Krzysztof Tybor

Cortical mapping by functional magnetic resonance imaging in patients with brain tumors

The aim of our study was to establish the effectiveness of the functional MRI (fMRI) technique in comparison with intraoperative cortical stimulation (ICS) in planning cortex-saving neurosurgical interventions. The combination of sensory and motor stimulation during fMRI experiments was used to improve the exactness of central sulcus localization. The study subjects were 30 volunteers and 33 patients with brain tumors in the rolandic area. Detailed topographical relations of activated areas in fMRI and intraoperative techniques were compared. The agreement in the location defined by the two methods for motor centers was found to be 84%; for sensory centers it was 83%. When both kinds of activation are taken into account this agreement increases to 98%. A significant relation was found between fMRI and ICS for the agreement of the distance both for motor and sensory centers (p=0.0021–0.0024). Also a strong dependence was found between the agreement of the location and the agreement of the distance for both kinds of stimulation. The spatial correlation between fMRI and ICS methods for the sensorimotor cortex is very high. fMRI combining functional and structural information is very helpful for preoperative neurosurgical planning. The sensitivity of the fMRI technique in brain mapping increases when using both motor and sensory paradigms in the same patient.

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 Lovetts 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.

Supratentorial neurenteric cyst--a case report.

Supratentorial neurenteric cyst is a rare congenital lesion. We report here a case of a 33-year-old female who presented with seizures. A multicystic lesion in the left premotor cortex with moderate contrast enhancement was demonstrated with MRI. Microscopically, the lesion showed small cystic structures filled with a proteinaceous fluid. The wall of the cysts was lined with a single layer of ciliated columnar or cuboidal epithelium on a basement membrane. Glandular structures resembling gastrointestinal glands were also present. The cells of the cyst lining and glandular structures revealed strongly positive immunoreactions for epithelial markers (cytokeratin and epithelial membrane antigen).

Calcifying pseudoneoplasm of the foramen magnum—Case report and review of the literature

We present a case of a 29-year-old male with a calcifying pseudoneoplasm of the neuraxis (CAPNON) located in the region of the foramen magnum, treated successfully by complete resection. After a 2-year follow-up the patient remains recurrence free. Clinical and histopathological characterization of CAPNON is provided with special emphasis on the intraoperative and neuroradiological features of the lesion.