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Neurosurgical Techniques and Strategies
Published in David A. Walker, Giorgio Perilongo, Roger E. Taylor, Ian F. Pollack, Brain and Spinal Tumors of Childhood, 2020
Jonathan E. Martin, Ian F. Pollack, Robert F. Keating
Availability of intraoperative adjuncts requires prior planning.55 Frameless stereotactic navigation allows for optimized surgical planning, including incision and bone flap placement as well as localization of deep-seated pathology. Ultrasound provides real-time assessment of anatomy within the working field and beyond. It can be used to assess tumor and ventricular location, and evaluate the extent of resection. Intraoperative MRI (Figure 6.6) provides near-time assessment of exquisite cross-sectional anatomic detail, minimizes need for return to the operating room for residual disease, and allows for optimal resection of infiltrative tumors.56 Intraoperative neuromonitoring of modalities, to include brainstem auditory evoked responses, motor evoked potentials, and somatosensory evoked potentials, provides functional feedback during the case, and requires careful coordination with anesthesia to achieve optimal results.57,58 Finally, in children with intractable seizures from cerebral neoplasms, intraoperative or extraoperative electrocorticography (ECOG)59 may be used to define areas of epileptogenic cortex in and around the tumor to increase the likelihood that seizure control will be obtained postoperatively. Recently the use of intraoperative MRI has increased seizure control in patients with cortical dysplasias.60
Functional Image-Guided Neurosurgery
Published in Andrei I. Holodny, Functional Neuroimaging, 2019
Cameron W. Brennan, Nicole M. Petrovich Brennan
Electrocorticography (ECoG) and electrocortical stimulation (ECS) are commonly used intraoperative techniques for mapping and monitoring neurological function during surgery. ECoG can be used to map epileptic activity by recording voltage potentials on the cortical surface or through deep needle electrodes. Another common application of ECoG is as an initial means during surgery to identify the central sulcus dividing motor cortex and sensory cortex in the precentral and postcentral gyri, respectively. For this purpose, electrical current is delivered to the median nerve by surface electrodes on the patient’s wrist. This stimulation induces action potentials in the median nerve, which are conveyed to somatosensory and motor cortex, eliciting a series of electrical potentials. These somatosensory evoked potentials (SSEP) are detected by an array (or strip) of multiple-recording electrodes placed over the cortical surface. The central sulcus is identified by the two electrodes across which the sign of the wave is inverted (Fig. 1). The presence of underlying tumor can distort the central sulcus anatomy and alter the SSEP distribution leading to ambiguous or misleading phase reversals. Central sulcus location can be confirmed by direct cortical stimulation (ECS, Fig. 1). Conversely, for patients under general anesthesia, ECS may fail to elicit motor responses at safe currents and SSEP may be the only usable technique.
Cranial Neurosurgery
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
MRI is a mainstay, demonstrating for example reduced hippocampal volume and distorted architecture in mesial temporal sclerosis. Nuclear medicine modalities including singlephoton emmision CT and positron emission tomography are sometimes used to demonstrate ictal and inter-ictal metabolic abnormalities. Electroencephalography entails recording from an array of scalp electrodes, and comparison between ictal and inter-ictal recordings. This is especially helpful in lateralising the focus of complex partial seizures in temporal lobe epilepsy, and is combined with video monitoring of the seizure in a videotelemetry suite. A more detailed localisation may be achieved invasively by the preoperative placement of subdural or depth electrodes or by intraoperative electrocorticography.
THE effect of general anesthetics on genetic absence epilepsy in WAG/Rij rats
Published in Neurological Research, 2022
Lubna Al-Gailani, Ali Al-Kaleel, Gökhan Arslan, Mustafa Ayyıldız, Erdal Ağar
On the experiment day, the animals were kept in a glass cage and connected to PowerLab 16/35 data acquisition system. ECoG recording was performed online and stored on the computer via LabChart v7.3.7 software (ADInstruments, Australia). The electrocorticography (ECoG) recordings were obtained during 120 min before (control recording) and 120 min after the administration of the different anesthetic agents (Figure 2). The number of Spike Wave Discharge (SWD) (which is a cluster of spikes resulting from the epileptic activity), the duration of SWDs, the number of spikes in each SWD, and the average amplitudes of the spikes (peak to peak), were analyzed offline in the data analysis menu of LabChart v7.3.7 program. This calculation was made separately for the recordings obtained from all animals used in the experiment.
Cerebral blood flow dynamics before, during, and after seizures from epilepsy and the periictal state
Published in Baylor University Medical Center Proceedings, 2022
Kalarickal Oommen, Jonathan Kopel
The data are shown in three-dimensional graphs with CCBF represented on the y axis and time on the x axis (Figure 2). Four hours of CBF were plotted along the x axis at 10-minute intervals in all three graphs. The arrow indicates the electrical onset of the seizure in all three figures. The CCBF showed a subtle dip preictally but then rose concurrent with the onset of the ictal discharge in the subdural strip electrocorticography. Following the spike in CBF with the electrical onset of the seizure, the CBF fell to the preictal level with the cessation of the rhythmic electrocorticographic discharge during one of the seizures, as shown in Figure 2a. The CBF then remained stable except for a minor dip during the postictal phase. In Figure 2b, the postictal CBF fell below the preictal level after the initial CBF spike and slowly returned to the baseline level within 3 hours. Figure 2c shows another one of the patient’s seizures in which the postictal CBF did not immediately return to the preictal level after the initial spike, stayed high, fluctuated somewhat, and then returned slowly to baseline levels within about 3 hours.
Spreading depolarization occurs in repeating, recognizable, patient-specific patterns after human brain injury
Published in Brain Injury, 2021
Chanju D Fritch, Fares Qeadan, C. William Shuttleworth, Andrew P Carlson
Spreading Depolarization (SD) is a phenomenon increasingly recognized to contribute to injury progression in the neuro ICU. SD is characterized by a slowly propagating (1.7–9.2 mm/s) breakdown of neuronal transmembrane ion gradients that lead to disruption of physiologic brain function due to synaptic silencing, with accompanying cellular swelling and shrinking. SD has been implicated in primary and secondary injury types (1) in the contexts of stroke, subarachnoid hemorrhage (SAH), and traumatic brain injury (TBI), among other brain injury types (2–4). Furthermore, it is implicated in the initiation of cytotoxic edema and the neuronal death observed in primary and secondary injury types (5,6). Detection of SD via electrocorticography (ECoG) offers a novel way to characterize neurologic disease by its SD frequency, duration, and severity of SDs experienced. New precision medicine management based on SD characteristics offers a promising new realm of improved neurologic ICU care.