Compensation after vestibular neurectomy.

Dahlem, K.K.K. (Kilian Konrad Kenjiro) (2015) Compensation after vestibular neurectomy. thesis, Medicine.

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Abstract

Background: Unilateral vestibular neurectomy, performed during the removal of a vestibular schwannoma, causes a sudden total loss of vestibular function, which leads to symptoms such as dizziness, disequilibrium and vertigo. It is however not know in what ways the body compensates for this unilateral loss of function, called compensation, why symptoms persist, in one patient, for few weeks whereas in another it persists for months or years. Moreover it is not known if there are predictive factors, which can be determined preoperatively to improve postoperative symptoms and Quality of Life. This study aims at clarifying all the above. Methods: We longitudinally followed patients (n=3) undergoing vestibular neurectomy before surgery and 6weeks after surgery to study the process of compensation dynamically. We also tested a group of chronic deafferented subjects (n=10) to look at long-term outcome. We measured subjective outcome by five questionnaires (dizziness, headache, motion sickness, balance, anxiety) and measured, as objective outcome, the vestibulo-ocular reflex in three different ways to separate the cervical component, the efference copy and the vestibular component of the VOR, upper body sway during 8 balance tasks and perception of motion in a rotatory chair. Results: Preoperatively the tumor affects vestibular function in terms of balance, VOR and perception of motion. Interestingly balance is worse than the chronic deafferented people for one balance task (p=0,004). Active VOR is normal compared to chronic deafferented subjects (VORgain 1 compared to 0,8) but passive and en-bloc VORgain is as low as the chronic deafferented people. Moreover perception of motion is decreased for impulses towards the tumor ear, however not as severely affected than the chronic deafferented people who show more difficulties in differentiating velocity during en-bloc whole body rotations. Finally certain VOR components correlate with subjective outcome measures such as dizziness and balance outcome. Conclusion: Chronic deafferented subjects show the typical pattern of unilateral vestibular loss however in some tasks, such as balance and VOR, the preoperative group show that the tumor seems to affect vestibular function more than a total neurectomy does. This implies that the tumor affects the vestibular nerve creating a noise in the vestibular nuclei. It is also indicated that measuring VOR components can be predictive for outcome after vestibular neurectomy.

Item Type:	Thesis (Thesis)
Supervisor name:	Dikkers, F.G. MD
Supervisor name:	Lewis, Richard MD and Massachusetts Eye and Ear Infirmary and Harvard Medical Scho and Boston MA
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:38
Last Modified:	25 Jun 2020 10:38
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/17

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