Category: Vascular

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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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Optimal access route for pontine cavernous malformation resection with preservation of abducens and facial nerve function

J Neurosurg 135:683–692, 2021

The aim of this study was to analyze the differences between posterolateral and posteromedial approaches to pontine cavernous malformations (PCMs) in order to verify the hypothesis that a posterolateral approach is more favorable with regard to preservation of abducens and facial nerve function.

METHODS The authors conducted a retrospective analysis of 135 consecutive patients who underwent microsurgical resection of a PCM. The vascular lesions were first classified in a blinded fashion into 4 categories according to the possible or only reasonable surgical access route. In a second step, the lesions were assessed according to which approach was performed and different patient groups and subgroups were determined. In a third step, the modified Rankin Scale score and the rates of permanent postoperative abducens and facial nerve palsies were assessed.

RESULTS The largest group in this series comprised 77 patients. Their pontine lesion was eligible for resection from either a posterolateral or posteromedial approach, in contrast to the remaining 3 patient groups in which the lesion location already had dictated a specific surgical approach. Fifty-four of these 77 individuals underwent surgery via a posterolateral approach and 23 via a posteromedial approach. When comparing these 2 patient subgroups, there was a statistically significant difference between postoperative rates of permanent abducens (3.7% vs 21.7%) and facial (1.9% vs 21.7%) nerve palsies. In the entire patient population, the abducens and facial nerve deficit rates were 5.9% and 5.2%, respectively, and the modified Rankin Scale score significantly decreased from 1.6 ± 1.1 preoperatively to 1.0 ± 1.1 at follow-up.

CONCLUSIONS The authors’ results suggest favoring a posterolateral over a posteromedial access route to PCMs in patients in whom a lesion is encountered that can be removed via either surgical approach. In the present series, the authors have found such a constellation in 57% of all patients. This retrospective analysis confirms their hypothesis in a large patient cohort. Additionally, the authors demonstrated that 4 types of PCMs can be distinguished by preoperatively evaluating whether only one reasonable or two alternative surgical approaches are available to access a specific lesion. The rates of postoperative sixth and seventh nerve palsies in this series are substantially lower than those in the majority of other published reports.

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Recurrence and risk factors of posterior communicating artery aneurysms after endovascular treatment

Acta Neurochirurgica (2021) 163:2319–2326

Endovascular treatment (EVT) of posterior communicating artery aneurysms (PcomA) is challenging because of posterior communicating artery (Pcom) architecture. Additionally, these aneurysms have a high risk of recanalization compared with those located elsewhere.

Methods The radiographic findings of 171 patients treated with EVT at two institutions were retrospectively reviewed. Univariate and multivariate analyses were performed, and subgroup analyses were performed based on Pcom characteristics.

Results Recanalization of PcomAs occurred in 53 patients (30.9%). Seven patients (4.0%) were retreated (six endovascularly and one with microsurgical clipping). The mean follow-up duration was 27.7 months (range: 3.5–78.6). The maximum diameter (odds ratio [OR] 1.23, P = .006, 95% CI 1.07–1.44), a Raymond–Roy classification of grade II or III (OR 2.26, P = .03, 95% CI 1.08–4.82), and the presence of reinforcement (balloon or/and stent, OR 0.44, P = .03, 95% CI 0.20–0.91) were associated with recanalization using multivariate logistic regression. Significant differences were found in maximum aneurysm diameter (P = .03) between normal- and fetal-type Pcoms on analysis of variance.

Conclusions The recanalization rate of PcomAs after EVT was 30.9%; the retreatment rate was 4.0%. Maximum diameter, Raymond–Roy classification, and presence of reinforcement were significantly associated with recanalization but not associated with fetal-type Pcom. Aneurysm size was larger in patients with a fetal-type Pcom than in those with a normal Pcom. Pcom size was not related to recanalization rate.

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Cerebral venous drainage in patients with dural arteriovenous fistulas: correlation with clinical presentation

J Neurosurg 135:440–448, 2021

Dural arteriovenous fistulas (DAVFs) are abnormal, acquired arteriovenous connections within the dural leaflets. Their associated symptoms may be mild or severe and are related to the patient’s venous anatomy. With the hypothesis that the patient’s venous anatomy determines the development of symptoms, the authors aimed to identify which venous anatomy elements are important in the development of major symptoms in patients with a DAVF.

METHODS A multicenter study was performed based on the retrospective analysis of cerebral angiographies with systematic assessment of brain drainage pathways (including fistula drainage) in patients over 18 years of age with a single DAVF. The patients were divided into two groups: those with minor (group 1, n = 112) and those with major (group 2, n = 89) symptoms. Group 2 was subdivided into two groups: patients with hemorrhage (group 2a, n = 47) and patients with severe nonhemorrhagic symptoms (group 2b, n = 42).

RESULTS The prevalence of stenosis in DAVF venous drainage and the identification of tiny anastomoses between venous territories were significantly higher in group 2 (32.6% and 19.1%, respectively) compared with group 1 (2.68% and 5.36%, respectively). Stenosis of DAVF venous drainage was significantly more frequent in group 2a than in group 2b (51.1% vs 11.9%, p < 0.001). Group 2b patients had increased prevalence of shared use of the cerebral main drainage pathway (85.0% vs 53.2%, p = 0.002), the absence of an alternative route (45.0% vs 17.0%, p = 0.004), and the presence of contrast stagnation (62.5% vs 29.8%, p = 0.002) compared with group 2a patients. In patients with high-grade fistulas, the group with major symptoms had increased prevalence of a single draining direction (31.3% vs 8.33%, p = 0.003), stenosis in the draining vein (35.0% vs 6.25%, p = 0.000), the absence of an alternative pathway for brain drainage (31.3% vs 12.5%, p = 0.017), and the presence of contrast stagnation (48.8% vs 22.9%, p = 0.004).

CONCLUSIONS Major symptoms were observed when normal brain tissue venous drainage was impaired by competition with DAVF (predominance in group 2b) or when DAVF venous drainage had anatomical characteristics that hindered drainage, with consequent venous hypertension on the venous side of the DAVF (predominance in group 2a). The same findings were observed when comparing two groups of patients with high-grade lesions: those with major versus those with minor symptoms.

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Assessment and validation of proposed classification tools for brainstem cavernous malformations

J Neurosurg 135:410–416, 2021

Treatment indications for patients with brainstem cavernous malformations (BSCMs) remain difficult and controversial. Some authors have tried to establish classification tools to identify eligible candidates for surgery. Authors of this study aimed to validate the performance and replicability of two proposed BSCM grading systems, the Lawton- Garcia (LG) and the Dammann-Sure (DS) systems.

METHODS For this cross-sectional study, a database was screened for patients with BSCM treated surgically between 2003 and 2019 in the authors’ department. Complete clinical records, preoperative contrast-enhanced MRI, and a postoperative follow-up ≥ 6 months were mandatory for study inclusion. The modified Rankin Scale (mRS) score was determined to quantify neurological function and outcome. Three observers independently determined the LG and the DS score for each patient.

RESULTS A total of 67 patients met selection criteria. Univariate and multivariate analyses identified multiple bleedings (p = 0.02, OR 5.59), lesion diameter (> 20 mm, p = 0.007, OR 5.43), and patient age (> 50 years, p = 0.019, OR 4.26) as predictors of an unfavorable postoperative functional outcome. Both the LG (AUC = 0.72, p = 0.01) and the DS (AUC = 0.78, p < 0.01) scores were robust tools to estimate patient outcome. Subgroup analyses confirmed this observation for both grading systems (LG: p = 0.005, OR 6; DS: p = 0.026, OR 4.5), but the combined use of the two scales enhanced the test performance significantly (p = 0.001, OR 22.5).

CONCLUSIONS Currently available classification systems are appropriate tools to estimate the neurological outcome after BSCM surgery. Future studies are needed to design an advanced scoring system, incorporating items from the LG and the DS score systems.

 

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Hemorrhage Following Complete Arteriovenous Malformation ResectionWith No Detectable Recurrence

Neurosurgery 89:212–219, 2021

Although recurrence and de novo formation of arteriovenous malformations (AVMs) have been reported following complete resection, the occurrence of hemorrhage in the same location of an AVM with no detectable lesion (lesion-negative hemorrhage) has not been described after microsurgery.

OBJECTIVE: To characterize the incidence and properties of lesion-negative hemorrhage following complete microsurgical resection

METHODS: A prospectively maintained registry of AVM patients seen at our institution between 1990 and 2017 was used. Microsurgically treated patients were selected, and the incidence of a lesion-negative hemorrhage was calculated and described with a Kaplan- Meier curve. Baseline characteristics as well as functional outcome at last follow-up were compared between patients with and without a lesion-negative hemorrhage.

RESULTS: From a total of 789 AVM patients, 619 (79%) were treated, and 210 out of 619 patients (34%) underwent microsurgery with or without preoperative embolization or radiosurgery. The microsurgically treated cohort was followed up for a mean of 6.1 ± 3.0 yr after surgery with 5 (2.4%) patients experiencing postresection lesion-negative hemorrhage (3.9 per 1000 person-years) at an average of 8.6 ± 9.0 yr following surgery. Follow-up angiograms after hemorrhage (up to 2 mo posthemorrhage) confirmed the absence of a recurrent or de novo AVM in all cases. All patients with a lesion-negative hemorrhage initially presented with rupture before resection (Fisher P = .066; log-rank P = .057). The occurrence of a lesion-negative hemorrhage was significantly associated with worse modified Rankin scale scores at last follow-up (P = .031).

CONCLUSION: A lesion-negative hemorrhage can occur following complete microsurgical resection in up to 2.4% of patients. Exploration of possible underlying causes is warranted.

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The middle communicating artery: a novel fourth-generation bypass for revascularizing trapped middle cerebral artery bifurcation aneurysms

J Neurosurg 134:1879–1886, 2021

The anterior and posterior communicating arteries are natural connections between arteries that enable different adjacent circulations to redistribute blood flow instantly in response to changing supply and demand. An analogous communication does not exist in the middle cerebral circulation. A middle communicating artery (MCoA) can be created microsurgically between separate middle cerebral artery (MCA) trunks, enabling flow to redistribute in response to changing supply and demand. The MCoA would draw blood flow from an adjacent circulation such as the external carotid circulation. The MCoA requires the application of fourth-generation techniques to reconstruct bi- and trifurcations after occluding complex MCA trunk aneurysms.

In this report, the authors describe two recent cases of complex MCA biand trifurcation aneurysms in which the occluded efferent trunks were revascularized by creating an MCoA. The first MCoA was created with a “double-barrel” superficial temporal artery–M2 segment bypass and end-to-end reimplantation of the middle and inferior MCA trunks. The second MCoA was created with an external carotid artery–radial artery graft–M2 segment interpositional bypass and end-to-side reimplantation of the inferior trunk onto the superior trunk. Both aneurysms were occluded, and both patients experienced good outcomes.

This report introduces the concept of the MCoA and demonstrates two variations. Angioarchitectural and technical elements include the donation of flow from an adjacent circulation, a communicating bypass, the application of fourth-generation bypass techniques, and a minimized ischemia time. The MCoA construct is ideally suited for rebuilding bi- and trifurcated anatomy after trapping or distally occluding complex MCA aneurysms.

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Observation Versus Intervention for Low-Grade Intracranial Dural Arteriovenous Fistulas

Neurosurgery 88:1111–1120, 2021

Low-grade intracranial dural arteriovenous fistulas (dAVF) have a benign natural history in the majority of cases. The benefit from treatment of these lesions is controversial.

OBJECTIVE: To compare the outcomes of observation versus intervention for low-grade dAVFs.

METHODS: We retrospectively reviewed dAVF patients from institutions participating in the CONsortium for Dural arteriovenous fistula Outcomes Research (CONDOR). Patients with low-grade (Borden type I) dAVFs were included and categorized into intervention or observation cohorts. The intervention and observation cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was modified Rankin Scale (mRS) at final follow-up. Secondary outcomes were excellent (mRS 0-1) and good (mRS 0-2) outcomes, symptomatic improvement, mortality, and obliteration at final follow-up.

RESULTS: The intervention and observation cohorts comprised 230 and 125 patients, respectively. We found no differences in primary or secondary outcomes between the 2 unmatched cohorts at last follow-up (mean duration 36 mo), except obliteration rate was higher in the intervention cohort (78.5% vs 24.1%, P < .001). The matched intervention and observation cohorts each comprised 78 patients. We also found no differences in primary or secondary outcomes between the matched cohorts except obliteration was also more likely in the matched intervention cohort (P < .001). Procedural complication rates in the unmatched and matched intervention cohorts were 15.4% and 19.2%, respectively.

CONCLUSION: Intervention for low-grade intracranial dAVFs achieves superior obliteration rates compared to conservative management, but it fails to improve neurological or functional outcomes. Our findings do not support the routine treatment of low-grade dAVFs.

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