The human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) is a worldwide pandemic that affects the lives of millions of people across all ages. Its devastating effects are far-reaching and affect all aspects of an individual’s daily life. HIV/AIDS is responsible for widespread clinical manifestations involving the head and neck. Disorders of the auditory and vestibular systems are often associated with HIV/AIDS, however the extent and nature of these vestibular manifestations is still largely unknown. The main aim of this research study was to investigate vestibular functioning and pathology in adults with HIV/AIDS. This was achieved through three main research steps: a systematic literature review of the body of peer-reviewed literature on HIV/AIDS related vestibular manifestations and pathology, a description and comparison of vestibular involvement in adults with and without HIV/AIDS and an investigation to determine if HIV/AIDS influence the vestibulocollic reflex (VCR) pathways. For the first study a systematic literature review related to vestibular findings in individuals with HIV infection and AIDS was conducted. A varied search strategy was used across several electronic databases to identify relevant peer-reviewed reports in English. Several databases (Medline, Scopus and PubMed) and search strategies were employed. Where abstracts were not available, the full paper was reviewed, and excluded if not directly relevant to the study’s aims. Articles were reviewed for any HIV/AIDS associated vestibular symptoms and pathologies reported. For the second and third study, a cross-sectional, quasi-experimental comparative research design was employed. A convenience sampling method was used to recruit subjects. The sample consisted of 53 adults (29 male, 24 female, aged 23-49 years, mean = 38.5, SD = 4.4) infected with HIV, compared to a control group of 38 HIV negative adults (18 male, 20 female, aged 20-49 years, mean = 36.9, SD = 8.2). A structured interview probed the subjective perception of vestibular complaints and symptoms. Medical records were reviewed for cluster of differentiation 4+ (CD4+) cell counts and the use of antiretroviral (ARV) medication. An otologic assessment and a comprehensive vestibular assessment (bedside assessments, vestibular evoked myogenic potentials, ocular motor and positional tests and bithermal caloric irrigation) were conducted on all subjects. The systematic literature review identified 442 records, reduced to 210 after excluding duplicates, reviews, editorials, notes, letters and short surveys. These were reviewed for relevance to the scope of the study. There were only 13 reports investigating vestibular functioning and pathology in individuals affected by HIV/AIDS. This condition can affect both the peripheral and central vestibular system, irrespective of age and viral disease stage. Post-mortem studies suggest direct involvement of the entire vestibular system, while opportunistic infections such as oto- and neurosyphilis and encephalitis cause secondary vestibular dysfunction resulting in vertigo, dizziness and imbalance. The second study showed an overall vestibular involvement in 79.2% of subjects with HIV in all categories of disease progression, compared to 18.4% in those without HIV. Vestibular involvement increased from 18.9% in the Centers for Disease Control and Prevention (CDC) category 1 to 30.2% in category 2. Vestibular involvement was 30.1% in category 3. There was vestibular involvement in 35.9% of symptomatic HIV positive subjects and 41.5% in asymptomatic HIV positive subjects. Individuals with HIV were 16.6 times more likely to develop vestibular involvement during their lifetime, than among individuals without this disease. Vestibular involvement may occur despite being asymptomatic. The third study showed that abnormal cervical vestibular evoked myogenic potentials and caloric results were significantly higher in the HIV positive group (p=.001), with an odds ratio of 10.2. Vestibulocollic reflex and vestibulo-ocular reflex involvement increased with progression of the disease. There were more abnormal test results in subjects using ARV therapies (66.7%) compared to those not using ARV therapies (63.6%), but this difference was not statistically significant. Vestibular involvement was significantly more common in subjects with HIV than among those without this disease. This disease and its associated risk profile include direct effects of the virus on the vestibular system as demonstrated by postmortem studies. Opportunistic infections may compromise the functioning of the sensory and neural structures of hearing and the vestibular system indirectly, causing vertigo, dizziness or disequilibrium. Ototoxicity may also be related to vestibular dysfunction, due to the ototoxic nature of certain ARV medications. HIV/AIDS influence not only the vestibulo-ocular reflex, but also the vestibulocollic reflex pathways. Primary health care providers could screen HIV positive patients to ascertain if there are symptoms of vestibular involvement. If there are any, then they may consider further vestibular assessments and subsequent vestibular rehabilitation therapy, to minimize functional limitations of quality of life. / Thesis (DPhil)--University of Pretoria, 2014. / lk2014 / Speech-Language Pathology and Audiology / DPhil / Unrestricted