Right parietal cortex and calculation processing: intraoperative functional mapping of multiplication and addition in patients affected by a brain tumor.
OBJECTIVE
The role of parietal areas in number processing is well known. The significance of intraoperative functional mapping of these areas has been only partially explored, however, and only a few discordant data are available in the surgical literature with regard to the right parietal lobe. The purpose of this study was to evaluate the clinical impact of simple calculation in cortical electrostimulation of right-handed patients affected by a right parietal brain tumor.


METHODS
Calculation mapping in awake surgery was performed in 3 right-handed patients affected by high-grade gliomas located in the right parietal lobe. Preoperatively, none of the patients presented with calculation deficits. In all 3 cases, after sensorimotor and language mapping, cortical and intraparietal sulcus areas involved in single-digit multiplication and addition calculations were mapped using bipolar electrostimulation.


RESULTS
In all patients, different sites of the right parietal cortex, mainly in the inferior lobule, were detected as being specifically related to calculation (multiplication or addition). In 2 patients the intraparietal sulcus was functionally specific for multiplication. No functional sites for language were detected. All sites functional for calculation were spared during tumor resection, which was complete in all cases without postoperative neurological deficits.


CONCLUSIONS
These findings provide intraoperative data in support of an anatomofunctional organization for multiplication and addition within the right parietal area. Furthermore, the study shows the potential clinical relevance of intraoperative mapping of calculation in patients undergoing surgery in the right parietal area. Further and larger studies are needed to confirm these data and assess whether mapped areas are effectively essential for function.
Departments of Neurosurgery.
Alessandro
A
Della Puppa
Serena
S
De Pellegrin
Elena
E
d'Avella
Giorgio
G
Gioffrè
Marina
M
Munari
Marina
M
Saladini
Elena
E
Salillas
Renato
R
Scienza
Carlo
C
Semenza
D000368:Aged; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods*; D001932:Brain Neoplasms / Q000601:surgery*; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005910:Glioma / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010296:Parietal Lobe / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome