Cochlear Implant and Vestibular Function.

Vestibular Function Evaluated by the Video Head Impulse Test (vHIT) and Vertigo Perceived by the Patients Before and After Cochlear Implant Surgery.

This study investigate weather one type of cochlear implant (CI) surgery (insertion of the electrode via paracentesis of the round window (RWA)) leads to less vertigo than another type of CI surgery (cochleostomy). The participants will be randomized into 2 groups: RWA or cochleostomy. They will be examined with a video head impulse test (vHIT) before and after CI surgery to clarify their vestibular function.

Cochlear implant is an advanced type of hearing advice. It consists of an outer microphone, which picks up sound and sends it through an electrode into the cochlear. With a cochlear implant people, that are profoundly deaf or have severe hearing loss, can get their hearing back. Vertigo is one of the most common side effects to cochlear implant surgery. In this study we will investigate if one type of CI surgery (insertion of the electrode via paracentesis of the round window) leads to less vertigo than another type of CI surgery (cochleostomy). In the randomization there will be stratified according to age (60+/-), residual hearing (yes/no) and gain before surgery (+/-0,68). Three different surgeons will do the surgeries. All technical aspect of the surgery, other than the insertion of the electrode into cochlea, is being done identically. Electrodes from Cochlear, MEDEL and AB is being used. We will compare the findings from the vHIT examination with the subject dizziness perceived of the patient. The patients will be examined before surgery, the day after their surgery and one month after their surgery. The same examinator will perform all the vHIT tests. The test will be performed in continuation of the patient's other visits at the Department of Audiology and Department of Otorhinolaryngology -Head and Neck Surgery.

In this group the insertion of the electrode into cochlea will be performed by drilling a hole in cochlea (cochleostomy).

In this group the insertion of the electrode into cochlea will be performed through an incision in the membrane (paracentesis) of the round window (round window approach = RWA)

In this group the insertion of the electrode into cochlea will be performed through an incision in the membrane (paracentesis) of the round window (round window approach = RWA).

In this group the insertion of the electrode into cochlea will be performed by drilling a hole in cochlea (cochleostomy).

Measured by video head impulse test one month after CI surgery in connection with consultation for CI activation

T level is a electropsysiological value. It is the minimum electrical signal in the electrode required for the patient to sense sound.

C level is the maximum electrical signal in the electrode that is acceptable for the patient to tolerate the sound.

Neural response telemetry, is an electrical response of the auditory nerve, when stimulated electrically.

Inclusion Criteria: deaf or severe hard of hearing normal or slightly affected vestibular function (gain >0,50) Exclusion Criteria: subjects with otosclerosis subject who will have the CI surgery for preservation of the residual hearing

Wanscher JH, Faber CE, Grontved AM. [Cochlear implantation in deaf adults: effect on quality of life]. Ugeskr Laeger. 2006 Aug 14;168(33):2656-9. Danish.

Ovesen T, Johansen LV. Post-operative problems and complications in 313 consecutive cochlear implantations. J Laryngol Otol. 2009 May;123(5):492-6. doi: 10.1017/S0022215108003691. Epub 2008 Oct 10.

Todt I, Basta D, Ernst A. Does the surgical approach in cochlear implantation influence the occurrence of postoperative vertigo? Otolaryngol Head Neck Surg. 2008 Jan;138(1):8-12. doi: 10.1016/j.otohns.2007.09.003.

Krause E, Louza JP, Hempel JM, Wechtenbruch J, Rader T, Gurkov R. Effect of cochlear implantation on horizontal semicircular canal function. Eur Arch Otorhinolaryngol. 2009 Jun;266(6):811-7. doi: 10.1007/s00405-008-0815-5. Epub 2008 Sep 20.

Richard C, Fayad JN, Doherty J, Linthicum FH Jr. Round window versus cochleostomy technique in cochlear implantation: histologic findings. Otol Neurotol. 2012 Sep;33(7):1181-7. doi: 10.1097/MAO.0b013e318263d56d.

Sun CH, Hsu CJ, Chen PR, Wu HP. Residual hearing preservation after cochlear implantation via round window or cochleostomy approach. Laryngoscope. 2015 Jul;125(7):1715-9. doi: 10.1002/lary.25122. Epub 2015 Jan 13.

Macdougall HG, McGarvie LA, Halmagyi GM, Curthoys IS, Weber KP. The video Head Impulse Test (vHIT) detects vertical semicircular canal dysfunction. PLoS One. 2013 Apr 22;8(4):e61488. doi: 10.1371/journal.pone.0061488. Print 2013.

Havenith S, Lammers MJ, Tange RA, Trabalzini F, della Volpe A, van der Heijden GJ, Grolman W. Hearing preservation surgery: cochleostomy or round window approach? A systematic review. Otol Neurotol. 2013 Jun;34(4):667-74. doi: 10.1097/MAO.0b013e318288643e.

Zawawi F, Alobaid F, Leroux T, Zeitouni AG. Patients reported outcome post-cochlear implantation: how severe is their dizziness? J Otolaryngol Head Neck Surg. 2014 Dec 10;43(1):49. doi: 10.1186/s40463-014-0049-z. eCollection 2014.