Multiple Network Disconnection in Anosognosia for Hemiplegia

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

doi:10.3389/fnsys.2020.00021

Multiple Network Disconnection in Anosognosia for Hemiplegia

Front Syst Neurosci. 2020 Apr 29:14:21. doi: 10.3389/fnsys.2020.00021. eCollection 2020.

Authors

Elena Monai^{1

2}, Francesca Bernocchi^{1

2}, Marta Bisio^{1

2}, Antonio Luigi Bisogno^{1

2}, Alessandro Salvalaggio^{1

2}, Maurizio Corbetta^{1

2

3}

Affiliations

¹ Department of Neuroscience, Neurological Clinic, University of Padua, Padua, Italy.
² Padova Neuroscience Center, University of Padua, Padua, Italy.
³ Department of Neurology, Radiology, and Neuroscience, Washington University in St. Louis, St. Louis, MO, United States.

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.

Keywords: anosognosia; awareness; hemiplegia; network; stroke; structural disconnection.