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

Mobilization of the Anterior Inferior Cerebellar Artery When Firmly Adherent to the Petrous Dura... Abstract 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. Vestibular schwannoma, Anterior inferior cerebellar artery, Retrosigmoid approach, Transmeatal approach, Internal acoustic canal, Vessel adherence to dura mater, Vascular mobilization/transposition View largeDownload slide Watch now at https://academic.oup.com/ons/article-lookup/doi/10.1093/ons/opy052 View largeDownload slide Watch now at https://academic.oup.com/ons/article-lookup/doi/10.1093/ons/opy052 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 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 Close Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Lang J. Clinical Anatomy of the Posterior Cranial Fossa and its Foramina  New York, NY: Thieme Medical Publishers Inc, 1991. 2. Tanriover N, Rhoton AL Jr. The anteroinferior cerebellar artery embedded in the subarcuate fossa: a rare anomaly and its clinical significance. Neurosurgery . 2005; 57( 2): 314- 319. Google Scholar CrossRef Search ADS PubMed  3. Hitselberger WE, House WF. Acoustic neuroma diagnosis. External auditory canal hypesthesia as an early sign. Arch Otolaryngol . 1966; 83( 3): 218- 221. Google Scholar CrossRef Search ADS PubMed  COMMENTS We enjoyed viewing this concise video that well demonstrates a very important anatomic variation that can be encountered when operating a vestibular schwannoma (VS). We also have encountered the main loop of AICA adherent within the petrous dura. As the authors expertly demonstrate, it is important to recognize this and be able to mobilize the artery safely away, leaving a safe cuff of dura around the vessel, to gain access to the tumor and, in particular, the intracanalicular portion. Our informal anatomic study of this variation, and clinical impression from encountering it in our practice, is that the reason AICA is sometimes encountered in this way is because the labyrinthine artery is very short. In our experience, this can make it very difficult to mobilize AICA without having to sacrifice the labyrinthine artery which theoretically markedly increases the risk of losing hearing during the operation. Rarely, we have also encountered AICA completely within the internal auditory canal or partly surrounded by bone, and it is necessary to drill before mobilization of the artery is safely accomplished. The authors are to be congratulated on their demonstration of the technique of mobilization of AICA when it is adherent to the dura surrounding the internal auditory canal and on their excellent clinical result. We would implore authors to report pre- and postoperative speech discrimination scores when reporting hearing outcomes in VS patients. Michael J. Link Maria Peris-Celda Rochester, Minnesota In this surgical video, the authors present their strategy for managing an AICA that is adherent to the petrous dura encountered in a retrosigmoid approach for resection of a vestibular schwannoma. As the authors mention, though the AICA is usually freely within the cerebellopontine cistern, in 6% of patients it may be adherent to the petrous dura. Importantly mentioned in the video is the identification of this AICA orientation on preoperative imaging. This anomaly presents an obstacle to drilling of the suprameatal tubercle and access to the IAC. The authors beautifully demonstrate a technique for mobilization of the AICA - incising the petrous dura allowing its elevation and mobilization of the dura and AICA together. As shown in the video, this mobilization medially allows access to the IAC without risk to the artery. Replacement of the artery to its native position at the conclusion of the surgery further helps to avoid kinking and subsequent vascular insult. The authors should be commended on their creative and effective technique to manage an unusual, albeit important, anomaly of the AICA that may be encountered during a retrosigmoid approach to vestibular schwannomas. Jacques J. Morcos Miami, Florida Copyright © 2018 by the Congress of Neurological Surgeons http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Operative Neurosurgery Oxford University Press

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

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Publisher
Oxford University Press
Copyright
Copyright © 2018 by the Congress of Neurological Surgeons
ISSN
2332-4252
eISSN
2332-4260
D.O.I.
10.1093/ons/opy052
Publisher site
See Article on Publisher Site

Abstract

Abstract 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. Vestibular schwannoma, Anterior inferior cerebellar artery, Retrosigmoid approach, Transmeatal approach, Internal acoustic canal, Vessel adherence to dura mater, Vascular mobilization/transposition View largeDownload slide Watch now at https://academic.oup.com/ons/article-lookup/doi/10.1093/ons/opy052 View largeDownload slide Watch now at https://academic.oup.com/ons/article-lookup/doi/10.1093/ons/opy052 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 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 Close Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Lang J. Clinical Anatomy of the Posterior Cranial Fossa and its Foramina  New York, NY: Thieme Medical Publishers Inc, 1991. 2. Tanriover N, Rhoton AL Jr. The anteroinferior cerebellar artery embedded in the subarcuate fossa: a rare anomaly and its clinical significance. Neurosurgery . 2005; 57( 2): 314- 319. Google Scholar CrossRef Search ADS PubMed  3. Hitselberger WE, House WF. Acoustic neuroma diagnosis. External auditory canal hypesthesia as an early sign. Arch Otolaryngol . 1966; 83( 3): 218- 221. Google Scholar CrossRef Search ADS PubMed  COMMENTS We enjoyed viewing this concise video that well demonstrates a very important anatomic variation that can be encountered when operating a vestibular schwannoma (VS). We also have encountered the main loop of AICA adherent within the petrous dura. As the authors expertly demonstrate, it is important to recognize this and be able to mobilize the artery safely away, leaving a safe cuff of dura around the vessel, to gain access to the tumor and, in particular, the intracanalicular portion. Our informal anatomic study of this variation, and clinical impression from encountering it in our practice, is that the reason AICA is sometimes encountered in this way is because the labyrinthine artery is very short. In our experience, this can make it very difficult to mobilize AICA without having to sacrifice the labyrinthine artery which theoretically markedly increases the risk of losing hearing during the operation. Rarely, we have also encountered AICA completely within the internal auditory canal or partly surrounded by bone, and it is necessary to drill before mobilization of the artery is safely accomplished. The authors are to be congratulated on their demonstration of the technique of mobilization of AICA when it is adherent to the dura surrounding the internal auditory canal and on their excellent clinical result. We would implore authors to report pre- and postoperative speech discrimination scores when reporting hearing outcomes in VS patients. Michael J. Link Maria Peris-Celda Rochester, Minnesota In this surgical video, the authors present their strategy for managing an AICA that is adherent to the petrous dura encountered in a retrosigmoid approach for resection of a vestibular schwannoma. As the authors mention, though the AICA is usually freely within the cerebellopontine cistern, in 6% of patients it may be adherent to the petrous dura. Importantly mentioned in the video is the identification of this AICA orientation on preoperative imaging. This anomaly presents an obstacle to drilling of the suprameatal tubercle and access to the IAC. The authors beautifully demonstrate a technique for mobilization of the AICA - incising the petrous dura allowing its elevation and mobilization of the dura and AICA together. As shown in the video, this mobilization medially allows access to the IAC without risk to the artery. Replacement of the artery to its native position at the conclusion of the surgery further helps to avoid kinking and subsequent vascular insult. The authors should be commended on their creative and effective technique to manage an unusual, albeit important, anomaly of the AICA that may be encountered during a retrosigmoid approach to vestibular schwannomas. Jacques J. Morcos Miami, Florida Copyright © 2018 by the Congress of Neurological Surgeons

Journal

Operative NeurosurgeryOxford University Press

Published: Mar 29, 2018

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