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| CASE REPORT |
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| Year : 2019 | Volume
: 25
| Issue : 3 | Page : 169-172 |
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Hearing loss in a child with cystic dilated internal auditory canal
Muath Alsabih, Khalid Alosaimi, Roa Halawani, Farid Alzhrani
King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh, Saudi Arabia
| Date of Submission | 25-Dec-2018 |
| Date of Acceptance | 26-Mar-2019 |
| Date of Web Publication | 18-Oct-2019 |
Correspondence Address:
Dr. Muath Alsabih
College of Medicine, King Saud University, Riyadh
Saudi Arabia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/indianjotol.INDIANJOTOL_127_18
We report a detailed retrospective chart review of a case of a child with bilateral enlarged cystic-like internal auditory canals (IACs) displaying profound sensory neural hearing loss. He was subsequently treated with cochlear implantation (CI) in one ear, thereby causing his hearing to improve. As far as we are aware, this is the first such case in the world that has been reported of a patient with cystic-like IACs.
Keywords: Cochlear implant, congenital hearing loss, internal auditory canal malformation, wide internal auditory canal
How to cite this article:
Alsabih M, Alosaimi K, Halawani R, Alzhrani F. Hearing loss in a child with cystic dilated internal auditory canal. Indian J Otol 2019;25:169-72 |
| Introduction | |  |
Having enlarged internal auditory canals (IACs) is a rare congenital variant and is a condition which is generally characterized by the appearance of bilateral, symmetrical, patulous IACs.[1] The condition may be clearly visualized, either alone or in combination with other anomalies of the cochlea and labyrinth.[2] In infants and children with severe to profound sensory neural hearing loss (SNHL), cochlear implantation (CI) surgery may cause an improvement in sound and speech perception abilities and therefore remains the best modality of management. Herein, this paper shall report the case of a child who presented with bilateral profound SNHL and enlarged cystic IAC on both sides. To the best of our knowledge, this is the first pediatric case in the world with the radiological manifestation: cystic dilated IAC.
| Case Report | | |
A 6-year-old boy was diagnosed as having congenital hearing loss at the age of 2. He was given a confirmed diagnosis of bilateral profound SNHL and was referred to King Abdullah Ear Specialist Center in 2016 for Precochlear Implant evaluation. The patient's physical examination, birth history, and developmental history were all unremarkable. There was no family history of any particular hearing abnormality or any history of his parent's consanguinity. Moreover, the patient did not demonstrate evidence of recurrent ear discharge, meningitis, or trauma. Hearing aids were prescribed for 3 months after visiting our institute without any consequent benefit.
Tympanometry showed “Type A” bilaterally. The auditory brainstem response as well as visual reinforcement audiometry showed profound bilateral hearing loss. High-resolution computed tomography (CT) scanning of the temporal bone showed bilateral dilated cystic-like IAC with normal looking cochlea without any associated dysplasia of the labyrinth [Figure 1]. This was confirmed upon magnetic resonance imaging [Figure 2]. Cerebrospinal fluid (CSF) collections were seen in the enlarged IACs, and its contents (the facial nerve, cochlear nerve, and superior vestibular and inferior vestibular nerves) were present on both sides. | Figure 1: Computed tomography scanning of the temporal bone showing bilateral dilated cystic-like internal auditory canal (arrow) with a normal looking cochlea
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 | Figure 2: A magnetic resonance imaging scan of the internal auditory canal showing a cochlear nerve present bilaterally and symmetrical cystic dilation of both internal auditory canals. A bilaterally preserved cerebellopontine angle along with the inner ear structures including cochlea, vestibule, and semicircular canal may also be observed
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The patient was subsequently reviewed by the CI committee at our center and was accepted for bilateral sequential CI treatment. Due to his inner ear anomalies, the patient was anticipated to experience a CSF gusher intraoperatively, which was explained to the family before surgery. CI was performed with a small postauricular incision (<5 cm), cortical mastoidectomy and posterior tympanotomy through the facial recess. Extended posterior tympanotomy was needed to identify the round window which was hidden. No gusher or ooze of CSF after opening the round window was encountered during the procedure. Smooth and complete insertion of the straight electrode was achieved. The intraoperative neural response telemetry (NRT) response was negative in all electrodes; therefore, the position of the electrode was confirmed by an intraoperative X-ray mastoid [Figure 3] and CT scan on the 2nd-day postsurgery [Figure 4]. | Figure 3: An intraoperative X-ray showed that the left-sided cochlear implant was in a correct position
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 | Figure 4: A postoperative computed tomography scan showed that the left-sided cochlear implant was in situ
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Three weeks' postoperation, the device programing began and the patient began responding to sounds. Ten weeks' postimplantation, an NRT response was present in all electrodes except 13, 14, and 16. Six months later, the NRT response was negative only in electrode 16. Significantly, the patient exhibited a positive response in speech-language therapy and was able to detect sounds generated using instrumental music as well as initiation and termination sounds. The patient showed fair six ling sound discrimination and was able to say the words “mama” and “baba”.
| Discussion | | |
Congenital ear anomalies can affect any portion of the ear; however, the IAC is rarely affected.[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13] The anomalies reported in the literature include the narrowing, dilation, absence, anteversion, verticalization, and presence of double IACs [Table 1]. The present case is a new variant of IAC malformations. Nevertheless, dilated IACs are extremely rare and are not always associated with SNHL.[5],[13] A study conducted on 645 patients (50% of them with SNHL) revealed only two patients with a dilated IAC along with concomitant SNHL.[5],[16] The presence of patulous canals in SNHL patients of unknown etiology and strikingly dilated IACs in both ears of an elderly patient with profound SNHL that had begun very early in life have also been reported.[17],[18] Dilated IAC could also be associated with pathological causes such as acoustic neuroma; sometimes, the dilated IAC is associated with syndromes such as Patau syndrome More Details. | Table 1: Comparison between internal auditory canal anomalies and their associations with labyrinth anomalies and hearing loss
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NRT testing can be used to determine the readaptation and recuperation of the cochlear nerve fibers after continued stimulation. The case under the study revealed an intraoperative negative NRT response, which is not correlated with future performance.[19] We are, therefore, in agreement with the findings of a previous study, which suggests that there is no significant correlation between intraoperative NRT and speech perception performance at 1 year, and the absence of NRT does not necessarily indicate a lack of stimulation. Similarly, in the current study too, although the NRT response was negative intraoperatively, it subsequently transitioned into a positive response after 10 weeks.
Prognosis
The positive outcome of the CI surgery along with a clear improvement in the patient's language performance would seem to encourage the execution of a sequential CI in the right ear for better localization and improved speech comprehension.
| Conclusion | | |
This paper has examined the case of a 6-year-old child with profound SNHL and enlarged cystic IACs on both sides. To the best of our knowledge, this is the first described case in the world with cystic dilated IAC that exhibited positive outcomes post-CI surgery.
Teaching point
- IAC anomalies are rare conditions [Table 1], and the paper is reporting a new variant cystic dilatation of IAC
- Absent NRT intraoperatively could happen in a small percentage of patients and will be positive on switch on or later on after continues CI stimulation.
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
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1]
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