PMC4369642_01
The admission CT-scan, (A) highlights the bone fragments close to the entry point behind the right ear (ring). (B) Illustrates the bullet (ring) and its trajectory (arrows).
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F1
A CT-scan of the head revealed several bone fragments in the right temporal lobe below the entrance of the bullet (Figure 1A), which progressed through the brain with a bihemispheric central and transventricular trajectory. Along the route, intraparenchymal- and subarachnoid-hemorrhages were present (Figure 1B).
Illustrating how the lactate:pyruvate ratio (LPR, black), the central perfusion pressure (CPP, blue), the intracranial pressure (ICP, green), and S100B (red) levels changed over time. The first red arrow indicates the time for hemicraniectomy ("surgery") while the other three highlight the timings for HBO treatment.
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F2
During the following day, the patient deteriorated with an increased ICP, increased intracerebral lactate:pyruvate ratio (LPR), and increased serum levels of the biomarker S100B (Figure 2). Following the procedure, the ICP returned to normal levels (<20 mmHg), although the LPR remained high (>40) (Figure 2). This lead to the initiation of hyperbaric oxygen (HBO) treatment (75 min, 2.8 bar with two air-brakes, followed by a stage-wise decompression during 40 min), which had an imminent, and stabilizing, effect on the LPR (Figures 2 and 4). The secondary increase of S100B stopped, and was followed by a steady decline (Figure 2).
Post-operative CT (after hemicraniectomy) day 2. The white arrows highlight the hypodense regions of brain parenchyma in the posterior circulation which is tissue at risk for subsequent ischemic injury.
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F3
The post-operative CT-scan revealed hypodense areas, indicating edema or that the tissue was at risk for ischemia, primarily in the cerebral areas supplied by the posterior circulation (Figure 3).
Lactate:pyruvate ratio (LPR, black), intracranial pressure (ICP, blue), and the brain tissue oxygen pressure (PBtO2, red) changes during HBO treatment (red blocks).
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F4
This lead to the initiation of hyperbaric oxygen (HBO) treatment (75 min, 2.8 bar with two air-brakes, followed by a stage-wise decompression during 40 min), which had an imminent, and stabilizing, effect on the LPR (Figures 2 and 4).
Illustrating how the brain tissue oxygen pressure (PBtO2, black), the arterial blood gas oxygen pressure (pO2, red), and fraction of inspired oxygen (FIO2, blue) changed over time. The red arrows indicate timing for HBO treatments. All the measurements presented are performed at normobaric conditions (before and after HBO).
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F5
The PBtO2 was not monitored during the HBO, because of technical issues, but showed a sustained increase to levels above 20 mmHg after the completed hyperbaric treatment, allowing the decrease of fraction of inspired oxygen (FiO2) (Figure 5). An increased FIO2 was tested, but failed to improve cerebral metabolic conditions (Figure 5).
MRI performed [susceptibility weighted imaging protocol (SWI)] on day 16 after injury reveals bilateral temporal damage and hemorrhage along the bullet, yet no signs of ischemic injury.
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F6
A MRI on day 16 showed bilateral temporal damage with cytotoxic edema along the trajectory, yet no ischemic injury or permanent damage to the frontal lobes (Figure 6).