By Marcello Cherchi, MD PhD
For patients
Some patients suffering from disequilibrium (whatever the underlying cause of that symptom is) experience a sensation of “disconnect” from their bodies (called “depersonalization”) or their surroundings (called “derealization”).
For clinicians
Overview
Dissociative experiences such as depersonalization and derealization are those in which there is a mismatch between an expected perception and an experienced perception, whether the discrepancy is in point of view (self versus outside of self), in self-perception (customary or baseline body image versus a distorted body image) or in reality (expected versus actual perception of the environment). There is an emerging literature regarding dissociative experiences accompanying peripheral and central vestibular disorders. From the perspective of internal modeling, it is plausible that these symptoms reflect multisensory integration’s failure to reconcile the mismatch between expected versus experienced vestibular input in patients with vestibular disease.
Introduction
Dissociative experiences such as depersonalization and derealization are those in which there is a mismatch between an expected perception and an experienced perception, whether the discrepancy is in point of view (self versus outside of self), in self-perception (customary or baseline body image versus a distorted body image) or in reality (expected versus actual perception of the environment).
The terminology in this area is not uniform, and includes:
- Out of body experiences (OBE) (Lopez and Elzière 2018) and autoscopic (AS) hallucinations (Mohr and Blanke 2005); “During an out-of-body experience (OBE), the experient seems to be awake and to see his body and the world from a location outside the physical body. A closely related experience is autoscopy (AS), which is characterized by the experience of seeing one’s body in extrapersonal space” (Blanke et al. 2004).
- Depersonalization (Jáuregui-Renaud et al. 2008; Lopez et al. 2018).
- Derealization (Jáuregui-Renaud et al. 2008; Lopez et al. 2018).
- Distorted body image (body dysmorphism) (Mohr and Blanke 2005).
Blanke and colleagues note that these abnormal perceptions “are frequently associated with pathological sensations of position, movement and perceived completeness of one’s own body. These include vestibular sensations (such as floating, flying, elevation and rotation), visual body-part illusions (such as the illusory shortening, transformation or movement of an extremity) and the experience of seeing one’s body only partially” (Blanke et al. 2004).
Epidemiology
Of the few studies that comment on the epidemiology of these symptoms, some describe a higher prevalence in women, and in patients with visual/vestibular hypersensitivity, migraine and motion sickness (Toupet et al. 2019). Other studies report a higher prevalence and frequency of these symptoms in patients with anxiety (Kolev et al. 2014).
Pathophysiological mechanism of disease
The underlying mechanism of these symptoms is unknown, but a series of observations has led to reasonable hypotheses. For example, several studies have noted that patients with peripheral otologic vestibular disorders report symptoms of depersonalization and derealization (Grigsby and Johnston 1989; Sang et al. 2006; Sun et al. 2021) and out of body experiences (Lopez and Elzière 2018). Similar findings have been reported in series of patients with peripheral and central vestibular disorders (Elyoseph et al. 2023; Toupet et al. 2019).
Several studies have proposed that these experiences result from failed multisensory integration in the temporo-parietal cortex (Blanke et al. 2004; Mohr and Blanke 2005), including failure to reconcile vestibular inputs with other sensory inputs (Cheyne and Girard 2009; Jáuregui Renaud 2015).
Experimental support for this idea comes from the observation that subjects undergoing caloric testing (which by its nature elicits a non-physiologic vestibular perception that is discrepant with other sensory inputs) sometimes report depersonalization/derealization (Jáuregui-Renaud et al. 2008; Sang et al. 2006) or distorted self-body perceptions (Lopez et al. 2018). Similar findings are reported in patients undergoing unilateral utricular stimulation during unilateral utricular centrifugation (Aranda-Moreno and Jáuregui-Renaud 2016).
Blake and colleagues speculate that:
“The complex experiences of OBE and AS represent paroxysmal disorders of body perception and cognition (or body schema). The processes of body perception and cognition, and the unconscious creation of central representation(s) of one’s own body based on proprioceptive, tactile, visual and vestibular information — as well as their integration with sensory information of extrapersonal space — is a prerequisite for rapid and effective action with our surroundings. Based on our findings, we speculate that ambiguous input from these different sensory systems is an important mechanism of OBE and AS, and thus the intriguing experience of seeing one’s body in a position that does not coincide with its felt position. We suggest that OBE and AS are related to a failure to integrate proprioceptive, tactile and visual information with respect to one’s own body (disintegration in personal space) and by a vestibular dysfunction leading to an additional disintegration between personal (vestibular) space and extrapersonal (visual) space. We argue that both disintegrations (personal; personal-extrapersonal) are necessary for the occurrence of OBE and AS” (Blanke et al. 2004).
From the perspective of control systems analysis, these experiences reflect a discrepancy between predictions of internal models (of self and environment) (Saini et al. 2022; Vogeley et al. 1999) and experienced perceptions.
Final comments
In our clinical experience, patients presenting to an otoneurology clinic frequently have difficulty articulating their symptoms of disequilibrium, and often use phrases such as, “I just feel weird,” “Something’s just not right,” “I feel a disconnect,” and so forth. We suspect that these reflect the dissociative experiences that can accompany vestibular disorders irrespective of etiology.
References
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Blanke O, Landis T, Spinelli L, Seeck M (2004) Out-of-body experience and autoscopy of neurological origin. Brain 127: 243-58. doi: 10.1093/brain/awh040
Cheyne JA, Girard TA (2009) The body unbound: vestibular-motor hallucinations and out-of-body experiences. Cortex 45: 201-15. doi: 10.1016/j.cortex.2007.05.002
Elyoseph Z, Geisinger D, Zaltzman R, Gordon CR, Mintz M (2023) How vestibular dysfunction transforms into symptoms of depersonalization and derealization? J Neurol Sci 444: 120530. doi: 10.1016/j.jns.2022.120530
Grigsby JP, Johnston CL (1989) Depersonalization, vertigo and Ménière’s disease. Psychol Rep 64: 527-34. doi: 10.2466/pr0.1989.64.2.527
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