Microsurgical Resection of an Intracranial Dural Arteriovenous Fistula

Case Overview

Intracranial dural arteriovenous fistulas (dAVFs) are abnormal shunts between the meningeal arteries supplying the dura mater and the venous sinuses or cortical veins.¹ These lesions represent 10–15% of all intracranial vascular malformations.² DAVFs can be classified into different types based on their angioarchitecture and venous drainage patterns. Type I dAVFs involve a direct connection between the dural arteries and venous sinuses, with benign clinical outcomes.³ In contrast, types II, III, and IV dAVFs are associated with more aggressive features, such as retrograde venous drainage (RVD) and cortical venous reflux (CVR), and can lead to an aggressive clinical course, with a high risk of an intracranial hemorrhage, venous hypertension, and neurological deficits.^4,5 Even in cases of dAVFs without CVR, treatment may be required for patients experiencing intolerable symptoms, such as severe headache, intractable tinnitus, ophthalmoplegia, and/or decreased vision.⁶

Endovascular embolization is frequently the first-line treatment for dAVFs, as it allows for targeted occlusion of the fistulous points with minimal invasiveness. However, in cases where endovascular approaches have failed or are deemed unsuitable due to the angioarchitecture of the fistula, microsurgical resection remains a viable and potentially curative option.^7,8 This approach involves the precise identification and obliteration of the fistulous points and associated vessels, thereby eliminating the abnormal shunt and restoring normal cerebral hemodynamics.⁹

This video outlines the surgical steps involved in the microsurgical resection of an intracranial dAVF in a 74-year-old male patient, highlighting the importance of meticulous planning, intraoperative imaging, and precise dissection techniques. The patient has previously undergone embolization, but recurrence occurred despite the initial treatment and patient symptoms liked headaches and weakness restarted. A decision was made to perform microsurgical resection of dAVF. The video provides a comprehensive illustration of this procedure, emphasizing the value of microsurgery as a definitive treatment modality for these challenging clinical scenarios.

Preoperative imaging, such as computed tomography (CT) angiography is thoroughly reviewed to determine the location, angioarchitecture, and venous drainage patterns of the dAVF. The surgical procedure begins with patient positioning and preparation. The patient is set up in a supine position with the head higher than the heart level. A skin incision is made in a straightforward manner. The neuronavigation systems are employed to precisely localize the dAVF and plan the optimal craniotomy size and trajectory. To reach the surgical site, a solitary parietal burr hole is created at the predetermined position determined by preoperative imaging and surgical planning. The bone is carefully extracted using a craniotome, through a continuous circular incision that starts and ends at the burr hole. This creates a bone flap that can be temporarily repositioned during the procedure.

Upon completion of the craniotomy, the surgical team proceeds to elevate the flap, revealing unexpected adhesions that warranted a shift to microscopic visualization for enhanced control and clarity. Following the establishment of bleeding control, the surgical team proceeds with the opening of the dura mater. Upon opening the dura, the fistula points are found to be localized more laterally than anticipated. This unexpected anatomical presentation underscores the rationale for performing a wider dural opening, as the precise location of the fistula points cannot always be predicted with 100% accuracy.

However, the surgical procedure unfolds with an unexpected revelation. Upon the initial dural exposure, the two fistula points were immediately encountered, leading to their inadvertent sectioning during the dural opening. Despite this unforeseen occurrence, additional pathological vascular connections are identified. Intraoperative indocyanine green (ICG) angiography is employed to assess vascular flow within the identified vessels. By integrating fluorescence imaging with navigational guidance, the potential locations of fistulas are carefully examined for their anatomical significance. The confirmation of the drainage of veins and the supply of arteries helps to determine the exact locations for intervention. Subsequent excision is performed. The cessation of vascular perfusion in the draining veins, confirmed by ICG angiography, signifies the successful closure of the fistula points. Given the comprehensive nature of the surgical approach and the successful disruption of multiple pathological connections, the prognosis for the patient is deemed highly favorable.

After the successful resection of the dAVF, the final step involves closing the surgical site. The dura is carefully closed using sutures to prevent cerebrospinal fluid leakage. The previously removed bone flap is repositioned and secured in place using titanium plates and screws. The subcutaneous tissue and skin are closed in layers using absorbable and non-absorbable sutures, respectively.

The microsurgical resection of intracranial dAVFs is a complex and technically demanding procedure that requires a thorough understanding of cerebrovascular anatomy, advanced microsurgical skills, and the judicious use of intraoperative imaging modalities. The successful resection of the intracranial dAVF, in this case, underscores the value of microsurgery as a definitive treatment option, particularly in cases where endovascular embolization has failed. By precisely identifying and resecting the dAVF and its associated vessels, the risk of potentially life-threatening complications, such as intracranial hemorrhage or venous hypertension, is prevented. Furthermore, the video serves as an invaluable educational resource for neurosurgeons in training, as well as a reference for experienced practitioners. It emphasizes the importance of maintaining a high level of vigilance and adaptability during the procedure, as unexpected anatomical variations or adhesions may necessitate adjustments to the surgical approach. In conclusion, the microsurgical resection of intracranial dAVFs remains an important treatment method in the field of neurosurgery.

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.