Clinical Impact and Implication of Real-Time Oscillation Analysis for Language Mapping.
BACKGROUND
We developed a functional brain analysis system that enabled us to perform real-time task-related electrocorticography (ECoG) and evaluated its potential in clinical practice. We hypothesized that high gamma activity (HGA) mapping would provide better spatial and temporal resolution with high signal-to-noise ratios.


METHODS
Seven awake craniotomy patients were evaluated. ECoG was recorded during language tasks using subdural grids, and HGA (60-170 Hz) maps were obtained in real time. The patients also underwent electrocortical stimulation (ECS) mapping to validate the suspected functional locations on HGA mapping. The results were compared and calculated to assess the sensitivity and specificity of HGA mapping. For reference, bedside HGA-ECS mapping was performed in 5 epilepsy patients.


RESULTS
HGA mapping demonstrated functional brain areas in real time and was comparable with ECS mapping. Sensitivity and specificity for the language area were 90.1% ± 11.2% and 90.0% ± 4.2%, respectively. Most HGA-positive areas were consistent with ECS-positive regions in both groups, and there were no statistical between-group differences.


CONCLUSIONS
Although this study included a small number of subjects, it showed real-time HGA mapping with the same setting and tasks under different conditions. This study demonstrates the clinical feasibility of real-time HGA mapping. Real-time HGA mapping enabled simple and rapid detection of language functional areas in awake craniotomy. The mapping results were highly accurate, although the mapping environment was noisy. Further studies of HGA mapping may provide the potential to elaborate complex brain functions and networks.
Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan.
Hiroshi
H
Ogawa
Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan. Electronic address: kamady-k@umin.ac.jp.
Kyousuke
K
Kamada
g.tec Medical Engineering GmbH, Graz, Austria.
Christoph
C
Kapeller
g.tec Medical Engineering GmbH, Graz, Austria.
Robert
R
Prueckl
Center for Advanced Research and Education, Asahikawa Medical University, Asahikawa, Japan.
Fumiya
F
Takeuchi
Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan.
Satoru
S
Hiroshima
Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan.
Ryogo
R
Anei
g.tec Medical Engineering GmbH, Graz, Austria.
Christoph
C
Guger
D000328:Adult; D001927:Brain Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D001931:Brain Mapping; D003399:Craniotomy / Q000379:methods; D004569:Electroencephalography; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014851:Wakefulness
Awake craniotomy; Electrocorticogram; Functional dynamics; High gamma activity; Real-time mapping