Evidence suggests that oxytocin has a neuroprotective role on a systemic and cellular level in the context of acute ischemic stroke (AIS). The investigators therefore hypothesize that high levels of circulating oxytocin measured within the first 72 hours after symptom onset are associated with lower mortality and favorable outcome in acute ischemic stroke.

The preliminary data suggest a possible neuroprotective role of oxytocin via endocrine as well as paracrine effects, underscoring that oxytocin levels in the acute phase of stroke may have a considerable influence on patient outcomes. However, the role of oxytocin in acute ischemic stroke patients has, to our knowledge, never been investigated. If oxytocin really shows a strong associated with functional outcomes after stroke and given the fact that commercially available oxytocin can be safely administered via nasal spray, oxytocin would become an innovative and highly interesting novel therapeutic agent for ischemic stroke patients in the near future. For the ROXANE cohort the investigators plan to recruit patients with acute ischemic stroke from the University Hospital in Basel. The study is designed as an observational cohort study, because an observational study is currently at this stage of knowledge (effect of oxytocin in vitro and in vivo (animal models)), the best study design. It harbors minimal harm, but still allows us to adequately estimate the association of oxytocin levels in humans with stroke outcome. If it is possible to establish this association in humans based on results of the planned observation study, the investigators will be able to plan an interventional trial, which may directly beneficially impact clinical outcome of stroke patient.

Inclusion Criteria:

• Rapid onset of a focal neurologic deficit, with signs or symptoms persisting beyond 24 hours and not associated with infection, trauma, or tumor of the brain, severe metabolic disorders, or chronic degenerative neurologic disease; or
• the development of an acute focal neurologic deficit persisting >24 hours in conjunction with brain imaging consistent with acute ischemic stroke. The CT or MRI may either show a new infarct or no change from the study performed at entry, i.e., the diagnosis is clinical and does not require CT/MRI confirmation. Secondary hemorrhagic infarction is permissible.
• First blood sample at the stroke unit is taken within 24 hours from symptom onset.

Exclusion Criteria:

• Patients below 18 years
• Hemorrhagic stroke or patients discharged from the hospital with a diagnosis different from ischemic stroke (i.e., stroke mimics)
• Missing informed consent

For the ROXANE cohort the investigators plan to recruit patients with acute ischemic stroke from the University Hospital in Basel.