Monopolar high-frequency language mapping: can it help in the surgical management of gliomas? A comparative clinical study

Abstract

T he current strategy for addressing intrinsic brain lesions, such as gliomas, is aimed at maximal tumor resection while preserving the patient's functional integrity. 9,31,33,[36][37][38] Achieving these aims can be hampered by the infiltrative nature of gliomas, which can involve essential functional structures. 16 Intraoperative direct electrical stimulation (DES) coupled with neuropsychological testing has been increasingly recognized as an efficient strategy to improve the extent of resection (EOR) and reduce postoperative morbidity. 10,13,18 In fact, DES allows identification and localization (mapping) of eloquent structures, at both the cortical and subcortical level. 5,15,[17][18][19]30,34,39 In addition, a tailored neuropsychological evaluation provides an appropriate cognitive picture of the patient, leading to an objective definition of their cognitive status and guiding resection during language and cognitive mapping. obJective Intraoperative language mapping is traditionally performed with low-frequency bipolar stimulation (LFBS). High-frequency train-of-five stimulation delivered by a monopolar probe (HFMS) is an alternative technique for motor mapping, with a lower reported seizure incidence. The application of HFMS in language mapping is still limited. Authors of this study assessed the efficacy and safety of HFMS for language mapping during awake surgery, exploring its clinical impact compared with that of LFBS. methods Fifty-nine patients underwent awake surgery with neuropsychological testing, and LFBS and HFMS were compared. Frequency, type, and site of evoked interference were recorded. Language was scored preoperatively and 1 week and 3 months after surgery. Extent of resection was calculated as well. results High-frequency monopolar stimulation induced a language disturbance when the repetition rate was set at 3 Hz. Interference with counting (p = 0.17) and naming (p = 0.228) did not vary between HFMS and LFBS. These results held true when preoperative tumor volume, lesion site, histology, and recurrent surgery were considered. Intraoperative responses (1603) in all patients were compared. The error rate for both modalities differed from baseline values (p < 0.001) but not with one another (p = 0.06). Low-frequency bipolar stimulation sensitivity (0.458) and precision (0.665) were slightly higher than the HFMS counterparts (0.367 and 0.582, respectively). The error rate across the 3 types of language errors (articulatory, anomia, paraphasia) did not differ between the 2 stimulation methods (p = 0.279). coNclusioNs With proper setting adjustments, HFMS is a safe and effective technique for language mapping.

Mapping the brain network of the phonological loop

“…To collect a sufficient number of stimulation per area, we considered as target areas, Broca's region (including pars opercularis, triangularis, and orbitalis) and the SMG‐AG, and we gathered all the remaining parietal, temporal, and frontal sites as “control” sites. The location of Broca's area is variously described as being in the pars triangularis of the inferior frontal gyrus, in the pars opercularis, or more commonly in the “posterior inferior frontal gyrus.” A further functional definition was done intraoperatively, as previously described [Riva et al, ; Quinones‐Hinojosa et al, ]. As patients differed in their span (Table and Supporting Information), ad‐hoc, “personalized” sequences were used for each patient.…”

“…All studies in this field, exploring cortical and subcortical functions, adopted this technique to investigate the central nervous system, due to its spatial and temporal resolution which is still unparalleled by other methods [Desmurget et al, ]. The current propagation in the white matter of the bipolar pulse technique is known to be millimetric on average [Riva et al, ].…”

Prediction of Isocitrate Dehydrogenase Genotype in Brain Gliomas with MRI: Single-Shell versus Multishell Diffusion Models

“…Surgery was performed by a team of three boardcertified neurosurgeons as previously described (25). Diffusion MR images were available on a neuronavigation system (Brainlab, Munich, Germany).…”

Direct electrical stimulation of the premotor cortex shuts down awareness of voluntary actions

“…HF-DES was delivered in trains of 1 to 5 constant anodal current pulses (pulse duration 0.5 ms; interstimulus interval, ISI: 3-4 ms) at a variable intensity (1-40 mA) depending on the patient's cortical excitability. The choice of technique used by the surgeon depends on the clinical setting and on the structure to be explored 12,13,35,55 . Note that, during the present experimental tasks (HMt coupled with MMt), only the LF-DES paradigm, routinely used during mapping of language and cognitive functions 13 , was used.…”