Autonomic Dysfunction and Dizziness: Associated Subjective Assessment Indices and Clinical Application

Abnormal autonomic function has a significant impact on the appearance and severity of dizziness. Therefore, it is important to evaluate the autonomic nervous system function in clinical practice. While the autonomic nervous system is anatomically classified as a peripheral nervous system, it is innervated by a higher central nervous system that is associated with psychological factors such as stress and emotion. Abnormal autonomic function has both organic and functional aspects, and both often coexist and are difficult to categorize clearly. However, the degree of dysfunction perceived by the patients themselves can be assessed by means of several questionnaires. The Toho Medical Index consists of 43 questions on symptoms related to autonomic dystonia and 51 questions on psychological symptoms, which can be answered with a “yes” or “no”. The index can be classified into four patterns, such as “Vegetative syndrome,” by answering “yes” or “no” to questions consisting of 43 autonomic nervous system-related symptoms and 51 mental symptoms. Another method is to observe autonomic dysfunction indirectly by evaluating the effects of the central nervous system, known as central sensitization. The Central Sensitization Inventory is used internationally to evaluate central sensitization. The Somatic Symptom Scale-8 is a questionnaire that assesses the burden caused by physical symptoms, including dizziness, through eight questions. In our previous study, we were able to extract the effects of central sensitization in somatic symptom disorder with high accuracy by utilizing this questionnaire. In the clinical evaluation of dizziness, it is necessary to evaluate not only organic abnormalities of the autonomic nervous system but also functional disorders of the autonomic nervous system, and the questionnaires mentioned above may serve as simple screening tools.