Surgical resection of tumors located in subcortex of language area

Speech and Language Errors during Awake Brain Surgery and Postoperative Language Outcome in Glioma Patients: A Systematic Review

Awake craniotomy with direct electrical stimulation (DES) is the standard treatment for patients with gliomas in eloquent areas. Even though language is monitored carefully during surgery, many patients suffer from postoperative aphasia, with negative effects on their quality of life. Some perioperative factors are reported to influence postoperative language outcome. However, the influence of different intraoperative speech and language errors on language outcome is not clear. Therefore, we investigate this relation. A systematic search was performed in which 81 studies were included, reporting speech and language errors during awake craniotomy with DES and postoperative language outcomes in adult glioma patients up until 6 July 2020. The frequencies of intraoperative errors and language status were calculated. Binary logistic regressions were performed. Preoperative language deficits were a significant predictor for postoperative acute (OR = 3.42, p < 0.001) and short-term (OR = 1.95, p = 0.007) language deficits. Intraoperative anomia (OR = 2.09, p = 0.015) and intraoperative production errors (e.g., dysarthria or stuttering; OR = 2.06, p = 0.016) were significant predictors for postoperative acute language deficits. Postoperatively, the language deficits that occurred most often were production deficits and spontaneous speech deficits. To conclude, during surgery, intraoperative anomia and production errors should carry particular weight during decision-making concerning the optimal onco-functional balance for a given patient, and spontaneous speech should be monitored. Further prognostic research could facilitate intraoperative decision-making, leading to fewer or less severe postoperative language deficits and improvement of quality of life.

Parallel and distributed encoding of speech across human auditory cortex

Speech perception is thought to rely on a cortical feedforward serial transformation of acoustic into linguistic representations. Using intracranial recordings across the entire human auditory cortex, electrocortical stimulation, and surgical ablation, we show that cortical processing across areas is not consistent with a serial hierarchical organization. Instead, response latency and receptive field analyses demonstrate parallel and distinct information processing in the primary and nonprimary auditory cortices. This functional dissociation was also observed where stimulation of the primary auditory cortex evokes auditory hallucination but does not distort or interfere with speech perception. Opposite effects were observed during stimulation of nonprimary cortex in superior temporal gyrus. Ablation of the primary auditory cortex does not affect speech perception. These results establish a distributed functional organization of parallel information processing throughout the human auditory cortex and demonstrate an essential independent role for nonprimary auditory cortex in speech processing.

The Use of Standardized Intraoperative Language Tests in Awake Craniotomies: A Scoping Review

Assessment of speech and language functions is an essential part of awake craniotomies. Although standardized and validated tests have several advantages compared to homemade (or mixed) batteries, in the literature it is unclear how such tests are used or whether they are used at all. In this study, we performed a scoping review in order to locate standardized and validated intraoperative language tests. Our inquiry included two databases (PubMED and MEDLINE), gray literature, and snowball referencing. We discovered 87 studies reporting use of mixed batteries, which consist of homemade tasks and tests borrowed from other settings. The tests we found to meet the validation and standardization criteria we set were ultimately three (n = 3) and each one has its own advantages and disadvantages. We argue that tests with high sensitivity and specificity not only can lead to better outcomes postoperatively, but they can also help us to gain a better understanding of the neuroanatomy of language.

Treatment of cavernous malformations in supratentorial eloquent areas: experience after 10 years of patient-tailored surgical protocol

BACKGROUND

Eloquent area surgery has become safer with the development of intraoperative neurophysiological monitoring and brain mapping techniques. However, the usefulness of intraoperative electric brain stimulation techniques applied to the management and surgical treatment of cavernous malformations in supratentorial eloquent areas is still not proven. With this study, we aim to describe our experience with the use of a tailored functional approach to treat cavernous malformations in supratentorial eloquent areas.

METHODS

Twenty patients harboring cavernous malformations located in supratentorial eloquent areas were surgically treated. Individualized functional approach, using intraoperative brain mapping and/or neurophysiological monitoring, was utilized in each case. Eleven patients underwent surgery under awake conditions; meanwhile, nine patients underwent asleep surgery.

RESULTS

Total resection was achieved in 19 cases (95%). In one patient, the resection was not possible due to high motor functional parenchyma surrounding the lesion tested by direct cortical stimulation. Ten (50%) patients presented transient neurological worsening. All of them achieved total neurological recovery within the first year of follow-up. Among the patients who presented seizures, 85% achieved seizure-free status during follow-up. No major complications occurred.

CONCLUSIONS

Intraoperative electric brain stimulation techniques applied by a trained multidisciplinary team provide a valuable aid for the treatment of certain cavernous malformations. Our results suggest that tailored functional approach could help surgeons in adapting surgical strategies to prevent patients' permanent neurological damage.

Glioma surgery in eloquent areas: can we preserve cognition?

BACKGROUND

Cognitive preservation is crucial in glioma surgery, as it is an important aspect of daily life functioning. Several studies claimed that surgery in eloquent areas is possible without causing severe cognitive damage. However, this conclusion was relatively ungrounded due to the lack of extensive neuropsychological testing in homogenous patient groups. In this study, we aimed to elucidate the short-term and long-term effects of glioma surgery on cognition by identifying all studies who conducted neuropsychological tests preoperatively and postoperatively in glioma patients.

METHODS

We systematically searched the electronical databases Embase, Medline OvidSP, Web of Science, PsychINFO OvidSP, PubMed, Cochrane, Google Scholar, Scirius and Proquest aimed at cognitive performance in glioma patients preoperatively and postoperatively.

RESULTS

We included 17 studies with tests assessing the cognitive domains: language, memory, attention, executive functions and/or visuospatial abilities. Language was the domain most frequently examined. Immediately postoperatively, all studies except one, found deterioration in one or more cognitive domains. In the longer term (3-6/6-12 months postoperatively), the following tests showed both recovery and deterioration compared with the preoperative level: naming and verbal fluency (language), verbal word learning (memory) and Trailmaking B (executive functions).

CONCLUSIONS

Cognitive recovery to the preoperative level after surgery is possible to a certain extent; however, the results are too arbitrary to draw definite conclusions and not all studies investigated all cognitive domains. More studies with longer postoperative follow-up with tests for cognitive change are necessary for a better understanding of the conclusive effects of glioma surgery on cognition.

Subcortical language and non-language mapping in awake brain surgery: the use of multimodal tests

BACKGROUND

Awake craniotomy is currently considered the gold standard to maximise the extent of resection and to minimise postoperative deficits in patients with supratentorial tumours near eloquent areas. In addition to direct electrical stimulation (DES) of the cortex, intraoperative subcortical mapping is increasingly used as it optimises the benefit-to-risk ratio by decreasing (permanent) postoperative neurological deficits. However, only little attention has been paid to subcortical mapping procedures and especially the tasks to be used.

METHODS

In this article, language and non-language testing at the subcortical level is described and discussed by means of three right-handed cases with a glioma in the left hemisphere. To assess subcortical functions, a multimodal test named the Quick Mixed Test was developed (QMT). Pre-, intra- and postoperative test results are described and discussed in detail.

RESULTS

Based on the analysis of these preliminary observations, a number of clinical recommendations for intraoperative subcortical mapping may be made: (1) the selection of a set of language and non-language tests needs to be tailored according to the functional corticosubcortical regions affected by the tumoral lesion and the patient's characteristics (job/hobby/daily life activities); (2) language and non-language tests should be presented in a multimodal and alternating way during subcortical stimulation since this approach enables screening various functions simultaneously or in a very short period of time and (3) spontaneous speech is a useful adjunct to standardised tests since it most resembles daily life conversation.

CONCLUSION

Administration of multimodal tests during subcortical DES such as the experimental QMT may facilitate identification of eloquent pathways leading to avoidance of permanent neurological impairments.

Awake craniotomy for supratentorial gliomas: why, when and how?

Awake craniotomy has become an increasingly utilized procedure in the treatment of supratentorial intra-axial tumors. The popularity of this procedure is partially attributable to improvements in intraoperative technology and anesthetic techniques. The application of awake craniotomy to the field of neuro-oncology has decreased iatrogenic postoperative neurological deficits, allowed for safe maximal tumor resection and improved healthcare resource stewardship by permitting early patient discharge. In this article, we review recent evidence for the utility of awake craniotomy in the resection of gliomas and describe the senior author's experience in performing this procedure. Furthermore, we explore innovative applications of awake craniotomy to outpatient tumor resections and the conduct of neurosurgery in resource-poor settings. We conclude that awake craniotomy is an effective and versatile neurosurgical procedure with expanding applications in neuro-oncology.

Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere: surgical technique and functional results: clinical article

OBJECT

Maximal resection of symptomatic cavernous angioma (CA), including its surrounding gliosis if possible, has been recommended to minimize the risk of seizures or (re)bleeding. However, despite recent neurosurgical advances, such extensive CA removal is still a challenge in eloquent areas. The authors report a consecutive series of patients who underwent awake surgery for CA within the left dominant hemisphere in which intraoperative cortical-subcortical electrical stimulation was used.

METHODS

Nine patients harboring a CA that was revealed by seizures in 6 cases and bleeding in 3 cases underwent resection. All CAs were located in the left dominant hemisphere: 3 temporal, 2 insular, 2 parietal, and 2 in the parietotemporal region. Awake mapping was performed in all cases by using intraoperative cortical-subcortical electrical stimulation and ultrasonography (except in 1 insular CA in which a neuronavigation system was used).

RESULTS

Total removal of the CA was achieved in all patients, with identification and preservation of language and sensory-motor structures. In addition, the pericavernomatous gliosis was removed in 7 cases, according to the functional boundaries provided by intraoperative subcortical stimulation. In 2 cases, subcortical mapping revealed eloquent areas within the surrounding gliosis, which was voluntarily avoided. There was no postsurgical permanent deficit, no rebleeding, and no epilepsy in 7 cases (2 patients had rare seizures in the 1st year or two after surgery, and then complete arrest), with a mean follow-up of 28.5 months (range 3-64 months).

CONCLUSIONS

These results suggest that intraoperative cortical-subcortical stimulation in awake patients represents a valuable adjunct to image-guided surgery with the aim of selecting the safer surgical approach for CAs involving eloquent areas. Moreover, such online mapping can be helpful when removing the pericavernomatous gliosis while preserving functional structures, which can persist within the hemosiderin rim. Thus, the authors propose that awake surgery be routinely considered, both to optimize the resection and to improve the quality of life through seizure control and avoidance of (re)bleeding for CAs located in the left dominant hemisphere.

Awake Mapping Optimizes the Extent of Resection for Low-Grade Gliomas in Eloquent Areas

BACKGROUND

Awake craniotomy with intraoperative electrical mapping is a reliable method to minimize the risk of permanent deficit during surgery for low-grade glioma located within eloquent areas classically considered inoperable. However, it could be argued that preservation of functional sites might lead to a lesser degree of tumor removal. To the best of our knowledge, the extent of resection has never been directly compared between traditional and awake procedures.

OBJECTIVE

We report for the first time a series of patients who underwent 2 consecutive surgeries without and with awake mapping.

METHODS

Nine patients underwent surgery for a low-grade glioma in functional sites under general anesthesia in other institutions. The resection was subtotal in 3 cases and partial in 6 cases. There was a postoperative worsening in 3 cases. We performed a second surgery in the awake condition with intraoperative electrostimulation. The resection was performed according to functional boundaries at both the cortical and subcortical levels.

RESULTS

Postoperative magnetic resonance imaging showed that the resection was complete in 5 cases and subtotal in 4 cases (no partial removal) and that it was improved in all cases compared with the first surgery (P = .04). There was no permanent neurological worsening. Three patients improved compared with the presurgical status. All patients returned to normal professional and social lives.

CONCLUSION

Our results demonstrate that awake surgery, known to preserve the quality of life in patients with low-grade glioma, is also able to significantly improve the extent of resection for lesions located in functional regions.