Analysis of risk factors and clinical sequelae of direct electrical cortical stimulation-induced seizures and afterdischarges in patients undergoing awake mapping.

OBJECTIVE: Intraoperative stimulation has emerged as a crucial adjunct in neurosurgical oncology, aiding maximal tumor resection while preserving sensorimotor and language function. Despite increasing use in clinical practice of this stimulation, there are limited data on both intraoperative seizure (IS) frequency and the presence of afterdischarges (ADs) in patients undergoing such procedures. The objective of this study was to determine risk factors for IS or ADs, and to determine the clinical consequences of these intraoperative events. METHODS: A retrospective chart review was performed for patients undergoing awake craniotomy (both first time and repeat) at a single institution from 2013 to 2018. Hypothesized risk factors for ADs/ISs in patients were evaluated for their effect on ADs and ISs, including tumor location, tumor grade (I-IV), genetic markers (isocitrate dehydrogenase 1/2, O 6-methylguanine-DNA methyltransferase [MGMT] promoter methylation, chromosome 1p/19q codeletion), tumor volume, preoperative seizure status (yes/no), and dosage of preoperative antiepileptic drugs for each patient. Clinical outcomes assessed in patients with IS or ADs were duration of surgery, length of stay, presence of perioperative deficits, and postoperative seizures. Chi-square analysis was performed for binary categorical variables, and a Student t-test was used to assess continuous variables. RESULTS: A total of 229 consecutive patients were included in the analysis. Thirty-five patients (15%) experienced ISs. Thirteen (37%) of these 35 patients had experienced seizures that were appreciated clinically and noted on electrocorticography simultaneously, while 8 patients (23%) experienced ISs that were electrographic alone (no obvious clinical change). MGMT promoter methylation was associated with an increased prevalence of ISs (OR 3.3, 95% CI 1.2-7.8, p = 0.02). Forty patients (18%) experienced ADs. Twenty-three percent of patients (9/40) with ISs had ADs prior to their seizure, although ISs and ADs were not statistically associated (p = 0.16). The presence of ADs appeared to be correlated with a shorter length of stay (5.1 ± 2.6 vs 6.1 ± 3.7 days, p = 0.037). Of the clinical features assessed, none were found to be predictive of ADs. Neither IS nor AD, or the presence of either IS or AD (65/229 patients), was a predictor for increased length of stay, presence of perioperative deficits, or postoperative seizures. CONCLUSIONS: ISs and ADs, while commonly observed during intraoperative stimulation for brain mapping, do not negatively affect patient outcomes.

Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus.

Hydrocephalus is a common disorder caused by the buildup of cerebrospinal fluid (CSF) in the brain. Treatment typically involves the surgical implantation of a pressure-regulated silicone tube assembly, known as a shunt. Unfortunately, shunts have extremely high failure rates and diagnosing shunt malfunction is challenging due to a combination of vague symptoms and a lack of a convenient means to monitor flow. Here, we introduce a wireless, wearable device that enables precise measurements of CSF flow, continuously or intermittently, in hospitals, laboratories or even in home settings. The technology exploits measurements of thermal transport through near-surface layers of skin to assess flow, with a soft, flexible, and skin-conformal device that can be constructed using commercially available components. Systematic benchtop studies and numerical simulations highlight all of the key considerations. Measurements on 7 patients establish high levels of functionality, with data that reveal time dependent changes in flow associated with positional and inertial effects on the body. Taken together, the results suggest a significant advance in monitoring capabilities for patients with shunted hydrocephalus, with potential for practical use across a range of settings and circumstances, and additional utility for research purposes in studies of CSF hydrodynamics.

Epidermal electronics for noninvasive, wireless, quantitative assessment of ventricular shunt function in patients with hydrocephalus.

Hydrocephalus is a common and costly neurological condition caused by the overproduction and/or impaired resorption of cerebrospinal fluid (CSF). The current standard of care, ventricular catheters (shunts), is prone to failure, which can result in nonspecific symptoms such as headaches, dizziness, and nausea. Current diagnostic tools for shunt failure such as computed tomography (CT), magnetic resonance imaging (MRI), radionuclide shunt patency studies (RSPSs), and ice pack-mediated thermodilution have disadvantages including high cost, poor accuracy, inconvenience, and safety concerns. Here, we developed and tested a noninvasive, skin-mounted, wearable measurement platform that incorporates arrays of thermal sensors and actuators for precise, continuous, or intermittent measurements of flow through subdermal shunts, without the drawbacks of other methods. Systematic theoretical and experimental benchtop studies demonstrate high performance across a range of practical operating conditions. Advanced electronics designs serve as the basis of a wireless embodiment for continuous monitoring based on rechargeable batteries and data transmission using Bluetooth protocols. Clinical studies involving five patients validate the sensor's ability to detect the presence of CSF flow (P = 0.012) and further distinguish between baseline flow, diminished flow, and distal shunt failure. Last, we demonstrate processing algorithms to translate measured data into quantitative flow rate. The sensor designs, fabrication schemes, wireless architectures, and patient trials reported here represent an advance in hydrocephalus diagnostics with ability to visualize flow in a simple, user-friendly mode, accessible to the physician and patient alike.