Significance of contrast enhancement in cranial computerized tomography after subarachnoid hemorrhage

Blood-brain barrier permeability imaging as a predictor for delayed cerebral ischaemia following subarachnoid haemorrhage. A narrative review

BACKGROUND

Aneurysmal subarachnoid haemorrhage is associated with significant morbidity and mortality due to the myriad of complications contributing to early brain injury and delayed cerebral ischaemia. There is increasing interest in the exploration of the association between blood-brain barrier integrity and risks of delayed cerebral ischaemia and poor outcomes. Despite recent advances in cerebral imaging, radiographic imaging of blood-brain barrier disruption, as a biomarker for outcome prediction, has not been adopted in clinical practice.

METHODS

We performed a narrative review by searching for articles describing molecular changes or radiological identification of changes in BBB permeability following subarachnoid haemorrhage (SAH) on MEDLINE. Preclinical studies were analysed if reported structural changes and clinical studies were included if they investigated for radiological markers of BBB disruption and its correlation with delayed cerebral ischaemia.

RESULTS

There is ample preclinical evidence to suggest that there are structural changes in BBB permeability following SAH. The available clinical literature has demonstrated correlations between permeability imaging and outcomes following aneurysmal subarachnoid haemorrhage (aSAH).

CONCLUSION

Radiological biomarkers offer a potential non-invasive prognostication tool and may also allow early identifications of patients who may be at risk of DCI.

Spontaneous Subarachnoid Hemorrhage: Assessment of Prognosis and Initial Management in the Intensive Care Unit

Spontaneous subarachnoid hemorrhage (SAH) is asso ciated with high morbidity and mortality. Primary con servative or preoperative management in the intensive care unit aims at prevention, early detection, and treat ment of complications. In this article we review the literature on the value of initial clinical and laboratory findings in predicting complications and outcome after SAH. Current conservative management of SAH is briefly discussed.

Brain Metastasis of Pleural Mesothelioma after a Subarachnoid Hemorrhage

Malignant pleural mesothelioma (MPM) is an uncommon, fatal neoplasm induced by asbestos exposure. Brain metastases from MPM are extremely rare, with most such cases diagnosed only at the time of autopsy. This report describes what we believe to be the first case of MPM metastasizing to the brain after a subarachnoid hemorrhage, as well as the subsequent surgical removal of the brain metastasis.

Phenotypic transformation of smooth muscle in vasospasm after aneurysmal subarachnoid hemorrhage

Differentiated smooth muscle cells (SMC) control vasoconstriction and vasodilation, but they can undergo transformation, proliferate, secret cytokines, and migrate into the subendotherial layer with adverse consequences. In this review, we discuss the phenotypic transformation of SMC in cerebral vasospasm after subarachnoid hemorrhage. Phenotypic transformation starts with an insult as caused by aneurysm rupture: Elevation of intracranial and blood pressure, secretion of norepinephrine, and mechanical force on an artery are factors that can cause aneurysm. The phenotypic transformation of SMC is accelerated by inflammation, thrombin, and growth factors. A wide variety of cytokines (e.g., interleukin (IL)-1β, IL-33, matrix metalloproteinases, nitric oxidase synthases, endothelins, thromboxane A2, mitogen-activated protein kinase, platelet-derived vascular growth factors, and vascular endothelial factor) all play roles in cerebral vasospasm (CVS). We summarize the correlations between various factors and the phenotypic transformation of SMC. A new target of this study is the transient receptor potential channel in CVS. Statin together with fasdil prevents phenotypic transformation of SMC in an animal model. Clazosentan prevents CVS and improves outcome in aneurysmal subarachnoid hemorrhage in a dose-dependent manner. Clinical trials of cilostazol for the prevention of phenotypic transformation of SMC have been reported, along with requisite experimental evidence. To conquer CVS in its complexity, we will ultimately need to elucidate its general, underlying mechanism.

Spreading convulsions, spreading depolarization and epileptogenesis in human cerebral cortex

Spreading depolarization of cells in cerebral grey matter is characterized by massive ion translocation, neuronal swelling and large changes in direct current-coupled voltage recording. The near-complete sustained depolarization above the inactivation threshold for action potential generating channels initiates spreading depression of brain activity. In contrast, epileptic seizures show modest ion translocation and sustained depolarization below the inactivation threshold for action potential generating channels. Such modest sustained depolarization allows synchronous, highly frequent neuronal firing; ictal epileptic field potentials being its electrocorticographic and epileptic seizure its clinical correlate. Nevertheless, Leão in 1944 and Van Harreveld and Stamm in 1953 described in animals that silencing of brain activity induced by spreading depolarization changed during minimal electrical stimulations. Eventually, epileptic field potentials were recorded during the period that had originally seen spreading depression of activity. Such spreading convulsions are characterized by epileptic field potentials on the final shoulder of the large slow potential change of spreading depolarization. We here report on such spreading convulsions in monopolar subdural recordings in 2 of 25 consecutive aneurismal subarachnoid haemorrhage patients in vivo and neocortical slices from 12 patients with intractable temporal lobe epilepsy in vitro. The in vitro results suggest that γ-aminobutyric acid-mediated inhibition protects from spreading convulsions. Moreover, we describe arterial pulse artefacts mimicking epileptic field potentials in three patients with subarachnoid haemorrhage that ride on the slow potential peak. Twenty-one of the 25 subarachnoid haemorrhage patients (84%) had 656 spreading depolarizations in contrast to only three patients (12%) with 55 ictal epileptic events isolated from spreading depolarizations. Spreading depolarization frequency and depression periods per 24 h recording episodes showed an early and a delayed peak on Day 7. Patients surviving subarachnoid haemorrhage with poor outcome at 6 months showed significantly higher total and peak numbers of spreading depolarizations and significantly longer total and peak depression periods during the electrocorticographic monitoring than patients with good outcome. In a semi-structured telephone interview 3 years after the initial haemorrhage, 44% of the subarachnoid haemorrhage survivors had developed late post-haemorrhagic seizures requiring anti-convulsant medication. In those patients, peak spreading depolarization number had been significantly higher [15.1 (11.4–30.8) versus 7.0 (0.8–11.2) events per day, P = 0.045]. In summary, monopolar recordings here provided unequivocal evidence of spreading convulsions in patients. Hence, practically all major pathological cortical network events in animals have now been observed in people. Early spreading depolarizations may indicate a risk for late post-haemorrhagic seizures.

Serum and cerebrospinal fluid C-reactive protein levels as predictors of vasospasm in aneurysmal subarachnoid hemorrhage. Clinical article

OBJECT

Cerebral vasospasm is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). Inflammatory processes seem to play a major role in the pathogenesis of vasospasm. The C-reactive protein (CRP) constitutes a highly sensitive inflammatory marker. The association of elevated systemic CRP and coronary vasospasm has been well established. Additionally, elevation of the serum CRP levels has been demonstrated in patients with aSAH. The purpose of the current study was to evaluate the possible relationship between elevated CRP levels in the serum and CSF and the development of vasospasm in patients with aSAH.

METHODS

A total of 41 adult patients in whom aSAH was diagnosed were included in the study. Their demographics, the admitting Glasgow Coma Scale (GCS) score, Hunt and Hess grade, Fisher grade, CT scans, digital subtraction angiography studies, and daily neurological examinations were recorded. Serial serum and CSF CRP measurements were obtained on Days 0, 1, 2, 3, 5, 7, and 9. All patients underwent either surgical or endovascular treatment within 48 hours of their admission. The outcome was evaluated using the Glasgow Outcome Scale and the modified Rankin Scale.

RESULTS

The CRP levels in serum and CSF peaked on the 3rd postadmission day, and the CRP levels in CSF were always higher than the serum levels. Patients with lower admission GCS scores and higher Hunt and Hess and Fisher grades had statistically significantly higher levels of CRP in serum and CSF. Patients with angiographic vasospasm had higher CRP measurements in serum and CSF, in a statistically significant fashion (p < 0.0001). Additionally, patients with higher CRP levels in serum and CSF had less favorable outcome in this cohort.

CONCLUSIONS

Patients with aSAH who had high Hunt and Hess and Fisher grades and low GCS scores showed elevated CRP levels in their CSF and serum. Furthermore, patients developing angiographically proven vasospasm demonstrated significantly elevated CRP levels in serum and CSF, and increased CRP measurements were strongly associated with poor clinical outcome in this cohort.

Cerebral vasospasm after subarachnoid hemorrhage: putative role of inflammation

Cerebral vasospasm is a common, formidable, and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Despite intensive research efforts, cerebral vasospasm remains incompletely understood from both the pathogenic and therapeutic perspectives. At present, no consistently efficacious and ubiquitously applied preventive and therapeutic measures are available in clinical practice. Recently, convincing data have implicated a role of inflammation in the development and maintenance of cerebral vasospasm. A burgeoning (although incomplete) body of evidence suggests that various constituents of the inflammatory response, including adhesion molecules, cytokines, leukocytes, immunoglobulins, and complement, may be critical in the pathogenesis of cerebral vasospasm. Recent studies attempting to dissect the cellular and molecular basis of the inflammatory response accompanying SAH and cerebral vasospasm have provided a promising groundwork for future studies. It is plausible that the inflammatory response may indeed represent a critical common pathway in the pathogenesis of cerebral vasospasm pursuant to SAH. Investigations into the nature of the inflammatory response accompanying SAH are needed to elucidate the precise role(s) of inflammatory events in SAH-induced pathologies.

Immediate postoperative CT contrast enhancement following surgery of cerebral tumoral lesions

PURPOSE

Our goal was to evaluate the immediate postoperative contrast enhancement behavior of cerebral lesions and to gain further information about contrast enhancement in patients under general anesthesia.

METHOD

In the early postoperative period, CT scans with the without contrast medium were performed in 46 patients. The time interval between surgery and postoperative CT imaging ranged from 1 to 7.5 h (mean 4 h). Nineteen patients were under general anesthesia during CT investigation.

RESULTS

In the early postoperative period, contrast medium leakage into the tumor resection cavity was noted In 14 patients (30%). Another phenomenon that was observed was the appearance of a strong demarcation and distinct contrast of gray against white matter in 24 patients (52%). This characteristic, global contrast enhancement of the cerebral cortex, occurred in 17 of 19 patients (89%) investigated under general anesthesia.

CONCLUSION

In immediate postoperative CT scans, contrast medium leakage due to extravasation of contrast medium into the tumor resection cavity can be detected early. Moreover, a global contrast enhancement of the cerebral cortex can be detected as a frequent pattern in patients investigated under general anesthesia.

Cerebral oedema after subarachnoid haemorrhage. Pathogenetic significance of vasopressin

The authors report the frequency, characteristic clinical symptoms, laboratory alterations and diagnostic criteria of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) after subarachnoid haemorrhage. The data on 290 patients with subarachnoid haemorrhage (SAH) during a period of years at the Division of Neurosurgery, University Medical School, Szeged, are analysed. Twenty-seven (9.3%) patients developed SIADH. Thirteen (4.5%) patients had severe and 14 (4.8%) had mild SIADH. The problems of the treatment are discussed in detail and the different therapeutic methods are listed: NaCl infusion, water withdrawal and administration of Dilantin, diuretics, mineralocorticosteroids, lithium and demeclocycline. The undesirable side-effects observed accompanying various therapeutic regimen are analysed. The introduction of V2 antagonists into clinical practice appears to be a most perspective procedure. For study of the pathogenesis of SIADH following SAH, the possibility of treatment with V2 antagonists on an experimental model of SAH in rat was created. A significant water retention and increases in brain water and sodium content were observed in rats with SAH. Plasma AVP levels were also elevated after SAH. AVP plays an important role in the development of antidiuresis following water loading and disturbance of the brain water and electrolyte balance after SAH. Water retention and the higher brain water and sodium accumulation could be totally prevented by administration of a V2 antagonist. These results demonstrate that cerebral oedema generated by artificial cerebral bleeding in rats is significantly reduced following the administration of a highly specific V2 antagonist, suggesting a new approach to the treatment of SIADH.

Atrial natriuretic peptide (ANP) attenuates brain oedema accompanying experimental subarachnoid haemorrhage

The effects of centrally administered atrial natriuretic peptide (ANP) on the brain water and electrolyte contents were investigated in a rodent subarachnoid haemorrhage (SAH) model. SAH caused statistically significant increases in the brain sodium and water contents, while the potassium content did not change significantly, indicating that the brain oedema could be classified as having a primarily vasogenic component. Two micrograms or 5 micrograms of rat ANP administered into the lateral ventricle at the time of SAH induction statistically significantly decreased the water and sodium accumulation measured 90 minutes following SAH. The same treatment did not inhibit development of brain oedema measured 3 hours following SAH. However, when 5 micrograms of ANP was administered intraventricularly at the time of SAH induction and also 90 minutes later, the brain oedema 3 hours following SAH was again reduced statistically significantly. These effects of ANP were found not to be mediated by primary changes in serum osmolality and electrolyte concentrations. The present results confirm that centrally administered ANP may act directly on the central nervous system to inhibit brain water and sodium accumulation in SAH-induced brain oedema. The potentials of influencing the central neuro-endocrine system as a novel way of the treatment of brain oedema are discussed.

Prevention of delayed vasospasm by an endothelin ETA receptor antagonist, BQ-123: change of ETA receptor mRNA expression in a canine subarachnoid hemorrhage model

The authors investigated the roles of endothelin (ET)-1 and the ETA receptor in the pathogenesis of delayed cerebral vasospasm following subarachnoid hemorrhage (SAH). A study was made of the preventive effect of a novel ETA receptor antagonist, BQ-123, on vasospasm and the expression of the ETA receptor messenger ribonucleic acid (mRNA) using a canine two-hemorrhage SAH model. Continuous intrathecal administration of BQ-123 (5 x 10(-6) mol/day) prevented narrowing of the basilar artery on Day 7 after SAH in 97.6% of cases in the study group versus 70.7% of cases in the control group (p < 0.05). While expression of the mRNA-coding ETA receptor was not detected in the control animals, it markedly increased on Day 3 after SAH and was also detected on Day 7. The results suggest that endothelin-1 and the ETA receptor participate in the pathogenesis of delayed cerebral vasospasm following SAH.

Risks factors for cerebral infarction in good-grade patients after aneurysmal subarachnoid hemorrhage and surgery: a prospective study

A prospective series of 265 patients with aneurysmal subarachnoid hemorrhage (SAH) of Grades I to III (Hunt and Hess classification) upon admission were evaluated as to neurological outcome and computerized tomography (CT) findings 1 to 3 years (mean 1.4 years) after the SAH and surgery. A total of 73 patients underwent acute surgery (within 72 hours after the bleed: Days 0 to 3), 86 were operated on subacutely (between Days 4 and 7), and 91 had late surgery (on Day 8 or later). Fifteen patients died before surgery was undertaken and another 20 patients died during the follow-up period. A total of 104 patients received nimodipine and the rest of the patients received either placebo (109 patients) or no medication (52 patients). A logistical regression analysis revealed the following prognostic factors for cerebral infarction, in order of importance: the amount of blood on the primary CT scan; postoperative angiographic vasospasm; the timing of the operation; and a history of hypertension. The use of nimodipine was associated with a significant reduction of cerebral infarcts visualized by CT scanning in patients who received intermediate or late surgery. In patients who underwent acute surgery no significant difference between the incidence of cerebral infarcts was observed.

Etiology of the disruption in blood-arterial wall barrier following experimental subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage is associated with a sudden rise in intracranial pressure, acute arterial hypertension, and subarachnoid blood. The role that each of these factors may play in the development of the acute barrier disruption of the major cerebral arteries following subarachnoid hemorrhage was investigated in 42 rabbits. Horseradish peroxidase was given intravenously to assess the integrity of the barrier by transmission electron microscopy. Permeation of the tracer into the vessel was noted only in animals with increased intracranial pressure. A sudden rise in intracranial pressure is suggested to trigger acute barrier disruption following subarachnoid hemorrhage.

Value of contrast enhanced CT scanning in the non-trauma emergency room patient

To determine the value of performing contrast CT in addition to non-contrast CT in the evaluation of acute non-traumatic central nervous system disorders, we retrospectively reviewed 322 cases originating from the emergency room at our institution. The most common indication for scanning was seizure activity (34% of total), followed by headache (30%), focal neurological deficit (10%), and altered mental status (8%). 75% of the non-contrast scans were normal. The contrast-enhanced scan revealed abnormalities not evident on the non-contrast scan in only three of these cases, and the information did not alter patient management. We conclude that in the acute setting, if a non-contrast CT is normal, a contrast study is usually unnecessary. Therefore, given the additional risks of contrast infusion, the contrast study, if needed, is generally best obtained at a later date, after more careful evaluation of the patient's history and medical records. If the non-contrast CT scan is abnormal, a contrast enhanced CT scan may be beneficial, but, again, is often not needed to direct acute patient management.

Time course of the blood-arterial wall barrier disruption following experimental subarachnoid haemorrhage

The time course of the blood-arterial wall barrier disruption following experimental subarachnoid haemorrhage (SAH) was studied in 24 rabbits. Animals with SAH received two successive blood injections through the cisterna magna. Horseradish peroxidase (HRP) was given intravenously 30 minutes before sacrifice to assess the integrity of the barrier. In the basilar arteries taken from animals that were sacrificed 4 days after the first SAH, HRP-reaction products were diffusely observed in the subendothelial space. Three weeks following the first SAH, permeation of HRP was still observed in half of the animals. However, in animals sacrificed 7 weeks after the first SAH, no permeation of HRP into the subendothelial space was noted. Opening of the interendothelial space seemed to be the major mechanism for HRP permeation into the subendothelial space rather than transendothelial vesicular transport. Disruption of the blood-arterial wall barrier in the major cerebral arteries following SAH may play a role in the pathogenesis of vasospasm.

Positron emission tomography with 68-Ga-EDTA and computed tomography in patients with subarachnoid haemorrhage

26 patients with subarachnoid haemorrhage (SAH) were investigated with 68-Ga-EDTA and positron emission tomography (PET) in order to evaluate the presence of a blood brain barrier (BBB) disturbance. Only one patient showed a BBB disruption. It is suggested that increased levels of substances with higher molecular weight than 68-Ga-EDTA in the cerebrospinal fluid (CSF) are the result of a change in the metabolism of the CSF and the brain tissue caused by a SAH.

Protective effect of a 21-aminosteroid on the blood-brain barrier following subarachnoid hemorrhage in rats

The effects of subarachnoid injection of blood on blood-brain barrier permeability to albumin was assessed in a rat model. Subarachnoid injection of blood caused a significant sixfold increase in Evans blue extravasation, whereas sham operation or NaCl injection had no effect. In addition, subarachnoid injections of arachidonic acid or FeCl2 increased blood-brain barrier permeability to Evans blue 16- and 10-fold, respectively. The capillary permeability after subarachnoid injection of blood was normalized by pretreatment with a novel 21-aminosteroid, U-74006F, that has antioxidant and antilipolytic activity. Pretreatment with U-74006F also reduced the vascular leakage induced by subarachnoid injection of arachidonic acid or FeCl2 by 50% and 45%, respectively. We conclude that damage to membrane lipids by peroxidative and/or lipolytic processes is involved in the subarachnoid hemorrhage-induced blood-brain barrier opening and that U-74006F protects the blood-brain barrier against the effects of subarachnoid hemorrhage by preventing or limiting these pathologic membrane lipid changes.

Blood-arterial wall barrier disruption to various sized tracers following subarachnoid haemorrhage

Disruption of the blood-arterial wall barrier in the major cerebral arteries occurs following subarachnoid haemorrhage (SAH) and may be related to the pathogenesis of cerebral vasospasm. Using FITC dextrans of various sizes, the present study was undertaken to determine if the barrier disruption shortly after SAH occurs equally to various sized tracers. Forty-two Sprague-Dawley rats were divided into 5 groups. Four groups were injected with FITC-dextrans of differing molecular weights (MW): FD4 (MW = 4,080), FD 40 (MW = 40,500), FD 70 (MW = 71,400), and FD 150 (MW = 156,900). One group was injected with horseradish peroxidase (HRP: MW = 40,000). Each group was further divided into two subgroups: with or without SAH. SAH was induced by injecting arterial blood into the cisterna magna. To assess the integrity of the blood-arterial wall barrier by transmission electron microscope, the tracers were intravenously injected prior to sacrificing the animals. The groups without SAH showed no permeability of tracers into the subendothelial spaces of the basilar arteries. In contrast, with the exception of FD 150, FITC-dextrans (FD 4, FD 40, FD 70) were noticed in the subendothelial spaces. The distribution of FITC-dextrans in the elastic lamina was similar to that of HRP. These results suggest that barrier disruption occurs with a wide range of molecular sizes of FITC-dextrans, although there seems to be some limitation to the permeation of the larger molecules. The present study suggests that the mechanism of barrier disruption of the major cerebral arteries in the acute stage following SAH may be vesicular rather than by separation of tight junctions.

Effect of intracisternal thromboxane A2 analogue on cerebral artery permeability

Thromboxane, a highly vasoactive substance, is found in the cerebrospinal fluid of patients and experimental animals following subarachnoid haemorrhage. A stable synthetic analogue of thromboxane A2 was administered intracisternally in rabbits. This resulted in an increase in endothelial permeability of the major cerebral arteries to Evans Blue dye and horseradish peroxidase. Thromboxane may be involved in the pathogenesis of cerebral vasospasm and may be related to the contrast enhancement of the arteries in the basal cisterns on CT scans of patients who are prone to develop arterial narrowing.

Resistance to cerebrospinal fluid outflow and intracranial pressure in patients with hydrocephalus after subarachnoid haemorrhage

Resistance to CSF-outflow (Rout) and intracranial pressure (ICP) were measured in 33 patients with hydrocephalus after subarachnoid haemorrhage (SAH). Eleven patients examined between 10 to 30 days after SAH had high pressure hydrocephalus (HPH). Twenty-two patients had normal pressure hydrocephalus (NPH). All HPH-patients had ICP above 15 mmHg, plateau waves and B-waves, a median Rout of 59 mmHg x ml-1 x min-1 (range 29-100). All NPH-patients had a normal ICP level, no plateau waves, but long periods of B-waves and a median Rout of 22 mmHg x ml-1 x min-1 (range 6-47). Of the 11 patients with HPH six were shunted and five had temporary ventricular drainage. Five patients improved and six died. Of the five survivors only one went back to work. Of the 22 NPH-patients 18 were treated with a shunt, one refused shunt operation and three had normal Rout. Seventeen improved after shunting. At follow-up 12 had a normal social life, 5 lived in a nursing home and 1 was dead. Thus, early development of hydrocephalus after subarachnoid haemorrhage is associated with a high Rout and a high ICP, whereas late (more than one month) hydrocephalus may be associated with normal ICP and high Rout. Patients with NPH and a high Rout have frequent B-waves and should be shunted. Patients with a long interval from subarachnoid haemorrhage to the diagnosis of hydrocephalus often have a normal ICP, low frequency of B-waves, normal CSF-dynamics and need no shunting.

Increased vulnerability of the blood-brain barrier to experimental subarachnoid hemorrhage in spontaneously hypertensive rats

The influence of chronic arterial hypertension upon the permeability to albumin of the cerebral capillaries, i.e. the blood-brain barrier, was studied in normotensive Wistar and spontaneously hypertensive Wistar rats with experimental subarachnoid hemorrhage. The blood-brain barrier permeability to albumin was assessed quantitatively by spectrophotometric determination of Evans blue extravasation. Subarachnoid hemorrhage was produced by injecting autologous blood into the cortical subarachnoid space. A significant increase of Evans blue albumin extravasation was found in the spontaneously hypertensive rats with subarachnoid hemorrhage as compared with normotensive animals suffering from subarachnoid hemorrhage. Subarachnoid hemorrhage in this model alone caused a significant Evans blue extravasation, whereas sham-operation did not. These findings emphasize the necessity for effective attempts to reduce the leakage of the capillary system in the early stage of subarachnoid hemorrhage.

Emergency CT head scans in traumatic and atraumatic conditions

Head trauma and suspected subarachnoid hematoma are encountered frequently by the emergency physician. There are few data to indicate which patients need immediate computerized tomography (CT) and what is the role of lumbar puncture in subarachnoid hemorrhage. Reviewed are the classification of head trauma and subarachnoid hemorrhage, indications for immediate CT, persons needing contrast enhancement, and the use of CT in comparison to skull films, digital subtraction angiography, and magnetic resonance.

Outcome evaluation following subarachnoid hemorrhage

Seventy-eight individuals among a population of 1.46 million suffered aneurysmal subarachnoid hemorrhage (SAH) during 1983. Within 24 hours after the bleed, 32 of the 78 patients were in Hunt and Hess neurological Grades I to II, 13 were in Grade III, 21 were in Grades IV to V, and 12 were dead on admission to a hospital or forensic department. When the amount of blood visualized on computerized tomography (CT) scanning was integrated with the Hunt and Hess neurological classification in order to improve prediction of prognosis, only 16 patients were considered to have a good prognosis (CT-modified Grades I to II), 21 had a less favorable prognosis (CT-modified Grade III), and 29 had a poor prognosis (CT-modified Grades IV to V). Assessment at 1 year revealed that only 32 patients (41%) had a good physical recovery. The physical morbidity rate was 22%, and the overall mortality rate was 37%. Twenty-six individuals with a good neurological outcome and five with a fair outcome also underwent reexamination 1 year or more post-SAH, which included a comprehensive evaluation of the quality of life, assessment of cognitive dysfunction, and determination of general adjustment. Five of the patients with a good neurological outcome and all five with a fair outcome (four of whom had had a poor prognosis in the acute stage) showed severe psychosocial and cognitive incapacitation. When functional morbidity, based upon persistent severe cognitive and psychosocial impairment, was included in the outcome assessment, only 33% of the total series was considered to have a favorable outcome. Approximately 60% of the initially good-risk patients (Grades I and II) showed a good physical outcome without concomitant indications of severe cognitive dysfunction and/or psychosocial impairment. Among the good-risk patients with a CT-modified grade, the figure was 70%. It is suggested that in any outcome grading system, persistent cognitive and psychosocial disturbances be taken into account.

The pathogenetic and prognostic significance of blood-brain barrier damage at the acute stage of aneurysmal subarachnoid haemorrhage. Clinical and experimental studies

In a retrospective study, pathological tissue enhancement was found in nearly two fifths of patients with acute SAH on contrast-enhanced cranial computed tomography. By means of absorption measurements with the region of interest technique over the basal ganglia, it was proved indirectly that pathological tissue enhancement should be brought about not only by hyperaemia, i.e., a blood volume increase, but also by extravasation of the contrast material, i.e., blood-brain barrier (BBB) disruption. A similar conclusion was drawn from the retrospective isotope brain scintigraphy study. It was further established that, although the pathological contrast enhancement was most obvious in the cortex, and particularly in the neighbourhood of the subarachnoid spaces, the phenomenon is probably widespread throughout the brain. Patients with abnormal enhancement are likely to be in less favourable clinical grades, have a high incidence of marked or diffuse spasm, have a poorer outcome independent of surgical or conservative treatment, and develop cerebral infarction more frequently. Systemic arterial hypertension was associated with an increased incidence of abnormal enhancement. Pathological tissue contrast enhancement or isotope accumulation in the first few days of SAH may serve as prognostic signs indicative of the late development of vasospasm and ischaemia. As ischaemic disruption of the capillary system is not prominent in the initial days following any stroke, vasoactive substances arising from the breakdown of the blood clot should play important part in the BBB damage in the acute stage of SAH. The "cortical SAH" model developed in the animal experiments ensured a constant subarachnoid blood volume with minimal local brain damage. The intracranial pressure and mean arterial blood pressure did not change significantly, and perfusion defects did not arise. Thus, this model proved suitable for studying the influence on the BBB of vasoactive blood breakdown products (responsible for arterial spasm) without the accompanying effects of pathological conditions such as raised intracranial pressure, systemic hypertension, non-reflow phenomena, which also disrupt the BBB. Measurements on the water, electrolyte, albumin contents of brain tissue, as well as the immunohistochemical localization of albumin, clearly indicated that the brain oedema developing at the acute stage of experimental SAH could be classified as having a primary vasogenic component in addition to the cytotoxic component. This increased capillary permeability was found to be brought about by opening of tight junctions and pinocytosis in the endothelial cells. The pathological capillary permeabilit

Barrier disruption in the major cerebral arteries following experimental subarachnoid hemorrhage

The effects of experimental subarachnoid hemorrhage (SAH) on the blood-arterial wall barrier in the major cerebral arteries were studied in 20 normotensive dogs. Horseradish peroxidase (HRP) was given intravenously before the animals were sacrificed to assess the integrity of the barrier. Transient elevation of intracranial pressure (ICP) produced by cisternal injection of saline solution resulted in HRP leakage at the branching points of the major cerebral arteries. Extensive disturbance of the blood-arterial wall barrier was consistently observed in the major cerebral arteries after SAH, with or without elevation of ICP. These results suggest that both subarachnoid clot and a sudden rise in the ICP are important factors causing the breakdown of the blood-arterial wall barrier, but that the effect of the clot is the most profound. Electron microscopy revealed that opening of the interendothelial junctions is one of the important mechanisms responsible for the HRP leakage in the major cerebral arteries following SAH. Disturbance of arterial permeability in the major cerebral arteries following SAH probably accounts for the abnormal post-contrast enhancement that occurs in patients who are prone to develop vasospasm following aneurysm rupture, and is probably involved in the pathogenesis of vasospasm.

Cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Cerebral vasospasm following aneurysmal subarachnoid hemorrhage is one of the most important causes of cerebral ischemia, and is the leading cause of death and disability after aneurysm rupture. There are two definitions of cerebral vasospasm: angiographic and clinical. Care must be exercised to be certain that it is clear which entity is being addressed. The diagnosis of the clinical syndrome is one of exclusion and can rarely be made with absolute certainty. The pathogenesis of cerebral vasospasm is poorly understood. Most current theories focus on the release of factors from the subarachnoid clot. More attention must be given to the role of endothelial damage and alterations in the blood-arterial wall barrier. The application of modern techniques for studying vascular smooth muscle which have been developed as a result of research in the areas of hypertension and atherosclerosis must be applied to the problem of cerebral vasospasm. A stress test to select patients with angiographic arterial narrowing who have adequate cerebral vascular reserve to undergo surgery should be developed. The optimal treatment of vasospasm awaits development of agents for blocking or inactivating spasmogenic substances or blocking arterial smooth muscle contraction. Rheological or hemodynamic manipulations to prevent or reverse ischemic consequences of vasospasm are relatively effective, but complicated and hazardous, and should be viewed principally as interim measures awaiting development of more specific therapies for the arterial narrowing.