Final answer:
The most common causes of subarachnoid hemorrhage are ruptured aneurysms, arteriovenous malformations (AVMs), and head trauma, leading to intracranial bleeding and potential neurological complications.
Step-by-step explanation:
The most common etiologies of subarachnoid hemorrhage include a ruptured aneurysm, arteriovenous malformations (AVMs), and head trauma. A hemorrhagic stroke can occur when there is bleeding into the brain from a damaged blood vessel. This leads to blood filling a region of the cranial vault and pressing against brain tissue, which can cause loss of function and compromised blood flow. As blood pools in the nervous tissue and the blood-brain barrier is damaged, edema, or fluid accumulation, can occur. A subarachnoid hemorrhage may involve bleeding into the subarachnoid space, which can have devastating effects, leading to loss of neurological functions and often requiring surgical intervention.