Altered microstructure of the contralesional ventral premotor cortex and motor output after stroke

Paweł P Wróbel; Stephanie Guder; Jan F Feldheim; José A Graterol Pérez; Benedikt M Frey; Chi-Un Choe; Marlene Bönstrup; Bastian Cheng; Yogesh Rathi; Ofer Pasternak; Götz Thomalla; Christian Gerloff; Martha E Shenton; Robert Schulz

doi:10.1093/braincomms/fcad160

Altered microstructure of the contralesional ventral premotor cortex and motor output after stroke

Brain Commun. 2023 May 17;5(3):fcad160. doi: 10.1093/braincomms/fcad160. eCollection 2023.

Authors

Paweł P Wróbel¹, Stephanie Guder¹, Jan F Feldheim¹, José A Graterol Pérez¹, Benedikt M Frey¹, Chi-Un Choe¹, Marlene Bönstrup^{1

2}, Bastian Cheng¹, Yogesh Rathi^{3

4}, Ofer Pasternak^{3

4}, Götz Thomalla¹, Christian Gerloff¹, Martha E Shenton^{3

4}, Robert Schulz¹

Affiliations

¹ Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg 20251, Germany.
² Department of Neurology, University Medical Center, Leipzig 04103, Germany.
³ Psychiatry Neuroimaging Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston 02115, MA, USA.
⁴ Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston 02115, MA, USA.

Abstract

Cortical thickness analyses have provided valuable insights into changes in cortical brain structure after stroke and their association with recovery. Across studies though, relationships between cortical structure and function show inconsistent results. Recent developments in diffusion-weighted imaging of the cortex have paved the way to uncover hidden aspects of stroke-related alterations in cortical microstructure, going beyond cortical thickness as a surrogate for cortical macrostructure. We re-analysed clinical and imaging data of 42 well-recovered chronic stroke patients from 2 independent cohorts (mean age 64 years, 4 left-handed, 71% male, 16 right-sided strokes) and 33 healthy controls of similar age and gender. Cortical fractional anisotropy and cortical thickness values were obtained for six key sensorimotor areas of the contralesional hemisphere. The regions included the primary motor cortex, dorsal and ventral premotor cortex, supplementary and pre-supplementary motor areas, and primary somatosensory cortex. Linear models were estimated for group comparisons between patients and controls and for correlations between cortical fractional anisotropy and cortical thickness and clinical scores. Compared with controls, stroke patients exhibited a reduction in fractional anisotropy in the contralesional ventral premotor cortex (P = 0.005). Fractional anisotropy of the other regions and cortical thickness did not show a comparable group difference. Higher fractional anisotropy of the ventral premotor cortex, but not cortical thickness, was positively associated with residual grip force in the stroke patients. These data provide novel evidence that the contralesional ventral premotor cortex might constitute a key sensorimotor area particularly susceptible to stroke-related alterations in cortical microstructure as measured by diffusion MRI and they suggest a link between these changes and residual motor output after stroke.

Keywords: DWI; cortical; hemisphere; plasticity; unaffected.