Diffusion tensor tractography of pyramidal tracts in patients with brainstem and intramedullary spinal cord tumors: Relationship with motor deficits and intraoperative MEP changes

Abstract

Purpose: To evaluate whether pyramidal tracts course alterations observed in diffusion tensor tractography (DTT) in cases of brainstem and intramedullary spinal cord tumors reflect patient clinical status and prognosis.

Materials and methods: For this purpose, we assessed in 17 patients relationships between pyramidal tracts course alterations observed in DTT (classified into four categories: unaffected; displaced or interspaced; partially disintegrated and completely disintegrated) performed on a 1.5 Tesla scanner and the presence of preoperative motor deficits, changes observed in motor evoked potentials (MEPs) records at the beginning of the operation, deterioration of the MEPs records during the operation, and perioperative deterioration of muscle strength.

Results: We found that, if the picture of pyramidal tracts in DTT was worse, motor deficit was more common (P = 0.062). This observation was even more evident (P = 0.027), when cases with at least partially destroyed pyramidal tracts were compared with cases with normal or at most displaced or interspaced by tumor but still preserved pyramidal tracts. Significant relationships were also found between changes in DTT and abnormal MEP records at the beginning of the operation (P = 0.032) and perioperative deterioration of muscle strength (P = 0.0058).

Conclusion: A close relationship was found between pyramidal tracts course alterations in DTT imaging and preoperative motor status and especially with changes in the MEP records at the beginning of the operation. DTT may be a method that allows the better planning of brainstem and intramedullary spinal cord tumors operations and may help in the risk assessment of postoperative motor deficits.

Level of evidence: 3 Technical Efficacy: Stage 4 J. MAGN. RESON. IMAGING 2017;46:715-723.

Keywords: brainstem tumors; corticospinal tracts; diffusion tensor tractography; intramedullary spinal cord tumors; intraoperative neurophysiological monitoring; surgery.