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Understanding lateropulsion after stroke

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This thesis on post-stroke lateropulsion is organized in three parts. The first part sets the theoretical frame, assumes that post-stroke lateropulsion has been overlooked so far and is misunderstood, explained by our hypothesis at the light of the literature : 1) lateropulsion prevalence is high if one looks at beyond the pusher syndrome, the tree which hides the forest ; 2) lateropulsion is a trinity with lateral body tilt (the cardinal sign), resistance and pushing ; 3) lateropulsion is a deficit in body orientation with respect to gravity, and underlying mechanisms are in relation to a biased graviception and spatial neglect ; 4) lateropulsion plays a key role in post-stroke balance and gait disorders ; 5) one needs a new gold standard to assess lateropulsion.

The second part corresponds to personal contributions.

The first paper reviews the history of different terminologies used to describe post-stroke lateropulsion (historical letter in preparation).

The second paper (submitted) is systematic review and meta-analysis of post-stroke lateropulsion prevalence, following standardized protocol (PROSPERO-CRD42020175037). Eleven studies of supratentorial stroke (2669 individuals) gave a pooled lateropulsion prevalence of 48.6% (95%CI [37.6 ;59.6]), decreasing from 59% in the acute phase to 22.8% in the late subacute phase. The ratio of right to left-hemisphere stroke with lateropulsion much increased as a function of time. This study appeals for a systematic detection to guide appropriate interventions as early as possible.

Next studies were performed from the dataset of the DOBRAS Cohort ( : NCT03203109), with 220 consecutive individuals enrolled after a first hemisphere stroke, and comprehensively assessed at D30, D60, D90 and discharge from the rehabilitation ward. The third and fourth papers were published as companion studies (Neurology, April 2021).

- In one, we investigated on D30 lateropulsion underlying mechanisms in relation to a biased graviception (Visual vertical, VV) and spatial neglect. We showed that lateropulsion assessed with the Scale for Contraversive Pushing (SCP) was a trinity constituted by body tilt, pushing and resistance, corresponding to an impaired orientation of the body against gravity in relation to an altered graviception. Referring to straight above, lateropulsion might correspond to a form of spatial neglect (referring to straight ahead), which would advocate for 3-D maps in the human brain involving the internal model of verticality.

- In the other we showed that lateropulsion was the primary factor altering balance and gait disorders, especially after right hemisphere stroke where lateropulsion explained ≥90% of the information contained in balance disorders and ≥66% in gait disorders. This result suggests that in the post-stroke subacute stage, balance and gait rehabilitation should be rethought and be focused on body orientation with respect to gravity.

The next papers correspond to longitudinal studies, still performed with the DOBRAS data set. We performed a longitudinal study investigating lateropulsion recovery, balance recovery, and the responsiveness of their assessment tools (in preparation). Meanwhile we conducted a narrative review aiming to synthetize clinimetrics of current tools used to assess lateropulsion, in compliance with the COSMIN guideline. We conclude there is a need for a novel lateropulsion scale having the quality to become the future gold standard (paper in about to be submitted). We also analyzed the effect of white matter hyperintensities (WMHs) on lateropulsion and balance recovery. We found that WMHs was a detrimental biomarker for balance recovery, whose effects were more significant on body stabilization than on body orientation (one paper published and one revised in Ann Phys Rehabil Med).

Finally in the third and the last part is a general discussion.

Composition du jury :

Professeure Sylvie NADEAU, PT, PhD, Université de Montréal, Rapportrice

Professeur Philippe MARQUE, MD, PhD, Université Paul Sabatier Toulouse III, Rapporteur

Professeure Suzanne BABYAR, PT, PhD, Hunter College, Examinatrice

Professeur Alain YELNIK, MD, Université de Paris, Examinateur

Professeure Elena MORO, MD, PhD, FEAN, FAAN, Université Grenoble Alpes, Présidente du jury

Professeure Monica Baciu, MD, PhD, Université Grenoble Alpes, Invitée

Docteur Céline Piscicelli, PhD, Université Grenoble Alpes, Invitée

Professeur Dominic PERENNOU, MD, PhD, Université Grenoble Alpes, Directeur de thèse