The purpose of this study is to determine the relationship between the Neuroinflammatory response and headache pain after subarachnoid hemorrhage.

Persistent headache is a significant medical issue that affects 20% of patients who survive an aneurysmal subarachnoid hemorrhage (SAH). This headache may last years, severely affecting quality of life. Laboratory evidence suggests that the persistent headache may be a result of a maladaptive neuroinflammatory response to the hemorrhage injury that is more vigorous than necessary. The goal of this study is to measure key immunomodulators in the blood and the cerebrospinal fluid of these patients in order to determine the magnitude and dynamics of their neuroinflammatory response. In addition, the investigators will collect and analyze observational data about the success of medications to treat headache, with a specific focus on the anti-inflammatory agent dexamethasone, in managing acute headache pain and preventing the development of persistent headaches in patients after SAH.

Inclusion Criteria:

• Non-traumatic subarachnoid hemorrhage
• Age > 18 years
• Treated with external ventricular drainage

Exclusion Criteria:

• Pregnancy or lactation
• Age < 18 years
• Traumatic SAH

Eligible patients are patients with a non-traumatic subarachnoid hemorrhage who are treated with an external ventricular drain for symptomatic hydrocephalus.