Cortical reorganization of motor functional areas in cerebral arteriovenous malformations

Preoperative Embolization With Fused CT Angiography and Tractography Facilitates Safe Resection of a Spetzler-Martin Grade IV Arteriovenous Malformation

Brain arteriovenous malformations (BAVMs) are high-flow vascular lesions that have a propensity to rupture resulting in high rates of morbidity and mortality. Microsurgical resection of BAVMs is the standard of care for high-risk, resectable lesions. Multiple imaging modalities aid in the surgical planning and resection of high-grade BAVMs, but all have hidden variables that would prove useful if available. We present a 20-year-old male with a ruptured BAVM with concern for the involvement of the corticospinal tract (CST) and basal ganglia. We describe the melding of computed tomography angiography (CTA) and diffusion tensor imaging (DTI) in addition to preoperative embolization to aid in the planning and resection of a lesion close to eloquent structures. Post-operative CTA and DTI showed a total resection of the lesion with retained CST white matter tracts, and the patient retained the functional ability of the contralateral limbs. The combination of CTA, brain DTI, and preoperative embolization provides a framework to improve the safety of resection of BAVMs that occur near eloquent brain networks.

One-Stage Treatment in a Hybrid Operation Room to Cure Brain Arteriovenous Malformation: A Single-Center Experience

OBJECTIVE

To report the principles and techniques of using a hybrid operation room in the treatment of brain arteriovenous malformation (BAVM).

METHODS

From October 1, 2016 to December 31, 2018, we treated 54 consecutive patients with nonemergent BAVM in a hybrid operation room. The clinical data, radiologic images, and outcomes were collected to establish a prospective database for evaluation.

RESULTS

Thirty-two male and 22 female patients were enrolled with a mean age of 32.6 ± 13.1 years (range, 10-61 years). Bleeding (n = 32, 59.3%) was the main clinical presentation, followed by headache (n = 27, 50.0%), seizures (n = 14, 25.9%), neurofunctional deficits (n = 16, 29.6%), and no symptoms (n = 2, 3.7%). Thirty-one patients (57.4%) accepted resection without intraoperative embolization, 18 (33.3%) were treated with combined embolization and resection, and 5 (9.3%) were cured with intraoperative embolization and resection was cancelled. All patients achieved total BAVM obliteration confirmed with intraoperative angiography. There were no significant differences in outcomes between low-grade (Spetzler-Martin grades I, II, and modified grade III-) and high-grade (Spetzler-Martin grades ≥IV and modified grade III+) groups, except that the high-grade group had more blood loss (667.9 ± 647.5 vs. 284.3 ± 148.6 mL; P = 0.046) and longer postoperative hospitalization (17.1 ± 9.1 vs. 10.8 ± 5.4 days; P = 0.026). At discharge, 52 patients (96.3%) had favorable outcomes (Glasgow Outcome Scale score ≥4). Forty-three patients (79.6%) received 1 year follow-up after treatment; 97.7% (n = 42) of these had ongoing favorable outcomes. However, 4 patients with low-grade BAVM had recurrence.

CONCLUSIONS

The hybrid operation room can ensure safe, comprehensive treatment of BAVM, offering the opportunity for a favorable curative treatment in 1 stage.

Systematic Review of Functional Mapping and Cortical Reorganization in the Setting of Arteriovenous Malformations, Redefining Anatomical Eloquence

Objective: The goal of this study was to systematically review functional mapping and reorganization that takes place in the setting of arteriovenous malformations (AVMs) and its potential impact on grading and surgical decision making.

Methods: A systematic literature review was performed using the PubMed database for studies published between 1986 and 2019. Studies assessing brain mapping and functional reorganization in AVMs were included.

Results: Of the total 84 articles identified in the original literature search, 12 studies were ultimately selected. This includes studies evaluating the impact of cortical reorganization on patient outcomes and factors impacting and triggering cortical reorganization in AVM.

Conclusion: These studies demonstrate the utility of preoperative brain mapping and acknowledgment of functional reorganization in the setting of AVMs. While these findings led to alterations in Spetzler–Martin grading and subsequent surgical decision making, it remains unclear the clinical utility of this information when assessing patient outcomes. While promising, more research is required before recommendations can be made regarding functional brain mapping and cortical reorganization with respect to AVM surgery involving eloquent brain tissue.

Does eloquence subtype influence outcome following arteriovenous malformation surgery?

OBJECTIVE

Although numerous arteriovenous malformation (AVM) grading scales consider eloquence in risk assessment, none differentiate the types of eloquence. The purpose of this study was to determine if eloquence subtype affects clinical outcome.

METHODS

This is a retrospective review of a prospectively collected clinical database of brain AVMs treated with microsurgery in the period from 1997 to 2017. The only inclusion criterion for this study was the presence of eloquence as defined by the Spetzler-Martin grading scale. Eloquence was preoperatively categorized by radiologists. Poor outcome was defined as a modified Rankin Scale (mRS) score 3-6, and worsening clinical status was defined as an increase in the mRS score at follow-up. Logistic regression analyses were performed.

RESULTS

Two hundred forty-one patients (49.4% female; average age 33.9 years) with eloquent brain AVMs were included in this review. Of the AVMs (average size 2.7 cm), 54.4% presented with hemorrhage, 46.2% had deep venous drainage, and 17.0% were diffuse. The most common eloquence type was sensorimotor (46.1%), followed by visual (27.0%) and language (22.0%). Treatments included microsurgery alone (32.8%), microsurgery plus embolization (51.9%), microsurgery plus radiosurgery (7.9%), and all three modalities (7.5%). Motor mapping was used in 9% of sensorimotor AVM cases, and awake speech mapping was used in 13.2% of AVMs with language eloquence. Complications occurred in 24 patients (10%). At the last follow-up (average 24 months), 71.4% of the patients were unchanged or improved and 16.6% had a poor outcome. There was no statistically significant difference in the baseline patient and AVM characteristics among the different subtypes of eloquence. In a multivariate analysis, in comparison to visual eloquence, both sensorimotor (OR 7.4, p = 0.004) and language (OR 6.5, p = 0.015) eloquence were associated with poor outcomes. Additionally, older age (OR 1.31, p = 0.016) and larger AVM size (OR 1.37, p = 0.034) were associated with poor outcomes.

CONCLUSIONS

Unlike visual eloquence, sensorimotor and language eloquence were associated with worse clinical outcomes after the resection of eloquent AVMs. This nuance in AVM eloquence demands consideration before deciding on microsurgical intervention, especially when numerical grading systems produce a score near the borderline between operative and nonoperative management.

A Tractography-Based Grading Scale of Brain Arteriovenous Malformations Close to the Corticospinal Tract to Predict Motor Outcome After Surgery

Background: Surgical decision-making for brain arteriovenous malformations (AVMs) close to the corticospinal tract (CST) is always challenging. The purpose of this study was to develop a tractography-based grading scale to improve preoperative risk prediction and patient selection.

Methods: We analyzed a consecutive, surgically treated series of 90 patients with AVMs within a 10-mm range from the CST demonstrated by preoperative diffusion tensor tractography. Poor motor outcome was defined as persistent postoperative limb weakness. We examined the predictive ability of nidus-to-CST distance (NCD), the closest CST level (CCL), deep perforating artery supply, as well as variables of the supplemented Spetzler-Martin grading system. Three logistic models were derived from different multivariable logistic regression analyses, of which the most predictive model was selected to construct a prediction grading scale. Receiver operating characteristic analysis was conducted to test the predictive accuracy of the grading scale.

Results: Twenty-one (23.3%) patients experienced persistent postoperative limb weakness after a mean 2.7-year follow-up. The most predictive logistic model showed NCD (P = 0.001), CCL (P = 0.017), patient age (P = 0.004), and AVM diffuseness (P = 0.021) were independent predictors for poor motor outcome. We constructed the CLAD grading scale incorporating these predictors. The predictive accuracy of the CLAD grade was better compared with the supplemented Spetzler-Martin grade (area under curve = 0.84 vs. 0.68, P = 0.023).

Conclusions: Both NCD and CCL predict motor outcome after resection of AVMs close to the CST. We propose the CLAD grading scale as an effective risk-prediction tool in surgical decision-making.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT01758211 and NCT02868008

New predictive model for microsurgical outcome of intracranial arteriovenous malformations: study protocol

INTRODUCTION

Although microsurgical resection is currently the first-line treatment modality for arteriovenous malformations (AVMs), microsurgery of these lesions is complicated due to the fact that they are very heterogeneous vascular anomalies. The Spetzler-Martin grading system and the supplementary grading system have demonstrated excellent performances in predicting the risk of AVM surgery. However, there are currently no predictive models based on multimodal MRI techniques. The purpose of this study is to propose a predictive model based on multimodal MRI techniques to assess the microsurgical risk of intracranial AVMs.

METHODS AND ANALYSIS

The study consists of 2 parts: the first part is to conduct a single-centre retrospective analysis of 201 eligible patients to create a predictive model of AVM surgery based on multimodal functional MRIs (fMRIs); the second part is to validate the efficacy of the predictive model in a prospective multicentre cohort study of 400 eligible patients. Patient characteristics, AVM features and multimodal fMRI data will be collected. The functional status at pretreatment and 6 months after surgery will be analysed using the modified Rankin Scale (mRS) score. The patients in each part of this study will be dichotomised into 2 groups: those with improved or unchanged functional status (a decreased or unchanged mRS 6 months after surgery) and those with worsened functional status (an increased mRS). The first part will determine the risk factors of worsened functional status after surgery and create a predictive model. The second part will validate the predictive model and then a new AVM grading system will be proposed.

ETHICS AND DISSEMINATION

The study protocol and informed consent form have been reviewed and approved by the Institutional Review Board of Beijing Tiantan Hospital Affiliated to Capital Medical University (KY2016-031-01). The results of this study will be disseminated through printed media.

TRIAL REGISTRATION NUMBER

NCT02868008.

Cortical plasticity in patients with cerebral arteriovenous malformations

The aim of this review is to ascertain the evidence for cortical plasticity in arteriovenous malformation (AVM) patients. Chronic hypoperfusion due to vascular steal from cerebral AVM can result in a translocation of eloquent neurological functions to other brain areas, a phenomenon known as cortical plasticity. We performed a systematic literature review of the studies that have evaluated cortical plasticity in AVM patients. A total of 22 studies from 1996 to 2014 were included for the analyses. The evaluation of cortical plasticity was performed prior to AVM intervention in 109 patients, and during or after AVM intervention in 18. The most commonly assessed neurological functions were motor in 85% and language in 11% of the former cohort, and motor in 78% and language, cognition, and memory each in 39% of the latter cohort. Functional MRI was the most frequently used method for evaluating cortical plasticity, and was performed in 63% of the former and 56% of the latter cohort. In conclusion, cortical plasticity appears to be influenced by both AVM pathogenesis and intervention. Given the limited evidence that is currently available for cortical plasticity in AVM patients, further studies are warranted to determine its incidence and impact on long term clinical outcomes.

Testing the Reliability of BOLD-fMRI Motor Mapping in Patients with Cerebral Arteriovenous Malformations by Electric Cortical Stimulation and Surgery Outcomes

OBJECTIVE

To test the reliability of blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) in the primary hand motor cortex (M1) among patients with arteriovenous malformations (AVMs) by electric cortical stimulation (ECS) and surgery outcomes.

METHODS

Forty-three patients with AVMs involving/adjacent to M1 underwent blood oxygen level-dependent fMRI (BOLD-fMRI) with repetitive finger-to-thumb opposition movements. The generated image sets were processed on the iPlan 3.0 workstation. A site-by-site comparison between the fMRI and ECS maps was performed with the aid of neuronavigation. Surgical outcomes were analyzed as the change between preoperative and postoperative muscle strength (MS). Finally, fMRI sensitivity was calculated, and correlations of lesion-to-activation distances (LAD) and surgery outcomes were analyzed.

RESULTS

The highest activation location was found in the ipsilateral M1in 40 patients (93%). The highest activation relocated in the contralateral M1area in one patient (2.3%). No motor activation was found in the other 2 (4.7%) patients. ECS results were positive in 34 patients (85%, 34/40). The fMRI sensitivity was calculated as 85%. In total, 18 patients (41.9%) had worsened MS 1 week after surgery. Eight patients (18.6%) suffered from permanent muscle strength deterioration 6 months later. Moreover, an LAD ≤5 mm was significantly associated with permanent MS deterioration (P = 0.039).

CONCLUSION

BOLD-fMRI exhibits high sensitivity in motor mapping in patients with AVMs. LAD ≤5 mm may be associated with permanent MS deterioration in patients with AVM close to the motor cortex.

Risk factors for worsened muscle strength after the surgical treatment of arteriovenous malformations of the eloquent motor area

OBJECT Case selection for the surgical treatment of arteriovenous malformations (AVMs) of the eloquent motor area remains challenging. The aim of this study was to determine the risk factors for worsened muscle strength after surgery in patients with this disorder. METHODS At their hospital the authors retrospectively studied 48 consecutive patients with AVMs involving motor cortex and/or the descending pathway. All patients had undergone preoperative functional MRI (fMRI) and diffusion tensor imaging (DTI), followed by resection. Both functional and angioarchitectural factors were analyzed with respect to the change in muscle strength. Functional factors included lesion-to-corticospinal tract distance (LCD) on DTI and lesion-to-activation area distance (LAD) and cortical reorganization on fMRI. Based on preoperative muscle strength, the changes in muscle strength at 1 week and 6 months after surgery were defined as short-term and long-term surgical outcomes, respectively. Statistical analysis was performed using the statistical package SPSS (version 20.0.0, IBM Corp.). RESULTS Twenty-one patients (43.8%) had worsened muscle strength 1 week after surgery. However, only 10 patients (20.8%) suffered from muscle strength worsening 6 months after surgery. The LCD was significantly correlated with short-term (p < 0.001) and long-term (p < 0.001) surgical outcomes. For long-term outcomes, patients in the 5 mm ≥ LCD > 0 mm (p = 0.009) and LCD > 5 mm (p < 0.001) categories were significantly associated with a lower risk of permanent motor worsening in comparison with patients in the LCD = 0 mm group. No significant difference was found between patients in the 5 mm ≥ LCD > 0 mm group and LCD > 5 mm group (p = 0.116). Nidus size was the other significant predictor of short-term (p = 0.021) and long-term (p = 0.016) outcomes. For long-term outcomes, the area under the ROC curve (AUC) was 0.728, and the cutoff point was 3.6 cm. Spetzler-Martin grade was not associated with short-term surgical outcomes (0.143), although it was correlated with long-term outcomes (0.038). CONCLUSIONS An AVM with a nidus in contact with tracked eloquent fibers (LCD = 0) and having a large size is more likely to be associated with worsened muscle strength after surgery in patients with eloquent motor area AVMs. Surgical treatment in these patients should be carefully considered. In patients with an LCD > 5 mm, radical resection may be considered to eliminate the risk of hemorrhage.

Difference of language cortex reorganization between cerebral arteriovenous malformations, cavernous malformations, and gliomas: a functional MRI study

The authors attempted to demonstrate the difference in language cortex reorganization between cerebral malformations (AVMs), cavernous malformations (CMs), and gliomas by blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Clinical and imaging data of 27 AVM patients (AVM-L group), 29 CM patients (CM-L group), and 20 glioma patients (Glioma-L group) were retrospectively reviewed, with lesions overlying the left inferior frontal gyrus (Broca area). As a control, patients with lesions involving the right inferior frontal gyrus were also enrolled, including 14 AVM patients (AVM-R group), 20 CM patients (CM-R group), and 14 glioma patients (Glioma-R group). All patients were right-handed. Lateralization indices (LI) of BOLD signal activations were calculated separately for Broca and Wernicke areas. In AVM-L group, right-sided lateralization of BOLD signals was observed in 10 patients (37.0%), including 6 in the Broca area alone, 1 in the Wernicke area alone, and 3 in both areas. Three patients (10.3%) of CM-L group showed right-sided lateralization in both Broca and Wernicke areas, and 1 patient (5.0%) of Glioma-L group had right-sided lateralization in the Wernicke area alone. A significant difference of right-sided lateralization was observed between the AVM-L group and CM-L group (P = 0.018) and also between the AVM-L group and Glioma-L group (P = 0.027). No patient in AVM-R, CM-R, or Glioma-R groups showed right-sided lateralization. Language cortex reorganization may occur in AVM, CM, and glioma patients when the traditional language cortex was involved by lesions, but the potential of reorganization for CM and glioma patients seems to be insufficient compared with AVM patients.

Visual Field Preservation in Surgery of Occipital Arteriovenous Malformations: A Prospective Study

OBJECTIVE

We reviewed our prospective study of patients with occipital arteriovenous malformations (AVMs) to assess whether the display of optic radiation diffusion tensor imaging (DTI) during neuronavigation-guided surgery can reduce the severity of postoperative visual field deficits (VFDs) and to evaluate the factors associated with visual field preservation.

METHODS

Forty-six consecutive patients with occipital AVMs were randomized in our study. DTI of the optic radiation was displayed during neuronavigation surgery in 24 patients. The other 22 patients were treated surgically without neuronavigation. Modified Rankin Scale (mRS) scores and visual fields were evaluated preoperatively, immediately after surgery, and at the last follow-up.

RESULTS

The patients' baseline characteristics and AVM features were statistically similar between the 2 surgical groups. The postoperative obliteration rate was 100%. The postoperative mRS scores did not differ between the 2 groups (P > 0.05). Preexisting VFDs were more common (P = 0.00004) in patients who bled than in those with unruptured AVMs. The application of DTI-incorporated neuronavigation reduced the frequency and severity of postoperative VFDs (P = 0.013 and 0.001, respectively). Visual fields were more likely to be preserved in patients with an AVM >5 mm from the optic radiation (P = 0.025).

CONCLUSIONS

A history of hemorrhage is an independent risk factor for VFDs associated with occipital AVMs. Although not showing superiority in postoperative mRS, functional MRI navigation-guided surgery may help to radically resect occipital AVMs and preserve patient visual fields. A 5-mm distance from the optic radiation may be a suitable safety margin for visual field preservation.

Functional MRI-guided microsurgery of intracranial arteriovenous malformations: study protocol for a randomised controlled trial

INTRODUCTION

Intracranial arteriovenous malformations (AVMs) are associated with high morbidity and mortality. Modern microsurgery has improved the results of surgical treatment of AVMs; however, the treatment of AVMs, particularly eloquently located AVMs, still carries a high risk. Functional MRI (fMRI) has been reported to be used for the preoperative evaluation of AVMs in small case series. The purpose is to identify the utility and efficacy of fMRI-guided microsurgery of AVMs in a large randomised controlled trial.

METHODS AND ANALYSIS

The study is a prospective, randomised controlled clinical trial. This study will enrol a total of 600 eligible patients. These eligible patients will be randomised to the standard microsurgery group and the fMRI-guided microsurgery group in a 1:1 ratio. Patient baseline characteristics and AVM architecture and characteristics will be described. In the fMRI-guided group, fMRI mapping of an eloquent cortex in all AVMs will be identified. Surgical complications and outcomes at pretreatment, post-treatment, at discharge and at 1-month, 3-month and 6-month follow-up intervals will be analysed using the modified Rankin Scale (mRS). This trial will determine whether fMRI-guided microsurgery could improve outcomes in patients with AVMs and also identify the safety and efficacy of fMRI-guided microsurgery.

ETHICS AND DISSEMINATION

The study protocol and written informed consent were reviewed and approved by the Institutional Review Board of Beijing Tiantan Hospital Affiliated to Capital Medical University (ky2012-016-02). Study findings will be disseminated in the printed media.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01758211.

Functional reorganization oF the primary motor cortex in a patient with a large arteriovenous malFormation involving the precentral gyrus

It is known that the brain can compensate for deficits induced by acquired and developmental lesions through functional reorganization of the remaining parenchyma. Arteriovenous malformations (AVM) usually appear prenatally before a functional regional organization of the brain is fully established and patients generally do not present with motor deficits even when the AVM is located in the primary motor area indicating the redistribution of functions in cortical areas that are not pathologically altered. Here we present reorganization of the motor cortex in a patient with a large AVM involving most of the left parietal lobe and the paramedian part of the left precentral gyrus that is responsible for controlling the muscles of the lower limbs. Functional MRI showed that movements of both the right and left feet activated only the primary motor cortex in the right hemisphere, while there was no activation in the left motor cortex. This suggests that complete ipsilateral control over the movements of the right foot had been established in this patient. A reconstruction of the corticospinal tract using diffusion tensor imaging showed a near-complete absence of corticospinal fibers from the part of the left precentral gyrus affected by the AVM. From this clinical presentation it can be concluded that full compensation of motor deficits had occurred by redistributing function to the corresponding motor area of the contralateral