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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 16-18

Persistent endochondral cartilage in a child with profound sensorineural hearing loss: A roadblock for cochlear implantation


1 Department of Otolaryngology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Radiodiagnosis, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
3 Department of Pathology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Submission10-Oct-2019
Date of Acceptance20-Oct-2019
Date of Web Publication27-Jun-2020

Correspondence Address:
Prof. Naresh K Panda
Department of Otolaryngology, Head and Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aiao.aiao_24_19

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  Abstract 


A unique case of persistent endochondral cartilage in temporal bone in a child with profound hearing loss is being reported This has never been reported earlier. High-resolution computed tomography of the temporal bone suggested bilateral narrow internal auditory canal and absent semicircular canals with small vestibule but a normal cochlea. The mastoid cavity showed few lucent areas among the air cells. Magnetic resonance imaging showed similar findings along with bilateral thin auditory nerves. During the surgical procedure, the mastoid air cells on the right side were filled with cartilaginous tissue separating it from the posterior fossa. With absolutely no landmarks and a contracted antrum, further procedure was abandoned. Although there are a few contraindications for cochlear implantation, this unique case report highlights one of the rarest conditions which can provide a surgical challenge to the surgeon.

Keywords: Anomalies, embryonal cartilage, temporal bone


How to cite this article:
Panda NK, Nayak G, Ahuja C, Radotra BK. Persistent endochondral cartilage in a child with profound sensorineural hearing loss: A roadblock for cochlear implantation. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2020;4:16-8

How to cite this URL:
Panda NK, Nayak G, Ahuja C, Radotra BK. Persistent endochondral cartilage in a child with profound sensorineural hearing loss: A roadblock for cochlear implantation. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2020 [cited 2020 Jul 9];4:16-8. Available from: http://www.aiaohns.in/text.asp?2020/4/1/16/288172




  Introduction Top


The cartilaginous neurocranium forms the major part of the skull base, which includes sphenoid, temporal, and parts of occipital and ethmoid bones. These bones are formed by endochondral ossification of the cartilage anlage. By the 16th week of gestation, the petrous part starts to ossify which includes the otic capsule. The extracapsular part forms the mastoid process, tegmen tympani, middle ear floor, and wall of the eustachian tube. The ossification of otic capsule is completed by birth, but the further growth of extracapsular part occurs postnatally. The tympanic and squamous parts of temporal bone are formed by membranous ossification, whereas the styloid process is derived from the Reichert's cartilage of the second pharyngeal arch.[1]

Endochondral cartilage in any patient undergoing any form of ear surgery has not been reported. This report presents the case of a child with profound sensorineural hearing loss undergoing cochlear implantation with endochondral cartilage in the mastoid cavity.


  Case Report Top


A 5-year-old child born out of nonconsanguineous marriage presented to the outpatient clinic with inability to speak and not responding to loud stimuli. With no history of any form of perinatal or postnatal insult, the child had motor developmental delay as well as speech and language delay. On evaluation, the child had absent wave V in the bilateral ears on auditory brain response with absent transient evoked otoacoustic emission and distortion product otoacoustic emission. The child underwent radiological investigations, which included a high-resolution computed tomography of the temporal bone, which suggested bilateral narrow internal auditory canal and absent semicircular canals with small vestibule but a normal cochlea. The mastoid cavity showed lucent area among the air cells [Figure 1]a. With these findings, magnetic resonance imaging was done to delineate the membranous ear morphology, which showed similar findings with incomplete partition defect (? Type II) MRI showed a IP II cochlear anomaly with thin nerves, i.e., 0.6 mm on the right side and 0.4 mm on the left side [Figure 1]b.
Figure 1: (a) High-resolution computed tomography temporal bone showing some soft density in the mastoid air cells (white solid arrow). (b) Contrast-enhanced magnetic resonance imaging brain showing bilateral thin internal auditory canal. (c) Intraoperative pictures of mastoid air cells showing cartilaginous tissues (black arrow)

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The parents were counseled about the realistic outcome in view of thin nerves and bilateral thin internal auditory canal. The child was subsequently planned for cochlear implantation with conventional posterior tympanotomy approach. While drilling the mastoid, the dura was found to be low lying with anteriorly placed sigmoid sinus. The mastoid air cells were filled with cartilaginous tissue separating it from the posterior fossa [Figure 1]c. With absolutely no landmarks and a contracted antrum, further procedure was abandoned and the tissue was sent for histopathological analysis. The histopathological examination revealed the presence of chondrocytes in chondromyxoid background suggestive of endochondral cartilage [Figure 2]. Informed consent was taken from the patient's parents. The Institutional Ethics Committee approval was also obtained (INT/IEC/2019/000424).
Figure 2: Histopathological picture showing chondrocytes in chondromyxoid background (white solid arrow)

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  Discussion Top


Cochlear implantation is the standard of care for children with bilateral profound sensorineural hearing loss. The surgery can be challenging in cases with difficult anatomical situations. To date, various anatomical abnormalities have been reported such as malformed cochlea, narrow facial recess, and rotated cochlea.[2],[3] However, we have not come across any report of the presence of endochondral cartilage during cochlear implantation. In the absence of any report in literature and author's experience, this possibility of cartilage in mastoid cavity was never considered. The mastoid part of petrous bone is formed by endochondral ossification, but the cartilage anlages are replaced by osteoblasts and eventually bone formation occurs. Cartilage tissues disappear by the 29th week of gestation. Postnatal changes in the temporal bone occur by mastoid pneumatization, elongation of styloid process, and gradual change in orientation of tympanic membrane.[1] We, in our case, have found a unique congenital abnormality, which has not been reported in literature earlier.

During the surgical procedure, we encountered cartilaginous tissue in mastoid air cells which separated it from the posterior cranial fossa. The drilling in such endochondral cartilaginous tissue is extremely difficult as the landmarks have not been formed which can lead to greater surgical difficulty. Moreover, with absence of standard bony landmarks, the complication rates are also high such as injury to facial nerve, dura, carotid canal, and sigmoid sinus. Although a blind sac closure of the external auditory canal would have allowed plenty of room to approach the cochlea, the senior surgeon thought it was prudent to abandon the procedure to avoid complications. The presence of lucent areas in the mastoid air cells on computed tomography should raise suspicion of this entity. This could be seen more in cases of thin auditory nerve and narrow internal auditory canal. The presence of such congenital rests of cartilage in the mastoid cavity with thin nerves could be considered as an absolute contraindication for cochlear implantation.


  Conclusion Top


Although there are a few contraindications for cochlear implantation, this unique case report of persistent endochondral cartilage in mastoid air cells highlights one of the rarest conditions which can provide a surgical challenge to the surgeon.

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.



 
  References Top

1.
Dahm MC, Shepherd RK, Clark GM. The postnatal growth of the temporal bone and its implications for cochlear implantation in children. Acta Otolaryngol Suppl 1993;505:1-39.  Back to cited text no. 1
    
2.
Sennaroglu L, Sarac S, Ergin T. Surgical results of cochlear implantation in malformed cochlea. Otol Neurotol 2006;27:615-23.  Back to cited text no. 2
    
3.
Sennaroglu L, Tahir E. Cochlear implantation in a subject with a narrow facial recess: Importance of preoperative radiological findings. Cochlear Implants Int2016;17:158-61.  Back to cited text no. 3
    


    Figures

  [Figure 1], [Figure 2]



 

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