Mobilization of the Anterior Inferior Cerebellar Artery When Firmly Adherent to the Petrous Dura Mater-A Technical Nuance in Retromastoid Transmeatal Vestibular Schwannoma Surgery: 3-Dimensional Operative Video.

The anterior inferior cerebellar artery (AICA) usually runs loosely within the cerebellopontine cistern; in rare cases, however, it is firmly adherent to the petrous dura mater.1,2 Recognizing this variation is particularly important in vestibular schwannoma surgery via the retrosigmoid transmeatal approach to prevent the high morbidity associated with vascular injury. This video demonstrates a surgical technique to effectively mobilize the AICA when firmly adherent to the petrous dura mater. A 39-year-old man presented with a history of progressive right-sided hearing loss without facial weakness or other associated symptoms3. Magnetic resonance imaging (MRI) demonstrated an intracanalicular lesion, suggestive of vestibular schwannoma. During follow-up, audiometry confirmed a further slight deterioration of hearing and repeated MRI demonstrated tumor growth (T2 according to Hannover classification). Since the patient opted against radiosurgery, a retrosigmoid transmeatal approach under continuous intraoperative monitoring was performed in supine position. Following drainage of cerebrospinal fluid and exposure of the cerebellopontine cistern, the AICA was found to be firmly adherent to the petrous dura mater. Both structures were elevated conjointly and displaced medially for safe drilling of the inner auditory canal, sufficient exposure, and complete excision of the vestibular schwannoma. The patient had an excellent recovery, hearing and facial function were preserved, and no secondary neurological deficits noted.The patient consented to publication of this anonymized video.