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Traumatic Brain Injury and Aeromedical Licensing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Most acute management under these conditions is directed at improving and maintaining the blood supply to the brain and even increasing the blood pressure to maintain cerebral perfusion against an elevated intracranial pressure. Where maintenance of the cerebral perfusion pressure to a level of at least 60 mm Hg cannot be achieved, decompression of the cranial cavity, either by clot removal or extensive decompressive craniectomy, is to be considered. The latter now forms a significantly increasing part of the armamentarium of managing head injuries and is analogous to managing a so-called compartment syndrome in other parts of the body (Pompucci et al., 2007).
Current in vivo Models for Brain Disorders
Published in Carla Vitorino, Andreia Jorge, Alberto Pais, Nanoparticles for Brain Drug Delivery, 2021
Marta Guerra-Rebollo, Cristina Garrido
The most frequently used ischaemic stroke models are as follows: The middle cerebral artery (MCA) stroke model which can be divided into the intraluminal suture MCA model where the MCA is occluded [24] or the craniectomy model where a craniectomy and the section of the dura mater to expose the MCA is required. Cerebral ischaemia induced by this method compromises most of the frontal, parietal, temporal and rostral occipital cortices; the underlying white matter; and a marginal part of the striatum. This technique avoids the thalamic, hypothalamic, hippocampal and midbrain damage seen in the suture MCA model. Compared to the suture MCA model, this procedure induces smaller infarcts [25].The photothrombotic stroke model is based on intravascular photo-oxidation. A photoactive dye is injected intraperitoneally (mice) or intravenously (rats) and the skull is irradiated by a light beam at a specific wavelength [26, 27].The endothelin-1 (ET-1) focal stroke model is based on the application of ET-1, a potent vasoconstrictive peptide. ET-1 could be applied directly onto the exposed MCA, as an intracerebral injection or onto the cortical surface [28].The embolic stroke models can be divided into the micro-/macrosphere-induced stroke models and the thromboembolic clot models. Microspheres (diameter of 20–50 μm) are inserted into the MCA or the internal carotid artery (ICA) via the external carotid artery (ECA) using a microcatheter, resulting in multifocal and heterogeneous infarcts, while macrospheres (diameter of 100–400 μm) are instilled into the ICA providing reproducible occlusion of the MCA main stem which results in focal ischaemic lesions which are comparable to the suture MCA model [29]. The thromboembolic clot model is based on the application of spontaneously formed clots or thrombin-induced clots from autologous blood [30].
The RNS System: brain-responsive neurostimulation for the treatment of epilepsy
Published in Expert Review of Medical Devices, 2021
Beata Jarosiewicz, Martha Morrell
The implantable components of the RNS System are illustrated in Figure 1. The cranially seated 'neurostimulator' is connected to 1 or 2 depth and/or cortical strip 'leads' that are surgically placed in the brain at 1 to 2 seizure foci. Each lead contains 4 electrodes, each of which can be used for both sensing and stimulating. During surgery, the neurostimulator is placed within a ferrule that is secured to a full-thickness craniectomy, typically in the parietal skull, but the location can be modified based on the patient’s skull curvature and lead locations. The lead placement, lead types (depth vs. strip), as well as surgical approach and implantation strategy, are individualized for each patient depending on the extent and location of their seizure focus or foci (for representative case studies, see [17]). Initial detection and stimulation settings are typically as follows: 200 Hz, 160 µs pulse width per phase, 100 ms burst duration, and 1.0 mA current amplitude. Settings are adjusted over time for each individual based on the clinical response. Test stimulations are delivered while the patient is in clinic to ensure that stimulation is not perceived by the patient and does not induce afterdischarges on the real-time ECoG recording.
Reconstruction of calvarial bone defects using poly(amino acid)/hydroxyapatite/calcium sulfate composite
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Xiaoxia Fan, Haitao Peng, Hong Li, Yonggang Yan
Large reconstructive materials for cranioplasty are required for cosmetic improvement and protection. The goal, therefore, is to find strong composite materials with easy processability, while maintaining osteoconductivity for calvarial repair. Itokawa [23] developed the HA-PMMA composite for use as an implant material for cranioplasty, in view of the osteoconductivity of HA and the strength and ease of handling of PMMA; the results indicated that the composite had good osteoconductivity and biocompatibility after implantation in beagles for one year, but it only demonstrated a maximum compressive strength of 76.3 MPa. Eufinge [9] developed functionally graded implants of polylactides and calcium phosphate/calcium carbonate in an ovine model of computer-assisted craniectomy and cranioplasty. The formation of new bone from the dural layer of the meninges corresponded well to the degradation of the porous inner layer of the implants, and the skull contour was stabilized by the compact outer layer; however, this approach failed to provide adequate mechanical strength, thus, there was a risk of secondary damage after another attack. Furthermore, the degradation of the composite may fail to cater for the speed of formation of new bone, thereby losing the capacity to heal large calvarial defects in the adult population. Most of the materials mentioned in the literature possessed excellent properties for calvarial repair, such as degradability, osteoconductivity, and osteoinductivity; however, few reports refer to either the mechanical properties for protection against later harm or the osteoconductivity of the materials [24–26]. In this study, we used the PAA/HA/CS composite for calvarial repair and found that it possessed excellent mechanical strength for preventing external damage [21].
A review on patient-specific facial and cranial implant design using Artificial Intelligence (AI) techniques
Published in Expert Review of Medical Devices, 2021
Afaque Rafique Memon, Jianning Li, Jan Egger, Xiaojun Chen
Wu Chieh-Tsai et al. proposed a 3D deep learning framework to redesign cranial models. The author also investigated the performance in both simulated and clinical cases to verify its applicability [57]. Matzkin Franco et al. proposed a self supervised skull reconstruction in brain CT images with decompressive craniectomy reconstruction method consists of a CNN which operates on binary skull images obtained after pre-processing the CT. The researcher designed a virtual craniectomy procedure to simulate de-compressive craniectomy patients by removing bone flaps from specific areas [58].