Approach Considerations
Because of the root cause of the sensorineural hearing loss in patients with Mondini deformity, surgical therapy is the only treatment consideration.
Cochlear Implantation
Cochlear implantation has been described as an effective tool for treating sensorineural hearing loss due to incomplete partitioning.
Prior to surgery, imaging (specifically MRI) of the affected temporal bone is important to ascertain the presence of sufficient cochlear lumen for electrode placement and to assess for hypoplasia/aplasia of the eighth cranial nerve. [17]
Another concern for surgery is whether there is any aberrancy in the course of the facial nerve. Sixteen percent of individuals with inner-ear malformations were found to have an aberrant facial nerve. [16] “Gushers,” or oozing of cerebrospinal fluid (CSF) due to bony abnormalities found in the cribriform plate separating the internal auditory canal and the cochlea, have also been described in patients with incomplete partitioning. Oozing CSF more seems to be more common in patients with Mondini deformity. [18]
As for electrode selection for patients with Mondini deformity, because the basal turn is normal and research has shown that the majority of spiral ganglion cells reside in the basal turn, all types of electrodes should theoretically provide sufficient stimulation. [18]
Chen et al found that following cochlear implant surgery in 545 children (aged 7-36 mo) with severe to profound, prelingual hearing loss, auditory skills in the 31 patients with Mondini dysplasia developed similarly to those in the 514 patients with radiologically normal inner ears. No significant difference was found at 12-, 24-, and 36-month follow-up in the mean auditory skill scores for both groups. [19]
Consultations
Patients diagnosed with Mondini deformity should consult with a neurootologist to ascertain whether cochlear implantation is warranted. Additionally, an audiologist and speech/language pathologist should be consulted.
Long-Term Monitoring
Oozing of CSF due to the abnormal bony architecture of the inner ear has been reported among patients with Mondini deformity who have undergone cochlear implantation. Because these patients now have an inner ear in which CSF is exposed to perilymph, meningitis is an increased risk, so these patients should receive routine vaccinations. [18]
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Schematic representation of the normal cochlea and cochlear malformations. A: normal cochlea, mid-modiolar section; Mo = modiolus, CA = cochlear aperture, B = basal turn, M = middle turn, A = apical turn, arrowheads = interscalar septa. B: Normal cochlea, inferior section passing through the round window niche (RWN); arrowhead = interscalar septum between middle and apical turns. C: Cochlear aplasia with normal vestibule. D: Cochlear aplasia with enlarged vestibule. E: Common cavity. F: Incomplete partition type I. G: Incomplete partition type II. H: Incomplete partition type III. I: Cochlear hypoplasia, bud type (type I). J: Cochlear hypoplasia, cystic cochlea type (type II). K: Cochlear hypoplasia, with less than 2 turns (type III).
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Incomplete partition anomalies of the cochlea. A and B: Incomplete partitions. Cochlea (C), without the modiolus and interscalar septa, resembles an empty cystic structure (A) and is accompanied by dilated vestibule (v) (B). C and D: Incomplete partition type II. The apical part of the modiolus and the corresponding interscalar septa are defective (black arrow), giving the apex of the cochlea a cystic appearance due to the confluence of middle and apical turns (C). This is accompanied by minimally dilated vestibule (v) and large vestibular aqueduct (white arrow). E: Incomplete partition type III. Cochlea has interscalar septa (black arrow), but the modiolus is completely absent. Published by Cochlear Implants International.
