Vasospasm following rupture of cerebral aneurysms

Occurrence of vasospasm and infarction in relation to a focal monitoring sensor in patients after SAH: placing a bet when placing a probe?

INTRODUCTION

Vasospastic brain infarction is a devastating complication of aneurysmal subarachnoid hemorrhage (SAH). Using a probe for invasive monitoring of brain tissue oxygenation or blood flow is highly focal and may miss the site of cerebral vasospasm (CVS). Probe placement is based on the assumption that the spasm will occur either at the dependent vessel territory of the parent artery of the ruptured aneurysm or at the artery exposed to the focal thick blood clot. We investigated the likelihood of a focal monitoring sensor being placed in vasospasm or infarction territory on a hypothetical basis.

METHODS

From our database we retrospectively selected consecutive SAH patients with angiographically proven (day 7-14) severe CVS (narrowing of vessel lumen >50%). Depending on the aneurysm location we applied a standard protocol of probe placement to detect the most probable site of severe CVS or infarction. We analyzed whether the placement was congruent with existing CVS/infarction.

RESULTS

We analyzed 100 patients after SAH caused by aneurysms located in the following locations: MCA (n = 14), ICA (n = 30), A1CA (n = 4), AcoA or A2CA (n = 33), and VBA (n = 19). Sensor location corresponded with CVS territory in 93% of MCA, 87% of ICA, 76% of AcoA or A2CA, but only 50% of A1CA and 42% of VBA aneurysms. The focal probe was located inside the infarction territory in 95% of ICA, 89% of MCA, 78% of ACoA or A2CA, 50% of A1CA and 23% of VBA aneurysms.

CONCLUSION

The probability that a single focal probe will be situated in the territory of severe CVS and infarction varies. It seems to be reasonably accurate for MCA and ICA aneurysms, but not for ACA or VBA aneurysms.

Prediction of Cerebral Vasospasm in Patients Presenting with Aneurysmal Subarachnoid Hemorrhage: A Review

OBJECTIVE:

Cerebral vasospasm is a devastating medical complication of aneurysmal subarachnoid hemorrhage (SAH). It is associated with high morbidity and mortality rates, even after the aneurysm has been treated. A substantial amount of experimental and clinical research has been conducted in an effort to predict and prevent its occurrence. This research has contributed to significant advances in the understanding of the mechanisms leading to cerebral vasospasm. The ability to accurately and consistently predict the onset of cerebral vasospasm, however, has been challenging. This topic review describes the various methodologies and approaches that have been studied in an effort to predict the occurrence of cerebral vasospasm in patients presenting with SAH.

METHODS:

The English-language literature on the prediction of cerebral vasospasm after aneurysmal SAH was reviewed using the MEDLINE PubMed (1966–present) database.

RESULTS:

The risk factors, diagnostic imaging, bedside monitoring approaches, and pathological markers that have been evaluated to predict the occurrence of cerebral vasospasm after SAH are presented.

CONCLUSION:

To date, a large blood burden is the only consistently demonstrated risk factor for the prediction of cerebral vasospasm after SAH. Because vasospasm is such a multifactorial problem, attempts to predict its occurrence will probably require several different approaches and methodologies, as is done at present. Future improvements in the prevention of cerebral vasospasm from aneurysmal SAH will most likely require advances in our understanding of its pathophysiology and our ability to predict its onset.

Vasospasm prevention with postoperative intrathecal thrombolytic therapy: a retrospective comparison of urokinase, tissue plasminogen activator, and cisternal drainage alone

The authors report the results of a retrospective review, between January 1986 and December 1991, of the results of early surgery and intrathecal thrombolytic therapy in 111 patients with aneurysmal subarachnoid hemorrhage. Effects on clot lysis, angiographic and symptomatic vasospasm, cerebral infarction, and clinical outcome were compared in 60 patients treated with urokinase (UK) 60,000 IU/d for 7 days (UK group), 22 patients treated with 0.042 to 1 mg tissue plasminogen activator (tPA) every 6 to 8 hours for 5 days (tPA group), and 29 patients who did not receive treatment with either thrombolytic agent (no-treatment group). The no-treatment group consisted of all patients treated before July 1986 and of patients in whom thrombolytic therapy was attempted but failed to start or in whom the therapy was not used intentionally because of small subarachnoid clot. Treatment with UK was employed between July 1986 and March 1991, and tPA was employed during the remainder of the study for patients at a higher risk for vasospasm. The severity of angiographic vasospasm and the incidence of infarction in the UK and the tPA groups were less than those of the no-treatment group (P < 0.01), in spite of a larger amount of initial subarachnoid blood clot in both thrombolytic groups. This appears to be the result of the more rapid clearance of cisternal clot in the thrombolytic groups than the no-treatment group (P < 0.01). Only tPA therapy reduced the incidence of symptomatic vasospasm (P < 0.05). No serious complications were observed, although in the tPA group, asymptomatic intraventricular hemorrhage occurred in one patient, and transient confusion in another. Both received 4 mg tPA/d. Meningitis was suspected in 16 patients of the UK group. However, in this relatively small retrospective series, there were no differences among the three groups in overall outcome at 3 months. This study indicates that postoperative intrathecal thrombolytic therapies, especially with less than 4 mg/d of tPA, are effective in lysing subarachnoid clot and preventing vasospasm and infarction safely.

Effect of clot removal on cerebral vasospasm

The effect of clot removal on cerebral vasospasm was studied in 104 patients with aneurysmal subarachnoid hemorrhage (SAH). The series included patients who fulfilled all of the following criteria: operation was performed by Day 3 after the ictus; the patient's preoperative clinical grade was between Grades I and IV; there was no rebleeding; computerized tomography (CT) showed only SAH; and carotid angiograms were performed by Day 2 and repeated between Days 7 and 9. Both the degree of SAH on CT and angiographic vasospasm were graded from 0 to III. The relationship of the SAH grade in the basal frontal interhemispheric fissure (IHF) to the presence of vasospasm at the A2 segments of the anterior cerebral artery and the relationship of the SAH grade in the sylvian stems to the presence of vasospasm at the M1 segments of the middle cerebral artery were analyzed. Correlation of preoperative and postoperative SAH grades with the angiographic vasospasm grades, with the incidence of symptomatic vasospasm, and with the low-density area on CT could be found in the A2 and M1 territories. Decrease of cisternal blood measured by CT after the operation did not relate directly to the reduction of vasospasm. When the SAH was Grade II or III in the basal frontal IHF, the angiographic vasospasm grades at the A2 were significantly lower in patients with surgery via the interhemispheric approach than in those with surgery via the pterional approach. Symptomatic vasospasm occurred in two of the eight cases operated on by the interhemispheric approach compared with 11 of the 22 cases approached via the pterional route. In patients with a pterional approach, there was no significant difference in severity of vasospasm in the M1 territory between the side of approach and the opposite side. No consistent relationship could be found between the time interval from SAH to operation and the severity of vasospasm. While clot removal may ameliorate cerebral vasospasm, its effect per se does not seem to be significant.

Nimodipine treatment of selected good-risk patients with subarachnoid hemorrhage: no significant difference between present and historical results

Eighty-four patients were treated early with nimodipine intravenously, and thereafter orally, up to 21 days after aneurysmal subarachnoid hemorrhage. Thirty-nine patients in the nimodipine-treated group were carefully selected to be compared with similar patients from a historical control group (114 patients) conventionally treated. The causes of poor results were clinically identified as follows: delayed ischemic deterioration (DID), rebleeding, complications of surgery, or not defined. There was no significant difference in the distribution of DID or outcome at follow-up examination (at least 6 months later) between the nimodipine-treated group and the control group.

Nimodipine in the prevention of ischaemic deficits after aneurysmal subarachnoid haemorrhage. An analysis of recent clinical studies

An analysis of the recent trials on the effect of nimodipine on the prevention of delayed ischaemic deficits (DID) due to vasospasm provides strong evidence that the drug reduces the incidence and the severity of DID. Placebo-controlled prospective randomized studies with oral administration of nimodipine prove that patients treated with nimodipine suffer severe disability or death due to vasospasm less frequently than those not treated. Non-controlled open prospective trials with early surgery and intravenous and oral nimodipine present the lowest published incidence of DID in aneurysmal subarachnoid haemorrhage.

Endothelium-dependent relaxation of canine basilar arteries. Part 2: Inhibition by hemoglobin and cerebrospinal fluid from patients with aneurysmal subarachnoid hemorrhage

The effects of hemoglobin and cerebrospinal fluid from patients with subarachnoid hemorrhage (CSF-SAH) on endothelium-dependent relaxation were studied. At 10(-6) M, hemoglobin somewhat inhibited the endothelium-dependent relaxation induced by A23187 in rings of canine basilar artery. At 3 X 10(-6) M, it almost completely inhibited the same response. At 3 X 10(-6) M, hemoglobin did not significantly inhibit smooth muscle relaxation mechanisms as papaverine-induced relaxation was not inhibited by hemoglobin. It was also demonstrated that pretreatment of arterial rings with CSF-SAH resulted in a dose-dependent inhibition of relaxation induced by A23187. The inhibitory effect of CSF-SAH was prominent in the case in which a high oxyhemoglobin concentration was measured by spectrophotometry. Normal CSF from patients without SAH did not affect endothelium-dependent relaxation. These results suggest that hemoglobin released from lysed erythrocytes inhibits endothelium-dependent relaxation of canine basilar arteries and may also play an important role in the pathogenesis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage.

Disturbance in the intramural circulation of the major cerebro-pial arteries after experimental subarachnoid haemorrhage

The intramural fluid circulation of the cerebral arterial wall was investigated using horseradish peroxidase (HRP) as a tracer which was injected intravenously or intracisternally in dogs with or without subarachnoid haemorrhage (SAH). In the control dogs, the endothelial barrier function was confirmed for intravenous HRP, whereas the intracisternal HRP passed freely through the interstitial spaces of the adventitia and media to reach the intima within a few minutes. However, on the 5th day after SAH the barrier function of the intima for intravenous HRP was lost. In addition, there was a marked decrease in the amount of HRP reaching the intima when injected intracisternally. The intercellular space appears to be the main route for leakage of HRP into the subendothelial layer from the arterial lumen. Obstruction of the interstitial space in the adventitia by blood elements may be the cause of the disturbed intramural circulation of cerebrospinal fluid. These results suggest that this disturbance in the intramural circulation of the cerebral arterial wall plays a role in the development and/or progression of delayed cerebro-arterial narrowing after SAH.

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.

Aneurysmal subarachnoid hemorrhage--historical background from a Scandinavian horizon

The historical background of aneurysmal subarachnoid hemorrhage is depicted with emphasis in the Scandinavian contribution to improvements in the treatment. It is concluded that an aneurysmal subarachnoid hemorrhage with all certainty was the cause of death of the prospective King of Sweden, Charles August, in the year 1810. Despite advances in management and surgical treatment of this devastating disease the outcome in this important patient--which led to a new royal dynasty in Sweden--would certainly have turned out as fatal today as became the case 174 years ago.

Cerebral vasospasm after subarachnoid hemorrhage

Chronic cerebral vasospasm remains the most important cause of subsequent morbidity in patients who survive the first 48 to 72 hours after a subarachnoid hemorrhage. Prolonged arterial narrowing compromises cerebral hemodynamics and results in cerebral ischemia. Among patients in whom symptomatic chronic cerebral vasospasm develops, almost half die or have a serious residual neurologic deficit. Present evidence indicates that sustained vessel narrowing results from structural changes within the arterial wall rather than from active contraction of vascular smooth muscle. The mechanism (or mechanisms) responsible for these changes is unknown, but damage from prolonged active arterial contraction, depression of vessel wall respiration, and an inflammatory response have all been proposed as explanations. Despite more than 30 years of intensive study, an effective treatment program for chronic cerebral vasospasm remains elusive. Recent therapeutic trials, however, based on efforts to interrupt the mechanisms responsible for these structural changes hold some promise.

Analysis of 223 ruptured intracranial aneurysms with special reference to rerupture

A review of 223 patients with ruptured intracranial aneurysms, including 46 with rerupture, showed that the operability rate was higher and the prognosis better in patients with one rupture. Rerupture cases with low Hunt--Hess grades (0--II) had no better prognosis than one-rupture cases of grade IV. The mean interval between first rupture and rerupture was 12 days. Aneurysms located in the vertebrobasilar system showed the highest rate of rerupture. Daughter and bled-shaped aneurysms had a greater tendency to rerupture. The incidence of rerupture was increased in patients with narrowly localized vasospasm and acute hydrocephalus. Time-course studies of factors of the coagulating and fibrinolytic system suggested their usefulness in predicting the occurrence of vasospasm, infarction, and rerupture and the prognosis of patients with ruptured intracranial aneurysms. Patients at high risk for rerupture of aneurysm should undergo early operation.

Cerebral arterial constriction after experimental subarachnoid hemorrhage is associated with blood components within the arterial wall

Sequential cisternal blood injections in dogs reproduce some of the morphological and physiological features seen in man after subarachnoid hemorrhage-induced vasospasm. This study reports the morphological features observed in cerebral vessels in areas exposed to subarachnoid blood. Subarachnoid hemorrhage was produced in dogs by two cisternal injections of non-heparinized autologous blood 48 hours apart. Dogs were sacrificed 48 hours after the second injection. Angiographic narrowing of the basilar artery was routinely present 48 hours after the second injection, and there was a good correlation between angiographic vasospasm and a narrowed arterial lumen at postmortem examination. All basilar arteries showed structural changes with electron microscopic examination; these included endothelial cell vacuoles, early smooth-muscle cell necrosis, intimal changes, and adventitial erythrocytes, leukocytes, and mast cells. The finding that accompanied vessel constriction most uniformly was packing of the adventitial cerebrospinal fluid spaces with erythrocytes. Angiographically visible spasm was resistant to vasodilators. These data suggest that infiltration of blood elements into the arterial wall is an important concomitant feature of morphological and angiographic vasospasm.

Blood clot evacuation in aneurysm surgery in the acute stage (arguments pro and con)

In a series of 122 consecutive patients operated on by the senior author for rupture of an aneurysm the pterional approach was used in all but a few cases. A microsurgical technique was invariably utilized from opening to closing of the dura. Nearly half of our patients underwent surgery within the first week after subarachnoid haemorrhage (SAH). In the majority of cases operated on in the acute stage, a sizable subarachnoid blood clot was evacuated, mostly from the basal cisterns. The authors present their own experience in the field to show the superiority of the technically more demanding surgery carried out within the first days following SAH over other therapeutic procedures.

Progress in cerebrovascular disease. Management of cerebral aneurysm

The primary effort of neurosurgery over the past two or three decades has been to deal effectively with cerebral aneurysms surgically. Concomitantly with aggressive medical treatment, considerable progress has occurred in the prevention of early rebleeding and the treatment of the ischemic syndrome, the most serious features of the natural history of a ruptured aneurysm. The major problem now becoming evident is that in spite of this progress, the majority of patients are not seen by physicians and there has been only a small impact on the overall morbidity. It is dismaying to realize that many patients go unrecognized, at least until a massive brain-destroying hemorrhage has occurred. Only a small fraction of the patients are seen after the initial bleed when the greatest therapeutic reward would occur. The challenge for the future, then, will be the early recognition of the initial bleeding, the warning bleeding. It will require public education about the problem in a continuing fashion, as well as continuing emphasis on it for students and physicians. The potential for prevention of death or dreadful disability is large for thousands in the prime of life each year. While delayed surgery is safe, a significant amount of rebleeding and ischemia with vasospasm still occur, resulting in an unsatisfactory overall morbidity. A collaborative study is desirable to determine with sufficient patients whether very early modern operation in many hands will reduce this morbidity.

Vasospasm assessed by angiography and computerized tomography

In 44 consecutive cases of ruptured cerebral aneurysm, vasospasm was demonstrated pre- or postoperatively. These cases were examined by bilateral carotid angiography and computerized tomography (CT), and the relationship between the angiographically visualized distribution of vasospasm, the neurological symptoms, and infarction seen on CT was evaluated. Vasospasm occurred in only some intracranial portions of the cerbral arteries that were immersed in blood-stained cerebrospinal fluid. Angiographically, diffuse vasospasm extensively involving bilateral carotid systems indicated the gravest prognosis for patients. Vasospasm affecting one carotid system and the anterior cerebral arteries on the opposite side often produced permanent neurological deficits. On the contrary, when vasospasm was restricted to one carotid system or to bilateral anterior cerebral arteries, it was usually associated with temporary neurological symptoms; however, it always produced residual neurological symptoms if it extended to the ascending branches (M3) of the middle cerebral arteries. Computerized tomography definitely demonstrated a low-density area or infarction in the territory of the spastic arteries in 25 (71%) of 35 cases with vasospasm. A low-density area was always detected when vasospasm occurred in M3 segments.