a modified Rankin Scale score ≤ 2 at the last follow-up. Cadaveric dissection confirmed increased anteroposterior working angle and middle cerebellar peduncle exposure with the addition of horizontal fissure dissection.

CONCLUSIONS The RSTH approach leads to a direct lateral path to lateral pontine CM, with similar efficacy and shorter operative time compared with more extensive skull base exposure. The RSTH approach could be considered a valid alternative for resection of selected pontine CM.

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Detection of impending perfusion deficits by intraoperative computed tomography (iCT) in aneurysm surgery of the anterior circulation

Acta Neurochirurgica (2021) 163:3501–3514

The aim of our study was to evaluate the additional benefit of intraoperative computed tomography (iCT), intraoperative computed tomography angiography (iCTA), and intraoperative computed tomography perfusion (iCTP) in the intraoperative detection of impending ischemia to established methods (indocyanine green videoangiography (ICGVA), microDoppler, intraoperative neuromonitoring (IONM)) for initiating timely therapeutic measures.

Methods Patients with primary aneurysms of the anterior circulation between October 2016 and December 2019 were included. Data of iCT modalities compared to other techniques (ICGVA, microDoppler, IONM) was recorded with emphasis on resulting operative conclusions leading to inspection of clip position, repositioning, or immediate initiation of conservative treatment strategies. Additional variables analyzed included patient demographics, aneurysm-specific characteristics, and clinical outcome.

Results Of 194 consecutive patients, 93 patients with 100 aneurysms received iCT imaging. While IONM and ICGVA were normal, an altered vessel patency in iCTA was detected in 5 (5.4%) and a mismatch in iCTP in 7 patients (7.5%). Repositioning was considered appropriate in 2 patients (2.2%), where immediate improvement in iCTP could be documented. In a further 5 cases (5.4%), intensified conservative therapy was immediately initiated treating the reduced CBP as clip repositioning was not considered causal. In terms of clinical outcome at last FU, mRS0 was achieved in 85 (91.4%) and mRS1-2 in 7 (7.5%) and remained mRS4 in one patient with SAH (1.1%).

Conclusions Especially iCTP can reveal signs of impending ischemia in selected cases and enable the surgeon to promptly initiate therapeutic measures such as clip repositioning or intraoperative onset of maximum conservative treatment, while established tools might fail to detect those intraoperative pathologic changes.

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Cost-effectiveness analysis in patients with an unruptured cerebral aneurysm treated with observation or surgery

J Neurosurg 135:1608–1616, 2021

The main goal of preventive treatment of unruptured intracranial aneurysms (UIAs) is to avoid the morbidity and mortality associated with aneurysmal subarachnoid hemorrhage. A comparison between the conservative approach and the surgical approach combining endovascular treatment and microsurgical clipping is currently lacking. This study aimed to conduct an updated evaluation of cost-effectiveness comparing the two approaches in patients with UIA.

METHODS A decision tree with a Markov model was developed. Quality-adjusted life-years (QALYs) associated with living with UIA before and after treatment were prospectively collected from a cohort of patients with UIA at a tertiary center. Other inputs were obtained from published literature. Using Monte Carlo simulation for patients aged 55, 65, and 75 years, the authors modeled the conservative management in comparison with preventive treatment. Different proportions of endovascular and microsurgical treatment were modeled to reflect existing practice variations between treatment centers. Outcomes were assessed in terms of QALYs. Sensitivity analyses to assess the model’s robustness and completed threshold analyses to examine the influence of input parameters were performed.

RESULTS Preventive treatment of UIAs consistently led to higher utility. Models using a higher proportion of endovascular therapy were more cost-effective. Models with older cohorts were less cost-effective than those with younger cohorts. Treatment was cost-effective (willingness to pay < 100,000 USD/QALY) if the annual rupture risk exceeded a threshold between 0.8% and 1.9% in various models based on the proportion of endovascular treatment and cohort age. A higher proportion of endovascular treatments and younger age lowered this threshold, making the treatment of aneurysms with a lower risk of rupture more cost-effective.

CONCLUSIONS Preventive treatment of aneurysms led to higher utility compared with conservative management. Models with a higher proportion of endovascular treatment and younger patient age were most cost-effective.

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Burr hole craniostomy versus minicraniotomy in chronic subdural hematoma: a comparative cohort study

Acta Neurochirurgica (2021) 163:3217–3223

Chronic subdural hematoma (CSDH) is one of the most common neurosurgical diseases. In surgical management of CSDH, there is a lack of standardized guidelines concerning surgical techniques and a lack of consensus on which technique(s) are optimal. Neurosurgical centers have shown a wide variation in surgical techniques. The purpose of this study was to compare two different surgical techniques, one burr hole craniostomy with an active subgaleal drain (BHC) and minicraniotomy with a passive subdural drain (MC).

Methods We conducted a multicenter retrospective cohort study at two neurosurgical centers in Sweden which included patients with unilateral CSDHs that received surgical treatment with either BHC or MC. The primary outcomes in comparison of the techniques were 30-day mortality, recurrence rate, and complications according to the Landriel Ibañez grading system for complications.

Results A total of 1003 patients were included in this study. The BHC subgroup included 560 patients, and the MC subgroup included 443 patients. A 30-day mortality when comparing BHC (2.3%) and MC (2.7%) was similar (p = 0.701). Comparing recurrence rate for BHC (8.9%) and MC (10.8%) showed no significant difference (p = 0.336). We found that medical complications were significantly more common in the MC group (p = 0.001). Surgical complications (type IIb) was also associated with the MC group (n = 10, p = 0.003). Out of the 10 patients with type IIb complications in the MC group, 8 had postoperative acute subdural hematomas.

Conclusions BHC was comparable to MC concerning 30-day mortality rate and recurrence rates. We did, however, find that MC was significantly associated with medical complications and serious surgical postoperative complications.

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Aneurysm Wall Enhancement Is Associated With Decreased Intrasaccular IL-10 and Morphological Features of Instability

Neurosurgery 89:664–671, 2021

High-resolution vessel wall imaging plays an increasingly important role in assessing the risk of aneurysm rupture.

OBJECTIVE: To introduce an approach toward the validation of the wall enhancement as a direct surrogate parameter for aneurysm stability.

METHODS: A total of 19 patients harboring 22 incidental intracranial aneurysms were enrolled in this study. The aneurysms were dichotomized according to their aneurysm to- pituitary stalk contrast ratio using a cutoff value of 0.5 (nonenhancing < 0.5; enhancing ≥ 0.5). We evaluated the association of aneurysm wall enhancement with morphological characteristics, hemodynamic features, and inflammatory chemokines directly measured inside the aneurysm.

RESULTS: Differences in plasma concentration of chemokines and inflammatory molecules, morphological, and hemodynamic parameters were analyzed using the Welch test or Mann-Whitney U test. The concentration  IL-10 in the lumen of intracranial aneurysms with low wall enhancement was significantly increased compared to aneurysms with strong aneurysm wall enhancement (P = .014). The analysis of morphological and hemodynamic parameters showed significantly increased values for aneurysm volume (P=.03), aneurysm area (P=.044), maximal diameter (P=.049), and nonsphericity index (P=.021) for intracranial aneurysms with strong aneurysm wall enhancement. None of the hemodynamic parameters reached statistical significance; however, the total viscous shear force computed over the region of low wall shear stress showed a strong tendency toward significance (P = .053).

CONCLUSION: Aneurysmal wall enhancement shows strong associations with decreased intrasaccular IL-10 and established morphological indicators of aneurysm instability.

 

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Basal ganglia cavernous malformations: case series and systematic review of surgical management and long-term outcomes

J Neurosurg 135:1113–1121, 2021

Reports on basal ganglia cavernous malformations (BGCMs) are rare. Here, the authors report on their experience in resecting these malformations to offer insight into this infrequent disease subtype.

METHODS The authors retrospectively reviewed a prospectively managed departmental database of all deep-seated cerebral cavernous malformations (CCMs) treated at Stanford between 1987 and 2019 and included for further analysis those with a radiographic diagnosis of BGCM. Moreover, a systematic literature review was undertaken using the PubMed and Web of Science databases.

RESULTS The departmental database search yielded 331 patients with deep-seated CCMs, 44 of whom had a BGCM (13.3%). Headache was the most common presenting sign (53.5%), followed by seizure (32.6%) and hemiparesis (27.9%). Lesion location involved the caudate nucleus in 21.4% of cases compared to 78.6% of cases within the lentiform nucleus. Caudate BGCMs were larger on presentation and were more likely to present to the ependymal surface (p < 0.001) with intraventricular hemorrhage and hydrocephalus (p = 0.005 and 0.007, respectively). Dizziness and diplopia were also more common with lesions involving the caudate. Because of their anatomical location, caudate BGCMs were preferentially treated via an interhemispheric approach and were less likely to be associated with worsening perioperative deficits than lentiform BGCMs (p = 0.006 and 0.045, respectively). Ten patients (25.6%) were clinically worse in the immediate postoperative period, 4 (10.2%) of whom continued to suffer permanent morbidity at the last follow-up. A longterm good outcome (modified Rankin Scale [mRS] score 0–1) was attained in 74.4% of cases compared to the 69.2% of patients who had presented with an mRS score 0–1. Relative to their presenting mRS score, 89.8% of patients had an improved or unchanged status at the last follow-up. The median postoperative follow-up was 11 months (range 1–252 months). Patient outcomes after resection did not differ among surgical approaches; however, patients presenting with hemiparesis and lesions involving the globus pallidus or posterior limb of the internal capsule were more likely to suffer neurological deficits during the immediate perioperative period. Patients who had undergone awake surgeries were more likely to suffer neurological decline at the early as well as the late follow-up. When adjusting for awake craniotomy as a potential confounder of lesion location, a BGCM involving the posterior limb was predictive of developing early postoperative deficits, but this finding did not persist at the long-term follow-up.

CONCLUSIONS Surgery is a safe and effective treatment modality for managing BGCMs, with an estimated long-term permanent morbidity rate of around 10%.

 

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Clinical and Angioarchitectural Features of Hemorrhagic Brain Arterio-Venous Malformations in Adults and Children

Neurosurgery 89:645–652, 2021

Hemorrhage from brain arteriovenous malformations (bAVMs) is estimated at 3% per annum. Features influencing risk of hemorrhage include perforator/ posterior circulation supply, associated aneurysms, and deep drainage. Children are more likely to present with bAVM bleeds.

OBJECTIVE: To analyze differences in bAVM angioarchitecture between children and adults and describe predictors of poor outcome.

METHODS: Data were collected from adult and pediatric tertiary referral hospitals. Demographic data, bleed location, treatment, and follow-up modified Rankin Scale (mRS) were collected. Angioarchitectural assessment included aneurysm presence, nidus morphology, perinidal angiogenesis, intranidal shunting, steal phenomenon, venous ectasia, venous stenosis, venous reflux, and pseudophlebitic pattern. Regression analyses conducted to determine predictors of mRS > 2.

RESULTS: A total of 270 adult and 135 pediatric ruptured bAVMswere assessed.Median age was 42 (adults) and 10.9 (children) yr. Intranidal aneurysms were more frequent in children (P = .012), whereas prenidal aneurysms were more common in adults (P < .01). Children demonstrated more perinidal angiogenesis (P = .04), whereas steal phenomenon was commoner in adults (P<.01). Venous ectasia (P<.01), reflux (P<.01), and pseudophlebitic pattern (P = .012) were more frequent in adults. Children had better outcome (mRS score ≤ 2) (P < .01). Older age (odds ratio [OR] = 1.02), eloquent location (OR = 2.5), multicompartmental hemorrhage (OR = 1.98), venous reflux (OR = 2.5), diffuse nidus (OR = 1.83), pseudophlebitic pattern (OR = 1.96), intranidal shunts (OR = 2), and no treatment (OR = 3.68) were significant predictors of mRS > 2.

CONCLUSION: Children aremore likely to have intranidal aneurysms and perinidal angiogenesis, whereas adults have more prenidal aneurysms, venous ectasia, corticovenous reflux, and pseudophlebitic pattern. Eloquent location, diffuse nidus, intranidal shunts, venous reflux, and pseudophlebitic pattern predict poorer outcome.

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Magnetic Resonance Imaging-Guided Stereotactic Laser Ablation of Deep Cerebral Cavernous Malformations

Neurosurgery 89:635–644, 2021

Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (MRgLITT) has been used successfully to treat epileptogenic cortical cerebral cavernous malformations (CCM). It is unclear whether MRgLITT would be as feasible or safe for deep CCMs

OBJECTIVE: To describe our experience with MRgLITT for symptomatic deep CCMs

METHODS: Patients’records were reviewed retrospectively. MRgLITT was carried out using a commercially available system in an interventional MRI suite with efforts to protect adjacent brain structures. Immediate postoperative imaging was used to judge ablation adequacy. Delayed postoperative MRI was used to measure lesion volume changes during follow-up.

RESULTS: Four patients with CCM in the thalamus, putamen, midbrain, or subthalamus presented with persistent and disabling neurological symptoms. A total of 2 patients presented with disabling headaches and sensory disturbances and 2 with recurrent symptomatic hemorrhages, of which 1 had familial CCM. Patients were considered by vascular neurosurgeons to be poor candidates for open surgery or had refused it. Multiple trajectories were used in most cases. Adverse events included device malfunction with leakage of saline causing transient mass effect in one patient, and asymptomatic tract hemorrhage in another. One patient suffered an expected mild but persistent exacerbation of baseline deficits. All patients showed improvement from a previously aggressive clinical course with lesion volume decreased by 20% to 73% in follow-up.

CONCLUSION: MRgLITT is feasible in the treatment of symptomatic deep CCM but may carry a high risk of complications without the benefit of definitive resection. We recommend cautious patient selection, low laser power settings, and conservative temper- ature monitoring in surrounding brain parenchyma.

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Microsurgical management of midbrain cavernous malformations: does lesion depth influence the outcome?

Acta Neurochirurgica (2021) 163:2739–2754

The purpose of this study was to clarify whether the intrinsic depth of midbrain cavernous malformations (MCMs) influenced the surgical outcome.

Methods The authors conducted a retrospective study of 76 consecutive patients who underwent microsurgical resection of a MCM. The vascular lesions were categorized into 4 distinct groups based on how these lesions had altered the brainstem surface. Additionally, it was verified whether the actual aspect of the brainstem surface could be predicted only by evaluating the pertinent preoperative MRI slices. Clinical outcome was assessed by determining the modified Rankin Scale Score (mRS) before and after surgery.

Results Twenty-three MCMs (30.3%) were located deeply within the midbrain. The overlying midbrain surface appeared to be normal (group nl). In 33 patients (43.4%), the midbrain surface showed only a yellowish discoloration (group yw). In another 14 individuals (18.4%), the midbrain surface was distorted by the underlying MCM and bulging out while the vascular lesion still remained covered by a thin parenchymal layer (group bg). In the smallest group comprising 6 patients (7.9%), the exophytic MCM had disrupted the midbrain surface and was clearly visible at microsurgical exposure (group ex). The mean mRS decreased in the group nl from 1.43 preoperatively to 0.61 at follow-up.

Conclusion This study demonstrates in a large patient population that a deep intrinsic MCM location is not necessarily associated with an unfavorable clinical outcome after microsurgical lesionectomy. Predicting the aspect of the midbrain surface by evaluating preoperative MR images alone was not sufficiently reliable.

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Middle Meningeal Artery Embolization Versus Conventional Treatment of Chronic Subdural Hematomas

Neurosurgery 89:486–495, 2021

Middle meningeal artery (MMA) embolization is an emerging minimally invasive endovascular technique for chronic subdural hematoma (cSDH). Currently, limited literature exists on its safety and efficacy compared with conventional treatment (open- surgical-evacuation-only).

OBJECTIVE: To compare MMA embolization to conventional treatment.

METHODS: Retrospective analysis of patients with cSDHs treated with MMA embolization in a single center from 2018 to 2019 was performed. Comparisons were made with a historical conventional treatment cohort from 2006 to 2016. Propensity score matching analysis was used to assemble a balanced group of subjects.
RESULTS: A total of 357 conventionally treated cSDH and 45 with MMA embolization were included. After balancing with propensity score matching, a total of 25 pairs of cSDH were analyzed. Comparing the embolization with the conventional treatment group yielded no significant differences in complications (4% vs 4%; P > .99), clinical improvement (82.6% vs 83.3%; P = .95), cSDH recurrence (4.3% vs 21.7%; P = .08), overall re-intervention rates (12% vs 24%; P = .26), modified Rankin scale >2 on last follow-up (17.4% vs 32%; P = .24), as well as mortality (0% vs 12%; P = .09). Radiographic improvement at last follow-up was significantly higher in the open surgery cohort (73.9% vs 95.6%; P = .04). However, there was a trend for lengthier last follow-up for the historical cohort (72 vs 104 d; P = .07).

CONCLUSION: There was a trend for lower recurrence and mortality rates in the embolization era cohort. There were significantly higher radiological improvement rates on last follow-up in the surgical only cohort era. There were no significant differences in complications and clinical improvement.

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Microsurgical training: vascular control and intraoperative vessel rupture in the human placenta infusion model

Acta Neurochirurgica (2021) 163:2525–2532

Microsurgery is a challenging discipline. Regular lab training under the operating microscope has been the environment where most surgeons have mastered the skills and techniques inherent to most microneurosurgical procedures. However, some critical scenarios remain difficult to master or simulate. We describe a step-by-step method for how to build a low-cost, feasible, and widely available model that allows residents to familiarize themselves with demanding critical situations such as intraoperative rupture of major vessels.

Methods After delivery, nine fresh human placentas were transferred to the lab. The umbilical vein was cannulated for normal saline infusion. Several hands-on procedures were performed under direct microscope vision. Operating microscope setup, allantoic membrane splitting, vascular dissection and vessel injury, and repair exercises were simulated and video recorded. Indocyanine green was administered to simulate intraoperative angiography.

Results The model can be setup in less than 15 min, with minimal cost and infrastructure requirements. All the exercises described above can be conducted with a single placenta. Umbilical vein cannulation adds realism and allows quantification of the volume of saline required to complete the exercise. The final check with indocyanine green simulates intraoperative angiography and allows the assessment of distal vessel patency.

Conclusions Minimal infrastructure requirements, simplicity, and easy setup models provide a suitable environment for regular training. The human placenta is inexpensive and widely available, making it a feasible model for residents training. Neurosurgery residents may benefit from this model to familiarize with microsurgery and critical scenarios in a risk-free environment without time or resource constraints.

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Stereotactic radiosurgery with versus without prior Onyx embolization for brain arteriovenous malformations

J Neurosurg 135:742–750, 2021

Investigations of the combined effects of neoadjuvant Onyx embolization and stereotactic radiosurgery (SRS) on brain arteriovenous malformations (AVMs) have not accounted for initial angioarchitectural features prior to neuroendovascular intervention. The aim of this retrospective, multicenter matched cohort study is to compare the outcomes of SRS with versus without upfront Onyx embolization for AVMs using de novo characteristics of the preembolized nidus.

METHODS The International Radiosurgery Research Foundation AVM databases from 1987 to 2018 were retrospectively reviewed. Patients were categorized based on AVM treatment approach into Onyx embolization (OE) and SRS (OE+SRS) or SRS alone (SRS-only) cohorts and then propensity score matched in a 1:1 ratio. The primary outcome was AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiological and symptomatic radiation-induced changes (RICs), and cyst formation. Comparisons were analyzed using crude rates and cumulative probabilities adjusted for competing risk of death.

RESULTS The matched OE+SRS and SRS-only cohorts each comprised 53 patients. Crude rates (37.7% vs 47.2% for the OE+SRS vs SRS-only cohorts, respectively; OR 0.679, p = 0.327) and cumulative probabilities at 3, 4, 5, and 6 years (33.7%, 44.1%, 57.5%, and 65.7% for the OE+SRS cohort vs 34.8%, 45.5%, 59.0%, and 67.1% for the SRS-only cohort, respectively; subhazard ratio 0.961, p = 0.896) of AVM obliteration were similar between the matched cohorts. The secondary outcomes of the matched cohorts were also similar. Asymptomatic and symptomatic embolization-related complication rates in the matched OE+SRS cohort were 18.9% and 9.4%, respectively.

CONCLUSIONS Pre-SRS AVM embolization with Onyx does not appear to negatively influence outcomes after SRS. These analyses, based on de novo nidal characteristics, thereby refute previous studies that found detrimental effects of Onyx embolization on SRS-induced AVM obliteration. However, given the risks incurred by nidal embolization using Onyx, this neoadjuvant intervention should be used judiciously in multimodal treatment strategies involving SRS for appropriately selected large-volume or angioarchitecturally high-risk AVMs.

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Outcomes of stereotactic radiosurgery for hemorrhagic arteriovenous malformations with or without prior resection or embolization

J Neurosurg 135:733–741, 2021

The major concern about ruptured arteriovenous malformations (rAVMs) is recurrent hemorrhage, which tends to preclude stereotactic radiosurgery (SRS) as a therapeutic modality for these brain malformations. In this study, the authors aimed to clarify the role of SRS for rAVM as a stand-alone modality and an adjunct for a remnant nidus after surgery or embolization.

METHODS Data on 410 consecutive patients with rAVMs treated with SRS were analyzed. The patients were classified into groups, according to prior interventions: SRS-alone, surgery and SRS (Surg-SRS), and embolization and SRS (Embol- SRS) groups. The outcomes of the SRS-alone group were analyzed in comparison with those of the other two groups.

RESULTS The obliteration rate was higher in the Surg-SRS group than in the SRS-alone group (5-year cumulative rate 97% vs 79%, p < 0.001), whereas no significant difference was observed between the Embol-SRS and SRS-alone groups. Prior resection (HR 1.78, 95% CI 1.30–2.43, p < 0.001), a maximum AVM diameter ≤ 20 mm (HR 1.81, 95% CI 1.43–2.30, p < 0.001), and a prescription dose ≥ 20 Gy (HR 2.04, 95% CI 1.28–3.27, p = 0.003) were associated with a better obliteration rate, as demonstrated by multivariate Cox proportional hazards analyses. In the SRS-alone group, the annual post-SRS hemorrhage rates were 1.5% within 5 years and 0.2% thereafter and the 10-year significant neurological event–free rate was 95%; no intergroup difference was observed in either outcome. The exclusive performance of SRS (SRS alone) was not a risk for post-SRS hemorrhage or for significant neurological events based on multivariate analyses. These results were also confirmed with propensity score–matched analyses.

CONCLUSIONS The treatment strategy for rAVMs should be tailored with due consideration of multiple factors associated with the patients. Stand-alone SRS is effective for hemorrhagic AVMs, and the risk of post-SRS hemorrhage was low. SRS can also be favorably used for residual AVMs after initial interventions, especially after failed resection.

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Elective intervention for unruptured cranial arteriovenous malformations in relation to ARUBA trial: a National Inpatient Sample study

 

Acta Neurochirurgica (2021) 163:2489–2495

In 2014, A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) concluded that medical management alone for cranial arteriovenous malformations (AVMs) had better clinical outcomes than interventional treatment. The impact of the ARUBA study on changes in the rates of intervention and outcomes is unknown. Thus, we investigated whether the conclusions from ARUBA may have influenced treatment modalities and outcomes of unruptured AVMs.

Methods The National Inpatient Sample (NIS) was queried between 2006 and 2018, for adult patients with an AVM who were admitted on an elective basis. Interventions included open, endovascular, and stereotactic surgeries. Join-point regression was used to assess differences in slopes of treatment rate for each modality before and after the time-point. Logistic regression was used to assess the odds of non-routine discharge and hemorrhage between the two time-points for each treatment modality. Linear regression was used to assess the mean length of stay (LOS) for each treatment modality between the two time-points.

Results A total of 40,285 elective admissions for AVMs were identified between 2006 and 2018. The rate of intervention was higher pre-ARUBA (n = 15,848; 63.8%) compared to post-ARUBA (n = 6985; 45.2%; difference in slope − 8.24%, p < 0.001). The rate of open surgery decreased, while endovascular and stereotactic surgeries remained the same, after the ARUBA trial time-point (difference in slopes − 8.24%, p < 0.001; − 1.74%, p = 0.055; 0.20%, p = 0.22, respectively). For admissions involving interventions, the odds of non-routine discharge were higher post-ARUBA (OR 1.24; p = 0.043); the odds of hemorrhage were lower post-ARUBA (OR 0.69; p = 0.025). There was no statistical difference in length of stay between the two time-points (p = 0.22).

Conclusion The rate of intervention decreased, the rate of non-routine discharge increased, and rate of hemorrhage decreased post-ARUBA, suggesting that it may have influenced treatment practices for unruptured AVMs.

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Parietal trans‑sulcal para‑fascicular approach to lateral thalamic/internal capsule cavernous malformation

Acta Neurochirurgica (2021) 163:2497–2501

The surgical management of deep brain lesions is challenging, with significant morbidity. Advances in surgical technology have presented the opportunity to tackle these lesions.

Methods We performed a complete resection of a thalamic/internal capsule CM using a tubular retractor system via a parietal trans-sulcal para-fascicular (PTPF) approach without collateral injury to the nearby white matter tracts.

Conclusion PTPF approach to lateral thalamic/internal capsule lesions can be safely performed without injury to eloquent white matter fibres. The paucity of major vessels along this trajectory and the preservation of lateral ventricle integrity make this approach a feasible alternative to traditional approaches.

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Recurrent brainstem cavernous malformations following primary resection

J Neurosurg 135:671–682, 2021

Proximity of brainstem cavernous malformations (BSCMs) to tracts and cranial nerve nuclei make it costly to transgress normal tissue in accessing the lesion or disrupting normal tissue adjacent to the lesion in the separation plane. This interplay between tissue sensitivity and extreme eloquence makes it difficult to avoid leaving a remnant on occasion. Recurrences require operative intervention, which may increase morbidity, lengthen recovery, and add to overall costs. An approximately 20-year experience with patients with recurrent BSCM lesions following primary microsurgical resection was reviewed.

METHODS A prospectively maintained database of 802 patients who underwent microsurgical resection of cerebral cavernous malformations during 1997–2018 was queried to identify 213 patients with BSCMs. A retrospective chart review was conducted for patients with recurrent BSCM after primary resection who required a second surgery.

RESULTS Fourteen of 213 patients (6.6%) underwent repeat resection for recurrent BSCM. Thirty-four hemorrhagic events were observed among these 14 patients over 576 patient-years (recurrent hemorrhage rate, 5.9% per year; median discrete hemorrhagic events, 2; median time to rehemorrhage, 897 days). BSCM occurred in the pons in 10 cases, midbrain in 2 cases, and medulla in 2 cases. A blind spot in the operative corridor was the most common cause of residual BSCM (9 patients). All recurrent BSCMs were removed completely, although 2 patients each required 2 operations to treat recurrence. Twelve patients had unchanged or improved modified Rankin Scale scores at last clinical evaluation compared with admission, and 2 patients had worse scores. Recurrence was more common among patients who were operated on in the first versus the second half of the series (8.5% vs 4.7%).

CONCLUSIONS The 6.6% rate of BSCM recurrence requiring reoperation reflects the fine lines between complete resection and recurrence and between safe and harmful surgery. The detection of remnants is difficult postoperatively and remains so even at 6 months when the resection bed has healed. The 5.9% annual hemorrhage risk associated with recurrent BSCM in this experience is consistent with that reported for unoperated BSCMs. The right-angle method helps to anticipate blind spots and meticulously inspect the resection cavity for residual BSCM during surgery. A low percentage of recurrent BSCM (5%–10%) ensures ongoing effort toward an acceptable balance of safety and completeness.

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