Electrical stimulation-induced speech-related negative motor responses in the lateral frontal cortex.

OBJECTIVE: Speech arrest is a common but crucial negative motor response (NMR) recorded during intraoperative brain mapping. However, recent studies have reported nonspeech-specific NMR sites in the ventral precentral gyrus (vPrCG), where stimulation halts both speech and ongoing hand movement. The aim of this study was to investigate the spatial relationship between speech-specific NMR sites and nonspeech-specific NMR sites in the lateral frontal cortex. METHODS: In this prospective cohort study, an intraoperative mapping strategy was designed to identify positive motor response (PMR) sites and NMR sites in 33 consecutive patients undergoing awake craniotomy for the treatment of left-sided gliomas. Patients were asked to count, flex their hands, and simultaneously perform these two tasks to map NMRs. Each site was plotted onto a standard atlas and further analyzed. The speech and hand motor arrest sites in the supplementary motor area of 2 patients were resected. The 1- and 3-month postoperative language and motor functions of all patients were assessed. RESULTS: A total of 91 PMR sites and 72 NMR sites were identified. NMR and PMR sites were anteroinferiorly and posterosuperiorly distributed in the precentral gyrus, respectively. Three distinct NMR sites were identified: 24 pure speech arrest (speech-specific NMR) sites (33.33%), 7 pure hand motor arrest sites (9.72%), and 41 speech and hand motor arrest (nonspeech-specific NMR) sites (56.94%). Nonspeech-specific NMR sites and speech-specific NMR sites were dorsoventrally distributed in the vPrCG. For language function, 1 of 2 patients in the NMA resection group had language dysfunction at the 1-month follow-up but had recovered by the 3-month follow-up. All patients in the NMA resection group had fine motor dysfunction at the 1- and 3-month follow-ups. CONCLUSIONS: The study results demonstrated a functional segmentation of speech-related NMRs in the lateral frontal cortex and that most of the stimulation-induced speech arrest sites are not specific to speech. A better understanding of the spatial distribution of speech-related NMR sites will be helpful in surgical planning and intraoperative mapping and provide in-depth insight into the motor control of speech production.

Clinical applications of neurolinguistics in neurosurgery.

The protection of language function is one of the major challenges of brain surgery. Over the past century, neurosurgeons have attempted to seek the optimal strategy for the preoperative and intraoperative identification of language-related brain regions. Neurosurgeons have investigated the neural mechanism of language, developed neurolinguistics theory, and provided unique evidence to further understand the neural basis of language functions by using intraoperative cortical and subcortical electrical stimulation. With the emergence of modern neuroscience techniques and dramatic advances in language models over the last 25 years, novel language mapping methods have been applied in the neurosurgical practice to help neurosurgeons protect the brain and reduce morbidity. The rapid advancements in brain-computer interface have provided the perfect platform for the combination of neurosurgery and neurolinguistics. In this review, the history of neurolinguistics models, advancements in modern technology, role of neurosurgery in language mapping, and modern language mapping methods (including noninvasive neuroimaging techniques and invasive cortical electroencephalogram) are presented.

A Novel Intraoperative Brain Mapping Integrated Task-Presentation Platform.

BACKGROUND: To be efficient, intraoperative task-presentation systems must accurately present various language and cognitive tasks to patients undergoing awake surgery, and record behavioral data without compromising convenience of surgery. OBJECTIVE: To present an integrated brain mapping task-presentation system we developed and evaluate its effectiveness in intraoperative task presentation. METHODS: The Brain Mapping Interactive Stimulation System (Brain MISS) is a flexible task presentation system that adjusts for patient comfort, needs of the surgeon, and operating team, with multivideo recording for patients' behavior. A total of 48 patients from 3 centers underwent intraoperative language task test during awake brain surgery with the Brain MISS. Each patient was assigned 5 questions each on picture naming, reading, and listening comprehension before and during awake surgeries. The accuracy of intraoperative stimulus-response (without electrical stimulation) was recorded. The Brain MISS was to be considered effective, if the lower limit of 95% CI of patients' intraoperative response was ≥80% and also if the accuracy of intraoperative response of all patients was statistically higher than 80%. RESULTS: All patients successfully underwent intraoperative assessment with the Brain MISS. The overall accuracy of stimulus response was 95.8% (95% CI 90.18%-100.00%), with the lower limit being higher than 80% and the response accuracy also significantly being higher than 80% in all patients (P = .006). CONCLUSION: The Brain MISS is a portable and effective system for presenting and streamlining complicated language and cognitive tasks during awake surgery. It can also record standardized patient response data for neuroscientific research.

Infraoccipital Supratentorial Approach Resection of a Left Mesiotemporal and Atrium Epidermoid Cyst.

Classically mesiotemporal lesions are approached from the lateral temporal approach, which frequently injures the visual and language tracts. We present the posterior approach through which the language tracts and visual tracts at the roof and lateral wall of the temporal horn (Meyer loop) can be avoided, minimizing the risk of neurologic injury. The patient, a 32-year-old man, presented with the chief complaint of experiencing seizures for 6 years with rare, generalized, tonic-clonic seizures. Physical examination showed no neurologic deficits and past medical history was not remarkable. Magnetic resonance imaging revealed a left mesiotemporal lesion, which showed no contrast enhancement and infiltrated the atrium. For surgery, the patient was laid in prone position and a tailored bone flap was lifted. Next the occipital lobe was retracted gently to expose the lesion. Penfield dissectors were used to gradually resect the lesion. The roof and inner wall of the atrium were exposed during resection. These structures were protected. Residues of the lesion and its capsule were seen attached to the lateral ventricle and were carefully coagulated and removed. The hippocampus was also exposed and a small segment resected. Exposure of the roof and inner wall of the atrium confirmed that the entire lesion has been resected. Intraoperative magnetic resonance imaging evaluation confirmed a total resection of the lesion. Pathological analysis confirmed the diagnosis of epidermoid cyst. Cognitive evaluation results showed no postoperative deficiencies and his visual field was also not affected by the surgery. Informed patient content was obtained (Video 1).