Modified Rambo Transcanal Approach for Cochlear Implantation in CHARGE Syndrome

Video Type: CVideo
  • 2-5 min videos of a particular surgery or technique. These again show major events in the surgery
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Author: Cameron Wick
Published:
Specialties: Neurotology Otology, Otolaryngology, Pediatric Otolaryngology
Schools: University of Texas - Southwestern Medical Center
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Basic Info

Contributors:  Amy M. Moore,  and Brandon Isaacson

CHARGE syndrome is associated with a variety of temporal bone anomalies and deafness. The lack of surgical landmarks and facial nerve irregularities make cochlear implantation in this population a challenging endeavor. This video describes a safe and efficacious transcanal approach for cochlear implantation that obviates the need to perform a mastoidectomy and facial recess.

Advanced

Procedure

- The ear is prepped and draped in a standard fashion that includes utilization of facial nerve monitoring and pre-incision antibiotics. 1. Modified Rambo meatoplasty for closure of the external auditory canal. 2. Postauricular incision for access to the external auditory canal. Remove all canal skin and tympanic membrane to prevent future cholesteatoma formation. 3. Canaloplasty to ensure canal skin removal and increase exposure to the middle ear. 4. Identify the facial nerve course in the middle ear. The nerve stimulating probe can help to map it out. 5. Cochleostomy is preferably at the round window if it can be identified. In the case of round window atresia, its expected location or a safe location away from the mapped course of the facial nerve is selected as the cochleostomy site. 6. The internal device is secured in a standard fashion. The electrode is implanted and the electrode array can be positioned in a shallow suprameatal trough. Any excess electrode is coiled and secured within the expanded external auditory canal.

Indications

Standard age and device appropriate cochlear implant candidacy applies. This technique is consider in cases of severe middle or inner ear malformation, such as those associated with CHARGE syndrome.

Contraindications

Absolute: Absence of a cochlear nerve. This is particularly relevant in patients with CHARGE syndrome as they have a higher rate of cranial nerve eight aplasia. Relative: This is not the preferred implantation technique if normal mastoid, middle ear, and inner ear anatomy is present.

Instrumentation

Setup

Standard operative room setup for cochlear implantation including facial nerve monitoring, betadine skin prep, pre-incision antibiotics, and antibiotic irrigation.

Preoperative Workup

Preoperative evaluation consisted of computed tomography (CT), magnetic resonance imaging (MRI), audiometry, cochlear implant evaluation, and cognitive assessment. All patients underwent unilateral implantation after MRI confirmed an intact cochlear nerve on that side.

Anatomy and Landmarks

The typical anatomical landmarks for ear surgery are often absent or severely distorted. For more information on CHARGE syndrome and its anatomical variations, we suggest reviewing the references listed below.

Advantages/Disadvantages

Advantages: The transcanal approach eliminates the risk of performing a mastoidectomy and facial recess in this vulnerable patient population that often lacks standard anatomical landmarks like the lateral semicircular canal. Direct access to the middle ear allows early identification of the facial nerve and ability to map its course through the middle ear. Avoiding a mastoidectomy eliminates encountering any anomalous vasculature that may be running through a hypoplastic mastoid cavity. Disadvantages: Additional steps are necessary to close off the ear canal. Diligent canal skin and tympanic membrane removal must be performed to prevent future cholesteatoma formation. The facial nerve is still at risk of injury, particularly during the posterior aspect of the canaloplasty.

Complications/Risks

- Bleeding, infection, facial nerve injury, CSF leak/gusher, meningitis, improper electrode placement, electrode extrusion. - Cochlear implant outcomes are still multifactorial and vary widely in this patient population based on their other medical co-morbidities, developmental delay, supportive environment, and other factors known to influence cochlear implant performance.

Disclosure of Conflicts

- Bleeding, infection, facial nerve injury, CSF leak/gusher, meningitis, improper electrode placement, electrode extrusion. - Cochlear implant outcomes are still multifactorial and vary widely in this patient population based on their other medical co-morbidities, developmental delay, supportive environment, and other factors known to influence cochlear implant performance.

Acknowledgements

Not Available

References

1. Vesseur AC, Verbist BM, Westerlaan HE, et al. CT findings of the temporal bone in CHARGE syndrome: aspects of importance in cochlear implant surgery. Eur Arch Otorhinolaryngol 2016;273:4225-4240.
2. Morimoto AK, Wiggins RH 3rd, Hudgins PA, et al. Absent semicircular canals in CHARGE syndrome: radiologic spectrum of findings. ANJR Am J Neuroradiol 2006;27:1663-1671.
3. Zentner GE, Layman WS, Martin DM, Scacheri PC. Molecular and phenotypic aspects of CHD7 mutation in CHARGE syndrome. Am J Med Genet A 2010;152A:674-686.
4. Buchman CA, Copeland BJ, Yu KK, Brown CJ, Carrasco VN, Pillsbury HC. Cochlear implantation in children with congenital inner ear malformations. Laryngoscope 2004;114:309-316.

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