Tez Türü: Doktora
Tezin Yürütüldüğü Kurum: Universiteit Maastricht, Faculty of Health, Medicine and Life Sciences, Department of ENT, Hollanda
Tez Danışmanı: Raymond Van De Berg
Tezin Onay Tarihi: 2026
Tezin Dili: İngilizce
Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu
Desteklendiği Program: Diğer
Özet:
Summary
Vestibular compensation and rehabilitation lead to recovery in many patients with unilateral vestibular hypofunction (UVH). However, a subset of patients fails to achieve full recovery of symptoms. This observation forms the basis of this thesis: Chronic UVH is a multidimensional clinical condition that has a significant impact on patients’ quality of life (QoL). Furthermore, current assessment tools are not sufficient to capture the health impact of chronic UVH on daily life. To investigate these aspects, a multi-method approach was carried out. This included a systematic review, a qualitative approach, a retrospective cohort analysis, cross-sectional comparisons, and psychometric validation. Across these studies, key aspects of chronic UVH were investigated, including symptomatology, etiologies, clinical subtypes, diagnostic challenges, and impact on QoL. Therefore, the goal of this thesis is to enhance the understanding of chronic UVH. This could lead to more effective clinical management strategies.
Chapter 2 presents a systematic review synthesizing the full spectrum of chronic symptoms in patients with chronic UVH. It also illustrates the effects of vestibular interventions on symptoms. An analysis of 47 studies revealed a wide range of symptoms, with chronic dizziness (98%) and imbalance (81%) being the most frequently reported. These symptoms were followed by visually induced dizziness and symptoms worsening with head movements. In addition to vestibular symptoms, non-vestibular complaints such as tiredness, cognitive dysfunction, and autonomic disturbances were also prevalent. Oscillopsia was the least commonly reported symptom (22%). Vestibular rehabilitation led to significant reductions in perceived handicap. Nevertheless, a subset of patients (~30%) continued to experience moderate disability. This suggests the need for alternative treatments, such as vibrotactile feedback or vestibular implants. This chapter also demonstrated the limited ability of existing assessment tools to fully capture the health impact of chronic UVH on daily life. A qualitative study investigating these symptoms, was therefore needed.
In response, Chapter 3 presents a qualitative study based on semi-structured interviews with chronic UVH patients, analyzed within the framework of the International Classification of Functioning, Disability and Health (ICF). Results showed 16 physical, 4 cognitive, and 5 emotional symptoms, with crucial challenges in daily life, including difficulties with driving, in darkness, and with sleep. Additionally, fear of falling was reported. Patients adopted various coping strategies, such as moving cautiously and avoiding complex visual environments. Importantly, several domains, such as visual sensitivity, multitasking, and memory-related issues, were not adequately represented in commonly used PROMs. This demonstrated the need for a chronic UVH-specific assessment tool.
Chapter 4 reports findings from a retrospective cohort of 251 chronic UVH patients, aiming to classify etiologies, clinical subtypes, and QoL outcomes. Thirteen different etiologies were identified, with Menière’s disease being the most common etiology. Secondary diagnoses such as benign paroxysmal positional vertigo (BPPV) and persistent postural-perceptual dizziness (PPPD) frequently co-occurred and contributed to greater disability (21% and 19%, retrospectively). Five distinct clinical subtypes of chronic UVH were described, which indicated the condition’s heterogeneity. The presence of PPPD was found as a key predictor of reduced QoL. This finding demonstrates the importance of identifying and addressing co-morbid vestibular conditions in routine clinical evaluation.
Building on the identified need for a chronic UVH-specific assessment tool in Chapter 3, Chapter 5 compares patient-reported outcomes between patients with UVH and bilateral vestibulopathy (BVP). Data was used from 100 chronic UVH patients and 148 BVP patients. Differences in symptom burden, functional limitations, emotional well-being, and health-related QoL were evaluated. While BVP patients reported more severe symptoms on condition-specific PROMs, both groups exhibited significantly impaired outcomes compared to healthy normative data. These results demonstrate that although BVP is often considered the more debilitating condition, chronic UVH also imposes a significant burden. This burden is often under-recognized in clinic and research setting.
To address the need for a chronic UVH-specific assessment tool, Chapter 6 evaluates construct validity and reliability of the preliminary version full-length Bilateral Vestibulopathy Questionnaire (BVQ) in a cohort of patients with chronic UVH. Psychometric analyses, including confirmatory and exploratory factor analyses, revealed a refined four-factor structure: imbalance, visuo-spatial processing, behavior and limitation, as well as emotion. This revised 20-item version demonstrated strong construct validity, high internal consistency, and acceptable test–retest reliability. The adapted version offers preliminary evidence for the construct validity and reliability of the adapted BVQ in assessing the impact of chronic UVH. While these findings suggest that the adapted BVQ has potential as a chronic UVH-specific PROM, its development was not originally guided by the COSMIN framework. Crucially, it has not yet undergone expert panel review or cognitive interviews to ensure content validity. Future research should address these gaps to refine the tool into a fully validated, condition-specific questionnaire, potentially to be established as the Unilateral Vestibulopathy Questionnaire (UVQ).
Finally, Chapter 7 discusses the potential future implications of vestibular implants (VI) for chronic UVH. As an emerging intervention for patients with BVP, the VI has shown promising results in (partially) restoring vestibular function, improving postural control, and enhancing QoL. Although its current use is focused on patients with BVP, findings from chapters in thesis demonstrate the need for further research into its potential applicability in patients with chronic UVH.