Temporal lobe arteriovenous malformations: anatomical subtypes, surgical strategy, and outcomes

Location-based clinical and angiographic profile of brain arteriovenous malformations - a single-center observational study

BACKGROUND

The location of brain arteriovenous malformations (bAVM) is one of the most relevant prognostic factors included in surgical, endovascular and radiosurgical scores. However, their characteristics according to location are seldom described. The goal of this study was to describe the clinical and angiographic characteristics of bAVM classified according to their location.

METHODS

This retrospective observational study included patients diagnosed with bAVM and attending a national referral hospital during the period 2010-2020. Data regarding clinical and angiographic variables were extracted, including characteristics on nidus, arterial afferents, venous drainage and associated aneurysms. BAVM were classified in 8 groups according to their location: frontal, temporal, parieto-occipital, periventricular, deep, cerebellar, brainstem and mixed. Data distribution for each group was determined and between-group differences were assessed.

RESULTS

A total of 269 bAVM (in 258 patients) were included. The most frequent location was parieto-occipital; and the least frequent, brainstem. Statistically significant differences were observed between groups for most studied variables, including: clinical presentation, functional status at admission; nidus size and density, classification according to the Spetzler-Martin, Buffalo and modified Pollock-Flickinger scales; number, diameter, origin and type of afferents; number, diameter, type and direction of venous drainage, retrograde venous flow; and presence and size of flow-related aneurysms.

CONCLUSION

The clinical and angiographic differences observed between brain AVM groups allow the formulation of profiles according to their location.

When the Music Comes From the Brain: A Rare Case of Auditory Seizures Secondary to a Right Temporal Lobe Arteriovenous Malformation

Focal seizures with subjective auditory phenomena, known as auditory seizures, are uncommon and can include simple to complex auditory hallucinations. We present a case of a 59-year-old man who presented with motor and non-motor seizures. He had a four-month history of hearing things resembling continuous metallic sounds, pennies dropping into a bank, persistent music after radio cessation, and the sound of a passing train. Brain MRI showed multiple serpiginous flow voids in the right temporal lobes, consistent with an arteriovenous malformation that was confirmed eventually with a diagnostic brain angiogram. The etiology of the seizures was related to a structural lesion in the setting of a right temporal arteriovenous malformation (AVM). Treatment with 2000mg of levetiracetam twice daily and 300mg of oxcarbazepine twice daily improved symptoms, and subsequent stereotactic radiosurgery ablation successfully treated the AVM. Post-treatment MRI showed reduced visibility of parasitized vessels, with controlled generalized seizures but partial control of auditory seizures.

Cortical incisions and transcortical approaches for intra-axial and intraventricular lesions: A scoping review

Background

Transcortical approaches, encompassing various surgical corridors, have been employed to treat an array of intraparenchymal or intraventricular brain pathologies, including tumors, vascular malformations, infections, intracerebral hematomas, and epileptic surgery. Designing cortical incisions relies on the lesion location and characteristics, knowledge of eloquent functional anatomy, and advanced imaging such as tractography. Despite their widespread use in neurosurgery, there is a noticeable lack of systematic studies examining their common lobe access points, associated complications, and prevalent pathologies. This scoping review assesses current evidence to guide the selection of transcortical approaches for treating a variety of intracranial pathologies.

Methods

A scoping review was conducted using the PRISMA-ScR guidelines, searching PubMed, EMBASE, Scopus, and Web of Science. Studies were included if ≥5 patients operated on using transcortical approaches, with reported data on clinical features, treatments, and outcomes. Data analysis and synthesis were performed.

Results

A total of 50 articles encompassing 2604 patients were included in the study. The most common primary pathology was brain tumors (60.6%), particularly gliomas (87.4%). The transcortical-transtemporal approach was the most frequently identified cortical approach (70.48%), and the temporal lobe was the most accessed brain lobe (55.68%). The postoperative course outcomes were reported as good (55.52%), poor (28.38%), and death (14.62%).

Conclusion

Transcortical approaches are crucial techniques for managing a wide range of intracranial lesions, with the transcortical-transtemporal approach being the most common. According to the current literature, the selective choice of cortical incision and surgical corridor based on the lesion's pathology and anatomic-functional location correlates with acceptable functional outcomes.

An imaging review of the hippocampus and its common pathologies

The hippocampus is a complex structure located in the mesial temporal lobe that plays a critical role in cognitive and memory-related processes. The hippocampal formation consists of the dentate gyrus, hippocampus proper, and subiculum, and its importance in the neural circuitry makes it a key anatomic structure to evaluate in neuroimaging studies. Advancements in imaging techniques now allow detailed assessment of hippocampus internal architecture and signal features that has improved identification and characterization of hippocampal abnormalities. This review aims to summarize the neuroimaging features of the hippocampus and its common pathologies. It provides an overview of the hippocampal anatomy on magnetic resonance imaging and discusses how various imaging techniques can be used to assess the hippocampus. The review explores neuroimaging findings related to hippocampal variants (incomplete hippocampal inversion, sulcal remnant and choroidal fissure cysts), and pathologies of neoplastic (astrocytoma and glioma, ganglioglioma, dysembryoplastic neuroepithelial tumor, multinodular and vacuolating neuronal tumor, and metastasis), epileptic (mesial temporal sclerosis and focal cortical dysplasia), neurodegenerative (Alzheimer's disease, progressive primary aphasia, and frontotemporal dementia), infectious (Herpes simplex virus and limbic encephalitis), vascular (ischemic stroke, arteriovenous malformation, and cerebral cavernous malformations), and toxic-metabolic (transient global amnesia and opioid-associated amnestic syndrome) etiologies.

Role of the anterior choroidal artery in the endovascular treatment of brain arteriovenous malformations

The anterior choroidal artery (AchA) is a very important vessel that supplies certain crucial structures that have poor collateral circulation. When the AchA is recruited to supply brain arteriovenous malformations (BAVMs), can the AchA act as a safe path through which endovascular treatment (EVT) be performed? As few studies or reports have investigated this matter, we performed a review to expound upon the role of the AchA in the EVT of BAVMs. In this review, we discussed the anatomy and variation of the AchA, the angioarchitecture of BAVMs fed by the AchA, the status of EVT for BAVMs and its associated problems and their solutions, the choice of embolic materials, new EVT techniques, the complications and prognoses of EVT through the AchA, etc. The review revealed that although EVT of BAVMs through the AchA is challenging and can result in unpredictable complications, it may be an appropriate option prior to surgery and radiation therapies or serve as a curative procedure. A complete and thorough understanding of the functional anatomy and variant of the AchA and proper EVT techniques are crucial for successful embolization of BAVMs via the AchA.

Arteriovenous Malformations-Associated Epilepsy in Pediatrics

PURPOSE

Seizures are the second most common presentation of cerebral arteriovenous malformations (AVMs); pediatric patients are more likely to develop AVM-associated epilepsy. We examined the role of multimodality AVM treatment in pediatric AVM-associated epilepsy to characterize long-term epilepsy outcomes.

METHODS

A retrospective chart review identified pediatric patients with AVM-associated epilepsy seen at our institution from 2005 to 2018. Variables measured included demographic and descriptive data. Primary outcomes included seizure freedom, seizure control, and functional outcomes.

RESULTS

Of 105 pediatric patients with AVMs, 18 had AVM-related epilepsy. Thirteen underwent surgical resection, of which 6 underwent preoperative embolization. Twelve (92.31%) had complete resection; one (7.69%) with residual underwent redo craniotomy with subsequent complete resection. All had radiographic cure at most recent follow-up, with no recurrence seen during length of follow-up (mean 2.17 years, SD 1.40, range 0.25-4.41). Eight (61.54%) experienced seizure freedom postoperatively; 12 (92.31%) were modified Engel Class I at last follow-up. Five patients underwent treatment without open surgical resection, with conservative management (3, 60%) or endovascular embolization (2, 40%). None in our cohort underwent radiosurgery. Of those embolized, one had complete AVM obliteration and two had partial obliteration. Four of the 5 patients (80%) treated without open surgery achieved seizure freedom.

CONCLUSION

Long-term outcomes of AVM-related epilepsy are poorly characterized in children. We found that in addition to improved AVM outcomes regarding obliteration, treatment of residual, and recurrence, pediatric patients undergoing surgical AVM treatment had improved AVM-associated epilepsy outcomes, with 61.54% achieving seizure freedom and 92.31% classified as modified Engel Class I seizure control.

Brain Arteriovenous Malformations Classifications: A Surgical Point of View

Brain arteriovenous malformations (AVMs) classification has been the subject of extensive discussion. The aim of our work was to review the main classification schemes proposed in the literature, which can be summarized in four main groups: (a) traditional schemes oriented to evaluate the operability of AVMs have been joined by (b) specific classifications that evaluate the outcome and the predictability of obliteration of other treatment modalities and (c) others that evaluate the outcome of intracerebral hemorrhages in ruptured AVMs. Eventually, (d) topographical classifications that categorize the subtypes of AVMs located in specific anatomical regions have been drawn. For each classification, we discuss the implications on surgical management.

Hemodynamics Associated With Intracerebral Arteriovenous Malformations: The Effects of Treatment Modalities

The understanding of the physiology of cerebral arteriovenous malformations (AVMs) continues to expand. Knowledge of the hemodynamics of blood flow associated with AVMs is also progressing as imaging and treatment modalities advance. The authors present a comprehensive literature review that reveals the physical hemodynamics of AVMs, and the effect that various treatment modalities have on AVM hemodynamics and the surrounding cortex and vasculature. The authors discuss feeding arteries, flow through the nidus, venous outflow, and the relative effects of radiosurgical monotherapy, endovascular embolization alone, and combined microsurgical treatments. The hemodynamics associated with intracranial AVMs is complex and likely changes over time with changes in the physical morphology and angioarchitecture of the lesions. Hemodynamic change may be even more of a factor as it pertains to the vast array of single and multimodal treatment options available. An understanding of AVM hemodynamics associated with differing treatment modalities can affect treatment strategies and should be considered for optimal clinical outcomes.

Morbidity after Hemorrhage in Children with Untreated Brain Arteriovenous Malformation

BACKGROUND

Children with untreated brain arteriovenous malformations (bAVM) are at risk of encountering life-threatening hemorrhage very early in their lives. The primary aim of invasive treatment is to reduce unfavorable outcome associated with a bAVM rupture. A better understanding of the morbidity of bAVM hemorrhage might be helpful for weighing the risks of untreated bAVM and invasive treatment. Our aim was to assess the clinical outcome after bAVM rupture and identify features to predict severe hemorrhage in children.

METHODS

We identified all consecutive children admitted to our institution for bAVMs between July 2009 and December 2014. Clinical outcome after hemorrhagic presentation and subsequent hemorrhage was evaluated using the modified Rankin Scale (mRS) for children. The association of demographic characteristics and bAVM morphology with severe hemorrhage (mRS >3 or requiring emergency hematoma evacuation) was studied using univariate and multivariable regression analyses. A nomogram based on multivariable analysis was formulated to predict severe hemorrhage risk for individual patients.

RESULTS

A total of 134 patients were identified with a mean treatment-free follow-up period of 2.1 years. bAVM ruptured in 83 (62%) children: 82 had a hemorrhage at presentation and 6 of them experienced a recurrent hemorrhage during follow-up; 1 patient had other diagnostic symptoms but bled during follow-up. Among them, 49% (41/83) had a severe hemorrhage; emergency hematoma evacuation was required in 28% of them (23/83), and 24% (20/83) remained as disabled (mRS ≥3) at last follow-up. Forty-six percent (38/82) of children with hemorrhagic presentation were severely disabled (mRS >3). Forty-three percent (3/7) were severely disabled after subsequent hemorrhage. The annual rate of severe subsequent hemorrhage was 1% in the overall cohort and 3.3% in children with ruptured presentation. All the subsequent severe hemorrhage events occurred in children with severe hemorrhage history (7%, 3/41). Periventricular location, non-temporal lobe location, and long draining vein were predictors for severe hemorrhage in pediatric untreated bAVMs. A nomogram based on bAVM morphology was contracted to predict severe hemorrhage risk for individual patients, which was well calibrated and had a good discriminative ability (adjusted C-statistic, 0.72).

CONCLUSIONS

Evaluating bAVM morbidity and morphology might be helpful for weighing the risks of untreated bAVM in pediatric patients.

Cavernomas and Arteriovenous Malformations in the Mesial Temporal Region: Microsurgical Anatomy and Approaches

BACKGROUND

The mesial temporal region (MTR) is located deep in the temporal lobe and it is surrounded by important vascular and nervous structures that should be preserved during surgery.

OBJECTIVE

To describe microsurgical anatomy and approaches to the MTR in relation to cavernomas and arteriovenous malformations (AVMs).

METHODS

Five formalin-fixed and red silicone-embedded heads of adult cadavers were used for this study. Between January 2003 and June 2014, 7 patients with cavernomas and 6 patients with AVMs in the MTR underwent surgery.

RESULTS

The MTR of the cadavers was divided into 3 areas: anterior, middle, and posterior. Of the 7 patients with MTR cavernomas, 4 were located anteriorly, 2 were located medially, and 1 was located posteriorly. Of the 6 patients with MTR AVMs, 3 were located in the anterior sector, 2 in the middle sector, and 1 in the posterior sector. For the anterior portion of the MTR, a transsylvian-transinsular approach was used; for the middle portion of the MTR, a transtemporal approach was used (anterior temporal lobectomy); and for the posterior portion of the MTR, a supracerebellar-transtentorial approach was used.

CONCLUSION

Dividing the MTR into 3 regions allows us to adapt the approach to lesion location. Thus, the anterior sector can be approached via the sylvian fissure, the middle sector can be approached transtemporally, and the posterior sector can be approached via the supracerebellar approach.

Using a Machine Learning Approach to Predict Outcomes after Radiosurgery for Cerebral Arteriovenous Malformations

Predictions of patient outcomes after a given therapy are fundamental to medical practice. We employ a machine learning approach towards predicting the outcomes after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). Using three prospective databases, a machine learning approach of feature engineering and model optimization was implemented to create the most accurate predictor of AVM outcomes. Existing prognostic systems were scored for purposes of comparison. The final predictor was secondarily validated on an independent site's dataset not utilized for initial construction. Out of 1,810 patients, 1,674 to 1,291 patients depending upon time threshold, with 23 features were included for analysis and divided into training and validation sets. The best predictor had an average area under the curve (AUC) of 0.71 compared to existing clinical systems of 0.63 across all time points. On the heldout dataset, the predictor had an accuracy of around 0.74 at across all time thresholds with a specificity and sensitivity of 62% and 85% respectively. This machine learning approach was able to provide the best possible predictions of AVM radiosurgery outcomes of any method to date, identify a novel radiobiological feature (3D surface dose), and demonstrate a paradigm for further development of prognostic tools in medical care.

Radiosurgery for temporal lobe arteriovenous malformations: effect of temporal location on seizure outcomes

OBJECT

The temporal lobe is particularly susceptible to epileptogenesis. However, the routine use of anticonvulsant therapy is not implemented in temporal lobe AVM patients without seizures at presentation. The goals of this case-control study were to determine the radiosurgical outcomes for temporal lobe AVMs and to define the effect of temporal lobe location on postradiosurgery AVM seizure outcomes.

METHODS

From a database of approximately 1400 patients, the authors generated a case cohort from patients with temporal lobe AVMs with at least 2 years follow-up or obliteration. A control cohort with similar baseline AVM characteristics was generated, blinded to outcome, from patients with non-temporal, cortical AVMs. They evaluated the rates and predictors of seizure freedom or decreased seizure frequency in patients with seizures or de novo seizures in those without seizures.

RESULTS

A total of 175 temporal lobe AVMs were identified based on the inclusion criteria. Seizure was the presenting symptom in 38% of patients. The median AVM volume was 3.3 cm3, and the Spetzler-Martin grade was III or higher in 39% of cases. The median radiosurgical prescription dose was 22 Gy. At a median clinical follow-up of 73 months, the rates of seizure control and de novo seizures were 62% and 2%, respectively. Prior embolization (p = 0.023) and lower radiosurgical dose (p = 0.027) were significant predictors of seizure control. Neither temporal lobe location (p = 0.187) nor obliteration (p = 0.522) affected seizure outcomes. The cumulative obliteration rate was 63%, which was significantly higher in patients without seizures at presentation (p = 0.046). The rates of symptomatic and permanent radiation-induced changes were 3% and 1%, respectively. The annual risk of postradiosurgery hemorrhage was 1.3%.

CONCLUSIONS

Radiosurgery is an effective treatment for temporal lobe AVMs. Furthermore, radiosurgery is protective against seizure progression in patients with temporal lobe AVM–associated seizures. Temporal lobe location does not affect radiosurgery-induced seizure control. The low risk of new-onset seizures in patients with temporal or extratemporal AVMs does not seem to warrant prophylactic use of anticonvulsants.

Intraoperative arteriovenous malformation rupture: causes, management techniques, outcomes, and the effect of neurosurgeon experience

OBJECT

Intraoperative rupture can transform an arteriovenous malformation (AVM) resection. Blood suffuses the field and visualization is lost; suction must clear the field and the hand holding the suction device is immobilized; the resection stalls while hemostasis is being reestablished; the cause and site of the bleeding may be unclear; bleeding may force technical errors and morbidity from chasing the source into eloquent white matter; and AVM bleeding can be so brisk that it overwhelms the neurosurgeon. The authors reviewed their experience with this dangerous complication to examine its causes, management, and outcomes.

METHODS

From a cohort of 591 patients with AVMs treated surgically during a 15-year period, 32 patients (5%) experienced intraoperative AVM rupture. Their prospective data and medical records were reviewed.

RESULTS

Intraoperative AVM rupture was not correlated with presenting hemorrhage, but had a slightly higher incidence infratentorially (7%) than supratentorially (5%). Rupture was due to arterial bleeding in 18 patients (56%), premature occlusion of a major draining vein in 10 (31%), and nidal penetration in 4 (13%). In 14 cases (44%), bleeding control was abandoned and the AVM was removed immediately ("commando resection"). The incidence of intraoperative rupture was highest during the initial 5-year period (9%) and dropped to 3% and 4% in the second and third 5-year periods, respectively. Ruptures due to premature venous occlusion and nidal penetration diminished with experience, whereas those due to arterial bleeding remained steady. Despite intraoperative rupture, 90% of AVMs were completely resected initially and all of them ultimately. Intraoperative rupture negatively impacted outcome, with significantly higher final modified Rankin Scale scores (mean 2.8) than in the overall cohort (mean 1.5; p < 0.001).

CONCLUSIONS

Intraoperative AVM rupture is an uncommon complication caused by pathological arterial anatomy and by technical mistakes in judging the dissection distance from the AVM margin and in mishandling or misinterpreting the draining veins. The decrease in intraoperative rupture rate over time suggests the existence of a learning curve. In contrast, intraoperative rupture due to arterial bleeding reflects the difficulty with dysplastic feeding vessels and deep perforator anatomy rather than neurosurgeon experience. The results demonstrate that intraoperative AVM rupture negatively impacts patient outcome, and that skills in managing this catastrophe are critical.

Current surgical results with low-grade brain arteriovenous malformations

OBJECT

Resection is an appealing therapy for brain arteriovenous malformations (AVMs) because of its high cure rate, low complication rate, and immediacy, and has become the first-line therapy for many AVMs. To clarify safety, efficacy, and outcomes associated with AVM resection in the aftermath of A Randomized Trial of Unruptured Brain AVMs (ARUBA), the authors reviewed their experience with low-grade AVMs-the most favorable AVMs for surgery and the ones most likely to have been selected for treatment outside of ARUBA's randomization process.

METHODS

A prospective AVM registry was searched to identify patients with Spetzler-Martin Grade I and II AVMs treated using resection during a 16-year period.

RESULTS

Of the 232 surgical patients included, 120 (52%) presented with hemorrhage, 33% had Spetzler-Martin Grade I, and 67% had Grade II AVMs. Overall, 99 patients (43%) underwent preoperative embolization, with unruptured AVMs embolized more often than ruptured AVMs. AVM resection was accomplished in all patients and confirmed angiographically in 218 patients (94%). There were no deaths among patients with unruptured AVMs. Good outcomes (modified Rankin Scale [mRS] score 0-1) were found in 78% of patients, with 97% improved or unchanged from their preoperative mRS scores. Patients with unruptured AVMs had better functional outcomes (91% good outcome vs 65% in the ruptured group, p = 0.0008), while relative outcomes were equivalent (98% improved/unchanged in patients with ruptured AVMs vs 96% in patients with unruptured AVMs).

CONCLUSIONS

Surgery should be regarded as the "gold standard" therapy for the majority of low-grade AVMs, utilizing conservative embolization as a preoperative adjunct. High surgical cure rates and excellent functional outcomes in patients with both ruptured and unruptured AVMs support a dominant surgical posture for low-grade AVMS, with radiosurgery reserved for risky AVMs in deep, inaccessible, and highly eloquent locations. Despite the technological advances in endovascular and radiosurgical therapy, surgery still offers the best cure rate, lowest risk profile, and greatest protection against hemorrhage for low-grade AVMs. ARUBA results are influenced by a low randomization rate, bias toward nonsurgical therapies, a shortage of surgical expertise, a lower rate of complete AVM obliteration, a higher rate of delayed hemorrhage, and short study duration. Another randomized trial is needed to reestablish the role of surgery in unruptured AVM management.

Management of perisylvian arteriovenous malformations: a retrospective institutional case series and review of the literature

Object

Sylvian arteriovenous malformations (sAVMs) are challenging lesions of the central nervous system. The natural history of these unique lesions as well as clinical outcomes following treatment of sAVMs has been limited to case series owing to the rarity of these lesions. The authors present their experience with sAVMs and review the literature.

Methods

In accordance with the Henry Ford Institutional Review Board, medical records of patients with sAVMs treated from 2000 to 2012 were reviewed. Clinical data were retrospectively collected to calculate pre- and posttreatment modified Rankin Scale scores for all patients.

Results

The authors identified 15 patients with sAVMs who received treatment. Of these, 12 were female and 3 were male, and the average age at presentation was 39.6 ± 12.94 years (± SD). Two patients (13.3%) had Spetzler-Martin Grade I lesions, 6 patients (40%) had Grade II lesions, 5 patients (33.3%) had Grade III lesions, and another 2 (13.3%) harbored Grade IV arteriovenous malformations (AVMs). According to the Sugita classification, 6 patients (40%) had medial lesions, 6 (40%) had lateral lesions, 2 (13.3%) had deep lesions, and 1 patient (6.67%) had a pure sAVM. Eight patients (53.3%) underwent stereotactic radiosurgery while 7 patients (46.7%) had microsurgical resection; 1 patient underwent surgical extirpation after incomplete response following radiosurgery. After treatment, 9 patients were unchanged from pretreatment (60%), 3 patients worsened, and 2 patients had improved functional outcome (20% and 13.3%, respectively). The authors’ literature search yielded 348 patients with sAVMs, most of them harboring Spetzler-Martin Grade II and III lesions. Approximately 98% of the patients underwent resection with excellent outcomes.

Conclusions

While the ideal choice of therapeutic modality for cerebral AVMs remains controversial in light of the recent publication of the ARUBA (A Randomized trial of Unruptured Brain AVMs) trial, a multidisciplinary treatment approach for the management of sAVMs can lead to acceptable neurological outcome.