What is the treatment approach for patients with severe to profound sensorineural hearing loss who are not benefiting from traditional hearing aids, considering a cochleostomy (surgical procedure involving the cochlea)?

Cochleostomy for Severe to Profound Sensorineural Hearing Loss

Cochlear implantation via cochleostomy is the definitive surgical treatment for patients with severe to profound sensorineural hearing loss who cannot benefit from traditional hearing aids, providing significant improvements in hearing, speech discrimination, sound localization, and quality of life. 1

Primary Indication and Patient Selection

• Cochlear implantation is indicated for patients with unrecovered severe to profound sensorineural hearing loss (SNHL) who do not achieve adequate benefit from conventional amplification. 1

• The procedure is particularly beneficial for patients with associated tinnitus, with 96% reporting tinnitus improvement post-implantation. 1, 2

• Patients demonstrate improvements in sound localization and speech discrimination following cochlear implantation. 1

• Quality of life significantly improves after cochlear implantation, making this a priority outcome beyond just hearing restoration. 1

Surgical Approach Options

Cochleostomy Technique

• The cochleostomy approach involves creating a surgical opening into the cochlea, typically performed via the traditional mastoidectomy-posterior tympanotomy (MPT) route. 3, 4

• An alternative transcanal cochleostomy technique (combined approach technique or CAT) uses a transcanal approach combined with a small mastoidectomy and posterior tympanotomy, which is safe and efficient. 4

• The transcanal approach is especially appropriate when cochlear calcification or malformations are present, when cochleostomy must be performed anteriorly, or when facial nerve position prevents adequate posterior tympanotomy. 4

Round Window Approach Alternative

• The round window (RW) approach is an alternative to cochleostomy, though the optimal approach remains under investigation. 3

• Pre-operative temporal bone CT scan can predict surgical difficulty: poor mastoid aeration and lower tegmen position predict greater difficulty with cortical mastoidectomy, while presence of air cells around the facial nerve predicts easier facial recess access. 5

Pre-Operative Evaluation Requirements

• High-resolution CT of the temporal bone is essential for surgical planning, providing delineation of cochlear malformations, otospongiosis, round window occlusion, labyrinthitis ossificans, congenital bony fusion of ossicles, and variant facial nerve anatomy. 1

• CT temporal bone identifies the size of cochlear and vestibular aqueducts, alerting surgeons to the possibility of intraoperative cerebrospinal fluid gusher. 1

• MRI with internal auditory canal protocol should be obtained to exclude retrocochlear pathology (such as vestibular schwannoma) before proceeding with cochlear implantation. 1

Special Populations

Children with Chronic Middle Ear Disease

• Children who are cochlear implant candidates with chronic otitis media with effusion (OME) or recurrent acute otitis media (AOM) should have tympanostomy tubes placed before cochlear implantation to treat middle ear infection. 1

• The preponderance of evidence supports using tympanostomy tubes in otitis-prone children undergoing cochlear implantation, with no evidence showing increased infectious complications from tube presence. 1

Elderly Patients

• Cochlear implantation under local anesthesia is a safe and fast alternative for elderly patients who are high-risk for general anesthesia, with average operative time of 52 minutes and significant postoperative hearing improvement. 6

• The posterior suprameatal approach technique combined with local anesthesia presents a viable option for patients previously considered inoperable due to anesthesia risks. 6

Electrode Array Considerations

• Two electrode array designs are available: lateral wall (LW) "straight" arrays and perimodiolar (PM) "pre-curved" arrays, though the optimal design for hearing preservation remains under investigation. 3

• Minimizing insertion trauma to preserve residual hearing requires careful electrode selection and surgical technique. 3

Non-Cochlear Implant Candidates

• Auditory brainstem implantation (ABI) is reserved for patients who are not cochlear implant candidates due to absent cochlear nerves or non-implantable cochleae, such as those with neurofibromatosis type 2, bilateral cochlear nerve avulsion, complete cochlear ossification from meningitis, or severe cochlear malformations. 7

Rehabilitation and Follow-Up

• Post-operative audiologic rehabilitation is essential, with formal evaluation at 3-6 months to determine if communication goals are met and hearing-related quality of life has improved. 2

• Annual audiometry is recommended to monitor for progression of hearing loss. 2

• Referral to support groups such as the Hearing Loss Association of America provides valuable adjustment counseling. 1, 2

Critical Pitfalls to Avoid

• Do not delay cochlear implantation in appropriate candidates while attempting prolonged trials of conventional amplification—severe to profound SNHL that does not benefit from hearing aids warrants prompt surgical evaluation. 1

• Do not proceed with cochlear implantation without adequate pre-operative imaging (CT temporal bone and MRI IAC) to identify anatomical variants, malformations, and exclude retrocochlear pathology. 1, 5

• Do not overlook concurrent middle ear disease in pediatric candidates—treat chronic OME or recurrent AOM with tympanostomy tubes before implantation. 1