Relation between fractional anisotropy in the cerebral peduncles and changes in motor evoked potential after acute n~ddle cerebral artery territory infarction

Abstract

Objective To investigate the changing characteristics of the fractional anisotropy （FA） in cerebal peduncles and its relation with motor evoked potential （MEP） after acute cerebral infarction and to clear the clinical sigaificance of the low limit value of the FA in cerebral peduncles. Methods The low limit value of the FA in normal cerebral peduncles was determined based on mean - 1.64 standard deviation. The patients with acute cerebral infarction （n = 58） were divided into MEP positive group and MEP negative group according to the absence and presence of MEP, in which the patients in the MEP positive group were rexiivided into the FA in cerebral peduncles 〈 the low limit value and≥ the low limit value groups according to the FA in cerebral peduncles on the affected sides. Results The low limit value of the FA in normalcerebral peduncles was 0. 36. There was sigtificant difference in the FA in cerebral peduncles on the affected sides between the MEP negtive and MEP positive groups. The MEP negative group was the lowest （P =0. 000）. The FA in cerebral peduncles on the affected sides in the positive group was significantly lower than that on the unaffected sides （P =0. 000）, and the latency on the affected sides was longer than that on the normal sides （P = 0. 000）. The FA in cerebral peduncles on the affected sides was negatively correlated with the MEP latency （r = -0. 332, P =0. 042）. The MEP latency in the FA 〈 the low limit value group was significantly longer than that in the FA ≥ low limit value group （P = 0. 002）. There were no significant differences in the FA in cerebral peduncles on the normal sides and the MEP latency among all groups. The detection rate of the FA in cerebral peduncle 〈 0. 36 on the affected sides was the highest （50%）. Conclusions In the evaluation of the prognosis of the patients,,the changes of the FA in cerebral peduncles on the affected sides in patients with acute cerebral infarction had correlation, consistency, and complementarity with MEP. The detection rate of the low limit value of the FA in normal cerebral peduncles was the highest in the MEP negative patients. When the FA in cerebral peduncles was 〈 0.36 on the affected sides, particularly when MET was negative, it might predict that the prognosis was poor. Key words: Stroke; Brain infarction; Evoked potentials, motor; Magnetic resonanceim~aging; Anisotropy; Wallerian degeneration; Pyramidal tracts; Reference values