1/9. diffusion-weighted magnetic resonance imaging in brain death.BACKGROUND; Traditionally the diagnosis of brain death is established on the basis of a combination of clinical signs and paraclinical methods. diffusion-weighted MRI is a new method sensitive to cerebral ischemia. Its value in brain death has not been demonstrated until now. CASE DESCRIPTION: A patient was referred to MRI with suspicion of a brain stem stroke. Echo-planar whole-brain, multislice, diffusion-weighted MRI was performed in addition to conventional sequences and MR angiography sequences. In addition to the extensive bilateral hyperintensities observed on T2-weighted images, diffusion-weighted MRI showed diffuse hyperintensities involving both hemispheres as well as a severe drop in the apparent diffusion coefficient in both affected hemispheres. There was also transtentorial herniation with compression of the brain stem as well as absence of flow voids on the T2-weighted images and absence of intracranial vessels on MR angiography. On the basis of the clinical and imaging findings, it was concluded that the patient was in a state of brain death. The patient died the same day. CONCLUSIONS: With the use of new fast techniques such as diffusion-weighted imaging, now MRI can not only display anatomic changes associated with severe brain suffering but can also demonstrate ultrastructural changes secondary to brain death and differentiate them from edematous changes seen on T2-weighted images.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
2/9. Transcranial Doppler ultrasound in brain death: experience in 140 patients.The interpretation of clinical tests for brain death is often complicated by the presence of facial trauma, or the use of barbiturate therapy for reduction of intracranial pressure. We propose a non-invasive technique--transcranial Doppler (TCD) sonography for the diagnosis of brain death. One hundred and forty comatose patients, 111 of whom were believed to be brain dead underwent TCD examinations. TCD assessments of the middle cerebral arteries (MCAs) and the basilar artery were performed before formal clinical testing for brain death. The TCD spectra recorded in the brain dead (BD) patients consisted of short, sharp systolic peaks followed by retrograde flow during diastole or just systolic peaks with absent flow in either direction. There were no survivors among patients who displayed these two TCD patterns. The 29 comatose control patients always showed flow throughout the cardiac cycle--no retrograde flow was ever recorded in these patients all of whom survived. Of particular interest were the basilar artery results. In nine BD patients no MCA signals could be obtained while good quality signals were recorded from the basilar artery. The TCD results agreed essentially with 100% accuracy with clinical testing and four vessel cerebral angiography. This paper illustrates the usefulness of TCD examination of the MCAs and especially the basilar artery in the diagnosis of brain death.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
3/9. diagnosis of brain death with technetium 99m hexamethylpropylene amine oxime.We report on the utility of technetium 99m hexamethylpropylene amine oxime (99mTc-HMPAO) to diagnose brain death following cardiac surgery on a 49-year-old man with triple-vessel coronary artery disease. The imaging parameters and criteria to diagnose irreversible brain damage (brain death) with 99mTc-HMPAO are outlined. Brain imaging with this tracer seems to be more reliable than classic radionuclide angiography and has a potential value to confirm the diagnosis of brain death at an early stage. In addition, it may be used to evaluate the perfusion pattern to other vital organs with potential for transplantation.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
4/9. Lazarus sign and extensor posturing in a brain-dead patient. Case report.A man was declared brain dead after having sustained a gunshot wound to the head. All clinical criteria for the diagnosis of brain death were met. The electroencephalogram was isoelectric, and four-vessel angiography demonstrated the absence of cerebral blood flow. However, stereotypic spontaneous movements were observed which persisted for several hours. The possible mechanism is discussed and a short review of the literature is given.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
5/9. Pulsatile cerebral echo in diagnosis of brain death.Conclusive diagnosis of brain death can be made by the demonstration of prolonged cessation of cerebral blood flow. This report describes a simple method to determine the presence or absence of the blood flow in the brain by recording the pulsatile midline echo on one channel of the electroencephalogram (EEG) or on any four-channel monitoring system in the intensive care unit. A firm transducer holder has been developed to eliminate artifacts caused by transducer motion, The pulsations of the midline echo are assumed to be the result of displacement of the midline structures by the arterial injection of each cardiac systole. Thus, the absence of these midline pulsatile echoes correlates with the absence of cerebral blood flow and, if the absence persists over 30 minutes in the presence of normal blood pressure, then the result is brain death. Twenty-eight cases of clinical brain death with electrocerebral silence of EEG and 18 obtained patients with various types of cerebral pathology were examined by the echo-pulsation technique. Twenty-six of the 28 cases showed no pulsation of the midline echo. The validity of the technique was documented in four cases by four-vessel cerebral angiogram.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
6/9. Doppler ultrasonography in the determination of neonatal brain death.Both clinical and electroencephalographic criteria for brain death have limited value in the newborn. A simple test to determine the cessation of cerebral blood flow would be a useful adjunct to the determination of brain death in this population. In contrast to the invasive techniques used in older patients to estimate cerebral blood flow, the Doppler technique to estimate cerebral blood flow velocity from the anterior fontanelle of the newborn is noninvasive and can be used at bedside. In this study we define the changes in the flow velocity pattern in the anterior cerebral and the common carotid arteries in six newborn infants with clinical criteria for brain death: coma, absent brainstem function, and dependence on mechanical ventilation. A characteristic sequence of deterioration of the flow velocity waveform in both vessels was defined. This sequence consisted of (1) loss of diastolic flow, (2) appearance of retrograde flow during diastole, (3) diminution in systolic flow in the anterior cerebral artery, and, ultimately, (4) no detectable flow in the anterior cerebral artery, despite considerable flow in the common carotid artery. This constellation of findings suggests a progressive increase in cerebrovascular resistance and a progressive decrease in cerebral perfusion, compatible with the diffuse cerebral necrosis and edema documented postmortem. We conclude that the transcutaneous Doppler technique is a useful complement to other noninvasive methods, especially clinical assessment, in the determination of brain death in the newborn.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
7/9. Computer tomography in cerebral death.Computer tomography has been applied in a material of six patients meeting the criteria for cerebral death. The primary intracranial pathology, haemorrhages, infarction and contusions were demonstrable. No generalized reduction of the attenuation characteristic of infarction was found in spite of angiographic arrest of the intracranial circulation. Compression and obstruction of small brain vessels may in some cases be the primary cause of arrest of the brain circulation in cerebral death and not an increase of the intracranial pressure to levels approaching or surpassing the mean systemic arterial pressure.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
8/9. Preenhanced computed tomographic findings in brain death.A patient complying with the clinical criteria for brain death was studied by preenhanced computed tomography (CT). Preenhanced CT showed apparent increased density at the base of the brain along the course of the major arterial vessels, and abnormally dense-appearing deep venous structures, like those of contrast-enhanced CT. There was a diffuse decrease in brain density with a poorly delineated ventricular system. These CT findings were very characteristic. CT as a non-invasive method seems to be valuable in the diagnosis of brain death. The relevant literature is reviewed and mechanisms showing those CT findings are discussed.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |
9/9. Internal carotid artery occlusion in a child with sickle cell disease: case report and immunohistochemical study.PURPOSE: The purpose of this report is to describe the clinical and pathologic features of a patient with acute thrombosis of both internal carotid arteries leading to death. methods: This is a case report of special interest because of extensive brain vessel pathologic examination. RESULTS: The analysis of this case showed that the brain had suffered massive infarction and cerebral edema. The internal carotid arteries (ICAs) were occluded by acute thrombus. The arterial wall of the left ICA, studied at its distal segment, showed a small amount of intimal hyperplasia which did not cause encroachment on the lumen. Immunohistochemical stains indicated that this lesion was formed by proliferative vascular smooth muscle rather than incremental thrombus formation. CONCLUSION: Acute thrombus formation can occur in the large cerebral arteries of children with sickle cell disease in the presence of only minimal intimal hyperplasia. The intimal hyperplasia which forms the sickle related vasculopathy seen on angiography or detected by Transcranial Doppler may be more related to stimulation of smooth muscle cells than dysregulation of thromboregulation at the endothelial surface. Implications for preventive treatment are discussed.- - - - - - - - - - ranking = 1keywords = vessel (Clic here for more details about this article) |