The most common presentation of aneurysmal SAH is sudden “thunderclap headache” or “worst headache of life.” A smaller proportion, 10–15%, present in a comatose state. Additional exam findings may include nuchal rigidity, isolated cranial nerve palsy, and focal neurologic deficit [3]. Patients often report an antecedent, less severe headache syndrome referred to as a sentinel (or warning) headache. Several scales grade the severity of SAH. The Hunt and Hess scale (Table 4.1) is a clinical scale and one of the most widely used. It assigns a grade based on severity of clinical symptoms. The World Federation of Neurological Surgeons Subarachnoid Grade (Table 4.2) is based on the Glasgow Coma Scale with special emphasis on the presence of a motor deficit. While these scales are helpful for quantifying the severity of SAH and facilitating communication, their utility in predicting patient outcome is debated.

Non-contrast CT head is the recommended initial study for evaluation of suspected SAH with a sensitivity of 98% within 24 h of symptom onset. Classically, SAH appears as a starburst pattern of hemorrhage filling the basal cisterns [1, 2]. Intraventricular hemorrhage and parenchymal hematomas can be present as well, depending on the location and severity of aneurysm that has ruptured. Several grading scales based on CT hemorrhage pattern have been validated to predict the occurrence of symptomatic cerebral vasospasm, most notably the Fisher Scale (Table 4.3) and modified Fisher Scale (Table 4.4) [5, 6].

In cases where CT is negative for hemorrhage, but clinical suspicion for aneurysmal rupture remains high, a lumbar puncture should be performed to evaluate the cerebrospinal fluid for presence of xanthochromia. Xanthochromia is the yellowish appearance of CSF due to the presence of bilirubin, produced by the metabolism of the heme groups released by red blood cells circulating in the CSF after an aneurysmal rupture. The presence of xanthochromia is over 99% sensitive for SAH and persists for several weeks after initial aneurysm rupture [3].

Once the diagnosis of SAH is established, the cerebral vasculature must be evaluated for a causative lesion. Digital subtraction angiography (DSA), or conventional catheter angiography, is the gold standard of vascular evaluation, although most institutions now utilize noninvasive imaging as a first-line diagnostic strategy. CT angiography is the modality of choice, with excellent sensitivity and specificity for aneurysms >3 mm in size [7, 8]. MR angiography is a reasonable alternative for patients with contraindications to iodinated contrast, e.g., renal impairment [1].

The focus of early management in SAH is to prevent aneurysm rerupture, a clinical scenario that portends a poorer prognosis. Patients are at highest risk for rebleeding within the first hours after aneurysm rupture, so rapid stabilization and treatment are paramount [9]. While aneurysm repair should be performed as soon as possible, several medical strategies can minimize the risk of rebleeding prior to repair.

Blood pressure should be closely monitored from the time of diagnosis. A treatment parameter of systolic blood pressure <160 mmHg is generally accepted as a target for management [1, 10]. Hypotension should be avoided as this can cause a precipitous drop in cerebral perfusion resulting in secondary neurological injury. While pulsed IV medications are helpful for acute stabilization, titratable infusions offer more rapid and sustained effect. Nicardipine (typical infusion rate 5–15 mg/h), a calcium channel blocker, has shown to be superior in achieving systolic blood pressure control than labetalol [11].

Antifibrinolytic medications (tranexamic acid and aminocaproic acid) are sometimes administered in the setting of delayed aneurysm repair to help stabilize fibrin formation in the ruptured aneurysm. Caution must be employed when considering these medications as they can precipitate clot formation and are contraindicated for patients with known coronary artery disease, peripheral vascular disease, and hypercoagulable states. Prolonged administration (>72 h) has the added concern of contributing to delayed cerebral ischemia [12]. When used in appropriate patients for a short duration, antifibrinolytic medications are recommended to reduce the risk of aneurysm rebleeding when aneurysm repair is going to be delayed [1, 10, 12].

Seizures, both convulsive and nonconvulsive, commonly occur after SAH. While most seizures occur at the onset of hemorrhage, seizures are also associated with rebleeding, and patients remain at risk for seizure development throughout the disease course [13]. Patients with a seizure at presentation are placed on anticonvulsant therapy and should be monitored for further seizures. Prophylactic anticonvulsant medications are usually utilized in all patients until the culprit aneurysm is secured. This intervention is driven by the concern that uncontrolled seizure activity may precipitate rebleeding [10].

Repair of ruptured aneurysms can be accomplished by surgical clipping or endovascular techniques, typically coiling, although other strategies are now emerging. The decision to clip or coil an aneurysm is highly individualized and is based on multiple factors including available expertise, aneurysm characteristics, and patient characteristics.

Surgical clipping via craniotomy is the tried-and-true approach to securing an aneurysm and results in its complete exclusion from the circulation. It is a durable strategy with a very low aneurysm recurrence rate on long-term follow-up. A major drawback, however, is its invasiveness.

Alternatively, coiling is a minimally invasive, endovascular approach that refers to the packing of an aneurysm with high-tech metallic thread deployed under fluoroscopic guidance. At Yale University/Yale-New Haven Hospital, a coil-first approach is recommended for most ruptured aneurysms. This is supported by the results of two randomized controlled trials, International Subarachnoid Hemorrhage Trial (ISAT) and Barrow Ruptured Aneurysm Trial (BRAT). Both studies showed improved clinical outcomes after endovascular coiling [14, 15].

More recently, a new endovascular device called flow-diverting stent became available for aneurysm repair. Currently, the only flow-diverting stents available for use in the United States are the Pipeline (and Pipeline Flex) Embolization Devices (Medtronic Neurovascular). These low-porosity stents are deployed in the parent vessel and cover the neck of the aneurysm. In doing so, they promote aneurysm thrombosis and endothelialization across the neck of the aneurysm resulting in parent vessel reconstruction and exclusion of the aneurysm from the circulation (see Fig. 4.2 for case example of Pipeline Embolization Device). A major disadvantage of these flow-diverting stents is their inherent thrombogenicity that mandate the use of dual antiplatelet therapy after deployment, even in the setting of aneurysmal SAH. Notwithstanding, limited off-label experience with these devices for difficult-to-treat, ruptured aneurysms like blister aneurysms, is overall positive [16].

Regardless of the chosen method, aneurysm treatment should be pursued as early as possible to prevent rebleeding.