Peri-operative medical management of cerebral vasospasm

A Review of the Management of Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Despite decades of research, cerebral vasospasm (CV) continues to account for high morbidity and mortality in patients who survive their initial aneurysmal subarachnoid hemorrhage.

OBJECTIVE

To define the scope of the problem and review key treatment strategies that have shaped the way CV is managed in the contemporary era.

METHODS

A literature search was performed of CV management after aneurysmal subarachnoid hemorrhage.

RESULTS

Recent advances in neuroimaging have led to improved detection of vasospasm, but established treatment guidelines including hemodynamic augmentation and interventional procedures remain highly variable among neurosurgical centers. Experimental research in subarachnoid hemorrhage continues to identify novel targets for therapy.

CONCLUSIONS

Proactive and preventive strategies such as oral nimodipine and endovascular rescue therapies can reduce the morbidity and mortality associated with CV.

Time-dependent changes in cerebrospinal fluid metal ions following aneurysm subarachnoid hemorrhage and their association with cerebral vasospasm

Aneurysm subarachnoid hemorrhage affects 10 in 100,000 people annually, 40 % of whom will develop neurological deficits from ischemic stroke caused by cerebral vasospasm. Currently, the underlying mechanisms are uncertain. Metal ions are important modulators of neuronal electrophysiological conduction and smooth muscle cell activity, thereby potentially contributing to vasospasm. We hypothesized that metal ion concentrations in the cerebrospinal fluid (CSF) after aneurysm rupture would change over time and be associated with vasospasm. To test this hypothesis, for 21 days, we collected CSF from patients with aneurysmal rupture and subjected it to spectrometry to detect metals. A repeated measures analysis was performed to analyze concentration changes over time. Six of the seven patients with aneurysmal rupture experienced vasospasm, all resolving by day 14. Changes in Fe²⁺ and Zn²⁺ concentrations in the CSF paralleled the incidence of vasospasm in this study population. Na²⁺, Ca²⁺, Mg²⁺, and Cu²⁺ concentrations exhibited no statistically significant changes over time. In conclusion, Fe²⁺ concentration in the CSF was significantly elevated during days 7-10, whereas Zn²⁺ concentrations spiked shortly thereafter, during days 11-14. This suggests that Fe²⁺ may be related to the induction of vasospasm and Zn²⁺ may be a marker of early brain injury secondary to ischemic injury and inflammation.

Low-dose intravenous heparin infusion in patients with aneurysmal subarachnoid hemorrhage: a preliminary assessment

OBJECT

Aneurysmal subarachnoid hemorrhage (aSAH) predisposes to delayed neurological deficits, including stroke and cognitive and neuropsychological abnormalities. Heparin is a pleiotropic drug that antagonizes many of the pathophysiological mechanisms implicated in secondary brain injury after aSAH.

METHODS

The authors performed a retrospective analysis in 86 consecutive patients with Fisher Grade 3 aSAH due to rupture of a supratentorial aneurysm who presented within 36 hours and were treated by surgical clipping within 48 hours of their ictus. Forty-three patients were managed postoperatively with a low-dose intravenous heparin infusion (Maryland low-dose intravenous heparin infusion protocol: 8 U/kg/hr progressing over 36 hours to 10 U/kg/hr) beginning 12 hours after surgery and continuing until Day 14 after the ictus. Forty-three control patients received conventional subcutaneous heparin twice daily as deep vein thrombosis prophylaxis.

RESULTS

Patients in the 2 groups were balanced in terms of baseline characteristics. In the heparin group, activated partial thromboplastin times were normal to mildly elevated; no clinically significant hemorrhages or instances of heparin-induced thrombocytopenia or deep vein thrombosis were encountered. In the control group, the incidence of clinical vasospasm requiring rescue therapy (induced hypertension, selective intraarterial verapamil, and angioplasty) was 20 (47%) of 43 patients, and 9 (21%) of 43 patients experienced a delayed infarct on CT scanning. In the heparin group, the incidence of clinical vasospasm requiring rescue therapy was 9% (4 of 43, p = 0.0002), and no patient suffered a delayed infarct (p = 0.003).

CONCLUSIONS

In patients with Fisher Grade 3 aSAH whose aneurysm is secured, postprocedure use of a low-dose intravenous heparin infusion may be safe and beneficial.

Brain tissue oxygen monitoring to assess reperfusion after intra-arterial treatment of aneurysmal subarachnoid hemorrhage-induced cerebral vasospasm: a retrospective study

BACKGROUND AND PURPOSE

Cerebral vasospasm resistant to medical management frequently requires intra-arterial spasmolysis. Angiographic resolution of vasospasm does not provide physiologic data on the adequacy of reperfusion. We recorded pre- and postspasmolysis PbO(2) data in the endovascular suite to determine whether this physiologic parameter could be used to determine when successful reperfusion was established.

MATERIALS AND METHODS

Eight patients with 10 Licox monitors and cerebral vasospasm underwent intra-arterial spasmolysis. Pre- and postspasmolytic PbO(2) was recorded for comparison. Other physiologic parameters, such as CPP, ICP, SaO(2), and Fio(2), were also recorded.

RESULTS

Mean prespasmolysis PbO(2) recordings were 35.2 and 27.3 for the mild-to-moderate and moderate-to-severe vasospasm group, respectively. Mean postspasmolysis PbO(2) increased to 40.3 and 38.4, respectively, which was statistically significant (P < .05) for both groups. In 100% of instances in the moderate-to-severe group and 83% of instances in mild-to-moderate group, the mean PbO(2) increased after spasmolysis and correlated with improvement in angiographic vasospasm. Other physiologic parameters, such as CPP, ICP, SaO(2), and Fio(2), did not show any statistically significant difference before and after spasmolysis.

CONCLUSIONS

PbO(2) monitoring provides the interventionalist with an objective physiologic parameter to determine adequate spasmolysis. Further investigation is needed to establish target PbO(2) rates indicative of adequate reperfusion, which can be used in the endovascular suite.

Unfractionated heparin: multitargeted therapy for delayed neurological deficits induced by subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is associated with numerous "delayed neurological deficits" (DNDs) that have been attributed to multiple pathophysiological mechanisms, including ischemia, microthrombosis, free radical damage, inflammation, and vascular remodeling. To date, effective prophylactic therapy for SAH-induced DNDs has been elusive, due perhaps to the multiplicity of mechanisms involved that render typical, single-agent therapy seemingly futile. We hypothesized that heparin, which has multiple underappreciated salutary effects, might be useful as a multitargeted prophylactic agent against SAH-induced DNDs. We performed a comprehensive review of the literature to evaluate the potential utility of heparin in targeting the multiple pathophysiological mechanisms that have been identified as contributing to SAH-induced DNDs. Our literature review revealed that unfractionated heparin can potentially antagonize essentially all of the pathophysiological mechanisms known to be activated following SAH. Heparin binds >100 proteins, including plasma proteins, proteins released from platelets, cytokines, and chemokines. Also, heparin complexes with oxyhemoglobin, blocks the activity of free radicals including reactive oxygen species, antagonizes endothelin-mediated vasoconstriction, smooth muscle depolarization, and inflammatory, growth and fibrogenic responses. Our review suggests that the use of prophylactic heparin following SAH may warrant formal study.

Cerebral vasospasm and concurrent left ventricular outflow tract obstruction: requirement for modification of hyperdynamic therapy regimen

BACKGROUND

Medical treatment of arterial vasospasm following aneurysmal subarachnoid hemorrhage (SAH) generally consists of triple H therapy, which frequently relies on inotropic agents in order to increase cardiac output (CO). Patients with concurrent left ventricular outflow tract (LVOT) obstruction may have paradoxical decreases in CO following administration of inotropic pressors, placing them at significant risk for cerebral ischemia and stroke.

METHODS

The clinical courses of two patients with SAH-induced arterial vasospasm and underlying left ventricular outflow obstruction are reported. Both patients had hypotension and low cardiac output that were refractory to medical management with triple H therapy. Echocardiography in both patients demonstrated LVOT obstruction secondary to hypertrophic obstructive cardiomyopathy (HOCM).

RESULTS

Intervention in both patients included discontinuation of inotropic agents and maintenance of hypervolemia to a target pulmonary capillary wedge pressure range, resulting in improved cardiac output and mean arterial pressure.

CONCLUSION

Medical treatment for cerebral vasospasm with inotropic pressor agents may result in paradoxical decreases in hemodynamic parameters and cerebral perfusion in patients with LVOT obstruction. While HOCM is the most likely structural abnormality to cause this phenomenon, it can be induced by several physiological conditions encountered in the neurocritical care setting. Modifications in triple H therapy regimens may be required in order to optimize cerebral perfusion and prevent cerebral ischemia and stroke in these patients.