Does injury of the thalamocortical connection between the mediodorsal nucleus of the thalamus and the dorsolateral prefrontal cortex affect motor recovery after cerebral infarct?

Abstract

We assessed the state of the thalamocortical connection between the mediodorsal nucleus (MD) and the dorsolateral prefrontal cortex (DLPFC) in patients with corona radiata infarct using diffusion tensor tractography (DTT). Altogether, 110 patients with corona radiata infarct were recruited, all of whom underwent DTT at an early stage following infarct onset. Based on the integrity of CST (CST+: CST was preserved around the infarct, CST-: CST was interrupted by the infarct) and the integrity of thalamocortical connection between the MD of thalamus and the DLPFC (DLPFC+: the connection was preserved, DLPFC-: the connection was interrupted), patients were divided into 4 groups: CST+/DLPFC+ (37 patients), CST+/DLPFC- (21 patients), CST-/DLPFC+ (25 patients), and CST-/DLPFC- (27 patients) groups. Motor function was evaluated using the upper Motricity Index (MI), lower MI, modified Brunnstrom classification, and the functional ambulation category at baseline and at 6months post-onset. In patients with preserved CST integrity, the status of the thalamocortical connection had no impact on the assessed motor outcomes at 6months post-stroke. However, in patients with disrupted CST integrity, those with preserved thalamocortical connection integrity had significantly higher motor function scores in all assessed outcomes 6months post-stroke than those with disrupted thalamocortical connection integrity. The preservation or disruption of the thalamocortical connection between the MD of the thalamus and the DLPFC is an important factor for motor function recovery when CST integrity is also disrupted.