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Final Program


General Surgery

Mastoid emissary veins: A rare source of high-volume intraoperative bleeding during bone anchored hearing aid implantation

Location: Grandball Room 1-2
Introduction/Purpose: Bone anchored hearing aids (BAHA) are used in cases of conductive or mixed hearing loss to bypass the mechanics of the middle ear. BAHAs are typically surgically placed 2 cm posterior and 1 cm superior to the ear to avoid the sigmoid sinus which lies posterior to the ear and is large. Emissary veins are valveless structures that provide bidirectional flow, can vary in distribution between individuals, and are named for the foramina they traverse. In particular, the mastoid emissary vein passes into the mastoid foramen and connects the sigmoid sinus to the posterior auricular or occipital veins. The anatomical variability of the mastoid emissary vein poses a potential for intraoperative bleeding during surgical insertions of BAHAs.

Methods or Case Description: We report a rare case of large volume intraoperative bleeding in an 84-year-old female undergoing left BAHA implantation. The placement of the BAHA was reattempted for a total of 3 attempts due to massive bleeding during numerous anatomical corrections after multiple attempts of repositioning the drill 1 cm above the original location. Upon aborting the case, post-operative CT revealed a large diameter vessel coursing along the surgical field, which is consistent with a mastoid emissary vein, and ruled out intracranial bleeding.

Outcomes:


Here, we describe a case of large volume intraoperative hemorrhage secondary to repeated injury of a mastoid emissary vein. The placement of the BAHA was reattempted for a total of 3 attempts, each resulting in high volume bleeding controlled with bone wax. Ultimately, the case was aborted and a post-operative CT revealed a large diameter vessel coursing along the surgical field which is consistent with a mastoid emissary vein. Although the presence of such a large vein is rare, it is crucial the surgeon is aware of its existence and this case draws attention to the role of pre-operative imaging in cases of BAHA implantation. Appreciation of the mastoid emissary vein's proximity to area of surgical intervention, and it's potential for anatomic variation between patient to patient raises the importance for pre-operative imaging.

Conclusion: Although anatomical variations of the mastoid emissary vein are not a common surgical issue during placements of BAHAs, this case emphasizes the importance of preoperative imaging to avoid intraoperative complications. High volume blood loss and other surgical complications can alter the course of the procedure, decrease patient satisfaction, and/or lead to further complications. Preoperative imaging prior to BAHA implants and other similar surgical procedures can decrease adverse events and improve patient satisfaction.