Multiple Network Disconnection in Anosognosia for Hemiplegia.

Elena Monai,Marta Bisio,Maurizio Corbetta,Francesca Bernocchi,Antonio Luigi Bisogno,Alessandro Salvalaggio

doi:10.3389/fnsys.2020.00021

Abstract

Anosognosia for hemiplegia (AHP) is a complex syndrome whose neural correlates are still under investigation. One hypothesis, mainly based on lesion mapping studies, is that AHP reflects a breakdown of neural systems of the right hemisphere involved in motor function. However, more recent theories have suggested that AHP may represent a disorder of cognitive systems involved in belief updating, self-referential or body processing. Two recent studies, using a method to estimate the degree of white matter disconnection from lesions, have indeed shown that patients with AHP suffer from damage of several long-range white matter pathways in association cortex. Here, we use a similar indirect disconnection approach to study a group of patients with motor deficits without anosognosia (hemiparesis or hemiplegia, HP, n = 35), or motor deficits with AHP (n = 28). The HP lesions came from a database of stroke patients, while cases of AHP were selected from the published literature. Lesions were traced into an atlas from illustrations of the publications using a standard method. There was no region in the brain that was more damaged in AHP than HP. In terms of structural connectivity, AHP patients had a similar pattern of disconnection of motor pathways to HP patients. However, AHP patients also showed significant disconnection of the right temporo-parietal junction, right insula, right lateral and medial prefrontal cortex. These associative cortical regions were connected through several white matter tracts, including superior longitudinal fasciculus III, arcuate, fronto-insular, frontal inferior longitudinal, and frontal aslant. These tracts connected regions of different cognitive networks: default, ventral attention, and cingulo-opercular. These results were not controlled for clinical variables as concomitant symptoms and other disorders of body representation were not always available for co-variate analysis. In conclusion, we confirm recent studies of disconnection demonstrating that AHP is not limited to dysfunction of motor systems, but involves a much wider set of large-scale cortical networks.

Highlights

Anosognosia, or lack of awareness of having a disorder or disability (Mograbi and Morris, 2018) represents an impressive phenomenon whose neural correlates have not been completely clarified.Anosognosia for hemiplegia (AHP) refers to a syndrome in which a patient, typically following a stroke, fails to recognize his motor deficit
The search was conducted in April 2018 and consisted of all the following terms related to several bodyself disorders:/anosognosia, stroke//anosognosia, hemiplegia, stroke//asomatognosia stroke//misoplegia stroke/,/out of body experience stroke//personal neglect stroke//somatoparaphrenia stroke/
The center of damage in the HP group was in the basal ganglia and central white matter to Corbetta et al (2015)

Summary

Introduction

Anosognosia for hemiplegia (AHP) refers to a syndrome in which a patient, typically following a stroke, fails to recognize his motor deficit. AHP after stroke is the most investigated form of anosognosia, and it is clinically relevant due to its negative impact on motor rehabilitation (Vocat et al, 2010). Other forms of anosognosia have been described: for visual stimuli (hemianopia and Anton’s syndrome), spatial and body processing, and cognitive deficits (Goldenberg et al, 1995; Anton, 1898; Barrett et al, 2005; Spinazzola et al, 2008; Vossel et al, 2012; Ronchi et al, 2014; Baier et al, 2015). Monitoring systems for movement in the case of AHP. This view is supported by clinical reports showing dissociation of awareness between different types of deficits in the same patient. Anosognosia can be separated from general cognitive impairment (Bisiach et al, 1986; Berti et al, 1996; Spinazzola et al, 2008)

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