gms | German Medical Science

Objective: Quality of life preservation has become a priority in glioma surgery. The evolution of brain imaging and neurosurgical technique has made this goal possible: preoperative understanding of anatomy in relation with the tumor is fundamental for preoperative decision-making and surgical planning. The aim of our work is to depict qualitative and quantitative changes of corticospinal tract (CST) in patients affected by gliomas with preoperative motor deficits using diffusion tensor imaging (DTI) fiber tracking.

Method: A retrospective study was conducted on 22 subjects treated in our Institute with an initial diagnosis of primary cerebral glioma and preoperative motor deficits. Exclusion criteria were: involvement of motor cortex, lesion involving both hemispheres, previous surgical treatment. All patients were studied using magnetic resonance imaging (MRI) with DTI sequences. Data were transferred to navigation workstation and both CSTs were reconstructed. Volume, fractional anisotropy (FA) and mean diffusivity value (MD) of the entire CSTs were estimated. Moreover, distance from midline, diameters, FA and MD were calculated on axial images at the point of minimal distance between tumor and CST. Involvement of CST was classified using these parameters and all the values were compared with the contralateral (healthy) hemisphere and correlation with clinical data were performed.

Results: Depiction of CST was possible in all subjects. Mean CST volume of affected side was 7,861 cm³; mean FA and MD of the whole CST were 0,405 and 003 mm²/sec. The same parameters on healthy hemisphere were respectively 11,117 cm³, 0,433 and 0,002. Considering the axial plane with shortest distance between tumor and CST the FA was 0,470 on pathological hemisphere and 0.571 on the healty one. Corticospinal tract mean distance from midline was 16,995 mm on affected and 20,538 mm on contralateral side; antero-posterior/lateral diameters of CST were 12,01/ 5,562 mm on tumor side and 15,638/ 6,395 on other side. The statistical analysis showed a significant difference in FA and MD values, CST volume and antero-posterior diameter between the two hemispheres. The CSTs were classified as deviated, edematous and infiltrated.

Conclusions: DTI tractography is effective in depicting CST and can give important qualitative and quantitative information on CST and its involvement in patients affected by intraaxial lesions. This can be of great help for preoperative decision making and planning.