Proton spectroscopic imaging in cerebral ischaemia. Where we stand and what can be expected.
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Aspartic Acid↗
Biomedical subjects
C A Tulleken
Publications and source records attributed to C A Tulleken.
Spatial integration of multimodal brain images in cerebral infarction.
Different structural as well as functional imaging techniques are becoming increasingly important in the investigation of patients suffering from an ischemic stroke. Available imaging procedures usually provide complementary data, but the images can not easily be compared due to differences in patient positioning, angulation, and slice thickness. We studied the value of spatial integration of images from different modalities in a patient with an ischemic stroke and used skin markers to integrate the obtained information. Computed tomography (CT), magnetic resonance imaging (MRI), 99mTcHMPAO-single photon emission computed tomography (SPECT) and magnetic resonance spectroscopic imaging (MRSI) were performed in a patient, presenting with a right sided hemiparesis caused by an ischemic stroke. Combination of MRI with CT demonstrated that the infarction visible on CT and MRI corresponded in size and volume. Furthermore, structural and functional images could readily be integrated, thus allowing us to obtain accurate information in this stroke patient. Different imaging modalities provide complementary information in the acute phase of cerebral infarction and multimodality matching can be of great value for improvement of our understanding of the pathophysiology and course of ischemic stroke.
Brain↗
Temporal evolution of focal cerebral ischemia in the rat assessed by T2-weighted and diffusion-weighted magnetic resonance imaging.
The present study was undertaken to characterize the formation of ischemic brain edema using diffusion-weighted and T2-weighted magnetic resonance imaging in a rat model of focal ischemia. The extent of edema formation was measured from multislice diffusion-weighted and T2-weighted spin-echo images acquired at various times after ischemia. The spin-spin relaxation time (T2) and the apparent diffusion coefficient in normal and ischemic tissue were also determined. The results show that on the diffusion-weighted images the lesion was clearly visible at 30 minutes after ischemia, while on the T2-weighted images it became increasingly evident after 2-3 hours. On both types of images the hyperintense area increased in size over the first 48 hours. After 1 week the hyperintensity on the diffusion-weighted images rapidly disappeared and evolved as a hypointense lesion in the chronic phase. These results confirm the high sensitivity of diffusion-weighted MRI for the detection of early ischemia. The temporal course of the edema observed on T2W-images is in agreement with the reported increase of total water content occurring in this model. The increase of the lesion observed on the diffusion-weighted images during the first 2 days points to an aggravation of cytotoxic edema that parallels the changes in free water shown by the T2-weighted images. It is shown that the highly elevated T2's of the infarcted area several days after ischemia can substantially contaminate the diffusion-weighted images.
Animals↗
End-to-side anastomosis of small vessels using an Nd:YAG laser with a hemispherical contact probe. Technical note.
A new technique is described which enables the surgeon to perform an end-to-side anastomosis between arteries with little (less than 2 minutes) or no occlusion of the recipient artery. The technique was developed in rabbits, but has recently been successfully used in a patient in whom an anastomosis between the superficial temporal artery and a proximal branch of the middle cerebral artery was created.
Aged↗
Variability of the territories of the major cerebral arteries.
Recent morphological and functional studies on the circle of Willis suggest that the areas of supply of the six major cerebral arteries show a considerable variation in distribution, in contrast to the relatively consistent pattern generally accepted; therefore, the cortical and intracerebral distribution of the territories of these arteries was investigated in 25 unfixed human brains obtained at routine autopsy. The six major cerebral arteries were simultaneously injected under the same pressure with different-colored Araldite F mixtures under standardized conditions to obtain the most realistic territorial distribution. The cortical boundaries were examined and recorded in relation to the cerebral gyri and sulci, and the territories of the anterior, middle, and posterior cerebral arteries were analyzed and compared. The intracerebral distribution of these territories was investigated after the injected brains were cut in parallel slices. The variability of the territories of these arteries was much larger than generally described in the literature. Twenty-six variations in the territory of the anterior cerebral artery, 17 variations in the area of the middle cerebral artery, and 22 variations in the area of the posterior cerebral artery were found in the cortex of 50 hemispheres. Intracerebrally, the anterior, middle, and posterior cerebral arteries contributed in varying degrees to the blood supply of the lobar white matter, the internal capsule, the caudate nucleus, and the lentiform nucleus. The large variation in the area in which the cortical and intracerebral boundaries between these territories was located was demonstrated by illustrating the minimum and maximum extent of each. The results are compared with prior findings, and their implications for both experimental model studies and clinical practice are discussed.
Adolescent↗
[Balloon embolization of a large carotid-cavernous fistula].
A 58-year-old male patient with a giant carotid-cavernous fistula was treated by means of endovascular balloon embolisation. The fistula was closed, and good antegrade flow in the carotid artery and intracranial vessels was obtained. Based on this case history, the pathophysiology, ultrasonographic and angiographic evaluation and treatment options are reviewed.
Angiography, Digital Subtraction↗
[Surgical resection as treatment of spinal intramedullary tumors].
The authors retrospectively report the results of surgical treatment of spinal cord tumours in the Department of Neurosurgery, University Hospital Utrecht, Holland and review the recent literature. Twenty-eight patients were operated on for an intramedullary spinal cord tumour between 1981 and 1990. The mean follow-up period was 31 months. Neurological evaluation was done using the grading system described by Cooper and Epstein, immediately postoperatively and after 6 months. A total or subtotal resection could be performed in 22 (79%) of the 28 patients. Postoperatively, the neurological function of the legs improved or remained stable in 21 of the 28 patients, and the function of the arms in 26 of the 28 patients. After six months the neurological function in arms and legs had improved or remained stable in 19 of 21 patients. The most frequently occurring tumour, ependymoma, could be radically resected more often (82%) than astrocytoma (33%). Postoperative morbidity is closely related to the level of involvement. Microsurgical exploration at the cervical level is far less dangerous than has always been believed. Surgical mortality was 0%. Radical resection of intramedullary tumours should be attempted and can be achieved with stabilisation or improvement of neurological deficit in the majority of patients.
Adolescent↗
Effects of dextromethorphan on rat brain during ischemia and reperfusion assessed by magnetic resonance spectroscopy.
Using proton and phosphorus magnetic resonance spectroscopy, we evaluated the metabolic effects of preischemic administration of the N-methyl-D-aspartate antagonist dextromethorphan (50 mg/kg i.p.) during global forebrain ischemia and subsequent reperfusion in rats. Dextromethorphan-treated animals (n = 10) showed less lactate formation during ischemia than untreated animals (n = 11, p less than 0.001). During reperfusion, the lactate level in the treated group was reduced (p less than 0.05). Tissue pH declined less in the treated group during ischemia (p less than 0.01). There was no difference in the phosphocreatine/inorganic phosphate peak height ratio between groups. During ischemia, the N-acetylaspartate resonance peaks decreased in both groups. Histologic damage assessed in the hippocampal CA1 region 7 days after the ischemic insult was more severe in the untreated group (p less than 0.05). There was a significant correlation between end-ischemic tissue pH and hippocampal damage (r = -0.73, p less than 0.05). In the dextromethorphan-treated animals, 90% of the rats survived compared with 47% of the untreated animals (p less than 0.05). These results support findings in previous studies that dextromethorphan attenuates ischemic damage.
Animals↗
A comparative study of the circle of Willis in fetal and adult life. The configuration of the posterior bifurcation of the posterior communicating artery.
The configuration of the posterior bifurcation of the posterior communicating artery is commonly described as the 'adult configuration' if the diameter of the precommunicating part of the posterior cerebral artery (P1) is larger than the diameter of the posterior communicating artery itself (PCA). In these cases the blood supply to the occipital lobes is mainly from the vertebro-basilar system. Only in a minority of cases is the fetal or embryonic configuration found. Here the diameter of the PCA is larger than the diameter of the P1 and the blood supply to the occipital lobes is mainly from the internal carotid artery via the posterior communicating artery. In order to track the origin of these different configurations, 53 complete circles of Willis (106 sides) in brains of fetuses and infants aged from 12 weeks to 60 weeks after conception were examined with the aid of an operating microscope, and measurements were made of the diameters of the PCA, P1 and P2. It is concluded that the variations of this part of the circle of Willis are the result of developmental modifications. This is confirmed by a statistical analysis that shows a relation between the stage of development of the brain and the occurrence of the different configurations. The frequencies of the adult and fetal configurations gradually increase at the expense of the transitional configurations. This configuration is found early in development and is characterised by the equality of the diameters of the PCA and P1. These findings contradict the views, found in the literature, that the variations either exist early in development as a consequence of genetic factors or arise after birth as a consequence of mechanical genetic factors.
Adult↗
Local as well as remote functional and metabolic changes after focal ischemia in cats.
Behavior and limb placing ability were analyzed acutely and subacutely (up to 21 days) following unilateral occlusion of the middle cerebral artery (MCA) in cats. Immediately following occlusion, all tested cats started to display a sequence of different behaviors, characteristic for 1) an ipsilateral inhibition of dopaminergic activity in the caudate nucleus (CN); 2) an inhibition of GABAergic activity in the reticular substantia nigra (SNR); 3) a stimulation of GABA receptors in the deeper layers of the colliculus superior (CSDL) (starting-time of these phases: about 4, 12 and 25 min, respectively). The latter behavior was also present subacutely. In addition, unilateral orofacial dyskinetic movements were observed acutely as well as subacutely. Contralateral limb placing was deficient in all cats 60 min postocclusion; it was at least partly restored subacutely. Twenty-one days after the occlusion, [14C]-2-D-deoxyglucose uptake was relatively reduced in the ipsilateral CN (especially in its posterior part), the ipsilateral SNR and the ipsilateral CSDL. The anterior CN appeared to be less affected than the posterior CN. Metabolism was relatively reduced in the sensorimotor cortex only in part of the tested cats. The data show that unilateral MCA occlusion produces consistent functional changes in all structures studied apart from the sensorimotor cortex, viz. the CN, the SNR and the CSDL.
Animals↗
Cranial nerve palsy as a delayed complication of attempted infanticide by insertion of a stylet through the fontanel. Case report.
A child suffered a sixth and seventh cranial nerve palsy due to intracerebral insertion of a stylet. The stylet was introduced through the anterior fontanel, most probably in an attempt at infanticide. The migration of the stylet through the brain was monitored because the child was first examined 6 years earlier. At operation the cranial part of the stylet lay in the fourth ventricle, compressing the facial nerve as well as the nucleus of the abducens nerve. The lower part of the stylet had reached the C-5 level.
Abducens Nerve Injury↗
1H and 31P NMR measurement of cerebral lactate, high-energy phosphate levels, and pH in humans during voluntary hyperventilation: associated EEG, capnographic, and Doppler findings.
In order to explore the sensitivity of spatially resolved 1H and 31P NMR spectroscopy on a whole-body NMR instrument, cerebral metabolic changes in human volunteers were measured during hyperventilation provocation. During hyperventilation the flow velocity in the middle cerebral artery decreased significantly and the EEG showed a marked increase in slow activity. 1H NMR spectra revealed an increase in cerebral lactate concentration. 31P NMR spectra showed no changes in ATP or PCr peak heights, but a shift toward tissue alkalosis was derived from changes in Pi chemical shift. During subsequent recovery, lactate concentration decreased and a slight intracellular acidosis was detected. In three experiments broadening of the lactate resonance peak resulted in separation into two components at 1.32 and 1.48 ppm, in which the latter signal possibly arose from alanine.
Adult↗
Place of the extra-intra-cranial-bypass in aneurysm-surgery.
Before the use of the EC/IC-bypass, despite several tests to predict complications, ligation of the i.c.a. (e.g. in treatment of an unclippable aneurysm) offered a significant risk of cerebral ischemia, either acutely or on long term. In this article the hemodynamic background of the EC/IC-bypass as well as its probable effect on local cerebral blood flow are discussed. Next, a series of 26 patients is presented in which ligation of the i.c.a or the m.c.a. was considered. To prevent cerebral ischemia, first an EC/IC-bypass was established. After all, in 15 patients ligation of the i.c.a. was necessary. Beside one major complication the other complications after ligation were only minor and temporary.
Adult↗
Proton magnetic resonance imaging in experimental cerebral ischaemia.
MRI was performed on 11 primates, 7 with a proximal and 4 with a distal MCA occlusion. Chronic implanted electrodes created only minor image disturbances. The development of oedema formation was visualised in repetitive imaging. The site of the MCA occlusion determined the infarct-size.
Animals↗
The cavernous sinus syndrome. An anatomical and clinical study.
The cavernous sinus is often involved pathologically, which can cause ocular motor nerve palsies with or without facial sensory disturbances. Consequently several clinical features of ocular motor nerve palsies have been described. In this article we present a study of the cavernous sinus syndrome, and compare this syndrome with other nerve palsy syndromes caused by lesions in or adjacent to the cavernous sinus. The clinical features are explained by means of an anatomical study of the cavernous sinus.
Cavernous Sinus↗
Cerebral lactate detected by regional proton magnetic resonance spectroscopy in a patient with cerebral infarction.
Water-suppressed image-guided localized proton magnetic resonance spectroscopy was performed in a 59-year-old woman with two major brain infarcts. Spectra were measured in the infarcts, in an area between the infarcts, and in the healthy hemisphere. The volumes of interest were selected on the basis of a fast T2-weighted image. A 1331-2662 Hahn spin-echo sequence was used to suppress the water in the 8-cm3 volume that was selected by means of spatially resolved spectroscopy or stimulated echoes. The spectra were obtained in 5 minutes' accumulation time. Spectral editing was applied to separate the resonance of lactate from that of other substances. Our results show no increase of lactate concentration within the infarcts after 6 months; however, a resonance was observed at 1.6 ppm, which is assigned to fatty acids. Peak intensities of brain-specific compounds were decreased. Six months after the onset of clinical symptoms (at the time of bypass surgery), a fivefold increase in lactate concentration compared with normal values was observed in the area between the two infarcts. Four months after bypass surgery, the lactate concentration in this area had decreased to only twice normal. We speculate that lactate is a marker of reversible or impending brain damage.
Cerebral Infarction↗
The postorbital approach to the middle cerebral artery in cats.
The study of the relation between behavior, cerebral blood flow, and metabolism in animal models of cerebral ischemia has gained interest in the last 10 years. The most suitable models are those with the fewest side effects. One-sided blindness caused by decompression of the eye and coagulation of the optic nerve has been an inevitable side effect of transorbital occlusion of the middle cerebral artery. The postorbital technique is a new surgical approach to the middle cerebral artery that leaves the intraorbital structures intact. After resection of the postorbital processes and gentle retraction of the eye, the optic foramen is approached with the help of an operating microscope. This approach is possible because cats have no lateral bony orbital wall. A subperiostal approach to the optic foramen is made, after which the optic foramen is enlarged. Opening of the dura gives access to the middle cerebral artery in the same way as the transorbital approach. In this way, occlusion of the middle cerebral artery is possible with minimal impairment of vision.
Animals↗
New type of end-to-side anastomosis for small arteries: a technical and scanning electron microscopic study in rats.
A new type of end-to-side anastomosis between small arteries is described. The anastomosis is made for three-quarters of its circumference with a nonoccluded recipient artery. The recipient artery must be occluded for only 3 to 5 minutes to complete the anastomosis. The anastomosis site was studied with the scanning electron microscope at different times (1 hour to 3 months) after the operation in 20 rats. In every case, the anastomosis was widely patent and a gradual endothelialization of the anastomosis site was observed. After 7 to 10 days, the endothelialization was more or less complete and, during the following weeks, a further smoothing of the ridge protruding into the anastomosis was noted. As an addendum, the authors describe an improvement of this technique that was developed after the sapphire tip of the neodymium: YAG laser became available. Now the anastomosis is fully completed and the connection between the two vessels is made by the laser tip introduced via a side branch of the donor vessel. The recipient artery need not be occluded at all. The results are promising.
Anastomosis, Surgical↗