Awake Surgery for Brain Vascular Malformations and Moyamoya Disease

Awake craniotomy in patients with arteriovenous malformation: A systematic review and meta‑analysis

The present systematic review aimed to identify all the available literature on awake craniotomy (AC) in patients with arteriovenous malformation (AVM) in order to evaluate its safety, risks, benefits and effectiveness. All available literature on AC in patients with AVM was collected and evaluated in an aim to provide a better understanding of its safety, associated risks and benefits. A systematic search for studies employing AC in patients with AVM was conducted using the PubMed, Scopus and ScienceDirect databases without restrictions on the year of publication, language, or study design, from inception up to May 30, 2021. A total of 11 studies published between 2004 and 2021 with 106 patients who underwent ACs were considered eligible. The rate of complete resection was 93% [95% confidence interval (CI), 82 to 100%; I2 0%]. The intraoperative complication rate was 21% (95% CI, 1 to 41%; I2 55%) and the post-operative complication rate was 33% (95% CI, 19 to 48%; I2 40%). During follow-up, the complication rate was 6% (95% CI, 1 to 10%; I2 30%). The post-operative complication rate was higher in the Spetzler-Martin grade (SMG) III-V group (31%; 95% CI, 21 to 42%; I2 46%) than in the SMG I-II group (12%; 95% CI, 2 to 22%; I2 0%). Similarly, the follow-up complication rate was higher in the SMG III-V group (9%; 95% CI, 2 to 16%; I2 34%) than in the SMG I-II group (0%; 95% CI, 0 to 4%; I2 0%). On the whole, the present study provides preliminary evidence to indicate that AC is a possible and useful option for the resection of AVM in selected patients. Well-designed future studies with long-term follow-up are required however, to investigate various aspects of safety and provide solid data for AC in patients with AVM.

Surgical Outcomes of Awake Craniotomy for Treatment of Arteriovenous Malformations in Eloquent Cortex: A Systematic Review

OBJECTIVE

Arteriovenous malformations (AVMs) located in eloquent brain regions are historically associated with a poor prognosis. Awake craniotomy (AC) with the adjunct of brain mapping has the potential of identifying non-eloquent gyri to maximize resection, thereby theoretically decreasing the risk of neurologic deficits. With limited evidence regarding the efficacy of AC in treatment of eloquent AVMs, this review aims to investigate its surgical outcomes.

METHODS

A systematic search in the PubMed database was performed to identify all relevant studies up to February 2022.

RESULTS

A total of 13 studies were extracted for quantitative analysis, yielding a total of 46 patients. The mean age was 34.1 years, and most patients were female (54.8%). Seizures were the most frequently reported presenting symptom (41%, 19 of 46 cases). Spetzler-Martin Grade III was the most prevalent (45.9%, 17 cases) with a mean nidus size of 32.6 mm. Seventy-four percent of AVMs were located on the left side, with the frontal lobe being the most common location (30%, 14 of 46 cases). The most common eloquent regions were language (47.8%, 22 of 46 cases), motor (17.4%, 8 of 46 cases), and language + motor cortices (13.1%, 6 of 46 cases). Complete resection of AVM was achieved in 41 patients (89%). Intraoperative complications occurred in 14 of 46 cases (30.4%) with transient postoperative neurologic deficits in 14 patients (30.4%).

CONCLUSIONS

AC may enable precise microsurgical excision of eloquent AVMs with preservation of critical brain functions. Risk factors for poor outcomes include eloquent AVMs located in the language + motor regions and the occurrence of intraoperative complications such as seizures/hemorrhage.

High-resolution micro-Doppler imaging during neurosurgical resection of an arteriovenous malformation: illustrative case

OBJECTIVE

Given the high-risk nature of arteriovenous malformation (AVM) resections, accurate pre- and intraoperative imaging of the vascular morphology is a crucial component that may contribute to successful surgical results. Surprisingly, current gold standard imaging techniques for surgical guidance of AVM resections are mostly preoperative, lacking the necessary flexibility to cater to intraoperative changes. Micro-Doppler imaging is a unique high-resolution technique relying on high frame rate ultrasound and subsequent Doppler processing of microvascular hemodynamics. In this paper the authors report the first application of intraoperative, coregistered magnetic resonance/computed tomograpy, micro-Doppler imaging during the neurosurgical resection of an AVM in the parietal lobe.

OBSERVATIONS

The authors applied intraoperative two-dimensional and three-dimensional (3D) micro-Doppler imaging during resection and were able to identify key anatomical features including draining veins, supplying arteries and microvasculature in the nidus itself. Compared to the corresponding preoperative 3D-digital subtraction angiography (DSA) image, the micro-Doppler images could delineate vascular structures and visualize hemodynamics with higher, submillimeter scale detail, even at significant depths (>5 cm). Additionally, micro-Doppler imaging revealed unique microvascular morphology of surrounding healthy vasculature.

LESSONS

The authors conclude that micro-Doppler imaging in its current form has clear potential as an intraoperative counterpart to preoperative contrast-dependent DSA, and the microvascular details it provides could build new ground to further study cerebrovascular pathophysiology.

Intraoperative brain mapping during awake surgery in symptomatic supratentorial cavernomas

BACKGROUND

Complete resection of symptomatic supratentorial cavernoma (SCA) and removal of the surrounding gliotic area is recommended to minimize the risk of persistent seizures or (re)bleeding. Surgery of SCA located in an eloquent area, can carry out severe postoperative neurological morbidity. We report a study aimed to assess feasibility, extent of resection and outcome after surgical removal of CA by cortico-subcortical intraoperative brain stimulation (ioBS) in the awake patient.

METHODS

Six patients diagnosed of symptomatic SCA located on an eloquent area and operated on while awake under local anaesthesia ioBS, were included. Preoperative planning included neuropsychologic assessment of language-related functions, sociocognitive functions and executive functions. Intraoperatively, we recorded the results achieved in the planned neuropsychological tasks when stimulation was applied (cortical and subcortical). Postoperative control 3D MRI was scheduled at 1 month after surgery to calculate extent of resection. Neuropsychological assessment at 6 months after surgery was performed in all cases.

RESULTS

Six patients (5 females, 1 male) aged 24-48 years were included in our study. Locations of the lesions were right insular (n=1), left insular (n=1), left temporo-insular (n=1), left temporal (n=2) and left frontal (n=1). In all patients, positive findings were obtained during ioBS. In 5 patients, complete surgical resection was achieved. Two patients had postoperative transient neurological deficits, one case of hemiparesis, one case of dysnomia, both cleared over a 6-month period. Clinical follow-up revealed that all patients experienced complete recovery from preoperative symptoms within a year and five patients with seizures showed marked improvement and eventually quit antiepileptic drugs. Neuropsychological assessment at 6 months provided normal results compared to preoperative baseline in all domains.

CONCLUSIONS

Our study suggests that ioBS in the awake surgery of symptomatic SCA located in eloquent areas, allows to increase the rate of complete resection, minimizing postoperative neurological and neuropsychological deficit, and improving postoperative seizures control.

Intraoperative brain mapping during awake surgery in symptomatic supratentorial cavernomas

BACKGROUND

Complete resection of symptomatic supratentorial cavernoma (SCA) and removal of the surrounding gliotic area is recommended to minimize the risk of persistent seizures or (re)bleeding. Surgery of SCA located in an eloquent area, can carry out severe postoperative neurological morbidity. We report a study aimed to assess feasibility, extent of resection and outcome after surgical removal of CA by cortico-subcortical intraoperative brain stimulation (ioBS) in the awake patient.

METHODS

Six patients diagnosed of symptomatic SCA located on an eloquent area and operated on while awake under local anaesthesia ioBS, were included. Preoperative planning included neuropsychologic assessment of language-related functions, sociocognitive functions and executive functions. Intraoperatively, we recorded the results achieved in the planned neuropsychological tasks when stimulation was applied (cortical and subcortical). Postoperative control 3D MRI was scheduled at 1 month after surgery to calculate extent of resection. Neuropsychological assessment at 6 months after surgery was performed in all cases.

RESULTS

Six patients (5 females, 1 male) aged 24-48 years were included in our study. Locations of the lesions were right insular (n=1), left insular (n=1), left temporo-insular (n=1), left temporal (n=2) and left frontal (n=1). In all patients, positive findings were obtained during ioBS. In 5 patients, complete surgical resection was achieved. Two patients had postoperative transient neurological deficits, one case of hemiparesis, one case of dysnomia, both cleared over a 6-month period. Clinical follow-up revealed that all patients experienced complete recovery from preoperative symptoms within a year and five patients with seizures showed marked improvement and eventually quit antiepileptic drugs. Neuropsychological assessment at 6 months provided normal results compared to preoperative baseline in all domains.

CONCLUSIONS

Our study suggests that ioBS in the awake surgery of symptomatic SCA located in eloquent areas, allows to increase the rate of complete resection, minimizing postoperative neurological and neuropsychological deficit, and improving postoperative seizures control.

Anesthetic Management of Awake Craniotomy for Resection of the Language and Motor Cortex Vascular Malformations

BACKGROUND

Although the safety and feasibility of awake craniotomy are well established for epilepsy and brain tumor surgery, its application for resection of vascular lesions, including arteriovenous malformations (AVMs) and cavernomas, is still limited. Apart from the usual challenges of awake craniotomy, vascular lesions pose several additional problems. Our goal is to determine the safety and practicality of awake craniotomy in patients with cerebral vascular malformations located near the eloquent areas, using a refined anesthetic protocol.

METHODS

A retrospective case series was performed on 7 patients who underwent awake craniotomy for resection of AVMs or cavernomas located in the eloquent language and motor areas. Our protocol consisted of achieving deep sedation, without a definitive airway, using a combination of propofol, dexmedetomidine, and remifentanil/fentanyl during scalp block placement and surgical exposure, then transitioning to a wakeful state during the resection.

RESULTS

Six patients had intracranial AVMs, and 1 patient had a cavernoma. Six patients had complete resection; however, 1 patient underwent repeat awake craniotomy for residual AVM nidus. The patients tolerated the resection under continuous awake neurologic and neurophysiologic testing without significant perioperative complications or the need to convert to general anesthesia with a definitive airway.

CONCLUSIONS

Awake craniotomy for excision of intracranial vascular malformations located near the eloquent areas, in carefully selected patients, can facilitate resection by allowing close neuromonitoring and direct functional assessment. A balanced combination of sedative and analgesic medications can provide both adequate sedation and rapid wakeup, facilitating the necessary patient interaction and tolerance of the procedure.

Surgery for Moyamoya Disease in Children

Moyamoya disease is a chronic progressive cerebrovascular occlusive disease of the terminal portion of the internal carotid arteries associated with an acquired abnormal vascular network at the base of the brain, often leading to ischemic or hemorrhagic stroke. Moyamoya disease is a relatively common cause of pediatric stroke with a specific racial and well-identified clinical and imaging phenotype. Moyamoya disease is more prevalent in East Asian countries compared with other geographic regions with a higher incidence of familial cases and clinically more aggressive form. Moyamoya disease is one of the few causes of stroke that is amenable to effective surgical revascularization treatment. There are various surgical options available for revascularization, including the direct, indirect, or combined bypass techniques, each with variable responses. However, due to the heterogeneity of the diseases, different clinical course, geographical variables associated with the disease, and availability of a wide variety of surgical revascularization procedures, optimal selection of a surgical candidate and the surgical technique becomes challenging, particularly in the pediatric population. This brief review presents pertinent literature of clinical options for the diagnosis and surgical treatment of moyamoya disease in children.