Subarachnoid Hemorrhage Surgery 

Subarachnoid hemorrhage (SAH) surgery is used to treat the extravasation of blood into the subarachnoid space between the pial and arachnoid membranes, which has a detrimental effect on both local and global brain function and leads to high morbidity and mortality rates. An estimated 15% of patients die before reaching the hospital, and approximately 25% of patients die within 24 hours, with or without medical attention. The mortality rate at the end of 1 week approaches 40%. Half of all patients die in the first 6 months.

Subarachnoid hemorrhage (SAH) comprises half of spontaneous atraumatic intracranial hemorrhages (usually as the result of aneurysmal or arteriovenous malformation [AVM] leakage or rupture), with the other half consisting of bleeding that occurs within the brain parenchyma. Intracranial hemorrhage as a whole comprises 20% of all strokes.

Historical information

Ancient Greek, Egyptian, and Arabic literature all have references to intracranial aneurysms, but the first successful treatment was reported in the early 19th century. However, such outcomes did not become routine until the Dandy era and the advent of modern neurosurgical techniques.

Dandy performed the first successful clipping of an aneurysm in 1937, using a vascular clip designed by Harvey Cushing.^[1] In the following years, advancements in microneurosurgical techniques, including the operating microscope, microsurgical instruments, better anesthesia, and improved management of subarachnoid hemorrhage (SAH) complications, led to significant improvements in surgical outcomes.

Balloon embolization

Endovascular therapy for the treatment of intracranial aneurysms was pioneered in the mid 1970s by Serbinenko at the Moscow Institute of Neurosurgery. This initial approach, which attempted to achieve parent vessel occlusion using latex balloons, was moderately successful in a limited subset of cases. However, it never gained widespread applicability.

Other balloon devices, including detachable silicon and latex balloons, were subsequently developed in the United States, Europe, and Japan. The success of balloon embolization has been tempered by the associated complications of deflation and aneurysmal rupture.

Coil embolization

Arguably, the most significant recent development in endovascular therapy occurred in 1990, when Guglielmi and colleagues at the University of California Los Angeles (UCLA) Medical Center developed the Guglielmi detachable coil (GDC) system.

The GDC is a radiopaque platinum coil that is delivered through a microcatheter into an aneurysm, which then is detached by electrolysis. In 1995, GDCs gained approval by the US Food and Drug Administration (FDA) for treatment of aneurysms that have the potential for high surgical morbidity and mortality.

In Europe, GDCs have been used as a first-line intervention in lieu of surgical treatment for patients without contraindications to endovascular therapy. In the last decade, endovascular coiling has become first-line treatment for aneurysms at several centers in the United States and is continuing to gain popularity in those patients appropriate for the procedure.

Investigative endovascular techniques

Other endovascular techniques under investigation include liquid embolic agents, intravascular laser treatments, and intravascular stents. As endovascular occlusive techniques evolve, it seems likely that they will play a larger role in the management of SAH.

See also Subarachnoid Hemorrhage, Emergent Management of Subarachnoid Hemorrhage, Arteriovenous Malformation, and Cerebral Aneurysms.

Rupture of "berry," or saccular, aneurysms of the basal vessels of the brain comprises 77% of nontraumatic subarachnoid hemorrhage (SAH) cases.

Circle of Willis

Most saccular aneurysms occur at bifurcations of the vessels that comprise the circle of Willis. The circle of Willis is in close proximity to the ventral surface of the diencephalon and is adjacent to the optic nerves and tracts. It extends from the superior border of the pons to the longitudinal fissure between the cerebral hemispheres.

The circle of Willis is an important anastomosis for the 4 arteries that supply the brain—the 2 vertebral and the 2 internal carotid arteries. It can be divided into anterior and posterior sections.

Anterior portion of the circle of Willis

The anterior section of the circle of Willis consists of the internal carotid arteries, the anterior cerebral artery, and the anterior communicating artery, as follows:

• The right internal carotid artery, along with the right external carotid artery, branches from the common carotid artery most often at C3 or C4, with a range of C1 to T2
• The right common carotid artery originates from the brachiocephalic trunk, the first branch of the aorta
• The left common carotid artery, the second branch of the aorta, branches into the right internal and right external carotid arteries at about the same level as the right common carotid bifurcation
• The cerebral portions of the internal carotid arteries branch into the anterior and middle cerebral arteries at the medial end of the lateral sulcus
• The anterior communicating artery is a short segment that connects the 2 anterior cerebral arteries and forms the anterior border of the circle of Willis
• Posterior portion of the circle of Willis

The posterior segment of the circle of Willis consists of the proximal portions of the posterior cerebral arteries and the paired posterior communicating arteries, as follows:

• The 2 posterior cerebral arteries arise from the terminal bifurcation of the basilar artery
• The basilar artery is formed by the union of the 2 vertebral arteries, each of which begins as a branch of the first part of the subclavian artery
• The posterior communicating arteries connect the internal carotid and the posterior cerebral arteries and form the posterior-lateral borders of the circle of Willis

Location of aneurysm rupture

Approximately 85% of saccular aneurysms occur in the anterior circulation. The most common sites of rupture are as follows:

• The internal carotid artery, including the posterior communicating junction (41%)
• The anterior communicating artery/anterior cerebral artery (34%)
• The middle cerebral artery (20%)
• The vertebral-basilar arteries (4%)
• Other arteries (1%)

Clinical assessment of subarachnoid hemorrhage (SAH) severity commonly utilizes grading scales. The 2 clinical scales most often employed are the Hunt and Hess and the World Federation of Neurological Surgeons (WFNS) grading systems. A third, the Fischer scale, classifies subarachnoid hemorrhage (SAH) based on computed tomography (CT) scan appearance and quantification of subarachnoid blood.

The Hunt and Hess and the WFNS grading systems have been shown to correlate well with patient outcome. The Fischer classification has been used successfully to predict the likelihood of symptomatic cerebral vasospasm, one of the most feared complications of this condition.

All 3 grading systems are useful in determining the indications for and timing of surgical management. For an accurate assessment of subarachnoid hemorrhage (SAH) severity, these grading systems must be used in concert with the patient's overall general medical condition and the location and size of the ruptured aneurysm.

The Hunt and Hess grading system is as follows^[2] :

• Grade 1 – Asymptomatic or mild headache
• Grade 2 – Moderate to severe headache, nuchal rigidity, and no neurologic deficit other than possible cranial nerve palsy
• Grade 3 – Mild alteration in mental status (confusion, lethargy), mild focal neurologic deficit
• Grade 4 – Stupor and/or hemiparesis
• Grade 5 – Comatose and/or decerebrate rigidity

The WFNS scale is as follows:

• Grade 1 – Glasgow Coma Score (GCS) of 15, motor deficit absent
• Grade 2 – GCS of 13-14, motor deficit absent
• Grade 3 – GCS of 13-14, motor deficit present
• Grade 4 – GCS of 7-12, motor deficit absent or present
• Grade 5 – GCS of 3-6, motor deficit absent or present

The Fischer scale (CT scan appearance) is as follows:

• Group 1 – No blood detected
• Group 2 – Diffuse deposition of subarachnoid blood, no clots, and no layers of blood greater than 1 mm
• Group 3 – Localized clots and/or vertical layers of blood 1 mm or greater in thickness
• Group 4 – Diffuse or no subarachnoid blood, but intracerebral or intraventricular clots are present

Surgical methods for treatment of subarachnoid hemorrhage (SAH) have improved dramatically with the advent of modern microsurgical techniques and, more recently, with the success of endovascular therapy.

Current surgical options include direct aneurysmal clipping and endovascular methods. (See Surgical Clipping or Coil Embolization for the specific indications for treating an aneurysm surgically, endovascularly, or both).

No strict contraindications to surgery for aneurysmal subarachnoid hemorrhage (SAH) exist other than unstable medical status or a lesion not amenable to surgical therapy.

Direct aneurysmal clipping

Direct aneurysmal clipping is still considered first-line treatment of subarachnoid hemorrhage (SAH) in the United States. The aneurysmal neck is obliterated via application of a clip that occludes blood flow to the aneurysmal dome without compromising flow to the parent artery. Clips are available in various sizes and shapes. Giant aneurysms or aneurysms with a calcified neck require specialized clips with added strength (tandem or booster clips).

Endovascular methods

Of the various endovascular options currently available, most authors believe that Guglielmi detachable coils (GDCs) will have the largest influence with respect to treatment of subarachnoid hemorrhage (SAH); GDCs are first-line therapy in Europe.

These coils are soft, flexible, and can be contoured to the configuration of the aneurysm. Sizes range from 2 to 20 mm in diameter and 2 to 30 cm in length. In limited clinical trials, GDCs have been reported to achieve excellent rates of aneurysmal occlusion combined with a low complication rate in appropriate patients. Two experimental coils, the bidimensional GDC and the 3-dimensional (3-D) GDC may have even better potential for aneurysm occlusion than the current generation of GDCs, but further study is needed.

Balloon embolization is efficacious in selected patients, but it has a higher incidence of complications than coil embolization.

Other surgical options

Proximal ligation of the parent artery or trapping of aneurysms with or without bypass: Proximal ligation is effective for giant aneurysms. Trial balloon occlusion can be used to assess which cases necessitate a bypass graft during the trapping procedure.

Wrapping or coating of aneurysms may be the only option in rare cases of dissecting or fusiform aneurysms.

Emergent neurosurgical consultation should be obtained in all cases of suspected subarachnoid hemorrhage (SAH).

Surgical indications

The indications for surgery in patients with subarachnoid hemorrhage (SAH) can be stratified based on clinical grade (see Clinical Grading Systems). Other factors, such as overall medical condition of the patient, aneurysm size and location, accessibility of the aneurysm for surgical repair, and presence or absence of thrombus, also are important.

Clinical grade and surgical intervention

For patients with a mild- or intermediate-grade subarachnoid hemorrhage (SAH) (Hunt and Hess / World Federation of Neurological Surgeons [WFNS] grades 1-3), surgical treatment is strongly recommended, because the risks of complications from this condition greatly exceed the risk of surgical complications.

For patients with a poor grade of subarachnoid hemorrhage (SAH) (Hunt and Hess/WFNS grades 4-5), the decision whether to operate is controversial and largely depends on the institution. The overall outcome is poor, with or without surgical intervention.

Patients with a higher grade of subarachnoid hemorrhage (SAH) or poor medical status that does not qualify for early surgery may be candidates for delayed surgery or endovascular obliteration of the aneurysm.

Other indications for surgical intervention

Other indications for surgical management include the following:

• Large and giant aneurysm
• Wide-necked aneurysms
• Vessels emanating from the aneurysm dome
• Mass effect or hematoma associated with the aneurysm
• Recurrent aneurysm after coil embolization

Indications for endovascular treatment

Endovascular therapy (eg, coil embolization) has been used increasingly in recent years in lieu of surgical clipping, with promising results. More definitive data are required that compare the traditional treatment modality (aneurysmal clipping) with newer endovascular techniques before conclusive recommendations can be made.

Molyneux et al's attempt to answer this question was published in Lancet; the investigators found that independent survival was improved in the endovascular coiling group relative to the neurosurgical clipping group.^[3] However, although the risk of late rebleeding was low in both groups, it was higher in the endovascular coiling group. Despite the results of this study, controversy still exists over which treatment is superior.

In general, endovascular treatment of aneurysms is favored over surgery in the following situations:

• Patients with poor clinical grade (ie, Hunt and Hess / WFNS grades 4-5)
• Patients who are medically unstable
• In situations in which the aneurysm location imparts an increased surgical risk, such as cavernous sinus and many basilar tip aneurysms
• Small-neck aneurysms in the posterior fossa
• Patients with early vasospasm
• Cases in which the aneurysm lacks a defined surgical neck (although these are also difficult to "coil")
• Patients with multiple aneurysms in different arterial territories if the surgical risk is high

Surgery remains the standard reference for therapy and is favored over endovascular treatment when surgical risk is low or equal to that of endovascular therapy. However, many patients may be treated adequately with either method, and the ultimate choice of intervention often is guided by physician and institution preference.

When researchers used data from the Nationwide Inpatient Survey in a study that searched for specific International Classification of Diseases, Ninth Revision, (ICD-9) codes as well as looked for data before (2000-2002) and after (2004-2006) the International Subarachnoid Aneurysm Trial (ISAT), they found: (1) an increase in endovascular procedures post-ISAT period from 3% to 17% and (2) an increase in number of patients who received any treatment, 33% pre-ISAT to 40% post-ISAT.^[4] Additionally, the distribution of types of hospitals treating patients with ruptured intracranial aneurysms changed: The number of patients treated at urban teaching hospitals increased from 65% pre-ISAT to 73% post-ISAT.^[4]

A combined approach may benefit a particular subset of patients, for example, those with a poor clinical grade and an aneurysm that cannot be occluded completely by endovascular therapy.

The surgical indications for unruptured, symptomatic aneurysms as well as asymptomatic aneurysms are briefly discussed below.

Unruptured, symptomatic aneurysms

Surgery is usually indicated in patients with unruptured, symptomatic aneurysms, because the rate of subsequent rupture is high. Most symptomatic aneurysms are giant (large) aneurysms rather than saccular aneurysms. Patients with giant aneurysms face an increased surgical risk; however, this risk usually is much less than the morbidity and mortality associated with aneurysm rupture.

Asymptomatic aneurysms

The risk of aneurysmal rupture increases relative to the size of the aneurysm; however, the critical size with respect to increased risk of rupture is unknown.

Unruptured aneurysms are reported to rupture at a rate of 1-1.4% per year. Most authors propose that surgical risks are eclipsed by the risks of mass effect and aneurysm rupture in patients younger than 65 years who have aneurysms larger than 1 cm. The impact of the size of the aneurysm is controversial.

The timing of surgery for subarachnoid hemorrhage (SAH) has been a controversial topic for over 3 decades.

Early surgery

Early surgery (0-3 d) has the following advantages:

• Prevention of rebleeding, which is associated with a high mortality rate
• Possible prophylaxis against vasospasm by removal of subarachnoid clot
• Prevention and treatment of ischemic complications
• Prevention of medical complications
• Decreased duration of hospitalization

The following are among the disadvantages of early surgery for subarachnoid hemorrhage (SAH):

• Technical problems associated with edematous brain tissue
• High risk of intraoperative rupture of fragile aneurysm
• Higher surgical morbidity and mortality rates

Delayed surgery

Delayed surgery for subarachnoid hemorrhage (SAH) (>10d posthemorrhage) has the following advantages:

• Less edematous brain tissue
• Lower risk of intraoperative aneurysm rupture
• Lower surgical morbidity and mortality rates
• Flexibility of scheduling

The disadvantages of delayed surgery are as follows:

• Increased rate of morbidity and mortality due to rebleeding
• Technical difficulties due to adhesions around the aneurysm

Published findings on early vs delayed surgery and SAH clinical grade

Findings from the International Cooperative Study on Timing of Aneurysm Surgery include the following^{[5, 6]} :

• Surgical outcomes are usually superior with delayed surgery; however, the increased morbidity and mortality rate associated with delay (as high as 30% in some studies for patients with low-grade subarachnoid hemorrhage [SAH]) negated these results
• Overall results were comparable for early and delayed surgery with the exception that patients with low-grade subarachnoid hemorrhage (SAH) (Hunt and Hess / World Federation of Neurological Surgeons [WFNS] grades 1-2) had a better outcome with early surgery
• Subsequently, many centers have published favorable results with early surgery for low-grade subarachnoid hemorrhage (SAH), and it now is a common treatment decision

Intermediate-grade SAH

For patients with an intermediate-grade of subarachnoid hemorrhage (SAH) (Hunt and Hess/WFNS grade 3), the published results are less conclusive, as follows:

• Several studies showed no difference in morbidity and mortality rates between early and delayed surgery
• A study in Japan suggested that early surgery is beneficial in this group of patients
• Greater microsurgical experience and advances in neuroanesthesia and neurointensive management are likely to improve the outcomes for early surgery in this group of patients

High-grade SAH

The timing of surgical management for patients with high-grade subarachnoid hemorrhage (SAH) (Hunt and Hess/WFNS grades 4-5) must be individualized depending on the following criteria:

• Admission clinical examination findings and Glasgow Coma Score (GCS)
• Computed tomography (CT) scan evidence of brain destruction
• Intracranial pressure (ICP) measurement
• Concurrent medical problems
• Presence of absence of cerebral vasospasm

Data suggest that some patients with an initial GCS less than 5 can have good outcomes if the following occur:

• A ventricular drain is placed emergently
• ICP does not exceed 30 mm Hg
• Angiography shows normal intracranial filling

Patients with significant evidence of brain destruction, increased ICP, and an angiogram revealing poor intracranial filling have a universally poor outcome regardless of treatment.

The overall outcome in patients with high-grade subarachnoid hemorrhage (SAH) is poor with or without surgical intervention; however; because surgical treatment seems to benefit some patients, many authors suggest an aggressive approach to management.

The presurgical examination in a patient with subarachnoid hemorrhage (SAH) should consist of a general assessment, a neurologic assessment, and a radiologic assessment.

General assessment

Cardiac and pulmonary function can decline with subarachnoid hemorrhage (SAH); therefore, all patients should undergo electrocardiographic (ECG) and arterial blood gas (ABG) monitoring. Hemodynamic status should be monitored with a pulmonary artery catheter in patients that show evidence of compromise.

A funduscopic examination should be performed. As many as 10% of patients with subarachnoid hemorrhage (SAH) have subretinal hemorrhage, which can lead to loss of vision.

Neurologic assessment

Serial neurologic examinations should be performed until the time of surgery for early detection of complications. Minor changes in mood, mentation, or focal neurologic function can be an early indicator of an impending complication, such as arterial vasospasm.

Radiologic assessment

Cerebral angiography, ultrasonography, computed tomography (CT) scanning, and magnetic resonance imaging (MRI) are briefly discussed below. It is important to note that performing angiography may result in a life-threatening delay in treatment, therefore, evaluate the patient's overall medical condition and neurologic status when considering this procedure.

Cerebral angiography

Transfemoral cerebral angiography can provide important information about the size, shape, and configuration of the aneurysmal dome and neck, as well as the relationship of the parent vessel and perforators. Multiple views should be obtained to best delineate the anatomy of the aneurysmal neck.

During diagnostic angiography, a trial balloon occlusion of the parent artery can be performed and may help to guide preoperative surgical planning. This can be important in giant and fusiform aneurysms that may need to be "trapped," because they lack a defined neck for surgical clipping. A trial balloon occlusion also may provide important information about collateral blood flow.

If cerebral angiography findings are negative (10-20%), a repeat test should be performed 3-4 weeks later. Patients with subarachnoid hemorrhage (SAH) and a negative finding on cerebral angiography may have an improved prognosis. A negative study finding can result from aneurysm obliteration secondary to clotting. Hemorrhage secondary to a ruptured arteriovenous malformation (AVM) or spinal cord aneurysm may be present despite a negative finding on cerebral angiogram. Perimesencephalic venous hemorrhage should also be considered.

Follow-up angiogram is also useful postsurgically to detect the presence of aneurysmal obliteration and to evaluate for possible cerebral vasospasm.

In summary, cerebral angiography can provide the following important surgical information in the setting of subarachnoid hemorrhage (SAH):

• Cerebrovascular anatomy
• Aneurysm location and source of bleeding
• Aneurysm size and shape, as well as orientation of the aneurysm dome and neck
• Relation of the aneurysm to the parent artery and perforating arteries
• Presence of multiple or mirror aneurysms (identically placed aneurysms in both the left and right circulations)

Ultrasonography, CT scanning, and MRI

Transcranial Doppler ultrasonographic studies are useful in detecting and following the course of arterial vasospasm.

CT scanning may detect calcification of the aneurysmal dome and neck, as well as the presence of thrombus. This information can have important surgical implications. CT angiography may be helpful in demonstrating the anatomy and relationships to other vessels.

An MRI can help delineate the degree of intramural thrombus in giant aneurysms.

Intraoperative details of surgical clipping for aneurysmal subarachnoid hemorrhage (SAH) are briefly reviewed below.

Approaches

Most anterior circulation aneurysms can be approached from the pterion. Exceptions include: (1) aneurysms arising from the division of the anterior cerebral artery into the pericallosal and callosal marginal branches and (2) small, mycotic aneurysms on distal branches of the middle cerebral artery.

Posterior circulation aneurysms are less accessible, and a number of modified approaches have been developed.

The modified pterional approach can be employed for aneurysms arising from the head of the basilar artery where the head is above the dorsum sellae.

The subtemporal approach is used for aneurysms that initiate at the head of the basilar artery in which the bifurcation of the basilar artery is below the dorsum sellae. A posterior subtemporal approach can be used for most aneurysms arising from the trunk of the basilar artery.

A far lateral inferior approach can be used for certain lower basilar trunk and midline vertebral artery aneurysms. A midline suboccipital approach can be utilized for aneurysms extending from the vertebral artery where it pierces the dura. The midline suboccipital approach may also be used for a group of aneurysms that arise from the distal posterior inferior communicating artery.

Retraction

Skillful brain retraction is paramount in aneurysm surgery, with care taken to minimize tissue and vessel damage. Use of one blade only of a self-retaining retractor (eg, Yasargil, Greenburg, Sugita) is usually sufficient for adequate exposure of most saccular aneurysms and allows for the compensatory expansion and displacement of nonretracted areas of the brain, thus minimizing tissue trauma.

Dissection

Dissection is undertaken to identify the parent artery for possible temporary clipping in the event of aneurysmal rupture.

Incision of the arachnoid overlying the aneurysm is accomplished with the tip of a #11 blade scalpel.

The walls of the aneurysm are dissected away from the perforating vessels with a small aneurysm dissector or spatula. Aneurysmal sac volume can be decreased, under hypotension, by compression with a suction device placed over a cotton pad.

Clip placement

Mobilization of the aneurysm in all directions is necessary for visualization of any perforating vessels that might inadvertently be incorporated by clip misplacement.

Occlusion of the aneurysm is accomplished with an appropriately sized clip placed across the base. Use of a clip that is as small as possible helps to facilitate the visualization of perforating vessels after aneurysm repair.

Avoid placing the clip too close to the parent artery, which may cause a tear in the aneurysmal sac. If a tear does occur, a clip graft is used for repair. Use of a clip graft is associated with the risk of damage to perforating vessels, so it should be employed only when necessary.

Suturing in close proximity to an aneurysm can result in damage to the parent artery and should be avoided.

Some authors suggest that early cerebrospinal fluid (CSF) drainage via a ventricular drain may decrease the incidence of vasospasm. This intervention is performed after the aneurysm has been secured. Use caution to prevent rapid or overly aggressive drainage of CSF, which may precipitate aneurysmal rebleeding. One author suggests draining the CSF if the intracranial pressure (ICP) exceeds 20 mm Hg. The drain should be set at a height to drain at 20 mm Hg to avoid an excessive reduction in ICP.

Intraoperative sodium chloride lavage to clear blood products from the subarachnoid space may be of some benefit to prevent cerebral vasospasm, but its effectiveness remains unproved.

Clot removal

An attempt should be made to gently open the basal cisterns and to carefully remove as much of the subarachnoid blood as possible with suction, lavage, and, possibly, intracisternal infusion of antifibrinolytics, when appropriate.

Note that aspiration and irrigation of the subarachnoid clot at the time of aneurysmal clipping usually results in suboptimal removal of the clot and is associated with a significant risk of iatrogenic trauma to pial surfaces and small vessels.

The following discussion regarding endovascular therapy of subarachnoid hemorrhage (SAH) is with use of the Guglielmi detachable coil (GDC) system.

Adequate airway protection, oxygenation, sedation, blood pressure management, and intracranial pressure (ICP) management are paramount during the procedure.

Ideally, endovascular treatment for patients with subarachnoid hemorrhage (SAH) should be performed under general anesthesia. Complete immobilization of the patient during catheterization and embolization is mandatory.

Initial steps

After the femoral artery puncture and initial angiogram, anticoagulation is initiated with heparin. The risk of thromboembolic events during the procedure in patients with acute subarachnoid hemorrhage (SAH) eclipses the risk of hemorrhage.

A guide catheter (6F) is placed in the internal carotid or vertebral artery. This allows for the passage of the microcatheter and facilitates contrast injection for angiograms and road mapping. Road mapping is a computer-generated technique that allows for real-time visualization of endovascular equipment superimposed over a map of the intracranial arteries.

Aneurysm sizing

The size of the aneurysm must be approximated before embolization by estimation based on the size of the adjacent intracranial arteries, by using objects such as coins for reference, or by use of a guiding catheter with a known size.

The clinician should find the projection that allows for optimal visualization of the parent artery in relation to the aneurysm; this usually requires views in multiple planes.

The plastic microcatheter tip and the Micro-Guide wire are shaped according to the configuration of the aneurysm.

Catheterization and GDC placement

The aneurysm is catheterized with the microcatheter and guide wire using road mapping. The microcatheter should not touch the walls of the aneurysm.

When the microcatheter is in the desired position within the aneurysm, the first GDC can be delivered. The first coil should be slightly smaller than the diameter of the aneurysm, and it should cross the neck of the aneurysm several times to form a receptacle. Delivery of the GDC typically takes 1-4 minutes; however, newer GDC systems can detach in 20-30 seconds.

After placement of the first coil has been achieved, the aneurysm is filled with coils of decreasing size until densely packed. Complete packing of the aneurysmal sac and neck usually is possible with small aneurysms. In some larger aneurysms, the neck cannot be occluded completely. These aneurysms have a higher risk of recurrence. Often, aneurysms with larger necks can be treated successfully with a balloon-assisted GDC technique.

Final steps

The microcatheter is withdrawn cautiously from the aneurysm, and a final angiogram is obtained.

Heparinization is reversed with protamine, the femoral sheath is removed, and the patient is transferred to the neurologic intensive care unit.

The postoperative management of subarachnoid hemorrhage (SAH) is directed at prophylaxis and treatment of the complications, including the following:

• Rebleeding
• Vasospasm (see below)
• Hydrocephalus
• Hyponatremia
• Seizures: Some patients may require steroid and/or anticonvulsant therapy as outpatients; oral nimodipine therapy is often continued for 3-4 weeks after subarachnoid hemorrhage (SAH)
• Pulmonary complications
• Cardiac complications

Patients with neurologic deficits may require outpatient rehabilitation. Cognitive and psychologic rehabilitation is often needed.

Cerebral vasospasm is the delayed narrowing of the large capacitance vessels at the base of the brain, is a leading cause of morbidity and mortality in survivors of nontraumatic subarachnoid hemorrhage (SAH). Vasospasm is reported to occur in as many as 70% of patients with subarachnoid hemorrhage (SAH) and is clinically symptomatic in as many as 30% of patients. Most commonly, this occurs 4-14 days after the hemorrhage. Vasospasm can lead to impaired cerebral autoregulation and may progress to cerebral ischemia and infarction. Most often, the terminal internal carotid artery or the proximal portions of the anterior and middle cerebral arteries are involved. The arterial territory involved is not related to the location of the ruptured aneurysm.

If vasospasm becomes symptomatic, most authors advocate the use of hypertensive, hypervolemic, and hemodilutional (HHH) therapy. Although the efficacy of HHH therapy still is subject to debate, a number of studies have demonstrated improved cerebral blood flow and resolution of the ischemic effects of vasospasm.

Initiation of HHH therapy requires placement of a pulmonary artery catheter in order to guide volume expansion and inotropic or vasopressor therapy. This therapy should be reserved for patients with aneurysms secured by surgical clipping or endovascular techniques in order to reduce the risk of rebleeding.

Transluminal balloon angioplasty is recommended for treatment of vasospasm after failure of conventional therapy. One study reported improved neurologic outcome in 70% of patients with symptomatic vasospasm after transluminal angioplasty.^[7] Case series reports have indicated that angioplasty appears to be effective in treating vasospasm of large proximal vessels.^[8] It is not effective in direct treatment of vasospasm of more distal vessels; however, distal blood flow may be increased as a result of increased proximal vessel diameter. The potential complications of angioplasty itself include vessel rupture, dissection, or occlusion, as well as intracerebral hemorrhage.

Postsurgical complications

Specific postsurgical problems include the following:

• Jaw pain and stiffness due to temporalis muscle scarring
• Paralysis of the frontalis muscle
• Deranged or absent sense of smell due to intraoperative traction on the olfactory tract
• Local neuralgias
• Wound infection

Surgical clipping

Complications of surgical clipping include the following:

• Hemorrhagic complications
• Ischemic complications
• Damage to parent artery or perforating arteries
• Acute or delayed neurologic deficits from iatrogenic trauma
• Meningitis
• Cellulitis and wound infection
• Nonspecific postsurgical syndrome similar to postconcussive syndrome (eg, headache, dizziness, blurred vision, poor concentration, poor short-term memory, emotional lability, insomnia, fatigue)

Endovascular intervention

Common complications of endovascular therapy include the following:

• Aneurysm rupture (Guglielmi detachable coils [GDCs], balloons)
• Thromboembolism (GDCs) with acute or delayed neurologic deficit
• Balloon rupture or deflation

Mortality and morbidity are influenced by the magnitude of the bleed, the age of the patient, the presence or absence of comorbid conditions, and the occurrence of medical complications.

Despite advances in medical and surgical therapy, the mortality rate for aneurysmal subarachnoid hemorrhage (SAH) remains 50% at 1 year.

Survival is inversely proportional to subarachnoid hemorrhage (SAH) grade upon presentation (see Clinical Grading Systems). Reported data demonstrate an approximate 70% survival rate for Hunt and Hess grade 1, 60% for grade 2, 50% for grade 3, 20% for grade 4, and 10% for grade 5.

The IAAC, a cerebrovascular pressure reactivity index based on single ICP-arterial blood pressure wave identification, has been shown to be significantly related to the early clinical state and 12-month outcome. In addition, impaired cerebrovascular pressure regulation during the first week after a bleed is related to a worse outcome.^[9]

Approximately 25% of survivors have persistent neurologic deficits. Most survivors have either a transient or a permanent cognitive deficit.

The future of subarachnoid hemorrhage (SAH) management most likely will revolve around the continuing development and refinement of minimally invasive endovascular techniques.

Controversy remains regarding the question of which aneurysms are appropriate for surgical or endovascular treatment; rigorous studies coupled with additional clinical experience will help with the formation of guidelines. Some aneurysms may require a combined approach.

Although detachable coil (GDC) therapy is, to date, the most promising development in the realm of endovascular methodologies for subarachnoid hemorrhage (SAH), the future almost certainly will provide materials that are even safer and more efficacious in occluding aneurysms.