The effects of corticospinal tract glioma on motor function evaluated by diffusion tensor imaging

Objective To evaluate the damage effect of glioma on corticospinal tract (CST) and motor function of lower extremities by using diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT). Methods A total of 45 patients with histopathologically confirmed gliomas (13 cases of low-grade gliomas and 32 cases of high-grade gliomas) were included in this pilot study. Motor cortex was not involved in all cases. Manual Muscle Testing (MMT) was used to measure contralateral muscle strength of knee joint. DTI images were used to measure the affected and contralateral posterior limb of internal capsule fractional anisotropy (FA) and relative FA (rFA, rFA = affected FA / contralateral FA). DTT images were used to measure affected and contralateral CST fiber density index (FDi) and relative FDi (rFDi, rFDi = affected FDi / contralateral FDi). Results In 45 patients, there were 6 cases (13.33% ) of MTT grade 2, 12 cases (26.67%) of grade 3, 21 cases (46.67%) of grade 4 and 6 cases (13.33%) of grade 5. All patients had different degrees of CST injury, including 21 cases (46.67%) of grade 1, 6 cases (13.33%) of grade 2 and 18 cases (40%) of grade 3. There were significant differences in the degree of CST injury (H = 38.560, P = 0.000), rFA (F = 37.453, P = 0.000) and rFDi (F = 6.734, P = 0.001) in different muscle strength groups. Among them, MTT grade 2 group had significantly higher degree of CST injury (Z = -4.088, P = 0.000; Z = -3.317, P = 0.001) and lower rFDi values (t = -3.850, P = 0.000; t = -3.481, P = 0.001) than MTT grade 4 and grade 5 groups, while had lower rFA values than MTT grade 3, grade 4 and grade 5 groups (t = -8.218, P = 0.000; t = -8.898, P = 0.000; t = -12.028, P = 0.000). Spearman rank correlation analysis showed that muscle strength was negatively correlated with CST injury (rs = -0.840, P = 0.000) and positively correlated with rFA values of posterior limb of internal capsule (rs = 0.615, P = 0.000) and rFDi (rs = 0.567, P = 0.000). Conclusions The degree of CST injury in patients with glioma in CST area is related to the degree of motor dysfunction. DOI: 10.3969/j.issn.1672-6731.2018.10.01