Changes of power are less sensitive to artifacts than changes of the integral of power (see below).Ĥ. Trace: Squared 0.5-45 Hz bandpass-filtered ECoG (also called AC-ECoG power) provides better visualization of amplitude loss during spreading depression. Trace: 0.5-45 Hz bandpass-filtered ECoG shows spreading depolarization-induced spreading depression as an amplitude reduction.īandpass(rch 0.5,45)ģ. (Negative DC shift is only seen with DC-coupled amplifiers, and is not shown here.)Ģ. Trace: Near-DC/AC ECoG (0.01-45 Hz) shows a spreading depolarization as a characteristic negative, slow potential change. Review of the raw signal alongside a leaky integral of power of the bandpass filtered AC-ECoG most reliably shows this loss of amplitude.ġ. Spreading depolarization-induced spreading depression presents as a more or less rapidly developing, propagating reduction of the raw amplitude of spontaneous brain electrical activity in the 0.5-45 Hz band, or any derived measure based on amplitude. In the following section, the term DC shift also refers to the slow potential change in the AC-ECoG. However, only the unfiltered DC shift allows assessment of the local duration of spreading depolarization, and it is a true measure of tissue energy status and risk of injury. We can use the AC-recorded slow potential change to identify spreading depolarizations. AC-coupled amplifiers with a lower frequency limit of 0.01 or 0.02 Hz distort the cortical DC shift of spreading depolarization but a typical slow potential change is still visible. The raw DC can only be seen with DC-coupled amplifiers (see section above). The hallmark signature of spreading depolarization in the ECoG is a negative DC shift with sequential onset in adjacent electrodes. If you are not recording Laser Doppler flowmetry (LDF), you may use those channels to connect other devices. if electrode 5 breaks, exchange it for electrode 6). If any of the monopolar electrodes (2 or 5) break, they should be exchanged to allow calculation of as many monopolar channels as possible (e.g. Recommendations for PowerLab connections are shown on the close-up view of the amplifier’s front panel. Powerlab 16/SP analog/digital converter.Licox, Integra Lifesciences Corporation, Plainsboro, NJ, USA Brain tissue oxygen monitoring system with intraparenchymal oxygen sensor.LabChart ADInstruments, New South Wales, AustraliaīrainVision Recorder BrainProducts GmbH, Munich Electrode 1 of the strip electrode serves as ground. This is customary practice for intracranial pressure (ICP) and tissue partial pressure of oxygen (p tiO 2) monitoring.ĪDInstruments, New South Wales, AustraliaĮlectrodes 2-6 of the strip electrode are connected in sequential unipolar fashion to this amplifier, each referenced to an ipsilateral subgaleal platinum electrode. Here, it is also possible to place a subdural electrode strip through a burr hole, or to monitor with an intraparenchymal electrode array (Spencer, 1.1mm diameter, Ad-Tech, Racine, WI, USA) that is placed through a burr hole or a multi-lumen bolt. Antibiotic treatment beyond standard preoperative prophylaxis is not recommended. an additional fully penetrating skin suture should be performed with some distance to the scalp exit point, and a sufficient amount of absorbable hemostatic gelatin sponge should be placed under the bone flap - particularly in the area of the strip.the subcutaneous tunnel should be made sufficiently long and dilated, e.g.no plating hardware should be used next to the location of the strip and. ![]() the tail of the strip should exit the craniotomy and scalp in line with the rest of the electrode, and not be curved or bent at an angle.a sufficient bone should be removed with an osteotome or rongeur where the tail of the strip exits, and through which the electrode can be withdrawn by gentle traction at the end of monitoring.Therefore, the following precautions should be taken: Gentle traction may not be sufficient to remove the strip after the monitoring period when it is trapped/pinched by the bone flap or the titanium fixation, or if the subcutaneous tunnel is too tight.Ī cerebrospinal fluid (CSF)-fistula may develop.
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