Monitoring of auditory and vestibular function during destructive labyrinth surgery

Bilateral vestibular loss (BV) represents a major handicap with strong balance
disturbances, higher risk of fall, visual symptoms (oscillopsia) and a loss of
autonomy [1,2].
Prognosis is poor and treatment options are limited [3]. At this moment, the
department of ORL of Maastricht University Medical Center is working on a
vestibular implant. Aim is to (partially) restore vestibular function [4,5,6].
However literature about hearing preservation during vestibular implantation is
scarce. Until now, hearing preservation is only proven in a few animals. Humans
who underwent implantation, were already deaf (our previous study) [6] or lost
hearing as a result of implantation (Washington group). The surgical technique
and electrodes currently used, are not able to preserve hearing [7,8,9].
Therefore surgical technique and electrode design must be improved in order to
be able to implant people with (sub)normal hearing. This study investigates an
improved surgical technique, together with a new electrode design and
histopathological examination of implanted inner ears, aimed at preservation of
hearing and vestibular function.

REFERENCES:
1. B. K. Ward, Y. Agrawal, H. J. Hoffman, J. P. Carey, and C. C. Della Santina,
*Prevalence and impact of bilateral vestibular hypofunction: results from the
2008 US National Health Interview Survey.,* JAMA Otolaryngol. Head Neck Surg.,
vol. 139, no. 8, pp. 803*10, Aug. 2013.
2. N. Guinand, F. Boselie, J. Guyot, and H. Kingma, *Quality of Life of
Patients With Bilateral Vestibulopathy,* vol. 121, no. 225929, pp. 1*7, 2012
3. van de Berg R, Guinand N, Stokroos RJ,Guyot J-P and Kingma H (2011)The
vestibular implant: quo vadis? Front.Neur. 2:47. doi: 10.3389/fneur.2011.00047
4. van de Berg R,Guinand N, Guyot J-P,Kingma H and Stokroos RJ (2012) The
modified ampullar approach for vestibular implant surgery: feasibility and its
first application in a human with a long-term vestibular loss.Front.Neur. 3:18.
doi:10.3389/fneur.2012.00018
5. Perez Fornos A, Guinand N, van de Berg R, Stokroos R, Micera S, Kingma H,
Pelizzone M and Guyot J-P(2014) Artificial balance: restoration of the
vestibulo-ocular reflex in humans with a prototype vestibular neuroprosthesis.
Front.Neurol. 5:66. doi: 10.3389/fneur.2014.00066
6. Van de Berg R, Guinand N, Nguyen TAK, Ranieri M, Cavuscens S, Guyot J-P,
Stokroos R, Kingma H and Perez-Fornos A (2015) The vestibular implant:
frequency- dependency of the electrically evoked vestibulo-ocular reflex in
humans. Front.Syst. Neurosci. 8:255.
7. Rubinstein JT, Bierer S, Kaneko C, Ling L, Nie K, Oxford T, Newlands S,
Santos F, Risi F, Abbas PJ, Phillips, J.O. Implantation of the semicircular
canals with preservation of hearing and rotational sensitivity: a vestibular
neurostimulator suitable for clinical research. Otology & Neurotology
33:789-796, 2012.
8. Bierer SM, Ling L, Nie K, Fuchs AF, Kaneko CR, Oxford T, Nowack AL, Shepherd
SJ, Rubinstein JT, Phillips JO. Auditory outcomes following implantation and
electrical stimulation of the semicircular canals. Hear Res. May;287(1-2):51-6,
2012.
9. Dai C, Fridman GY, Della Santina CC Effects of vestibular prosthesis
electrode implantation and stimulation on hearing in rhesus monkeys. Hearing
research 277:204- 210, 2011.

1. Monitoring of auditory function during destructive labyrinth surgery to
study hearing preservation and vestibular implantation
2. Monitoring of vestibular function during destructive labyrinth surgery to
study better electrode position and vestibular implantation
3. Histopathological examination of labyrinth to study damage on tissue and
cellular level after vestibular implantation

Explorative Study

These patients are scheduled for destructive surgery of their labyrinth by
opening their labyrinth completely. This means that they will undergo surgery
that will (as a necessary side effect) cause hearing loss and loss of balance.
During this surgery, their labyrinth is destructed in an abrupt way. This study
will not destruct their labyrinth abruptly, but in steps: the labyrinth will
not be opened completely, but first just three small portions of it. After the
electrode insertion and measurements, the labyrinth will be destroyed
completely. BERA-monitoring is a non-invasive way of measuring hearing
thresholds and is routinely used in surgery. It adds no additional risks to the
surgery. However, the patients will have to undergo a 30-minute BERA test at
the outpatient department, in order to investigate whether a BERA signal can be
obtained (if not, it can also not be obtained during surgery).
Electrocochleography is an investigation method that measures physiologic
responses of the cochlea. It does not add any additional risks for the patient.
Video recordings will be made from the moment the mastoid is opened. This
implies that only images of the mastoid will be recorded and therefore the
patient cannot be recognized (e.g. de face of the patient is below the sterile
sheets). This means that except time, the patients will not be exposed to any
other risks than already was intended for the surgery.
When the canals are opened and inserted with the electrodes, waiting and
measuring hearing after opening the labyrinth takes two minutes for each canal.
Insertion of the electrode takes a couple of seconds, while monitoring hearing
again will take two more minutes for each canal. Manipulation of electrodes
takes approximately two minutes for all canals together. Measuring VECAP*s
takes 15 minutes. VECAP*s are a safe way of stimulating the vestibular system,
as has been shown in the protocol.
For short, surgery will take approximately 3x(2+2)+2+15=29 minutes longer than
the normal procedure (as a reference: the initial surgical procedure takes more
than three hours). Next to this, the patients have to come to the outpatient
department to look whether a BERA-signal can be obtained (if not, it can also
not be obtained during surgery).
The membranous labyrinth is taken out of the patient as part of the regular
surgical procedure. For this study, the membranous labyrinth is anonymously
used for histopathological examination instead of being thrown away as medical
waste. Privacy of patients is therefore not compromised.