Original ArticleAwake Craniotomy in Arteriovenous Malformation Surgery: The Usefulness of Cortical and Subcortical Mapping of Language Function in Selected Patients
Introduction
Safe microsurgical resection of arteriovenous malformations (AVMs) in eloquent areas of the dominant cerebral hemisphere can be challenging. Several landmark studies have indicated that most low-grade AVMs are best treated microsurgically, because the obliteration rate is very high with low morbidity 8, 9, 16, 24. In more contemporary AVM literature, there has been increasing evidence that the true surgical risks we quote may not be as straightforward as much of the historical literature has portrayed. Convincing evidence has demonstrated that AVMs in eloquent locations approaching 3 cm, and up to 6 cm actually, represent a group with greater surgical risks not fully appreciated in neurovascular practice 5, 11, 17, 24.
In this work, we describe our experience in 4 patients harboring AVMs very close to the language cortex. All patients underwent awake mapping and neuropsychological assessment to confirm resectability and inform the optimal surgical approach to the lesion. We also describe the use of subcortical stimulation with interrogation of language function throughout the process of microsurgical resection, which to our knowledge has not been reported before. On the basis of our experience and careful review of the literature, we believe there exists a subgroup of patients with AVMs near eloquent language cortex in which this approach should be considered.
Section snippets
Methods
Between March 2009 and September 2014, 42 patients with brain AVMs were operated on by the lead author (A.D.). A flow chart depicting the management of these patients is depicted in Figure 1. Four patients who harbored AVMs near critical speech areas in the left hemisphere were selected for wakeful resection. These 4 patient's demographics and the AVM characteristics are described in Table 1. Eloquent location was first identified anatomically on magnetic resonance imaging (MRI) and then
Results
Each of the 4 patients demonstrated some language activation on fMRI 5–10 mm from the AVM nidus. The AVM locations were frontal-opercular in 2 and posterior temporal in 2. The AVM Spetzler-Martin grade (SMG) was II (2 patients) and III (2 patients). Preoperative embolization was performed in one patient. Cortical or subcortical stimulation influenced the surgical approach in 2 of 4 cases. These interrogations did not result in a subtotal resection or abortion of the procedure in any case. In 1
Understanding of Surgical Risk and Eloquence
As the number of published series addressing surgical risk in AVM resection has grown, it is evident that the surgical risks for lower-grade AVMs have been underestimated. It has been demonstrated that resection of grades 1–2 in noneloquent areas resulted in adverse outcomes in 0.6% of the time and as high as 9.5% for AVMs in eloquent brain (17). Lawton et al. (11) proposed an expanded SMG scale separating the heterogeneous grade III into three distinct subgroups, (3−, 3, and 3+). In their
Conclusions
Certain anatomical features of AVMs and fMRI activation profiles may identify patients with SMG 2–3 AVMs in close proximity (5 mm or more) to eloquent language cortex where awake cortical mapping is a viable strategy to maximize safety of AVM resection. Furthermore, maintenance of a wakeful state during dissection and resection of the AVM may provide valuable information to the surgeon via stimulation of subcortical white matter. We believe this methodology is a reasonable and effective
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Cited by (23)
Feasibility of awake craniotomy for brain arteriovenous malformations: A scoping review
2024, World Neurosurgery: XAwake Surgery for Arteriovenous Malformations in Eloquent Areas Does Not Increase Intraoperative Risks and Allows for Shorter-Term Recovery and Improved Status
2022, World NeurosurgeryCitation Excerpt :Eloquence is determined by the normal anatomic position of the eloquent regions;7 the anatomical landmarks used to localize eloquent cortical regions can be imprecise, and these areas are subject to considerable variability in the location of both motor and language cortex.8 Also, it has been recently assumed that there may be a variable reorganization of eloquent areas in the presence of AVMs with altered functional areas displaced to other locations.9,10 Preoperative functional imaging can facilitate the localization of the eloquent areas, but recent studies have discussed the usefulness and reliability of functional magnetic resonance imaging (fMRI) in the anatomic localization of language function.5,7
Intracranial Vascular Procedures
2021, Anesthesiology ClinicsAwake Craniotomy in Low-Resource Settings: Findings from a Retrospective Cohort in the Philippines
2021, World NeurosurgeryCitation Excerpt :Awake craniotomy is increasingly used to maximize resection of lesions in eloquent areas of the brain and preserve function.1 These lesions include brain tumors (e.g., gliomas, meningiomas, and metastases) and vascular lesions (e.g., aneurysms, cavernomas, and arteriovenous malformations [AVMs]).2-6 For gliomas, in particular, awake craniotomy has been shown to result in a greater extent of resection, less complication rate, less postoperative nausea and vomiting, shorter hospital stay, and higher overall patient satisfaction.7,8
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.