Vestibular Preservation in CI Surgery

Introduction

Improved surgical techniques, low-trauma electrodes, and the use of steroids can be effective in preserving residual hearing after cochlear implantation (ICIT CI Surgery Blog: 9/16; 8/16; 6/16; 3/16; 2/16; 1.1/16…). However, less attention has been given to preservation of vestibular function. This is understandable because from a clinical practice perspective, post-CI vestibular complaints are surprisingly uncommon; possibly due to the remarkable capacity for central vestibular compensation and adaptation.

Although spontaneous complaints are few, when recipients are specifically questioned, post-CI vestibular symptoms have been reported to be as high as 75%(1). And as surgical indications expand and bilateral implantation becomes more common, preservation of vestibular function may take on an important clinical role. Can vestibular function be preserved by techniques used for hearing preservation?

Buchman et al, using a hearing preservation surgical technique including bony cochleostomy, found that unilateral CI rarely results in significant adverse effects on the vestibular system and that postural stability actually improved post-implantation(2). Recent studies tend to validate those findings.

What’s New

Chen and colleagues from Zhengzhou University School of Medicine described vestibular function studies of severe-profoundly deaf CI recipients who were implanted using round window cochleostomies and a ‘standard’ technique(3). With this ‘standard’ technique, vestibular damage was frequently caused by implantation. Reduction in pre-operative caloric responses occurred in 93% of subjects and 40% lost VEMP waveforms. These results and similar previous studies(4-6) suggest that preservation of residual vestibular function may be less likely in CI recipients who do not undergo hearing preservation type surgery.

In contrast, Tsukada and colleagues from the Shinshu University School of Medicine performed a similar study using hearing preservation techniques (7). Like Buchman, Tsukada et al report little or no additional loss of caloric or VEMP function with sensory-preservation surgery.

Take Home

These studies suggest that preservation of residual vestibular function may be more likely in patients who undergo cochlear implantation using sensory-preservation surgical techniques. And like hearing preservation, vestibular preservation is a desirable outcome of cochlear implantation.

References

1. Buchman CA, Joy J, Hodges A, Telischi FF, Balkany TJ. Vestibular effects of CI. Laryngoscope 2004;114:1–22.
2. Steenerson RL, Cronin GW, Gary LB. Vertigo after cochlear implantation. Otol Neurotol 2001;22:842–843.
3. Chen X, Chen X, Zhang F, & Qin Z. (2016) Influence of cochlear implantation on vestibular function, Acta Oto-Laryngologica, 136:7, 655-659.
4. Melvin TA, Della Santina CC, Carey JP, Migliaccio AA. The effects of cochlear implantation on vestibular function. Otol Neurotol 2009;30:87–94.
5. Krause E, Louza JP, Wechtenbruch J, Gürkov R. Influence of cochlear implantation on peripheral vestibular receptor function. Otolaryngol Head Neck Surg 2010;142:809–13.
6. Licameli G, Zhou G, Kenna MA. Disturbance of vestibular function attributable to cochlear implantation in children. Laryngoscope 2009;119:740–5.
7. Tsukada K, Moteki H, Fukuoka H, Iwasaki S, Usami S-I. Effects of EAS cochlear implantation surgery on vestibular function. Acta Oto-Laryngologica. 2013; 133: 1128–1132.

‍