Placement of a subdural evacuating port system for management of iatrogenic hyperacute subdural hemorrhage following intracranial monitor placement.

A 22-year-old man was admitted with a severe traumatic brain injury developed a hyperacute subdural hematoma (SDH) following attempted brain tissue oxygen monitor placement. This patient was successfully treated by placement of a subdural evacuation portal system (SEPS). The patient presented to a Level I trauma center after a severe bike versus auto accident. On admission, he was found to have a Glasgow Coma Scale (GCS) score of 3. The patient had small areas of intraparechymal hemorrhage as well as suspicion for diffuse axonal injury in the midbrain. Based on the patient's GCS score, neurological monitoring was indicated as a part of his intensive care unit treatment, however a SDH occurred during an attempted placement of a brain tissue oxygen monitor. This iatrogenic hyperacute SDH after burr hole monitoring device placement was treated with a SEPS drain. The SEPS drain has been shown to provide complete and/or temporary decompression of liquefied SDH. To our knowledge, this is the first report of using the SEPS to treat iatrogenic SDH associated with an intracranial monitoring device. This technique should be added to the armament of treatment options for a neurosurgeon to treat or temporize a hyperacute SDH with increased intracranial pressure in specific patients.

Noninvasive oxygen partial pressure measurement of human body fluids in vivo using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The oxygen partial pressure (pO2) of human body fluids reflects the oxygenation status of surrounding tissues. All existing fluid pO2 measurements are invasive, requiring either microelectrode/optode placement or fluid removal. The purpose of this study is to develop a noninvasive magnetic resonance imaging method to measure the pO2 of human body fluids. MATERIALS AND METHODS: We developed an imaging paradigm that exploits the paramagnetism of molecular oxygen to create quantitative images of fluid oxygenation. A single-shot fast spin echo pulse sequence was modified to minimize artifacts from motion, fluid flow, and partial volume. Longitudinal relaxation rate (R1 = 1/T1) was measured with a time-efficient nonequilibrium saturation recovery method and correlated with pO2 measured in phantoms. RESULTS: pO2 images of human and fetal cerebrospinal fluid, bladder urine, and vitreous humor are presented and quantitative oxygenation levels are compared with prior literature estimates, where available. Significant pO2 increases are shown in cerebrospinal fluid and vitreous following 100% oxygen inhalation. Potential errors due to temperature, fluid flow, and partial volume are discussed. CONCLUSIONS: Noninvasive measurements of human body fluid pO2 in vivo are presented, which yield reasonable values based on prior literature estimates. This rapid imaging-based measurement of fluid oxygenation may provide insight into normal physiology as well as changes due to disease or during treatment.

Measurement of cerebrospinal fluid oxygen partial pressure in humans using MRI.

Fluid-attenuated inversion recovery (FLAIR) images obtained during the administration of supplemental oxygen demonstrate a hyperintense signal within the cerebrospinal fluid (CSF) that is likely caused by T1 changes induced by paramagnetic molecular oxygen. Previous studies demonstrated a linear relationship between the longitudinal relaxation rate (R1 = 1/T1) and oxygen content, which permits quantification of the CSF oxygen partial pressure (P(csf)O2). In the current study, CSF T1 was measured at 1.5 T in the lateral ventricles, third ventricle, cortical sulci, and basilar cisterns of eight normal subjects breathing room air or 100% oxygen. Phantom studies performed with artificial CSF enabled absolute P(csf)O2 quantitation. Regional P(csf)O2 differences on room air were observed, from 65 +/- 27 mmHg in the basilar cisterns to 130 +/- 49 mmHg in the third ventricle. During 100% oxygen, P(csf)O2 increases of 155 +/- 45 and 124 +/- 34 mmHg were measured in the basilar cisterns and cortical sulci, respectively, with no change observed in the lateral or third ventricles. P(csf)O2 measurements in humans breathing room air or 100% oxygen using a T1 method are comparable to results from invasive human and animal studies. Similar approaches could be applied to noninvasively monitor oxygenation in many acellular, low-protein body fluids.