The pathophysiology of cerebral vasospasm, and pharmacological approaches to its management

Significance of C-reactive protein and transcranial Doppler in cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Objective

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. C-reactive protein (CRP) constitutes a highly sensitive inflammatory marker. Elevation of serum CRP levels has been demonstrated in patients with aSAH. The purpose of the current study was to evaluate the possible relationship between CRP levels in the serum and transcranial Doppler (TCD) and the development of vasospasm in patients with aSAH.

Methods

A total of 61 adult patients in whom aSAH was diagnosed were included in the study from November 2008 to May 2011. The patients' demographics, Hunt and Hess grade, Fisher grade, CT scans, digital subtraction angiography studies, and daily neurological examinations were recorded. Serial serum CRP measurements were obtained on days 1, 3, 5, 7, 9, 11 and 13 and TCD was measured on days 3, 5, 7, 9, 11 and 13. All patients underwent either surgical or endovascular treatment within 24 hours of their hemorrhagic attacks.

Results

Serum CRP levels peaked on the 3rd postoperative day. There were significant differences between the vasospasm group and the non-vasospasm group on the 1st, 3rd and 5th day. There were significant differences between the vasospasm group and the non-vasospasm group on the 3rd day in the mean middle cerebral artery velocities on TCD.

Conclusion

Patients with high levels of CRP on the 1st postoperative day and high velocity of mean TCD on the 3rd postoperative day may require closer observation to monitor for the development of vasospasm.

Intraoperative microvascular Doppler in intracranial aneurysm surgery

OBJECTIVE

The usefulness of intraoperative microvascular Doppler (IMD) in preventing an incorrect placement of the clip during intracranial aneurysm surgery is described. Such incorrect placement of the clip may cause new bleeding or ischemic accident as a consequence of incomplete exclusion of the aneurysm or stenosis/occlusion of the parent and/or adjacent arteries.

METHODS

One hundred thirty patients, harboring 136 aneurysms, were operated on using IMD. IMD study was performed on the aneurysm and adjacent arterial vessels before and after the clip placement. Mechanical arterial spasm was treated by topical sodium nitroprusside (SNP) and its efficacy verified by IMD.

RESULTS

In 55 aneurysms (42.3%), IMD was helpful in understanding the microvascular anatomy before clip placement. Complete exclusion resulted in 129 aneurysms (94.9%). In 5 cases (3.7%) in which IMD revealed a persistent blood flow in the aneurysm, the clip was repositioned. In 2 cases (1.4%), we obtained false-negative results. In 25 cases (18.3%) in which IMD data documented a severe flow reduction in the vessel harboring the aneurysm or in the vessel originating very close to the aneurysm neck, the clip was repositioned. There were no complications due to the use of IMD. In 20 patients (15%) in which IMD revealed arterial spasm by surgical manipulation, topical SNP was followed by resolution of the spasm.

CONCLUSION

IMD is a feasible, safe, and very reliable technique in aneurysm surgery. Compared to other procedures such as intraoperative angiography, the cost efficiency of IMD is favorable.

Comparison of intrathecal administration of urokinase and tissue plasminogen activator on subarachnoid clot and chronic vasospasm in a primate model

Safety and efficacy of the thrombolytic agent urokinase (URO) in the elimination of subarachnoid clot and prevention of chronic vasospasm was compared with tissue-type plasminogen activator (rt-PA) in a blind, randomized placebo-controlled trial. Twenty monkeys were randomly assigned to one of five groups of four. Each group underwent baseline cerebral angiography followed by bilateral craniectomy and experimental subarachnoid hemorrhage. An Ommaya reservoir was inserted on the right side with its catheter placed into the ipsilateral subarachnoid space. Twenty-four hours later, depending upon group assignment, the animals received 100,000 IU URO, 200,000 IU URO, 1 mg rt-PA, 2 mg rt-PA, or the equivalent volume of normal saline (control group). On Day 7, angiography was repeated and the animals were killed. One animal died as a result of complications during the baseline angiography, presumably due to blood loss and prolonged anesthesia, and a replacement animal was obtained. No animals demonstrated any delayed neurological deficits. The study demonstrated that a single intracisternal bolus injection of rt-PA, 2.0 mg in 2 ml sterile water, or URO, 200,000 IU in 2 ml sterile water, 24 hours after induction of experimental subarachnoid hemorrhage in primates, was equally effective in thrombolysing ipsilateral clot, but neither dosage prevented angiographic vasospasm. Vasospasm occurred bilaterally in all groups. Whereas gross subarachnoid clot was found bilaterally in all animals in the placebo group and both smaller-dose URO and rt-PA groups, right-sided subarachnoid clot was virtually absent and left-sided clot reduced in both higher-dose URO and rt-PA groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal in vivo and in vitro time-course study of chronic cerebrovasospasm in the rabbit basilar artery

Subarachnoid hemorrhage (SAH) was induced by multiple injections of autologous blood into the prepontine cistern in the rabbit. Long-lasting angiographic narrowing was recorded over a period of nine days after SAH. Papaverine (PPV) reversed angiographic narrowing in the first three days after SAH. Vasospasm was refractory to PPV from day five to day nine after SAH. PPV - refractoriness (in vivo) was positively correlated with decreased vessel wall distensibility (in vitro). Arterial segments showed spontaneous increases in tone in the first two days after SAH. Other alterations observed include a marked gradual reduction in the capacity of the vessel wall to contract, reduction in constrictor nerve influences on vascular tone, and impaired acetylcholine - induced vasorelaxation. Tonic contraction to the maximum dose of serotonin was increased in acute spasm and decreased in chronic spasm. It is suggested that the initial cause of arterial narrowing after SAH is the action of vasoactive substances released in the close vicinity of the arterial wall; this then leads to abnormal tone, tissue damage, and structural changes.

Effect of nimodipine on canine cerebrovascular responses to 5-hydroxytryptamine and potassium chloride after exposure to blood

The stainless steel cannula inserting method was used to investigate the blocking effects of nimodipine on vascular responses to intraluminal administration of 5-hydroxytryptamine (5-HT) or potassium chloride (KCl) before and after application of abluminal blood containing thrombin in isolated and perfused canine basilar arteries. A transient elevation of perfusion pressure was observed initially, and during the course of the experiment the perfusion pressure gradually increased. Nimodipine significantly depressed both transient and prolonged changes of perfusion pressure. Dose-dependent vasoconstriction induced by 5-HT was significantly enhanced, while that evoked by KCl was significantly attenuated for up to 8 hours after the application of blood. Pretreatment with nimodipine inhibited vasoconstriction to 5-HT less effectively than to KCl both before and after application of blood. The proportion of the 5-HT-induced vasoconstriction, which was sensitive to nimodipine, was reduced after application of blood, while no such change was observed in the responses to KCl. It is suggested that the augmentation of cerebrovascular responses to 5-HT in the early stage of subarachnoid hemorrhage may be mediated mainly by changes in intracellular calcium utilization rather than by the increase of calcium influx through nimodipine-sensitive channels.

The effect of timing of clot removal on chronic vasospasm in a primate model

The effect of complete clot removal at times from 48 to 96 hours after subarachnoid hemorrhage (SAH) on the development of chronic cerebral vasospasm was evaluated to determine whether there is a critical point after which clot removal is ineffective in preventing vasospasm. Thirty cynomolgus monkeys were randomized to one of five groups: sham-operated group, clot removal at 48 hours after SAH (48-hour group), clot removal at 72 hours after SAH (72-hour group), clot removal at 96 hours after SAH (96-hour group), and clot placement only (clot group). Standard microsurgical techniques were used to dissect bilaterally the major cerebral arteries free of arachnoid. An autologous blood clot averaging 4.2 gm was placed around the vessels in the subarachnoid space of the monkeys in the 48-hour, 72-hour, 96-hour, and clot groups. Physiological saline was instilled into the subarachnoid space of the sham-operated animals. Animals in the clot-removal groups underwent surgical clot removal at the determined times for each group. Two animals in each of the sham-operated and clot groups were subjected to reoperation at each of 48, 72, and 96 hours after SAH. The incisions were reopened and then simply reclosed. Neurological status, angiographic cerebral vessel caliber, and physiological status were evaluated before and 7 days after SAH induction. There were no significant neurological deficits in the sham-operated, 48-hour, or 72-hour groups. Two animals in each of the 96-hour and clot groups showed deterioration in level of consciousness developing on Day 4 or 5 after SAH induction. All the major cerebral arteries of the animals in the clot and 96-hour groups showed significant vasospasm (p less than 0.01) on Day 7. Animals in the 72-hour group had significant vasospasm (p less than 0.05) of the internal carotid and middle cerebral arteries but not the anterior cerebral arteries. There was no significant vasospasm (p greater than 0.05) in any of the cerebral arteries in the 48-hour group. Severity of vasospasm paralleled the duration of contact between the blood clot and the cerebral vessels. Evacuation of the subarachnoid hematoma later than 48 hours after SAH resulted in no significant reduction in the degree of chronic cerebral vasospasm. It is suggested that clot removal at early operation is likely to be useful only if it is performed within 48 hours of SAH.

Effect of clot removal at 24 hours on chronic vasospasm after SAH in the primate model

The efficacy of complete clot removal 24 hours after subarachnoid hemorrhage (SAH) in the prevention of chronic cerebral vasospasm was evaluated in monkeys in a blind randomized controlled trial. Twenty-four monkeys were randomized to one of three groups to undergo sham-operation (sham-operated group), clot placement only (clot group), or clot placement and removal (clot-removal group). By means of standard microsurgical techniques, the major cerebral vessels bilaterally were dissected free of arachnoid. An autologous hematoma averaging 5 gm was placed around the vessels in the subarachnoid spaces in the clot and clot-removal groups. Saline solution was instilled in the subarachnoid spaces of the sham-operated group. All animals underwent reoperation 24 hours after the first procedure. In the clot-removal group, the hematoma was evacuated. In the sham-operated and clot groups, the incision was simply closed again after 3 hours of anesthesia. Indices monitored before and 7 days after SAH induction included neurological status, angiographic cerebral vessel caliber, and arterial blood pressure. All animals were evaluated with magnetic resonance imaging (MRI); representative animals were evaluated with computerized tomography (CT) brain scans. There were no neurological deficits in either the sham-operated or the clot-removal groups. One animal in the clot group developed a progressive delayed ischemic deficit on Day 5 after SAH. A second animal in this group died suddenly on Day 4 post-SAH. An autopsy revealed a recent infarct in the territory of the superior cerebellar artery. Clinical findings correlated with MRI and CT images. Significant vasospasm (25% to 100% reduction in vessel caliber) was present on Day 7 in 100% of the clot animals (p less than 0.01). There was no significant vasospasm (p greater than 0.05) on Day 7 in either the sham-operated or the clot-removal groups. A large volume of clot placed bilaterally resulted in a 25% incidence of delayed ischemic deficit. Evacuation of subarachnoid hematoma within 24 hours of SAH prevented the development of chronic vasospasm and delayed ischemic deficit in the primate model.

Basilar artery narrowing and hyperparathyroidism: illustrative case

A patient presenting with a pontine infarction caused by mid-basilar artery narrowing associated with hyperparathyroidism is described. The narrowing reversed with surgical removal of his parathyroid adenoma and normalization of his serum calcium. This patient's illness lends evidence to the role of calcium in cerebral vasoconstriction.

S-100 protein and calmodulin levels in cerebrospinal fluid after subarachnoid hemorrhage

The levels of two calcium-binding proteins, S-100 protein and calmodulin, were measured serially in the cerebrospinal fluid (CSF) of patients after subarachnoid hemorrhage (SAH) and aneurysm surgery. These two proteins have a similar molecular structure and are highly concentrated in the central nervous system (CNS). The levels of S-100 protein found in the earliest postoperative CSF samples correlated with the preoperative SAH grades. High S-100 protein levels in the CSF were found in patients with poor SAH grades. Moreover, the prognosis of the patients correlated with the S-100 protein levels in the CSF samples taken during the immediate postoperative period and with the daily changes of the S-100 protein levels. Severe diffuse cerebral vasospasm was followed by a sharp S-100 protein increase. These results suggest that S-100 protein levels in the CSF provide a useful index of organic damage in the CNS, and furthermore that S-100 protein levels and their changes may have prognostic value for patients after SAH. On the other hand, there was a lack of correlation between the calmodulin levels and the preoperative grade or outcome. It would be inappropriate, however, to speculate from the results of this study that these calcium-binding proteins in the CSF play any causative role in pathological processes such as cerebral vasospasm or brain ischemia after SAH, since changes in the levels of these proteins followed the onset of clinical signs of deterioration.

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.

Intracarotid slow bolus injection of nimodipine during angiography for treatment of cerebral vasospasm after SAH. A preliminary report

Nimodipine was given as an intracarotid slow bolus injection in six patients with subarachnoid hemorrhage (SAH) due to rupture of a cerebral aneurysm, with angiographically demonstrated vasospasm. The patients were followed by serial angiograms for demonstration of the effect of nimodipine on vasospasm. After angiography, all patients were treated with a constant venous infusion of this new calcium antagonist. Although the therapeutic regimen was started only a few hours after onset of vasospasm, there was no change in cerebral vessel caliber detectable on angiograms following the intracarotid injection. Three patients died, two patients finally recovered with neurological deficits due to cerebral ischemia, and one patient with asymptomatic vasospasm remained symptom-free. Although nimodipine may act to prevent cerebral vasospasm after SAH, the authors believe that the intracarotid application is not effective after vasospasm has occurred.

A randomized placebo-controlled double-blind trial of nimodipine after SAH in monkeys. Part 1: Clinical and radiological findings

The authors have developed a method to induce chronic cerebral vasospasm after subarachnoid hemorrhage (SAH) in monkeys. With microsurgical techniques, 33 monkeys had a frontotemporal craniectomy and unilateral opening of the subarachnoid cisterns. Cerebrospinal fluid was drained and a fresh hematoma, obtained from an average of 7 ml of autologous blood, was carefully placed against the major arteries of the anterior circulation on one side. The 30 monkeys studied for 7 to 14 days after the SAH were allocated randomly to two treatment groups of 15: one group received placebo and the other nimodipine, 1 mg/kg every 8 hours. Indices monitored before and after SAH included neurological status, cerebral blood flow, computerized tomography, and angiographic vessel caliber. In the placebo group, delayed ischemic neurological deficit developed in one monkey 4 days after clot placement and was present at sacrifice on Day 14. No such deficit occurred in the nimodipine group. The effect of nimodipine on vessel caliber at this dosage was equivocal. Significant vasospasm (31% to 100% reduction in vessel caliber) developed in 87% (26 of 30) of the animals. Overall, vasospasm was slightly more common in the placebo group: in this group, on Days 7 and 14, the incidence of vasospasm was significantly higher (p less than 0.05) than in the nimodipine group. However, the average percentage reduction in vessel caliber of the maximally constricted vessel in each monkey was not significantly different between the two groups.

Calcium antagonists, cerebral ischemia and vasospasm

The past fifteen years has seen the classification of diverse substances into a group known as calcium antagonists (CAs). They have a common ability to reduce the transmembrane transport of extracellular calcium ions (CAe2+). This flow of calcium into vascular smooth muscle is ultimately associated with the development of tension and vasoconstriction. Some CAs appear to have a predilection for cerebral as opposed to systemic arteries and so may function as specific cerebral arterial vasodilators. It has been proposed that they might be useful in certain types of cerebral ischemia such as that due to arterial occlusion or prolonged vasoconstriction. Animal experiments and initial clinical trials give grounds for cautious optimism that CAs may become as useful in neurology as they have recently become in cardiology.

Balloon catheter technique for dilatation of constricted cerebral arteries after aneurysmal SAH

The authors describe the technique and explain the reason for the use of an intravascular balloon catheter technique in the treatment of vasospasm in cases of subarachnoid haemorrhage due to rupture of a cerebral aneurysm. In 33 patients with SAH 105 major cerebral arteries were dilated (in the system of internal carotid and basilar arteries). Only in one case vasodilatation could not be accomplished. The effect of dilatation of vasospastic arteries was stable and the functional state of the brain was ameliorated, local and general cerebral dysfunctional signs and symptoms due to vasospasm regressed. The authors discuss indications and contraindications for intravascular balloon dilatation of spastic arteries, the time for the operation, the length of arteries to be dilated, and the possible mechanism of amelioration of cerebral blood flow to the brain stem.

The angiopathy of subarachnoid hemorrhage I. Role of vessel wall catecholamines

Subarachnoid hemorrhage (SAH) due to rupture of the right middle cerebral artery (RMCA) produced specific anatomical and biophysiological responses in the involved feline vessels. The RMCA showed morphological alterations that became progressively more severe with time and were widespread within the cerebral vascular tree. SAH also resulted in an acute depletion of vessel catecholamine levels which remained depressed over a 30 day period. When the cerebral vessels of cats were severely depleted of catecholamines (using reserpine) prior to induced SAH, morphological alterations were significantly reduced both in severity and in degree of spread within the cerebral vascular network. The results of this study suggest that the concentration of norepinephrine within the vessel at the time of hemorrhage plays a significant role in the production of the angiopathy that follows SAH.

Calcium channel antagonist binding sites labeled by 3H-nimodipine in human brain

In vitro binding of 3H-nimodipine to human brain membranes is demonstrated in this study. This binding was specific and saturable, and had an apparent affinity constant (KD) of 0.27 nM. The maximal number of binding sites for 3H-nimodipine was 5.8 pmoles/gm wet weight of human frontal cortex. The binding was shown to be dependent on calcium, with half-maximal stimulation obtained at 3 X 10(-5) M CaCl2. Other 1,4-dihyropyridine calcium antagonists were shown to be competitive antagonists of 3H-nimodipine binding. In contrast, the calcium antagonists, verapamil and diltiazem, had complex interactions with 3H-nimodipine binding. These results represent the first identification of 3H-calcium antagonist binding sites in human brain, and they confirm that various calcium antagonist drugs may differ with respect to both their potency and their molecular site of action.

Acute surgery of cerebral aneurysms and prevention of symptomatic vasospasm

A treatment protocol for a controlled open study in patients with subarachnoid haemorrhage (SAH) from cerebral aneurysms is presented, applying acute surgery and pharmacological prevention of symptomatic vasospasm: In patients clinically graded I-III (Hunt and Hess), operation is performed within 48 to 72 hours. After aneurysm clipping, the calcium-antagonist Nimodipine is administered 1. topically during operation, 2. intravenously until day 14 after SAH, 3. perorally until day 21 after SAH. Preliminary results in the first 31 patients show no management mortality and no severe management morbidity. Severe symptomatic vasospasm has never occurred. At 3 months follow-up investigation in 27 of the 31 patients, 5 had minimal neurological deficit; all patients are fully resocialized, working in their previous professions.

Prevention of symptomatic vasospasm by topically applied nimodipine

A 2.4 x 10(-5) M solution of the Calcium-antagonist Nimodipine was administered to the exposed cerebral vessels in 17 patients intraoperatively clipping of a ruptured aneurysm. The interval between subarachnoid haemorrhage and operation was 48 to 72 hours. The CT investigation had revealed blood accumulation in the basal cisterns in all cases. Vasodilatation was observed in all instances; the percentage being greater in small vessels as compared to large vessels. Postoperatively, a neurological deficit combined with angiographically verified vasospasm occurred in two patients, but was reversible in both. Fifteen patients remained free from symptomatic vasospasm and were discharged without neurological deficit. In 13 of these patients and 3 additional cases, a plastic cannula was placed intraoperatively so that postoperative topical administration of Nimodipine was possible. Postoperative control-angiograms after a mean interval of 7 days from SAH did not show severe spasm in any of the patients; localised moderate asymptomatic spasm was found in 8 cases and was reserved in 5. Moderate postoperative symptomatic spasm was observed in 2 patients, treated and reversed in one patient. In 5 of 7 cases without evidence of spasm in the angiogram postoperative topical administration of Nimodipine caused vasodilatation. It is concluded, that topical intracisternal administration of Nimodipine reverses intraoperative vascular spasm and decreases the probability of postoperative symptomatic vasospasm after early surgery.