Concordance between Wada, Transcranial Magnetic Stimulation, and Magnetoencephalography for Determining Hemispheric Dominance for Language: A Retrospective Study.

Determination of language hemispheric dominance (HD) in patients undergoing evaluation for epilepsy surgery has traditionally relied on the sodium amobarbital (Wada) test. The emergence of non-invasive methods for determining language laterality has increasingly shown to be a viable alternative. In this study, we assessed the efficacy of transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG), compared to the Wada test, in determining language HD in a sample of 12 patients. TMS-induced speech errors were classified as speech arrest, semantic, or performance errors, and the HD was based on the total number of errors in each hemisphere with equal weighting of all errors (classic) and with a higher weighting of speech arrests and semantic errors (weighted). Using MEG, HD for language was based on the spatial extent of long-latency activity sources localized to receptive language regions. Based on the classic and weighted language laterality index (LI) in 12 patients, TMS was concordant with the Wada in 58.33% and 66.67% of patients, respectively. In eight patients, MEG language mapping was deemed conclusive, with a concordance rate of 75% with the Wada test. Our results indicate that TMS and MEG have moderate and strong agreement, respectively, with the Wada test, suggesting they could be used as non-invasive substitutes.

Plasticity in the developing brain: neurophysiological basis for lesion-induced motor reorganization.

The plasticity of the developing brain can be observed following injury to the motor cortex and/or corticospinal tracts, the most commonly injured brain area in the pre- or peri-natal period. Factors such as the timing of injury, lesion size and lesion location may affect a single hemisphere's ability to acquire bilateral motor representation. Bilateral motor representation of single hemisphere origin is most likely to occur if brain injury occurs before the age of 2 years; however, the link between injury aetiology, reorganization type and functional outcome is largely understudied. We performed a retrospective review to examine reorganized cortical motor maps identified through transcranial magnetic stimulation in a cohort of 52 patients. Subsequent clinical, anthropometric and demographic information was recorded for each patient. Each patient's primary hand motor cortex centre of gravity, along with the Euclidian distance between reorganized and normally located motor cortices, was also calculated. The patients were classified into broad groups including reorganization type (inter- and intrahemispheric motor reorganization), age at the time of injury (before 2 years and after 2 years) and injury aetiology (developmental disorders and acquired injuries). All measures were analysed to find commonalities between motor reorganization type and injury aetiology, function and centre of gravity distance. There was a significant effect of injury aetiology on type of motor reorganization (P < 0.01), with 60.7% of patients with acquired injuries and 15.8% of patients with developmental disorders demonstrating interhemispheric motor reorganization. Within the interhemispheric motor reorganization group, ipsilaterally and contralaterally projecting hand motor cortex centres of gravity overlapped, indicating shared cortical motor representation. Furthermore, the data suggest significantly higher prevalence of bilateral motor representation from a single hemisphere in cases of acquired injuries compared to those of developmental origin. Functional outcome was found to be negatively affected by acquired injuries and interhemispheric motor reorganization relative to their respective counterparts with developmental lesions and intrahemispheric motor reorganization. These results provide novel information regarding motor reorganization in the developing brain via an unprecedented cohort sample size and transcranial magnetic stimulation. Transcranial magnetic stimulation is uniquely suited for use in understanding the principles of motor reorganization, thereby aiding in the development of more efficacious therapeutic techniques to improve functional recovery following motor cortex injury.

Localization of Expressive Language Cortex in a 2-Year-Old Child Using High-Gamma Electrocorticography.

Cortical stimulation mapping is the gold standard for presurgical language mapping; however, it cannot be reliably performed in very young patients. Language mapping using noninvasive modalities is also challenging in very young patients. Although utility of language mapping using power of high-gamma in electrocorticographic recordings was demonstrated in adults and older children, there is a gap of knowledge in the ability of this procedure for localizing language-specific cortex in very young patients. We describe a case of a 2-year-old patient who, to our knowledge, is the youngest person to undergo successful high-gamma electrocorticographic presurgical language mapping for localization of the expressive language cortex (Broca area). The surgical plan was to resect a cortical tuber within the left inferior frontal gyrus and there was a strong concern about postoperative language deficit after resection. Presurgical language mapping using noninvasive modalities were attempted without success. Cortical stimulation mapping was not feasible in this patient. Therefore, high-gamma electrocorticography was the only viable option for language mapping, and it successfully localized the expressive language cortex. The patient underwent surgery for resection of the IFG tuber based on results of high-gamma electrocorticography and had no postoperative language deficit. High-gamma electrocorticography can be used for localizing language-specific cortex, especially Broca's area, in very young patients.

Predicting postoperative language outcome using presurgical fMRI, MEG, TMS, and high gamma ECoG.

OBJECTIVE: To predict the postoperative language outcome using the support vector regression (SVR) and results of multimodal presurgical language mapping. METHODS: Eleven patients with epilepsy received presurgical language mapping using functional MRI (fMRI), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), and high-gamma electrocorticography (hgECoG), as well as pre- and postoperative neuropsychological evaluation of language. We constructed 15 (24-1) SVR models by considering the extent of resected language areas identified by all subsets of four modalities as input feature vector and the postoperative language outcome as output. We trained and cross-validated SVR models, and compared the cross-validation (CV) errors of all models for prediction of language outcome. RESULTS: Seven patients had some level of postoperative language decline and two of them had significant postoperative decline in naming. Some parts of language areas identified by four modalities were resected in these patients. We found that an SVR model consisting of fMRI, MEG, and hgECoG provided minimum CV error, although an SVR model consisting of fMRI and MEG was the optimal model that facilitated the best trade-off between model complexity and prediction accuracy. CONCLUSIONS: A multimodal SVR can be used to predict the language outcome. SIGNIFICANCE: The developed multimodal SVR models in this study can be utilized to calculate the language outcomes of different resection plans prior to surgery and select the optimal surgical plan.

Comorbid psychosocial issues seen in pediatric otolaryngology clinics.

Common disorders seen in frequently have related comorbid psychosocial issues and conditions. This article reviews the literature on these comorbidities in commonly seen otolaryngology conditions and heightens awareness of the cognitive, developmental, behavioral, emotional, and social correlates of these commonly treated conditions. Evidence-based practice would suggest identification and appropriate referrals would be helpful; therefore, a time-efficient and accurate screening mechanism is needed within the context of a busy clinical practice. A screening algorithm for identifying these issues and providing appropriate referrals is provided.