Manuscript: Authors: Journal: Indications and contra-indications of auditory brainstem implants. Systematic review and illustrative cases Merkus P (p.merkus@vumc.nl), Di Lella F, Di Trapani G, Pasanisi E, Beltrame MA, Zanetti D, Negri M, Sanna M European Archives of Oto-Rhino-Laryngology Full description of cases presented in Table 1 and Fig 1 Case A A 41 year old male had progressive SNHL since childhood on the right side, resulting in anacusis since 20 years of age. In another center in 2003 the patient was counseled for an extrameatal 1.5cm vestibular schwannoma in the only hearing left side. He underwent a suboccipital removal of and placement of ABI soon after. Following surgery he had a left sided total hearing loss and facial nerve palsy grade III (House Brackmann). The patient mentioned that immediately after surgery the ABI worked sufficiently for basic speech comprehension, but function declined over time. In 2010, during a second opinion, a CT scan revealed bilateral cochlear patency. Because the ABI was only used for environmental sound detection and lip-reading he was scheduled for CI in the right ear in March 2010 at the Parma University Hospital, Parma, Italy. The results of this right-sided CI after 6 months were words recognition 75%, sentences 60% and daily use of the CI, no use of ABI. Case B In early 2009 a 37 years old man affected by bilateral cochlear otosclerosis was evaluated at the Gruppo Otologico. He had previously been operated for a left side ABI through a suboccipital approach in another department without benefit on hearing. Audiological evaluation demonstrated anacusis in the left ear and a mixed hearing loss on the right side with a bone conduction PTA of 50 db (only on 500 and 1000 Hz) and an air conduction PTA of 95 db with 65% speech discrimination. He rarely used his left sided ABI for lip-reading support and was depending on his hearing aid in the right ear. A CT scan was performed confirming the diagnosis of cochlear otosclerosis but showing the presence of a patent cochlear lumen although typical bone remodeling was evident, graded a retrofenestral otosclerosis type 2a [Rotteveel et al.,2004] (Fig. 2) 21. A CI was then performed in the left side, the same side as the ABI. In September 2009 a CI was completely inserted in the left cochlea through a standard transmastoid facial recess approach. The patient is currently using the left CI and the right hearing aid. With this bimodal stimulation he has satisfactory results.
Case C A thirty year old man with bilateral cochlear otosclerosis was advised to undergo either stapedotomy or ABI in another department. After 10 days from the first visit he was scheduled for ABI in the left ear. Preoperative hearing was PTA 65 db sloping on higher frequencies with an ABG of 10dB; Speech discrimination was 100% in both ears although at different loudness (60dB right ear and 80dB left). After placement of the ABI at the other department, 4/22 electrodes could be used and there were numerous fitting problems and lower cranial nerves stimulations. Overall there was no benefit from the ABI, resulting in non usage. The patient was evaluated in the department of Otolaryngology, University of Brescia, Italy in June 2010: PTA 90 db with high frequency slope; no measurable ABG. With a hearing aid on this right ear a speech discrimination of 50% was reached. A hearing aid on the operated left ear still gives some results. The patient has received a CI, especially because imaging shows cochlear remodeling, but still a patent cochlea. Images of this patient resemble Fig 2. Speech performance with CI is 60% and no use of ABI. Case D A 60 years old female, with a history of bilateral stapedectomy, was using bilateral hearing aids because of right-sided profound SNHL and left-sided profound mixed hearing loss. In 2003 the patient was evaluated in another department and an ABI was placed through a suboccipital craniotomy on the right side. There was no functional hearing result and her hearing aid on the right side was not usable anymore as a result of the ABI implant surgery of that ear. In 2010 she was evaluated at the Gruppo Otologico and a CT scan was performed, revealing bilaterally patent morphologically normal cochleae on both sides. ABI was not routinely used and she relied on her left hearing aid. After adequate adjustment of her hearing aid, her hearing ability improved substantially with a words-, and sentences recognition score of 60% and 100% respectively and comprehension of 100%. Case E Male, 68 years old and proven bilateral cochlear otosclerosis on CT scan. He used a hearing aid in the left ear. In 2005 he received an ABI in another department through a suboccipital approach on the right side with no functional results. In 2009 a CT scan performed in S.Maria del Carmine Hospital, Rovereto, Italy, which showed bilateral mild retrofenestral otosclerosis with patent cochleae (type 2a retrofenestral otosclerosis). Audiological evaluation showed profound SNHL on the right and severe to profound SNHL on the left. During early 2009 right side cochlear implant was performed and in 2010 the second side was implanted in Rovereto, both with complete insertion of the array.
At last audiological follow up, 2 years after first CI placement, words- and sentences recognition scores were almost 100% with open set comprehension and telephone use. The ABI was never used/ useful. Case F A male of 55 years old, with a history of post-meningitis right sided SNHL at the age of 12. He received no hearing aids after meningitis. In October 2006 he had a traumatic transverse petrous bone fracture on the left ear (otic capsule involved) resulting in total bilateral deafness. In another clinic he was admitted for a left side ABI through a retrosigmoisd approach in 2006 with 6 out of 21 active electrodes. Word recognition score postimplantation was maximal 35% (with auditory and visual stimulation). Free field PTA was 55 db with no speech discrimination. Due to the dissatisfactory result in September 2009 he visited the University of Parma, Parma, Italy, where they discovered a cochlear patency in the right ear and a partially obliterated cochlea on the contralateral side. In Parma in November 2009 a CI was placed in the right cochlea making it possible again for him to use the telephone on that side (word recognition: 85%, sentences: 90%). Case G A female of 40 years old had a head trauma in 2001 resulting in total bilateral deafness and left facial nerve palsy. The diagnosis of a disruption of both cochlear nerves without any radiological evidence was made in another department and an ABI was inserted through a suboccipital craniotomy in the right side (2002). She had no hearing sensation with her ABI, resulting in no use of it. In 2006 she was evaluated at the Gruppo Otologico; CT and MRI showed totally obliterated cochlea on the left side but an open fluid-filled cochlea on CT and MRI on the right side with an intact nerve on both sides. A CI was subsequently implanted on the right side in 2006, resulting in a word-, and sentences recognition score of 40% and daily use of CI and not the ABI. (Fig 3) Case H A male of 61 years old had an acute bilateral total deafness due to a head trauma in 2001. In 2002 he received in another department an ABI on the right side with early satisfactory audiological results that declined rapidly over time. Word recognition score postoperatively was maximal 60% and in 2010 only vowels where recognized without word recognition. In retrospective, there was no visible otic capsule fracture present and also both cochlea were patent.(fig 4) The only justified diagnosis to try an ABI would then have been a theoretical bilateral cochlear nerve disruption. In June 2010 we performed an uncomplicated
CI in the right ear, as the MRI did not show any disruption of the nerves. At last audiological follow up (6 months after surgery) the patient showed an open set speech recognition of 65% and daily use of CI. Case I A 55 years old medical doctor has become totally deaf after a severe accident in March 2010. Skull imaging showed bilateral temporal bone fractures (resemble Fig 4). To investigate the possibility for CI also MR imaging was performed showing fluid filled cochleae and intact cochlear nerves. Three months after his trauma he received bilateral CI. Six months postoperatively his speech discrimination scores are 45% (right CI) and 85% (left CI). Bilateral use of CI result in a 100% speech discrimination. ABI has not been considered in this patient with a bilateral otic capsule fracture. Case J The progressive hearing loss of a 31 years old female with Cogan syndrome became total deafness in 2002. She received in another center a right side ABI in 2003 resulting in a word recognition score of 30%, sentence discrimination of 48% and comprehension score of 60% (test performed with auditory and visual stimulation). In our clinic the CT and MRI (after magnet removal) showed open cochleae on both sides (Online resource 4), postoperative images resemble the images of Online resource 5 In 2008 a cochlear implant was placed in the left ear, leading to very satisfactory results and regaining her ability to listen to the television and use the telephone. At last follow-up audiological scores were: identification 100%, words 100%, sentences 100%, comprehension 100%, telephone use. Although in auto-immune inner ear disease like in this case of Cogan calcification can occur but a bilateral fully obliterated cochlea has not been reported. As shown in this case there was no reason for an ABI. Case K A female of 16 years old (who was adopted), had hereditary profound bilateral hearing loss since childhood. She received in 2005 an ABI on the left side, performed elsewhere, resulting in vowel recognition of 50% and no word recognition. During fitting she encountered an epileptic insult and in 2007 myoclonia of left face, arm and leg. CT and MRI performed at our clinic in November 2009 showed a patent cochlea and intact nerves on both sides. She received a CI in January 2010 in the left ear and is still improving her hearing ability (vowels identification 75%, word recognition 30%). Postoperative CT scanning shows the incorrect and right means of rehabilitation in the same ear (Online resource 5).
Case L A female of 69 years old with profound bilateral SNHL due to sudden deafness on the left side in 2002 and progressive SNHL in the right ear. In 2003 she received in another center an ABI on the left side complicated by temporary cerebellar edema, palpebral ptosis and dyplopia immediately after surgery. Maximal words recognition score with ABI was 45%. In January 2010, she went to Ramazzini Hospital, Carpi, Italy, were a patent cochlea was revealed and a CI was placed in the right ear without any complications. After 10 months her scores were 100% vowels recognition, 80% word recognition and 80% comprehension. There is a daily use of the CI, the ABI is not used anymore. Case M A male of 60 years old, with progressive SNHL since childhood in both ears resulted in hearing aids with functional hearing. When he went to a clinic to improve his hearing, he was scheduled for an ABI at the right side resulting in total hearing loss at that side. Only 5 of 21 electrodes had active acoustical response and a maximal word recognition score of 40%. When he came to our clinic we revealed that both cochleae were patent. Images resemble Online resource 4. He was scheduled for a CI in the right ear, but has now withdrawn from the waiting list because he is afraid that it will not work again. Case N A male of 45 years old had asymmetrical SNHL due to a common cavity on the left side. He received an ABI elsewhere on the right side in 2006 with no functional results. His preoperative hearing prior to ABI placement is unknown. At consultation at our clinic, CT and MRI proved a patent and normal anatomy and patency of the cochlea on the right side. He is therefore scheduled for a right side CI. There is also an intact nerve at the side of the common cavity and lateral wall cochlear electrode stimulation could also be suggested in this case. In this case ABI should not have been performed or even suggested. Unfortunately he has postponed the CI surgey several times and is anxious for the surgery due to the inconvenient surgical experience before.