Asomatognosia: Structured Interview and Assessment of Visuomotor Imagery.

Gianluca Saetta,Olivia Zindel-Geisseler,Gilles Vannuscorps,Peter Brugger,Franziska Stauffacher,Carlo Serra

doi:10.3389/fpsyg.2020.544544

Gianluca Saetta, Olivia Zindel-Geisseler + Show 4 more

Open Access

https://doi.org/10.3389/fpsyg.2020.544544

Copy DOI

Abstract

Asomatognosia designates the experience that one’s body has faded from awareness. It is typically a somaesthetic experience but may target the visual modality (“asomatoscopy”). Frequently associated symptoms are the loss of ownership or agency over a limb. Here, we elaborate on the rigorous nosographic classification of asomatognosia and introduce a structured interview to capture both its core symptoms and associated signs of bodily estrangement. We additionally report the case of a pure left-sided hemiasomatognosia occurring after surgical removal of a meningioma in the right atrium. Despite the wide lesions of the right angular gyrus and of the temporo-parietal junction, the patient did not present visuospatial deficits or bodily awareness disorders other than hemiasomatognosia. The patient and 10 matched controls’ motor imagery was formally assessed with a limb laterality task in which they had to decide whether hands and feet presented under different angles of rotation depicted a left or a right limb. Bayesian statistics showed that patient’s reaction times were significantly impaired exclusively for the left foot and especially for mental rotations requiring somatomotor rather than visual limb representations. This was in accordance with a more enduring left-sided hemiasomatognosia for the lower limbs confined to the somesthetic modality. Our findings shed new light on motor imagery in asomatognosia and encourage the future use of the structured interview introduced here. In addition, the limb laterality task may capture phenomenological elements of a case by chronometric means. This allows a more standardized reporting of phenomenological detail and improves communication across different clinical facilities.

Highlights

Asomatognosia is defined as the impression that one’s own body has ceased to exist (Critchley, 1953)
We describe a patient with pure hemiasomatognosia after extirpation of an intraventricular meningioma in the right atrium
We report the results of a visuomotor imagery task administered to the patient

Summary

Introduction

Asomatognosia is defined as the impression that one’s own body has ceased to exist (Critchley, 1953). Only one half of the body (usually the left) is affected (“hemiasomatognosia”); “the characteristic feature is a subjective sensation as if there existed nothing to the left of the midline of the body” A patient of Carp’s felt the right half of her body absent but could convince herself that this somesthetic impression was, illusory by looking at the missing side and seeing it (somesthetic, but no visual asomatognosia; Carp, 1952). A patient with a right thalamic tumor felt his sensation of an absent left hemibody confirmed by looking at the void body space and not seeing his left side (somesthetic and visual asomatognosia; Stockert, 1934). Cases in which the own body or parts of it have faded from vision but can still be felt are described but should explicitly be referred to as visual asomatognosia or asomatoscopy (Magri and Mocchetti, 1967; Arzy et al, 2006)

Methods

Results

Conclusion