Cerebrovascular Emergencies: Aneurysmal Subarachnoid Hemorrhage (SAH)

4 Cerebrovascular Emergencies: Aneurysmal Subarachnoid Hemorrhage (SAH)

Norman Ajiboye, Yu Kan Au, and Syed Omar Shah

Abstract

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating neurologic disorder which requires early recognition for optimal patient management. It is associated with a very high mortality if it is not recognized early and treated appropriately. This chapter provides a quick guide to the early diagnosis and proper management of patients with SAH. It reveals the barriers to early diagnosis and it provides the tools needed to manage such patients. Furthermore, it provides the treatments of frequently encountered medical complications of SAH. Finally, it provides a synoptic algorithm that may be used for the evaluation and management of patients with SAH.

Keywords: subarachnoid hemorrhage, rebleeding, hydrocephalus, delayed cerebral ischemia, vasospasm

4.1 Epidemiology ¹^,²^,³

• Incidence: 10 to 15 per 100,000 in USA.

• Average age of onset is 50 years old.

• It affects up to 30,000 persons annually in the Unites States of America.

• In-hospital mortality rates range between 18 and 21.5%.

• Overall mortality rates continue to decline but still remain high between 40 and 70%.

4.2 Risk Factors ¹^,⁴

See ▶ Table 4.1.

4.3 Diagnosis ¹^,⁴^,⁵

• A high level of suspicion is warranted when a patient presents with the worst headache of life (thunderclap headache). It is described in 80% of patients with SAH. A sentinel headache, which is a less severe headache and could precede the aneurysm rupture, occurs in approximately 20%.

Table 4.1 Risk factors for aneurysm formation

Nonmodifiable	Modifiable
Prior SAH	HTN
Family history of aneurysms	Tobacco use
Genetic syndrome (PCKD, Ehlers-Danlos)	Alcohol use
Female	Sympathomimetic drug use
Black or Hispanic ethnicity
Abbreviations: HTN, hypertension; PCKD, polycystic kidney disease; SAH, subarachnoid hemorrhage. Note: Autosomal Dominant Polycystic kidney disease, Fibromuscular dysplasia, Ehlers-Danlos Type IV, Sickle Cell Disease, Osler-Weber-Rendu Syndrome, Arteriovenous Malformations.

• Nausea and/or vomiting, stiff neck, loss of consciousness, or focal neurologic deficits may occur.

• The diagnostic sensitivity of computed tomography (CT) of the head is about 95% within the first 12 hours. Therefore, if the initial CT of head is negative and clinical suspicion is high a lumbar puncture (LP) is warranted.

• LP findings of xanthochromia (yellow discoloration of cerebrospinal fluid [CSF]) can be seen around 12 hours after rupture.

• CT angiography (CTA) should be considered in the workup of aneurysmal SAH. If the CTA is negative, digital subtraction angiography (DSA) is recommended.

• Misdiagnosis or delay in diagnosis carries a fourfold increased risk of death or disability.

4.4 Grading System

There are two main grading scales that are primarily commonly used to describe the severity of the hemorrhage. The scale can be used to help in prognosis; however, it should not be used as an absolute. Hemorrhage is graded based on either the presenting symptoms or Glasgow Coma Scale with the presence or absence of motor deficit.

4.4.1 Hunt and Hess Grade ⁶

See ▶ Table 4.2.

4.4.2 World Federation of Neurological Surgeons Grade ⁷

See ▶ Table 4.3.

4.4.3 Modified Fischer Scores ⁸^,⁹

The Modified Fisher Score first published in 2001 serves to predict the risk of symptomatic vasospasm that can develop after aneurysm rupture.

See ▶ Table 4.4.

4.5 Management of Subarachnoid Hemorrhage

There are two phases to the management of aneurysmal subarachnoid hemorrhage ¹⁰:

1. Early phase comprises preventing rebleeding, securing the aneurysm, and managing immediate complications.

Table 4.2 Hunt and Hess Grade

Grade 1	Asymptomatic or mild headache and slight nuchal rigidity
Grade 2	Moderate to severe headache, nuchal rigidity, no neurologic deficit other than cranial nerve palsy
Grade 3	Drowsiness, confusion, or mild focal deficit
Grade 4	Stupor, moderate to severe hemiparesis
Grade 5	Deep coma, decerebrate rigidity, moribund appearance

Table 4.3 World Federation of Neurological Surgeons Grade

WFNS Grade	GCS Score	Motor Deficit
I	15	Absent
II	13–14	Absent
III	13–14	Present
IV	7–12	Present or absent
V	3–6	Present or absent
Abbreviations: GCS, Glasgow Coma Scale; WFNS, World Federation of Neurological Surgeons Grade.

Table 4.4 Modified Fisher Score

Scale	Findings	Percentage with symptomatic vasospasm
1	Focal or diffuse thin SAH, no IVH	24
2	Focal or diffuse thin SAH, with IVH	33
3	Thick SAH present, no IVH	33
4	Thick SAH present, with IVH	40
Abbreviations: IVH, intraventricular hemorrhage; SAH, subarachnoid hemorrhage.

2. Late phase comprises maintenance of metabolic homeostasis as well as monitoring and prevention of delayed cerebral ischemia.

▶ Fig. 4.1 details Thomas Jefferson University protocol for subarachnoid hemorrhage.

4.5.1 Early Phase Rebleeding ¹⁰

• Suspect if early deterioration occurs. Mortality is reported to be as high as 80%.

• There is higher risk if patient has a poor-grade SAH, previous sentinel headache, or a large aneurysm.

• Rebleeding is at its highest risk within 12 to 24 hours, with rates of rebleeding estimated to occur at 30% within 3 hours, 50% within 6 hours, and 4 to 13% in first 24 hours. Time to treatment is crucial.

• To minimize the risk of rebleeding prior to securing the aneurysm, current recommendations include¹¹:

◦ Early repair (> 6 hours post rupture) when appropriate

◦ Blood pressure control with systolic blood pressure (SBP) < 160 mm Hg or mean arterial pressure (MAP) < 110 mm Hg; care should be taken to avoid extremes in either direction

◦ Early use of anti-fibrinolytics can be considered from admission until time of aneurysm securing. Anti-fibrinolytics should not be started > 48 hours or used longer than 72 hours due to risk of rebleeding.⁴^,¹⁰^,¹¹

◦ Anyone treated with anti-fibrinolytics should be screened for deep vein thrombosis.

• No current consensus on blood pressure management prior to securing the aneurysm. Current recommendation for SBP < 160 mm Hg or MAP < 110 mm Hg.

Fig. 4.1 Thomas Jefferson University early management of acute aneurysmal subarachnoid hemorrhage protocol.

Aneurysm Treatment

There are two current methods for securing aneurysms: surgical clipping or endovascular coiling/embolization. The details regarding aneurysm treatment are outside the scope of this book.

Hydrocephalus ⁴^,⁵^,¹²

1. Acute hydrocephalus occurs in about 30% of patients but can vary widely from 15 to 87%. Drainage with external ventricular drainage (EVD) is associated with improved neurologic status.

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