Intraoperative Management of Double Anterior Inferior Cerebellar Artery Vascular Loops Adherent to Dura During Vestibular Schwannoma Resection: 2-Dimensional Operative Video

Abstract

Although vestibular schwannoma is a benign entity and the most commonly encountered cerebellopontine angle mass lesion, it is a diverse disease. 1,2 Microsurgical management of vestibular schwannoma requires technical mastery and a nuanced ability to respond to dynamic neuroanatomic conditions. [3][4][5][6] One such anatomic variation of note is the presence of an anterior inferior cerebellar artery (AICA) vascular loop near cranial nerves VII and VIII. 7,8 Here, we report an unusual case in which we encountered 2 loops of AICA adherent to the dura during resection of a vestibular schwannoma. The patient is a 31-year-old female with a history of right-sided hearing loss, who was diagnosed with a presumed vestibular schwannoma on MRI. The decision was made to perform a hearing preservation surgery using a right retrosigmoid craniotomy. The patient consented to this procedure. Unexpectedly, we encountered 2 AICA loops that were found to be tethered to the petrous temporal dura. Both AICA loops were displaced and protected from the surgical plane by creation and subsequent reflection of dural flaps. The remainder of the procedure proceeded in a routine fashion, and a gross total resection was achieved. Postoperatively, the patient had intact House-Brackmann grade 1 facial nerve function, as well as subjectively preserved hearing. The patient has been diseasefree for more than 4 years, and there has been no evidence of tumor recurrence or additional hearing loss. Overall, this video demonstrates strategies for management of this uncommon but potentially dangerous anatomic variant, alongside a hearing-preserving resection of the patient's moderately large vestibular schwannoma. Images at 3:03 reused with permission.

Anatomic Variants in the Anterior Inferior Cerebellar Artery Encountered During Resection of Vestibular Schwannomas

“…Many reports of AICA variants are case reports or small cohort series, although several provide valuable technical notes. 8,9,[14][15][16][17] Careful surgical consideration should be given for how to manage these variants when encountered during surgery, not only for risk to the primary artery but also additional important branches including the labyrinthine artery and brainstem microvascular perforators, which may limit manipulation of AICA during VS resection. Pending the discrete arterial location, an AICA stroke may cause lateral pontine syndrome.…”

Commentary: Intraoperative Management of Double Anterior Inferior Cerebellar Artery Vascular Loops Adherent to Dura During Vestibular Schwannoma Resection: 2-Dimensional Operative Video

“…Both were gently handled by raising small dural flaps around their area of attachment, thereby reducing the risk of injury to the small and fragile vessels. 3 As reported in the literature, discerning the position of the AICA relative to the VS is a key to avoiding cerebellar or brainstem infarctions. For instance, in a case series of 150 patients who underwent microsurgical treatment of VS using a retrosigmoid approach, 7% of cases were found to have challenging AICA anatomy.…”

“…Their skillful, careful, and gentle mobilization of the 2 loops by raising 2 small dural flaps likely contributed to the excellent outcome. 3…”

“…These cases were managed successfully by preserving the AICA with dura and displacing it rostrally, like the surgical nuances used by the authors of the video. 3 Interestingly, more challenging scenarios may present where the AICA loop is not only adhered but also embedded into the dura and bone of the fossa subarcuata. 14 These considerations must be recognized to preserve AICA integrity, as injury to this vessel, although rare, can result in microvasculature and macrovasculature infarctions leading to vertigo, vestibular dysfunction, tinnitus, hearing loss, facial paralysis, and dysmetria.…”

“…Their skillful, careful, and gentle mobilization of the 2 loops by raising 2 small dural flaps likely contributed to the excellent outcome. 3 VSs arise mostly from the myelin sheath of the inferior division of the vestibulocochlear nerve and represent approximately 80% of lesions originating in the CPA. 1,2 Over the past half century, the incidence of VSs has increased from 1.5 to 4.2 per 100 000 person-years, 4 largely because of the more common utilization of MRI; however, attributable environmental factors have also been a controversial matter of discussion.…”