Rearrangement of motor centers and its relationship to the neurological status of low-grade glioma examined on pre- and postoperative fMRI

Objective

Well-developed compensatory mechanisms, based on the phenomenon of brain plasticity, exist in patients with neuroepithelial tumors, especially with highly differentiated gliomas (WHO grade II). We studied phenomenon of rearrangement of sensorimotor cortex using functional magnetic resonance imaging (fMRI), and verified relationship between observed changes and results of neurological and neuropsychological assessment.

Methods

Study group included 20 patients with WHO grade II gliomas located within motor or sensory cortex. fMRI examination, as well as clinical, neurological (Karnofsky performance score [KPS] and Lovett's scale [Lo]), and neuropsychological assessment (Digit Coding Symbol Test and Digit Span Test) were performed pre-operatively and 3 months post-surgery.

Results

There were no significant differences in pre- and postoperative performance status of patients. Although statistically insignificant, an increase in frequency of activation of primary and secondary cortical motor centers was observed postoperatively (p > 0.05). Prior to surgery, motor centers were characterized by lower values of t-statistics than in postoperative period (p > 0.05). In contrast, values of parameters describing the size of examined centers, i.e. mean number of clusters, were lower, but not statistically significant on postoperative examination (p > 0.05). Compared to individuals without motor deficit, patients with preoperative Lo3/Lo4 paralysis showed significantly higher mean values of t-statistics in the accessory motor area on postoperative examination (p < 0.05).

Conclusions

The processes of motor cortex rearrangement seemed to be associated with the pre- and postoperative neurological and neuropsychological status of patients. After contralateral primary motor cortex, accessory motor area was the second most frequently activated center, both pre- and postoperatively.