Application of transcranial transmission ultrasound in the detection of vasospasm in patients with aneurysmal subarachnoid hemorrhage: illustrative cases.

BACKGROUND: Effective management of patients with aneurysmal subarachnoid hemorrhage (aSAH) demands vigilant monitoring and treatment, given the risks of complications such as cerebral vasospasm and delayed ischemic neurological deficits (DINDs). Transcranial transmission ultrasound (TTUS) is a well-established technique for assessing brain pulsatility. This pilot study aims to explore the utility of TTUS in detecting impaired intracerebral blood flow associated with DINDs. OBSERVATIONS: The authors examined 2 male patients, ages 45 and 52 years, with aSAH Hunt and Hess grades 4 and 2, respectively, who developed DINDs during their clinical course. Simultaneous recordings of arterial blood pressure, heart rate, and TTUS measurements were obtained in the intensive care unit. TTUS analysis revealed abnormal arrhythmic wave patterns during DIND episodes, whereas baseline measurements on DIND-free days showed no abnormalities. Following endovascular spasmolysis, TTUS demonstrated a normalization of abnormal waves, returning to baseline levels, alongside the resolution of neurological symptoms. LESSONS: TTUS, a noninvasive method for assessing brain pulsatility, shows promise as a novel tool for monitoring aSAH patients, potentially aiding in prompt diagnostics and additional therapeutic interventions. Its capacity to provide further insights for individuals at risk of delayed cerebral ischemia warrants further investigation in clinical studies. https://thejns.org/doi/10.3171/CASE24146.

Transcranial Transmission Ultrasound for Reliable Noninvasive Exclusion of Intracranial Hypertension in Traumatic Brain Injury Patients: A Proof of Concept Study.

For many years, noninvasive methods to measure intracranial pressure (ICP) have been unsuccessful. However, such methods are crucial for the assessment of patients with nonpenetrating traumatic brain injuries (TBIs) who are unconscious. In this study, we explored the use of transcranial transmission ultrasound (TTUS) to gather experimental data through brain pulsatility, assessing its effectiveness in detecting high ICP using machine learning analysis. We included patients with severe TBI under invasive ICP monitoring in our intensive care unit. During periods of both normal and elevated ICP, we simultaneously recorded ICP, arterial blood pressure, heart rate, and TTUS measurements. Our classification model was based on data from 9 patients, encompassing 387 instances of elevated ICP (>15 mmHg) and 345 instances of normal ICP (<10 mmHg), and validated through a leave-one-subject-out method. The study, conducted from October 2021 to October 2022, involved 25 patients with an average age of 61.6 ± 17.6 years, producing 279 datasets with an average ICP of 11.3 mmHg (1st quartile 6.1 mmHg; 3rd quartile 14.8 mmHg). The automated TTUS analysis effectively identified ICP values over 15 mmHg with 100% sensitivity and 47% specificity. It achieved a 100% negative predictive value and a 14% positive predictive value. This suggests that TTUS can accurately rule out high ICP above 15 mmHg in TBI patients, indicating patients who may need immediate imaging or intervention. These promising results, if confirmed and expanded in larger studies, could lead to the first reliable, noninvasive screening tool for detecting elevated ICP.

Toward a systematic grading for the selection of patients to undergo awake surgery: identifying suitable predictor variables.

Background: Awake craniotomy is the standard of care for treating language eloquent gliomas. However, depending on preoperative functionality, it is not feasible in each patient and selection criteria are highly heterogeneous. Thus, this study aimed to identify broadly applicable predictor variables allowing for a more systematic and objective patient selection. Methods: We performed post-hoc analyses of preoperative language status, patient and tumor characteristics including language eloquence of 96 glioma patients treated in a single neurosurgical center between 05/2018 and 01/2021. Multinomial logistic regression and stepwise variable selection were applied to identify significant predictors of awake surgery feasibility. Results: Stepwise backward selection confirmed that a higher number of paraphasias, lower age, and high language eloquence level were suitable indicators for an awake surgery in our cohort. Subsequent descriptive and ROC-analyses indicated a cut-off at ≤54 years and a language eloquence level of at least 6 for awake surgeries, which require further validation. A high language eloquence, lower age, preexisting semantic and phonological aphasic symptoms have shown to be suitable predictors. Conclusion: The combination of these factors may act as a basis for a systematic and standardized grading of patients' suitability for an awake craniotomy which is easily integrable into the preoperative workflow across neurosurgical centers.

Function-guided differences of arcuate fascicle and inferior fronto-occipital fascicle tractography as diagnostic indicators for surgical risk stratification.

BACKGROUND: Several patients with language-eloquent gliomas face language deterioration postoperatively. Persistent aphasia is frequently associated with damage to subcortical language pathways. Underlying mechanisms still need to be better understood, complicating preoperative risk assessment. This study compared qualitative and quantitative functionally relevant subcortical differences pre- and directly postoperatively in glioma patients with and without aphasia. METHODS: Language-relevant cortical sites were defined using navigated transcranial magnetic stimulation (nTMS) language mapping in 74 patients between 07/2016 and 07/2019. Post-hoc nTMS-based diffusion tensor imaging tractography was used to compare a tract's pre- and postoperative visualization, volume and fractional anisotropy (FA), and the preoperative distance between tract and lesion and postoperative overlap with the resection cavity between the following groups: no aphasia (NoA), tumor- or previous resection induced aphasia persistent pre- and postoperatively (TIA_P), and surgery-induced transient or permanent aphasia (SIA_T or SIA_P). RESULTS: Patients with NoA, TIA_P, SIA_T, and SIA_P showed distinct fasciculus arcuatus (AF) and inferior-fronto-occipital fasciculus (IFOF) properties. The AF was more frequently reconstructable, and the FA of IFOF was higher in NoA than TIA_P cases (all p ≤ 0.03). Simultaneously, SIA_T cases showed higher IFOF fractional anisotropy than TIA_P cases (p < 0.001) and the most considerable AF volume loss overall. While not statistically significant, the four SIA_P cases showed complete loss of ventral language streams postoperatively, the highest resection-cavity-AF-overlap, and the shortest AF to tumor distance. CONCLUSION: Functionally relevant qualitative and quantitative differences in AF and IFOF provide a pre- and postoperative pathophysiological and clinically relevant diagnostic indicator that supports surgical risk stratification.

CompreTAP: Feasibility and reliability of a new language comprehension mapping task via preoperative navigated transcranial magnetic stimulation.

OBJECTIVE: Stimulation-based language mapping approaches that are used pre- and intraoperatively employ predominantly overt language tasks requiring sufficient language production abilities. Yet, these production-based setups are often not feasible in brain tumor patients with severe expressive aphasia. This pilot study evaluated the feasibility and reliability of a newly developed language comprehension task with preoperative navigated transcranial magnetic stimulation (nTMS). METHODS: Fifteen healthy subjects and six brain tumor patients with severe expressive aphasia unable to perform classic overt naming tasks underwent preoperative nTMS language mapping based on an auditory single-word Comprehension TAsk for Perioperative mapping (CompreTAP). Comprehension was probed by button-press responses to auditory stimuli, hence not requiring overt language responses. Positive comprehension areas were identified when stimulation elicited an incorrect or delayed button press. Error categories, case-wise cortical error rate distribution and inter-rater reliability between two experienced specialists were examined. RESULTS: Overall, the new setup showed to be feasible. Comprehension-disruptions induced by nTMS manifested in no responses, delayed or hesitant responses, searching behavior or selection of wrong target items across all patients and controls and could be performed even in patients with severe expressive aphasia. The analysis agreement between both specialists was substantial for classifying comprehension-positive and -negative sites. Extensive left-hemispheric individual cortical comprehension sites were identified for all patients. Apart from one case presenting with transient worsening of aphasic symptoms, pre-existing language deficits did not aggravate if results were used for subsequent surgical planning. CONCLUSION: Employing this new comprehension-based nTMS setup allowed to identify language relevant cortical sites in all healthy subjects and severely aphasic patients who were thus far precluded from classic production-based mapping. This pilot study, moreover, provides first indications that the CompreTAP mapping results may support the preservation of residual language function if used for subsequent surgical planning.

Improving specificity of stimulation-based language mapping in stuttering glioma patients: A mixed methods serial case study.

Objective: Stimulation-based language mapping relies on identifying stimulation-induced language disruptions, which preexisting speech disorders affecting the laryngeal and orofacial speech system can confound. This study ascertained the effects of preexisting stuttering on pre- and intraoperative language mapping to improve the reliability and specificity of established language mapping protocols in the context of speech fluency disorders. Method: Differentiation-ability of a speech therapist and two experienced nrTMS examiners between stuttering symptoms and stimulation-induced language errors during preoperative mappings were retrospectively compared (05/2018-01/2021). Subsequently, the impact of stuttering on intraoperative mappings was evaluated in all prospective patients (01/2021-12/2022). Results: In the first part, 4.85 % of 103 glioma patients stuttered. While both examiners had a significant agreement for misclassifying pauses in speech flow and prolongations (Κ ≥ 0.50, p ≤ 0.02, respectively), less experience resulted in more misclassified stuttering symptoms. In one awake surgery case within the second part, stuttering decreased the reliability of intraoperative language mapping.Comparison with Existing Method(s): By thoroughly differentiating speech fluency symptoms from stimulation-induced disruptions, the reliability and proportion of stuttering symptoms falsely attributed to stimulation-induced language network disruptions can be improved. This may increase the consistency and specificity of language mapping results in stuttering glioma patients. Conclusions: Preexisting stuttering negatively impacted language mapping specificity. Thus, surgical planning and the functional outcome may benefit substantially from thoroughly differentiating speech fluency symptoms from stimulation-induced disruptions by trained specialists.