Pathology and pathophysiology of brain ischaemia

Histopathological analysis of cerebral hemorrhage in systemic lupus erythematosus complicated with antiphospholipid syndrome

A 53-year-old woman was admitted due to akinetic mutism and fever. On admission, brain computed tomography (CT) scan revealed a large hemorrhagic lesion in the left anterior lobe that required surgical operation for total removal. Her neuropsychiatric manifestation was not attenuated after the operation, and was gradually ameliorated by high doses of corticosteroid thereafter, suggesting a diagnosis of lupus psychosis. Histopathological examination revealed a necrotizing vasculature, sometimes with a disrupted lamina elastica interna, completely filled with thrombi and infiltrated with inflammatory cells and their debris. It is therefore suggested that the large frontal lobe hematoma in our patient was induced by thrombosis and arteritis in the subarachnoid space.

Effect of electroconvulsive stimulation on morphological and physiological aspects of post-cardiac arrest cerebral microcirculation

We investigated the effect of electroconvulsive stimulation (ECS) on cerebral circulation in vivo using the method for measuring microcirculation in real time with the photosensitizer dye Photosense and the fiber optic spectrofluorometer LESA-01-BIOSPEC. We have found that electroconvulsive stimulation significantly improved cerebral microcirculation (fourfold higher comparing to the control cerebral perfusion) after 30 min of room-temperature cardiac arrest. Morphologic study of the brain tissue showed the absence of rouleaux formation of erythrocytes ("sludged blood") in the cerebral cortex microcirculation after the application of electrical stimulus. Electroconvulsive stimulation may be useful for improving cerebral microcirculation (blood flow) in cases of long-term brain hypoxia/anoxia after prolonged cardiac arrest.

Electrophysiological assessment of the afferent sensory pathway in cardiac arrest survivors

BACKGROUND

Hypoxic-ischaemic brain damage in cardiac arrest survivors is global, but postmortem histology could identify parts of the brain that are selectively vulnerable to ischaemia, comprising the thalamus and cortex. We hypothesized that hypoxic-ischaemic brain damage increases along the afferent sensory pathway with a stepwise decrease of detectable somatosensory evoked potential peaks.

METHODS

Somatosensory evoked potentials were recorded within 72 h after cardiac arrest in 305 comatose patients after cardiopulmonary resuscitation. We measured the short latency SEP peaks N9, P15, N20, P25 (reflecting the peripheral-thalamo-cortical pathway) and the long latency SEP peaks N35 and N70 (reflecting complex cortico-cortical interactions). Patients with a Cerebral Performance Category score > 2 at 1 year were defined as patients with hypoxic-ischaemic brain damage.

RESULTS

Patients with hypoxic-ischaemic brain damage (n = 232) showed a statistically significant decrease of detectable peaks (P < 0.05) along the thalamo-cortical afferent pathway: N13, P15, N20, P25 and N70 peaks were detectable in 99%, 63%, 59%, 55% and 44% patients, respectively. In patients without hypoxic-ischaemic brain damage (n = 73) the N13, P15, N20, P25 peaks were detectable in all, and the N35 and N70 peaks in 98%. Furthermore, in patients with hypoxic-ischaemic brain damage and detectable SEP peaks, P15, N20, P25, N35 and N70, peak latencies were prolonged (P < 0.05) and N20 and N70 amplitudes were decreased (P < 0.05) compared with patients without hypoxic-ischaemic brain damage.

CONCLUSION

Extent of hypoxic-ischaemic brain damage in cardiac arrest survivors increases along the afferent sensory pathway, with pronounced vulnerability of thalamic and cortical brain regions.

Massive infarcts involving the territory of the anterior choroidal artery and cardioembolism

BACKGROUND AND PURPOSE

At neuropathological examination, the territory of the anterior choroidal artery is frequently found to be involved in massive infarcts of the internal carotid artery territory. The aim of our study was to analyze the clinical spectrum, the course, and the mechanism of these massive infarcts compared with the rare infarcts involving only the anterior choroidal artery territory.

METHODS

Retrospective clinical examination and pathological study were performed in 35 patients with cerebral infarcts affecting at least the territory of the anterior choroidal artery.

RESULTS

In no patient had the involvement of the anterior choroidal territory infarcts been recognized clinically, nor had the triad of clinical signs (hemiplegia, hemianesthesia, and hemianopsia) classically seen in infarcts restricted to this territory been found alone. Impairment of consciousness, cognitive disorders, or oculomotor palsies had been found in addition to one or more signs of the triad. This was probably related to the involvement of other territories (94%), especially the middle cerebral artery territory (68%) and the posterior cerebral artery territory (20%). The concomitant involvement of several territories was due most frequently to an occlusion of the internal carotid artery, which was found at autopsy in 74% of the patients. These occlusions were often associated with cardioembolism (54%). In contrast, artery-to-artery embolism (17%) and small-artery disease (6%) were seldom found. Only two cases of infarcts restricted to the anterior choroidal artery territory were observed.

CONCLUSIONS

The involvement of the territory of the anterior choroidal artery in massive infarcts was due mainly to a cardioembolic occlusion of the internal carotid artery.

Global cerebral ischemia and subsequent selective hypothermia. A neuropathological and morphometrical study on ischemic neuronal damage in cat

A new method of external selective brain cooling is described, showing its effectiveness in reducing neuronal damage following global cerebral ischemia in cat. The cooling apparatus consists of a specially fitted kind of water jacket in which the animal's head was laid. In a preliminary study it was verified that the device effectively reduces brain temperature without the risk of cardiac arrhythmias due to lowering of core temperature. In the main study cardiac arrest was induced in 23 adult cats, followed after 15 min by cardiopulmonary resuscitation (CPR). Eight cats could not be revived; of the 15 remaining animals, 7 were assigned to the control group (normothermia) and 8 to the treatment group (cerebral hypothermia). The latter received external brain cooling for 30 min, starting as soon as CPR was begun. Four hours after cardiac arrest all animals were transcardiacally perfused with glutardialdehyde. The brains were stored in fixative and subsequently processed for histopathological and morphometrical evaluation by light microscopy. Analysis of the resulting data showed that animals in the treatment group had a significantly higher percentage of undamaged neurons than animals in the control group, both in the cingulate gyrus (38% vs 10%) and in the parietal cortex (39% vs 14%). The treatment group also had more undamaged neurons in the hippocampus and fewer severely damaged neurons in all three regions, but these differences, though suggestive, were not statistically significant.

Dynamic CT of cranio-cervical vascular occlusive disease

Occlusive disease of the major vascular structures of the head and neck produce classic findings on conventional angiography that are mirrored in the sequences obtained on intravenous dynamic computed tomography (IVDCT). As a complement of the initial computed tomographic (CT) workup, IVDCT provides immediate, important diagnostic information, helps to direct appropriate clinico-radiologic triage with minimum delay, and may obviate more invasive studies in selected clinical settings.

Dynamic CT of micro- and macroangiopathic states of the cerebrum

Dynamic computed tomography utilizing intravenous contrast agents affords a unique opportunity to evaluate pathologic vascular states of the cerebrum in cross-section with an imaging system which is more contrast-sensitive than either conventional film-screen or digital subtraction angiography. Dynamic scanning therefore routinely allows the non-invasive detection of pathologic vascularity in-vivo in lesions that could previously only be detected reliably primarily with in-vitro techniques. The first section of this two part report examines the microscopic vascularity observed in active demyelination, inflammatory states, trauma, infarction and other forms of acquired cerebral disease. In the second section, the ability of intravenous dynamic cranial computed tomography to detect macroscopic pathologic vascularity is reviewed. The diagnostic principles of conventional angiography apply in this technique except that the lesion is viewed in cross-section, rather than in-toto with all structures superimposed. The method therefore yields a true tomographic angiogram. Abnormal vascular states associated with malignancies, vascular malformations, aneurysms, and vascular occlusions are simply evaluated and correlate precisely with the aberrant vascular patterns revealed angiographically.

Balance of T1-weighted images before and after application of a paramagnetic substance (Gd-DTPA)

Ten patients with encephalitis disseminata and 10 patients with cerebral ischemia underwent computed tomography and magnetic resonance imaging examinations. The results before and after the application of contrast media were compared. It is shown that T1-weighted MRI images, even after application of gadolinium-DTPA, are of little value for differential diagnosis of these diseases. In contrast, T2-weighted images did support the diagnosis of an acute stage of encephalitis disseminata versus acute ischemia. This was also true for lesions that had not been adequately depicted by computed tomography.