|Year : 2022 | Volume
| Issue : 1 | Page : 91-93
Cortical emissary vein: An important vessel to look for before bone anchored hearing aid implantation
Ahmad Faiz Dahlan1, Izny Hafiz Zainon2, Zhi Xiang Yeoh2, Mohd Khairi Md Daud3
1 Department of Otorhinolaryngology-Head and Neck Surgery, School of Medical Sciences, Universiti Sains Malaysia, Kelantan; Department of Otorhinolaryngology-Head and Neck Surgery, Hospital Sultanah Bahiyah, Kedah, Malaysia
2 Department of Otorhinolaryngology-Head and Neck Surgery, Hospital Sultanah Bahiyah, Kedah, Malaysia
3 Department of Otorhinolaryngology-Head and Neck Surgery, School of Medical Sciences, Universiti Sains Malaysia; Hospital Universiti Sains Malaysia, Health Campus, Kelantan, Malaysia
|Date of Submission||03-Oct-2021|
|Date of Decision||08-Dec-2021|
|Date of Acceptance||03-Jan-2022|
|Date of Web Publication||25-Apr-2022|
Dr. Mohd Khairi Md Daud
Department of Otorhinolaryngology-Head and Neck Surgery, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan
Source of Support: None, Conflict of Interest: None
Bone anchored hearing aid (BAHA) is a device that combines a sound processor with a small titanium fixture implanted at the mastoid area. It is indicated for those having conductive hearing loss, especially in those not suitable for hearing aids. Emissary veins are residual connections between intracerebral veins and their extracranial drainage. The vein may be injured at the time of drilling procedure such as during insertion of implant at the mastoid area. We report a case of difficult BAHA surgery after encounter with cortical emissary vein. Mastoid emissary vein is a rare but definite entity which if not diagnosed preoperatively could be a cause of severe hemorrhage intraoperatively.
Keywords: Bone conduction hearing, emissary vein, hearing loss
|How to cite this article:|
Dahlan AF, Zainon IH, Yeoh ZX, Md Daud MK. Cortical emissary vein: An important vessel to look for before bone anchored hearing aid implantation. Indian J Otol 2022;28:91-3
|How to cite this URL:|
Dahlan AF, Zainon IH, Yeoh ZX, Md Daud MK. Cortical emissary vein: An important vessel to look for before bone anchored hearing aid implantation. Indian J Otol [serial online] 2022 [cited 2022 May 18];28:91-3. Available from: https://www.indianjotol.org/text.asp?2022/28/1/91/343750
| Introduction|| |
Bone anchored hearing aid (BAHA) is a device that combines a sound processor with an osseointegrated titanium implant. It works via efficient coupling of the sound processor to the underlying bony structure through a small connector across the skin. The vibration is absorbed by the skull and directly stimulates the cochlea bypassing the external acoustic meatus and the middle ear. The indications of BAHA include conductive hearing loss due to anatomical abnormalities of the canal or middle ear, draining ear, mixed hearing loss, and single-sided deafness. The first implantation was reported by Tjellström and Granström in 1977. It has been estimated that more than 100,000 patients have been implanted worldwide. We report a case of difficult BAHA surgery after encounter with cortical mastoid emissary vein.
| Case Report|| |
A 13-year-old boy presented with reduced hearing over his bilateral ears since childhood. However, speech development was normal. There was no history of ear discharge, family history of congenital hearing loss, history of head and ear trauma, and no significant medical history. On examination, the patient was clinically comfortable. Ear examination and otoscopic findings were normal. Facial nerve was intact. Throat and nose examinations were unremarkable. Pure tone audiometry performed showed bilateral reversed sloping mild-to-moderate conductive hearing loss [Figure 1]. High-resolution computed tomography (HRCT) temporal was reported normal middle and inner ear structures as well as mastoid air cells on both sides.
|Figure 1: Preoperative audiogram showing right mild-to-moderate reversed sloping conductive hearing loss with large air–bone gap|
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The patient underwent right endoscopic exploratory tympanostomy. The middle ear inspection revealed the absence of the stapes suprastructure and the stapes footplate. The handle of malleus and the long process of incus were normal. Subsequently, the patient was offered and agreed to the right BAHA. In his case, BAHA Connect has been chosen. Intraoperatively, a cruciate incision was made over periosteum about 6 cm and 30° from the right ear canal. The area was drilled using a guide drill with a 3 mm spacer. Oozing of blood occurred when the drilling reached the spacer. Hemostasis was secured by bone wax. Similar bleeding episode occurred when another cruciate incision was done at 1 cm further as well as at 1 cm inferior to the first drilled site. Finally, the implant was successfully implanted at 5 cm and 30° from the ear canal [Figure 2]. Postoperative period was uneventful. On reviewing back, HRCT temporal postoperatively, it has been noted that there was present of venous sinus at the right cortical region [Figure 3]. Audiological assessment done after 12 weeks postoperatively revealed hearing level within the speech spectrum.
|Figure 2: Intraoperative photo showing the implant at 5 cm and 30° from the ear canal (arrow)|
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|Figure 3: High-resolution computed tomography temporal image showing the presence of right cortical venous sinus (arrow)|
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| Discussion|| |
Emissary veins are residual connection between intracerebral veins and their extracranial drainage. The vein originates from sigmoid sinus and communicates with extracranial veins. The emissary veins run reversely the skull by the foramina and connect directly between the superficial veins of the scalp and dura venous sinuses. There are no valves in these blood vessels. The blood may flow in both directions even though generally it flows from outside to inside. The cortical mastoid emissary vein may be opened during incision or stripping of the periosteum in various operative procedures, including BAHA or mastoidectomy. Therefore, it is very crucial to look for the presence of emissary vein in diploic skull bone on HRCT. The information will give a surgeon an idea of the safe surgical site for drilling over the mastoid area. Extra precaution taken may help prevent complications such as multiple hemorrhage and uncontrolled bleeding.
Nevertheless, BAHA procedure generally is considered less invasive as compared to mastoid surgery. To the best of our knowledge, this is the first reported case of bleeding during BAHA surgery secondary to involvement of the mastoid cortex emissary vein. However, Rauf et al. have reported a case of profuse bleeding during modified radical mastoidectomy secondary to injury of giant mastoid emissary vein. In their case, the bleeding was not controlled by routine methods such as local pressure, gel foam pack, and electric cauterization. At last, the bleeding was managed by keeping a surgical packing in the lumen of the vessel.
There are many factors that influence the successful of osseointegration which include the quality of bone at the site of implantation, the surgical factors, and the material used. The implant must be kept completely stable during the initial period of osseointegration. The osseointegration may fail due to the formation of a fibrous capsule around the implant. The intraoperative risks associated with BAHA surgery include insufficient thickness of temporal squamous, bleeding from emissary vein, injury to the dura leading to cerebrospinal fluid leakage, as well as subdural hematoma. Bleeding from diploic bone usually can be easily controlled using adrenalin-soaked gel foam and application of bone wax.
| Conclusion|| |
BAHA is an excellent hearing aid which shows its usefulness if candidates are appropriately selected. Mastoid emissary vein is a rare but definite entity which if not diagnosed preoperatively could be a cause of severe hemorrhage intraoperatively.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2], [Figure 3]