Minimum intraoperative testing battery for cochlear implantation: the international practice trend.

PURPOSE: In cochlear implantation (CI) surgery, there are a wide variety of intraoperative tests available. However, no clear guide exists on which tests must be performed as the minimum intraoperative testing battery. Toward this end, we studied the usage patterns, recommendations, and attitudes of practitioners toward intraoperative testing. METHODS: This study is a multicentric international survey of tertiary referral CI centers. A survey was developed and administered to a group of CI practitioners (n = 34) including otologists, audiologists and biomedical engineers. Thirty six participants were invited to participate in this study based on a their scientific outputs to the literature on the intraoperative testing in CI field and based on their high load of CI surgeries. Thirty four, from 15 countries have accepted the invitation to participate. The participants were asked to indicate the usage trends, perceived value, influence on decision making and duration of each intraoperative test. They were also asked to indicate which tests they believe should be included in a minimum test battery for routine cases. RESULTS: Thirty-two (94%) experts provided responses. The most frequently recommended tests for a minimum battery were facial nerve monitoring, electrode impedance measurements, and measurements of electrically evoked compound action potentials (ECAPs). The perceived value and influence on surgical decision-making also varied, with high-resolution CT being rated the highest on both measures. CONCLUSION: Facial nerve monitoring, electrode impedance measurements, and ECAP measurements are currently the core tests of the intraoperative test battery for CI surgery.

Awake brain mapping paradigms for nondominant hemisphere gliomas.

OBJECTIVE: Traditionally, resection of nondominant hemisphere brain tumors was performed under general anesthesia. An improved understanding of right-lateralized neural networks has led to a paradigm shift in recent decades, where the right or nondominant hemisphere is no longer perceived as "functionally silent." There is an increasing interest in awake brain mapping for nondominant hemisphere resections. The objective of this study was to perform a comprehensive review of the existing brain mapping paradigms for patients with nondominant hemisphere gliomas undergoing awake craniotomies. METHODS: In accordance with PRISMA guidelines, systematic searches of the Medline, Embase, and American Psychological Association PsycInfo databases were undertaken from database inception to July 1, 2023. Studies providing a description of the intraoperative mapping paradigm used to assess cognition during an awake craniotomy for resection of a nondominant hemisphere glioma were included. RESULTS: The search yielded 1084 potentially eligible articles. Thirty-nine unique studies reporting on 788 patients were included in the systematic review. The most frequently tested cognitive domains in patients with nondominant hemisphere tumors were spatial attention/neglect (17/39 studies, 43.6%), speech-motor/language (17/39 studies, 43.6%), and social cognition (9/39 studies, 23.1%). Within the frontal lobe, the highest number of positive mapping sites was identified for speech-motor/language, spatial attention/neglect, dual tasking assessing motor and language function, working memory, and social cognition. Within the parietal lobe, eloquence was most frequently found upon testing spatial attention/neglect, speech-motor/language, and calculation. Within the temporal lobe, the assessment of spatial attention/neglect yielded the highest number of positive mapping sites. CONCLUSIONS: Cognitive testing in the nondominant hemisphere is predominantly focused on evaluating two domains: spatial attention/neglect and the motor aspects of speech/language. Multidisciplinary teams involved in awake brain mapping should consider testing an extended range of functions to minimize the risk of postoperative deficits and provide valuable information about anatomo-functional organization of cognitive networks.

Awake craniotomy for supratentorial tumors or epileptogenic lesions in pediatric patients: a 16-year retrospective cohort study.

OBJECTIVE: Awake craniotomy with intraoperative mapping is the widely accepted procedure for adult patients undergoing supratentorial tumor or epileptogenic focus resection near eloquent cortex. In children, awake craniotomies are notably less common due to concerns for compliance and emotional or psychological repercussions. Despite this, successfully tolerated awake craniotomies have been reported in patients as young as 8 years of age, with success rates comparable to those of adults. The authors sought to describe their experience with pediatric awake craniotomies, including insight regarding feasibility and outcomes. METHODS: A retrospective review was completed for all pediatric (age < 18 years) patients at Children's Wisconsin for whom an awake craniotomy was attempted from January 2004 until March 2020. Institutional review board approval was granted. RESULTS: Candidate patients had intact verbal ability, cognitive profile, and no considerable anxiety concerns during neuropsychology assessment. Nine patients presented with seizure. Five patients were diagnosed with tumor and secondary epilepsy, 3 with tumor only, and 3 with epilepsy only. All patients who underwent preoperative functional MRI successfully completed and tolerated testing paradigms. A total of 12 awake craniotomies were attempted in 11 patients, with 1 procedure aborted due to intraoperative bleeding. One patient had a repeat procedure. The mean patient age was 15.5 years (range 11.5-17.9 years). All patients returned to or maintained baseline motor and speech functions by the latest follow-up (range 14-130 months). Temporary deficits included transient speech errors, mild decline in visuospatial reasoning, leg numbness, and expected hemiparesis. Of the 8 patients with a diagnosis of epilepsy prior to surgery, 7 patients achieved Engel class I designation at the 1-year follow-up, 6 of whom remained in class I at the latest follow-up. CONCLUSIONS: This study analyzes one of the largest cohorts of pediatric patients who underwent awake craniotomy for maximal safe resection of tumor or epileptogenic lesions. For candidate patients, awake craniotomy is safe, feasible, and effective in carefully selected children.

Language Assessment in Multilingualism and Awake Neurosurgery.

Multilingualism has become a worldwide phenomenon that poses critical issues about the language assessment in patients undergoing awake neurosurgery in eloquent brain areas. The accuracy and sensitivity of multilingual perioperative language assessment procedures is crucial for a number of reasons: they should be appropriate to detect deficits in each of the languages spoken by the patient; they should be suitable to identify language-specific cortical regions; they should ensure that each of the languages of a multilingual patient is tested at an adequate and comparable level of difficulty. In clinical practice, a patient-tailored approach is generally preferred. This is a necessary compromise since it is impossible to predict all the possible language combinations spoken by individuals and thus the availability of standardized testing batteries is a potentially unattainable goal. On the other hand, this leads to high inconsistency in how different neurosurgical teams manage the linguistic features that determine similarity or distance between the languages spoken by the patient and that may constrain the neuroanatomical substrate of each language. The manuscript reviews the perioperative language assessment methodologies adopted in awake surgery studies on multilingual patients with brain tumor published from 1991 to 2021 and addresses the following issues: (1) The language selected for the general neuropsychological assessment of the patient. (2) The procedures adopted to assess the dimensions that may constrain language organization in multilingual speakers: age and type of acquisition, exposure, proficiency, and use of the different languages. (3) The type of preoperative language assessment used for all the languages spoken by the patient. (4) The linguistic tasks selected in the intraoperative setting. The reviewed data show a great heterogeneity in the perioperative clinical workup with multilingual patients. The only exception is the task used during language mapping, as the picture naming task is highly preferred. The review highlights that an objective and accurate description of both the linguistic profile of multilingual patients and the specific properties of the languages under scrutiny can profitably support clinical management and decision making in multilingual awake neurosurgery settings.

Requiem for the STAT Test: Automation and Point of Care Testing.

OBJECTIVE: Quick turnaround of laboratory test results is needed for medical and administrative reasons. Historically, laboratory tests have been requested as routine or STAT. With a few exceptions, a total turnaround time of 90 minutes has been the usually acceptable turnaround time for STAT tests. METHODS: We implemented front-end automation and autoverification and eliminated batch testing for routine tests. We instituted on-site intraoperative testing for selected analytes and employed point of care (POC) testing judiciously. The pneumatic tube system for specimen transport was expanded. RESULTS: The in-laboratory turnaround time was reduced to 45 minutes for more than 90% of tests that could reasonably be ordered STAT. With rare exceptions, the laboratory no longer differentiates between routine and STAT testing. Having a single queue for all tests has improved the efficiency of the laboratory. CONCLUSION: It has been recognized in manufacturing that batch processing and having multiple queues for products are inefficient. The same principles were applied to laboratory testing, which resulted in improvement in operational efficiency and elimination of STAT tests. We propose that the target for in-laboratory turnaround time for STAT tests, if not all tests, be 45 minutes or less for more than 90% of specimens.

Testing of Direct Neurorrhaphy Strain.

PURPOSE: To investigate the ideal suture material to test strain at nerve repair sites. Based on nerve strain tolerance, we aimed to determine which suture reliably failed by an average of 5% and a maximum of 8% strain when loaded to failure. METHODS: The median nerve of 19 cadavers was exposed in the distal forearm, transected proximally, and attached to a spring gauge. It was marked 5 cm on either side of its midpoint to measure strain. A laceration was created at its midpoint. We performed a tension-free end-to-end repair with a single epineural suture. Load to failure of the repair site was recorded. We recorded strain at failure and mode of failure (pullout vs breakage). Eight different sutures were tested: 6-0, 8-0, 9-0, and 10-0 nylon; and 6-0, 7-0, 8-0, and 10-0 polypropylene. RESULTS: Average strain at failure of 9-0 nylon most closely approximated 5% (4.9%). Moreover, 8-0 polypropylene and 10-0 nylon and polypropylene failed with average strains less than 5% and a maximum strain of failure less than 8%. Regardless of type, 6-0 to 8-0 caliber suture failed primarily by pullout of the suture from the epineurium whereas 9-0 and 10-0 nylon and polypropylene failed by suture breakage. Decreased precision through increased variability was seen when testing sutures failing via pullout. CONCLUSIONS: Nylon suture size 8-0 has been advocated as the suggested intraoperative aid to test strain at nerve repair sites. Our study suggests that 9-0 nylon may be a more appropriate testing suture because of its more predictable failure via breakage and its failure by a threshold of 5% to 8% strain. Although 8-0 nylon and polypropylene may also represent reasonable testing sutures, 8-0 nylon failed on average above 5% strain, with strains exceeding 8%, and both failed via the mechanism of pullout. CLINICAL RELEVANCE: This study's findings provide information for surgeons attempting to decide during surgery whether to perform direct nerve repair.

Effects of antagonistic and synergistic muscles' co-activation on mechanics of activated spastic semitendinosus in children with cerebral palsy.

OBJECTIVES: Most activities involve co-activation of several muscles and epimuscular myofascial force transmission (EMFT) can affect their mechanics. This can be relevant for spastic muscles of cerebral palsy (CP) patients. Isometric spastic semitendinosus (ST) forces vs. knee angle (KA-FST) data were collected intra-operatively to test the following hypotheses: (i) Inter-antagonistic EMFT elevates FST, (ii) changes the shape of KA-FST characteristics, (iii) reduces the muscle's joint range of force exertion (Range-FST) and (iv) combined inter-antagonistic and synergistic EMFT further changes those effects. METHODS: 11 limbs of 6 patients with CP (mean (SD) = 7.7 (4.7) years; GMFCS levels = II-IV) were tested in 3 conditions from 120° to full extension: ST activated (I) exclusively, (II) simultaneously with an antagonist, and (III) with added activation of synergists. RESULTS: Condition II increased FST (e.g., peak force = 87.6 N (30.5 N)) significantly (by 33.6%), but condition III caused no further change. No condition changed the muscle's wide Range-FST (100.7° (15.9°)) significantly. Therefore, only the first hypothesis was confirmed. CONCLUSIONS: Co-activating its antagonist elevates forces of activated spastic ST substantially, but does not change its joint range of force exertion. Added activation of its synergists causes no further effects. Therefore, EMFT effects in CP can be relevant and need to be tested in other knee flexors.

Resection of Gliomas with and without Neuropsychological Support during Awake Craniotomy-Effects on Surgery and Clinical Outcome.

BACKGROUND: During awake craniotomy for tumor resection, a neuropsychologist (NP) is regarded as a highly valuable partner for neurosurgeons. However, some centers do not routinely involve an NP, and data to support the high influence of the NP on the perioperative course of patients are mostly lacking. OBJECTIVE: The aim of this study was to investigate whether there is a difference in clinical outcomes between patients who underwent awake craniotomy with and without the attendance of an NP. METHODS: Our analysis included 61 patients, all operated on for resection of a presumably language-eloquent glioma during an awake procedure. Of these 61 cases, 47 surgeries were done with neuropsychological support (NP group), whereas 14 surgeries were performed without an NP (non-NP group) due to a language barrier between the NP and the patient. For these patients, neuropsychological assessment was provided by a bilingual resident. RESULTS: Both groups were highly comparable regarding age, gender, preoperative language function, and tumor grades (glioma WHO grades 1-4). Gross total resection (GTR) was achieved more frequently in the NP group (NP vs. non-NP: 61.7 vs. 28.6%, P = 0.04), which also had shorter durations of surgery (NP vs. non-NP: 240.7 ± 45.7 vs. 286.6 ± 54.8 min, P < 0.01). Furthermore, the rate of unexpected tumor residuals (estimation of the intraoperative extent of resection vs. postoperative imaging) was lower in the NP group (NP vs. non-NP: 19.1 vs. 42.9%, P = 0.09), but no difference was observed in terms of permanent surgery-related language deterioration (NP vs. non-NP: 6.4 vs. 14.3%, P = 0.48). CONCLUSION: We need professional neuropsychological evaluation during awake craniotomies for removal of presumably language-eloquent gliomas. Although these procedures are routinely carried out with an NP, this is one of the first studies to provide data supporting the NP's crucial role. Despite the small group size, our study shows statistically significant results, with higher rates of GTR and shorter durations of surgery among patients of the NP group. Moreover, our data emphasize the common problem of language barriers between the surgical and neuropsychological team and patients requiring awake tumor resection.

Operating environment for awake brain surgery - Choice of tests.

INTRODUCTION: The indication for awake brain surgery depends on a prerequisite, i.e. recognition that the brain area concerned is truly eloquent, and identification of one or more functions that must be preserved. These functions are determined preoperatively in collaboration with the patient, and neuropsychological tests considered to be the most relevant are performed in the operating room according to each team's technical preferences. OPERATING ENVIRONMENT: The neurosurgeon must choose transfer equipment considered to be relevant. Although a minimal technological environment is an option, a surgical team with great human wealth is essential, composed of specialized personnel with complementary skills. CHOICE AND IMPLEMENTATION OF INTRAOPERATIVE TESTS: The choice of intraoperative tests, which can be relatively simple for certain primary functions, can be much more difficult for high-level cognitive functions. No consensus has been reached concerning these tests, which must therefore be selected on an individual basis. Intraoperative testing must be based on preoperative multidisciplinary decisions made jointly by the neurosurgeon, neurologist, speech therapist and neuropsychologist. CONCLUSIONS: Numerous operating tools and technology transfers are available for neurosurgical teams performing awake brain surgery but none - or very few - of them constitutes a mandatory prerequisite. In contrast, the transition from the concept of eloquent brain area to that of brain functions that must be preserved requires highly skilled multidisciplinary human resources. This goal will be more likely achieved in centers highly specialized in functional oncological neurosurgery.