Mechanisms of Functional Dizziness: A Window for Understanding Space-Motion Cognition

Persistent Postural-Perceptual Dizziness (PPPD) is one of the most common dizziness and balance disorders, the most prevalent form of chronic vestibular syndrome, the defining entity of functional vertigo, and a highly disabling issue for affected individuals. Its mechanisms and pathophysiology are the subject of intense debate and research. The more we learn, the more accurate we can define it as a functional syndrome: a disorder not linked to macro-structural abnormalities but characterized by persistent changes in certain brain networks, leading to abnormal self and external-motion perception.

The crucial question is which brain functions change in PPPD, how these processes occur, and to what extent they are the cause or consequence of the syndrome. Understanding PPPD is essential for advancing its management, aiming for diagnostic and therapeutic methods based on the disease's mechanisms. Additionally, this prevalent condition offers a unique model for studying functional brain disorders beyond the specific issues of PPPD.

Many vestibular disorders and conditions causing dizziness and vertigo are associated with identifiable structural damage or alterations seen through imaging or histopathology. They typically disrupt sub-cortical neural circuits that govern vestibular reflexes, leading to specific deficits in how the brain processes sensory-vestibular information or how the body responds motorically to balance challenges.

In contrast, PPPD does not seem to cause dysfunction of peripheral sensory afferents or motor reflex responses. Instead, the issue appears to lie within the brain's processing of all sensory inputs determining balance before generating any motor response.

This function of "vestibular" or "balance," what the brain does with sensory information to craft motor responses, should be approached more broadly. It includes not just the body’s positional information or cues of acceleration, rotation, and head movements in space but also the entire environment through which the body moves. The brain's reconstruction of the surrounding world seems to be part of this function. Thus, it is necessary to consider spatial cognitive functions (allowing us to build an internal representation of the world) and spatial navigation (enabling us to plan and execute movement within it). Recent evidence suggests that PPPD patients indeed exhibit impairments in spatial cognitive functions and navigation.

We hope this collection advances the management of PPPD and functional dizziness, deepens the understanding of spatial cognition and navigation using this patient group as a study model, and serves as a window into understanding functional brain disorders.

In this Research Topic, we invite contributions that expand knowledge by exploring these frontiers of neuro-otology. We welcome all article types accepted by Frontiers in neurology, and we seek research investigating but not limited to the following themes:
• The mechanisms underlying functional dizziness in PPPD.
• How the brain constructs spatial cognition and navigation in patients with dizziness and vertigo disorders.
• Findings regarding brain functional changes in PPPD and functional dizziness.
• Spatial (and non-spatial) cognition issues in vestibular patients in a broader sense, not limited to PPPD-specific patients.
• Clinical tests and treatments that provide insights into the nature and mechanisms of PPPD.

Keywords: Functional Dizziness, Space-Motion Cognition, Persistent Postural-Perceptual Dizziness, PPPD

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.