Treatment of ruptured lenticulostriate artery aneurysms

OBJECT

Lenticulostriate artery (LSA) aneurysms are rarely reported in the literature, making management decisions challenging. Conservative, endovascular, and surgical treatments have been described primarily through case reports and reports of individual authors' experiences. The purpose of this study is to report neurological outcomes in a single-institution experience of ruptured lenticulostriate aneurysms treated surgically.

METHODS

The authors have conducted a retrospective review of all cases involving patients with ruptured LSA aneurysms who presented to the Mt. Sinai Hospital neurosurgical service between September 2001 and January 2007.

RESULTS

Over 5.4 years, the authors treated 6 patients with 7 LSA aneurysms-6 ruptured and 1 unruptured. The Hunt and Hess grade on admission ranged from I to IV, with subarachnoid hemorrhage in 5 of the 6 patients. Catheter angiography confirmed the presence of the aneurysms, and all patients underwent a pterional craniotomy and clipping or resection of the aneurysm, performed by a single surgeon. Associated risk factors in our series of patients included hypertension, cocaine abuse, and intracranial occlusive disease suggestive of moyamoya disease. Two types of LSA aneurysms were identified. The mean size of the 6 ruptured aneurysms was 3.2 mm. The LSA was preserved in 3 of 6 patients, but LSA preservation did not correlate with development of a postoperative infarct, clinically or radiologically. In patients with ruptured aneurysms, the mean modified Rankin Scale score at discharge was 1.7. The 3 patients in whom the LSA was sacrificed had good outcomes, suggesting that loss of the artery is clinically well tolerated.

CONCLUSIONS

This case series demonstrates that surgical treatment of ruptured LSA aneurysms can be an appropriate, effective, and safe therapy.

Combined endoscope-assisted transclival clipping and endovascular stenting of a basilar trunk aneurysm: case report

OBJECTIVE

We describe a patient with a mid-basilar aneurysm treated with combined endoscope-assisted transsphenoidal clipping and endovascular stenting.

CLINICAL PRESENTATION

A 28-year-old woman was transferred to the cranial base surgery center with an acute Grade III subarachnoid hemorrhage. Cerebral angiography demonstrated a small basilar trunk aneurysm that was not amenable to acute endovascular treatment.

INTERVENTION

The patient underwent sublabial transsphenoidal/transclival endoscope-assisted clipping of the aneurysm and subsequent stenting of the affected segment. The aneurysm was repaired with a low-profile Weck clip (Weck Closure Systems Research, Triangle Park, NC) that permitted a watertight closure of the clival dura using cardiac Medtronic U-clips (Medtronic, Inc., Minneapolis, MN). Postoperatively, the patient had no evidence of cerebrospinal fluid leakage.

CONCLUSION

Watertight dural closure was possible due to the use of a low-profile aneurysm clip that did not protrude through the dural defect, as well as self-tying sutures.

A rare spontaneous osteosarcoma of the calvarium in a patient with long-standing fibrous dysplasia: CT and MR findings

A 52-year-old man with long-standing craniofacial polyostotic fibrous dysplasia (FD) and no history of prior radiation therapy developed a spontaneous right temporal bone osteosarcoma. Such spontaneous sarcomatous degeneration of FD is rare, particularly in the calvarium/skull, where, to our knowledge, only six prior cases have been reported in the literature. We report this case because it is a rare entity with well-documented CT and MR images, and to emphasize the importance of depicting imaging features of sarcomatous degeneration among the complex imaging findings of FD.

Clinical improvement related to thrombolysis of third ventricular blood clot in a patient with thalamic hemorrhage

Intraventricular extension of hemorrhage after intraparenchymal hemorrhage is associated with significant morbidity and mortality. Clinical improvement is reported in a patient with thalamic hemorrhage with intraventricular extension after third and fourth ventricular blood clot resolution with instillation of urokinase intraventricularly. A 49-year-old man with hypertension collapsed while at work. A computed tomography (CT) scan of the head revealed a left thalamic hemorrhage with extension into the lateral, third, and fourth ventricles and associated hydrocephalus. A left frontal intraventricular catheter (IVC) was placed and intraventricular urokinase was administered at a dose of 25,000 U every 12 hours. The CT scan revealed resolution of the lateral ventricular dilatation and blood clot but no decrease in third or fourth ventricular hemorrhage. No clinical improvement was noted. The IVC was reinserted on the right side with the catheter tip placed through the foramen of Monroe into the third ventricle. Twelve hours after receiving the first dose of urokinase through the new catheter, the patient's condition improved. The CT scan showed a reduction in the volume of blood of the third and fourth ventricles. This case report shows that treatment of hydrocephalus with an IVC was not sufficient to provide a therapeutic effect. Substantial clinical improvement occurred only after the blood clot was cleared from the third and fourth ventricles.

Petrous apex aspergillosis as a long-term complication of cholesterol granuloma

Aspergillus infection of the petrous apex is a rare and devastating condition. To date, only two such cases have been reported, which resulted from direct extension of chronic Aspergillus otitis media. We present a case of petrous apex aspergillosis occurring years after surgical drainage of a petrous apex granuloma cyst. Because of the potential lethal nature of this condition, aggressive surgical therapy should be considered early in this illness and may provide the best chance for survival.

Acute cerebral vascular injury after subarachnoid hemorrhage and its prevention by administration of a nitric oxide donor

Object

Structural changes in brain parenchymal vessels occur within minutes after subarachnoid hemorrhage (SAH). These changes include platelet aggregation, activation of vascular collagenases, and destruction of perivascular collagen IV. Because collagen IV is an important component of the basal lamina, the authors attempted to further define changes in vascular structure (length and luminal diameter) and their relationship to vascular permeability immediately after SAH. In addition, the authors explored whether such alterations were attenuated by administration of a nitric oxide (NO) donor.

Methods

Endovascular perforation was used to induce SAH in rats. Two sets of experiments were performed. The first established changes in vascular structure and permeability (collagen IV and endothelial barrier antigen [EBA] dual immunofluorescence) during the first 24 hours after SAH. In the second, the investigators examined the effects of an NO donor on vascular structure, permeability, and collagenase activity (in situ zymography). In this second study, animals received intravenous infusion of the NO donor S-nitrosoglutathione (GSNO, 1 μM/8 μl/min) 15 minutes after induction of SAH and were killed 3 hours after SAH onset. Controls were naive unoperated animals for the first study and saline-infused SAH animals for the second.

The authors found a time-dependent decrease in area fraction, length, and luminal diameter of collagen IV– and EBA-immunofluorescent vessels after SAH. The greatest change occurred at 3 hours after onset of SAH. Administration of GSNO was associated with striking preservation of collagen IV and EBA immunofluorescence compared with saline treatment. Zymography indicated decreased collagenase activity in GSNO-treated SAH animals compared with saline-treated SAH animals.

Conclusions

These results demonstrate changes in the structure and permeability of brain parenchymal microvessels after SAH and their reversal by treatment with an NO donor.

Acute microvascular platelet aggregation after subarachnoid hemorrhage

OBJECT

The mechanisms underlying acute cerebral ischemia after subarachnoid hemorrhage (SAH) are not well established. Platelets aggregate within major cerebral vessels hours after SAH, but this has not been studied in the microvasculature. Platelet aggregates within the microvasculature could mechanically obstruct the lumen and initiate events that injure vessel structure. In the present study the authors examined the hypothesis that platelets aggregate within the cerebral microvasculature acutely after SAH.

METHODS

Subarachnoid hemorrhage was induced in the rat by using the endovascular perforation model. The animals were killed between 10 minutes and 48 hours after SAH. Immunostaining for the platelet surface receptor glycoprotein (GP)IIb/IIIa, which mediates platelet aggregation, was used to detect platelet aggregation. Sham-operated animals were used as controls. The GPIIb/IIIa immunoreactive platelet aggregates were abundant in the microvasculature of the basal and frontal cortex, striatum, and hippocampus 10 minutes after SAH. These aggregates decreased in number from 1 to 6 hours post-SAH and then increased to a peak at 24 hours. No immunoreactive aggregates were observed 48 hours after SAH.

CONCLUSIONS

The data indicate that widespread platelet aggregation occurs very rapidly in response to SAH followed by a decrease within 6 hours and a subsequent increase 24 hours after SAH. Microvascular platelet aggregates may contribute to decreased cerebral blood flow and ischemic injury after SAH via a number of mechanisms.

Acute alterations in microvascular basal lamina after subarachnoid hemorrhage

Object. Aneurysmal subarachnoid hemorrhage (SAH) causes acute and delayed ischemic brain injuries. The mechanisms of acute ischemic injury following SAH are poorly understood, although an acute increase in microvascular permeability has been noted. The integrity of cerebral microvessels is maintained in part by components of basal lamina: collagen IV, elastin, lamina, and so forth. Destruction of basal lamina components by collagenases and matrix metalloproteinases (MMPs), especially MMP-9, has been known to occur in other ischemic models. The authors assessed the integrity of cerebral microvasculature after acute SAH by examining collagen IV and MMP-9 levels and collagenase activity in the microvessels.

Methods. Subarachnoid hemorrhage was induced in rats through endovascular perforation of the intracranial bifurcation of the internal carotid artery. Animals were killed 10 minutes to 48 hours after SAH or sham operation (time-matched controls). Levels of collagen IV and MMP-9 were studied in the microvasculature by performing immunoperoxidase and immunofluorescence staining, and collagenase activity was assessed by in situ zymography.

Little change occurred in collagen IV and MMP-9 immunostaining or collagenase activity at 10 minutes or 1 hour after SAH. Starting 3 hours after SAH, collagen IV immunostaining was reduced or eliminated along segments of microvessels whereas MMP-9 staining was segmentally increased. These effects reached a maximum at 6 hours and returned toward those values in sham-operated controls at 48 hours.

Conclusions. Results of this study demonstrated an acute loss of collagen IV from the cerebral microvasculature after SAH and indicated that MMP-9 contributes to this event. The loss of collagen IV might contribute to the known failure of the blood—brain barrier after SAH.

Nitric Oxide Synthase in Acute Alteration of Nitric Oxide Levels after Subarachnoid Hemorrhage

OBJECTIVE

Subarachnoid hemorrhage (SAH) is associated with acute decreases and subsequent recovery of cerebral nitric oxide (NO) levels, but the mechanisms of these alterations are not known. In this study, we measured NO synthase (NOS) protein and kinetics to determine its involvement in the alterations of cerebral NO levels after SAH.

METHODS

The endovascular rat model of SAH was used. The number of NOS-1 (neuronal) and NOS-2 (inducible)-positive cells (0-96 h) was determined by counting immunoreactive cells in 8-microm cryostat sections. The tissue content of active NOS and its kinetic parameters were studied with an enzymatic l-citrulline assay.

RESULTS

The number of NOS-1-positive cells increased between 1 and 3 hours after SAH, decreased to and below control values at 6 and 72 hours after SAH, and increased to control values 96 hours after SAH. The number of NOS-2-positive cells increased 1 hour after SAH, decreased to control values at 24 hours, and increased above control values 96 hours after SAH. The Michaelis-Menten kinetic parameters (V(max), K(m), slope) of NOS remained unchanged at 10 and 90 minutes after SAH.

CONCLUSION

NOS-1 and -2 proteins undergo a triphasic alteration after SAH, whereas the amount of active NOS and its kinetic parameters remain unchanged during the first 90 minutes after SAH. Depletion of NOS is not involved in the acute alterations of cerebral NO levels after SAH.

Angiographic documentation of a persistent otic artery

The persistent otic artery is a rare remnant of early fetal development that, to our knowledge, has been convincingly documented only once before with angiography. Other persistent vessels such as the trigeminal, hypoglossal, and proatlantal intersegmental arteries have been found to be associated with a variety of vascular anomalies. We believe we present the second case of a persistent otic artery documented by means of angiography and the first such case associated with multiple intracranial aneurysms.

Applications of fast-setting hydroxyapatite cement: cranioplasty

A variety of autogenous and synthetic materials have been used to repair cranial defects resulting from traumatic and iatrogenic causes. In theory, the ideal material should be readily available and safe. It should adequately protect the underlying central nervous system, resist cerebrospinal fluid fistula formation, and be easily contoured. One promising synthetic biomaterial that has been used for cranioplasty is hydroxyapatite cement. This biomaterial has successfully restored cranial contour in most patients in whom it has been used; however, difficulties have arisen because of the material's prolonged water solubility. When exposed to cerebrospinal fluid or blood, inadequate setting of the cement occurs, resulting in loss of its structural integrity. This problem can be alleviated with the use of fast-setting hydroxyapatite cement, which hardens 6 to 12 times faster than the traditional cement. We present, to the best of our knowledge, the first series of the use of this material in 21 patients requiring cranioplasty. The advantages and limitations of fast-setting hydroxyapatite cement will be discussed.

Decreased nitric oxide availability contributes to acute cerebral ischemia after subarachnoid hemorrhage

OBJECTIVE

Disturbances of the L-arginine-nitric oxide (NO) vasodilatory pathway have been implicated as a cause of acute vasoconstriction and ischemia after subarachnoid hemorrhage (SAH). Because NO-dependent vasodilatory mechanisms are still intact in this setting, acute vasoconstriction may be the result of limited NO availability after SAH. The present study examines this hypothesis by administration of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME).

METHODS

SAH was induced by the endovascular suture method in anesthetized rats. L-NAME (30 mg/kg intravenously) was injected 20 minutes before or 15, 30, or 60 minutes after SAH. Control rats received normal saline. Arterial and intracranial pressure and cerebral blood flow (CBF) were measured continuously for 60 minutes after SAH.

RESULTS

L-NAME administration 20 minutes before SAH produced a significant decrease in resting CBF (29.4 +/- 3.4%; P < 0.05), but it had no effect on the acute decrease in CBF after SAH or on its early recovery up to 30 minutes after SAH. However, a significant decrease in CBF recovery was found in animals receiving L-NAME injections (28.7 +/- 9.4%; P < 0.05 versus controls) 60 minutes after SAH. Administration of L-NAME 15 or 30 minutes after SAH had no effect on CBF recovery, as compared with controls. However, when administered 60 minutes after SAH, L-NAME decreased CBF significantly (45.4 +/- 8.8%; P < 0.05 versus controls).

CONCLUSION

These results indicate a biphasic pattern of NO availability after SAH. NO-mediated vasodilation is limited during the first 30 minutes of SAH and is restored 60 minutes after SAH.

Experimental models of subarachnoid hemorrhage in the rat: a refinement of the endovascular filament model

The rat endovascular filament model has been utilized to study subarachnoid hemorrhage (SAH). Because the severity of the hemorrhage with this model has proven difficult to modulate, we attempted to vary the hemorrhage by modifying filament size, and compared this model to the blood injection method with regards to acute physiological responses and hemorrhage size. SAH was achieved using either a 3-0 or 4-0 filament, or by injecting 0.3 cc of autologous blood into the cisterna magna. Peak ICP elevations were lowest in the 4-0 filament group. CBF decreased acutely and rose from its nadir in all three models with the injection model demonstrating the earliest recovery. In the injection group, mean arterial blood pressure rose acutely and remained elevated, whereas in the 3-0 group, MABP rose transiently and in the 4-0 group it did not rise significantly. Histologically, there was less subarachnoid blood in the 4-0 group vs. the injection or 3-0 groups and a different distribution of blood in the two experimental models. Varying filament size provides a method to modulate the severity of SAH in the filament model. In addition, the rat endovascular filament and blood injection models produce different distribution of blood and physiological responses.

Acute decrease in cerebral nitric oxide levels after subarachnoid hemorrhage

Disturbances in the nitric oxide (NO) vasodilatory pathway have been implicated in acute vasoconstriction and ischemia after subarachnoid hemorrhage (SAH). The authors hypothesize that blood released during SAH leads to vasoconstriction by scavenging NO and limiting its availability. This was tested by measuring the major NO metabolites nitrite and nitrate in five different brain regions before and after experimental SAH. The basal NO metabolites levels were as follows (mean +/- SD, micromol/mg wet weight): brain stem, 0.14 +/- 0.07; cerebellum, 0.12 +/- 0.08; ventral convexity cortex, 0.22 +/- 0.15; dorsal convexity cortex, 0.16 +/- 0.11; and hippocampus, 0.26 +/- 0.17. In sham-operated animals, no effect of the nitric oxide synthase (NOS) inhibitor L(G)-nitro-L-arginine-methyl-ester (30 mg/kg) was found on NO metabolites 40 minutes after administration, but a significant decrease was seen after 120 minutes. The NO metabolites decreased significantly 10 minutes after SAH in all brain regions except for hippocampus, and recovered to control levels in cerebellum at 60 minutes and in brain stem and dorsal cerebral cortex 180 minutes after SAH, while remaining low in ventral convexity cortex. Nitrite recovered completely in all brain regions at 180 minutes after SAH, whereas nitrate remained decreased in brain stem and ventral convexity cortex. Our results indicate that SAH causes acute decreases in cerebral NO levels by a mechanism other than NOS inhibition and provide further support for the hypothesis that alterations in the NO vasodilatory pathway contribute directly to the ischemic insult after SAH.

Adenosine-induced transient asystole for management of a basilar artery aneurysm. Case report

Advances in anesthetic and surgical management, such as induced deep hypothermic circulatory arrest and application of temporary clips, have improved outcome for patients with basilar artery aneurysms. Nonetheless, these techniques are associated with significant risks. The authors report a case in which three transient periods of cardiac asystole were induced during basilar artery aneurysm surgery. Adenosine-induced asystole facilitated the safe clipping of the aneurysm by producing consistent periods of profound hypotension and collapse of the aneurysm without the need for temporary clipping. This technique provided unencumbered identification of perforating arteries, precise definition of the local anatomy, and an ideal environment for the safe placement of the aneurysm clip.

Effects of S-nitrosoglutathione on acute vasoconstriction and glutamate release after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) causes acute vasoconstriction that contributes to ischemic brain injury shortly after the initial bleed. It has been theorized that decreased availability of nitric oxide (NO) may contribute to acute vasoconstriction. Therefore we examined the effect of the NO donor N-nitroso glutathione (GSNO) on acute vasoconstriction and early ischemic glutamate release after experimental SAH.

METHODS

SAH was induced by the endovascular suture method in anesthetized rats. GSNO (1 micromol/L/kg, n=31) or saline (n=21) was injected 5 minutes after SAH. Sham-operated rats received GSNO (1 micromol/L/kg, n=5) 5 minutes after sham surgery. Arterial and intracranial pressures, cerebral blood flow (CBF), and extracellular glutamate release were measured serially for 60 minutes after SAH. SAH size was determined, and vascular measurements were made histologically.

RESULTS

GSNO had no effect on resting blood pressure, intracranial pressure, cerebral perfusion pressure, or CBF in sham-operated animals. However, administration of GSNO after SAH was associated with significantly increased CBF (161.6+/-26.6% versus saline 37.1+/-5.5%, 60 minutes after SAH, P<0.05), increased blood vessel diameter (internal carotid artery [ICA] 285.0+/-16.5 microm versus saline 149.2+/-14.1 microm, P<0.01), decreased vessel wall thickness (ICA12.9+/-0.7 microm versus saline 25.1+/-1.6 microm, P<0.01), and decreased extracellular glutamate levels (3315.6+/-1048.3% versus saline469. 7+/-134.3%, P<0.05). Blood pressure decreased transiently, whereas intracranial pressure, cerebral perfusion pressure, and SAH size were not affected.

CONCLUSIONS

These results suggest that GSNO can reverse acute vasoconstriction and prevent ischemic brain injury after SAH. This further implies that acute vasoconstriction contributes significantly to ischemic brain injury after SAH and is mediated in part by decreased availability of NO.

Use of an acellular dermal allograft for dural replacement: an experimental study

OBJECTIVE

In this study, a nonimmunogenic, acellular, dermal collagen matrix termed XenoDerm (LifeCell Corp., The Woodlands, TX) was examined for use as a dural replacement material in a porcine model. This model was used to investigate whether AlloDerm (LifeCell), an almost identical material made from human dermis, could be safely used in neurological surgery.

METHODS

Bilateral temporoparietal dural defects were surgically created in 12 Yucatan minipigs. One side was repaired with autologous pericranium, and the other was repaired with XenoDerm. The pigs were killed after 1, 3, or 6 months, and the areas of dural repair were collected and examined macroscopically and histologically. XenoDerm is derived from porcine skin collected in thin sheets. It is processed so that the epidermis and all dermal cells are removed without disruption of the collagen matrix, rendering the material immunogenically inert and resistant to calcification. It is packaged as a freeze-dried sheet and is easily rehydrated at the time of surgery.

RESULTS

There were no postoperative complications, and all pigs survived. Both grafts performed well as dural replacements in all cases. There was no macroscopic evidence of inflammation or cerebrospinal fluid leakage. The XenoDerm grafts were intact, retained their original dimensions, and resembled the surrounding dura. The autologous pericranial grafts, in contrast, were thicker than when implanted and had bony excrescences firmly adhering to their surfaces. Again, however, there was no evidence of cerebrospinal fluid fistulae. There was no gross adherence to the underlying meninges or brain tissue in any specimen. Repopulation by fibroblasts and neovascularization were evident in the XenoDerm grafts as early as 1 month after surgery; by 3 months, the XenoDerm had been remodeled to assume the connective tissue appearance of the surrounding dura.

CONCLUSION

In this porcine model, an allograft of acellular dermis is a nearly ideal dural replacement. AlloDerm, the human equivalent of XenoDerm, would be an allograft of acellular dermis after implantation in human subjects. On the basis of this study and previous work with AlloDerm in other reconstructive applications, it is proposed that this material could be similarly used for duraplasty in human subjects.

Thyrocervical to vertebral artery transposition and ipsilateral carotid endarterectomy

BACKGROUND

We report a new method for treating patients with symptomatic high-grade stenosis of the proximal vertebral artery associated with high-grade stenosis of the ipsilateral carotid artery.

METHODS

Our patient had high-grade stenosis of the proximal right vertebral artery as well as high-grade stenosis of the ipsilateral carotid artery and suffered continued posterior circulation ischemic neurological deficits despite anticoagulation.

RESULTS

The patient was successfully treated with a carotid endarterectomy and thyrocervical-to-vertebral artery transposition in a single operation.

CONCLUSION

This procedure has the advantage in this setting of avoiding additional cross clamping on the diseased carotid artery that would normally be required for the vertebral-to-carotid artery transposition with carotid endarterectomy. Also, thrombosis at one anastamosis site would not endanger the other site as well.

Spontaneous caudate hemorrhage associated with ingestion of a decongestant containing phenylpropanolamine

Intracerebral hemorrhage has been associated with phenylpropanolamine, a sympathomimetic agent contained in many over-the-counter medications. Caudate hemorrhage is infrequent, usually related to hypertension, and has not been reported following ingestion of medications containing phenylpropanolamine. We report an unusual case of caudate hemorrhage which developed in a patient taking an over-the-counter nasal decongestant containing phenylpropanolamine.

Acute vasoconstriction after subarachnoid hemorrhage

OBJECTIVE

Decreased cerebral blood flow (CBF) and cerebral ischemia occurring immediately after subarachnoid hemorrhage (SAH) may be caused by acute microvascular constriction. However, CBF can also be influenced by changes in intracranial pressure (ICP) and cerebral perfusion pressure (CPP). The goal of these experiments was to assess the significance of acute vasoconstriction after SAH and its relationship to changes in CBF, ICP, CPP, and extracellular glutamate concentrations.

METHODS

Three experiments were performed using the endovascular filament technique to produce SAH. In the first experiment, CBF, ICP, and CPP were measured for 60 minutes after SAH (n = 21) and were correlated with the 24-hour mortality rate. In the second experiment, rats undergoing SAH (n = 23) or a sham procedure (n = 7) were perfused 60 minutes after SAH for measurement of the circumference and wall thickness of the internal carotid and anterior cerebral arteries and correlation with CBF, ICP, and CPP. In the third experiment (n = 11), extracellular glutamate concentrations determined by hippocampal and cortical microdialysis and high performance liquid chromatography were correlated with physiological changes.

RESULTS

CBF reductions to less than 40% of baseline for 60 minutes after SAH predicted 24-hour mortality with 100% accuracy and were used to define "lethal" SAH. In contrast, ICP and CPP 60 minutes after SAH were not correlated with the mortality rate. The vascular circumference was significantly smaller in lethal than in sublethal SAH or sham-operated rats (P < 0.001). Vessel measurements were correlated with both CBF and hemorrhage size (P < 0.01). Extracellular glutamate concentration increased to 600% of baseline after lethal SAH in both hippocampus and cortex and was inversely correlated with CBF (r = 0.9, P < 0.001) but did not increase after sublethal SAH.

CONCLUSION

Acute vasoconstriction after SAH occurs independently of changes in ICP and CPP and is associated with decreased CBF, larger hemorrhage size, persistent elevations of extracellular glutamate, and poor outcome. Acute vasoconstriction seems to contribute directly to ischemic brain injury after SAH. Further evaluations of pharmacological agents with the potential to reverse acute vasoconstriction may increase CBF and improve outcome.

Surgical management of subarachnoid hemorrhage

Spontaneous subarachnoid hemorrhage is usually caused by a ruptured cerebral aneurysm. Aneurysmal rupture classically presents with sudden severe headache, often accompanied by an altered mental status. Diagnosis is made with computed tomography or lumbar puncture. Patients with ruptured cerebral aneurysms are at risk for rebleeding, cerebral artery vasospasm (and subsequent ischemia or stroke), and hydrocephalus. Early surgical clipping of the aneurysm under the microscope is usually the initial treatment of choice. This surgery prevents rebleeding and allows for safe use of pressors in the event that clinical vasospasm develops. Factors that would favor delayed surgery, "coiling" procedures, or conservative management include poor patient condition, basilar artery aneurysms, and unusually large or irregular aneurysms. Patients with ruptured aneurysms are treated with nimodipine, a calcium-channel blocker, to help prevent vasospasm-related ischemia. The degree of vasospasm that develops in the first 2 wks after aneurysmal rupture is assessed by transcranial Doppler sonography and cerebral angiography, in addition to the clinical examination. Patients with symptomatic vasospasm are kept well hydrated and treated with pressors (provided the aneurysm has been successfully clipped).