Motor Cortex Plasticity Predicts Recovery in Acute Stroke

Abstract

Repetitive transcranial magnetic stimulation of the brain given as intermittent theta burst stimulation (iTBS) can induce long-term potentiation (LTP)-like changes in the stimulated hemisphere and long-term depression (LTD)-like changes in the opposite hemisphere. We evaluated whether LTP- and LTD-like changes produced by iTBS in acute stroke correlate with outcome at 6 months. We evaluated the excitability of affected hemisphere (AH) and unaffected hemisphere (UH) by measuring motor threshold and motor-evoked potential (MEP) amplitude under baseline conditions and after iTBS of AH in 17 patients with acute ischemic stroke. Baseline amplitude of MEPs elicited from AH was significantly smaller than that of MEPs elicited from UH, and baseline motor threshold was higher for the AH. Higher baseline MEP values in UH correlated with poor prognosis. iTBS produced a significant increase in MEP amplitude for AH that was significantly correlated with recovery. A nonsignificant decrease in MEP amplitude was observed for the UH. When the decrease in the amplitude of UH MEPs was added to the regression model, the correlation was even higher. Functional recovery is directly correlated with LTP-like changes in AH and LTD-like changes in UH and inversely correlated with the baseline excitability of UH.

Corticospinal excitability in patients with anoxic, traumatic, and non-traumatic diffuse brain injury

“…Our results are in agreement with several paired TMS studies reporting a significant decrease in SICI in the affected hemisphere in stroke patients in the acute phase and in the early stages of recovery [10,11,35,36]. Additionally, Di Lazzaro et al [37] demonstrated that through theta burst stimulation there was a reduction in the MT, an increase in the MEP amplitude, and a reduction in SICI in the affected hemisphere of stroke patients. On the contrary, no changes were found in SICI in patients with diffuse TBI two years after the injury [12].…”

“…However, we observed no statistically significant correlations between SICI and SAI parameters and the cognitive and functional level of the patient assessed using the RLAS and FIM. Also, Di Lazzaro et al [37] showed that an increase in MEP amplitude significantly correlated with recovery at 6 months following stroke, while the amount of SICI did not predict long-term recovery. However, it was shown that behavioural gains in motor function induced by somatosensory stimulation of the paretic hand were accompanied by a reduction in SICI and ICF in the ipsilesional primary motor area in patients with chronic stroke [38].…”

Effect of Weighted Hand Movements on Hand Function in Chronic Stroke Patients

“…This results in changing in the metabolic function of the brain and promoting the neural plasticity and motor recovery after stroke. This is agreed also by [21][22][23][24].…”

TMS-evoked N100 responses as a prognostic factor in acute stroke

“…Some studies conducted in the acute phase of stroke showed, using MEP threshold and amplitude measures, a relationship between motor recovery and the degree of motor impairment (Pennisi et al, 1999;Pizzi et al, 2009;Rapisarda et al, 1996). The absence of MEPs, more than amplitude variations, seems to be predictive of recovery (Di Lazzaro et al, 2010), but consensus on this issue is still lacking. On the contrary, changes in motor cortex excitability in the intact hemisphere have been reported as having solid prognostic value (Manganotti et al, 2002(Manganotti et al, , 2008.…”