A brain aneurysm is a weak, bulging spot in one of the blood vessels of the brain. Aneurysms can rupture catastrophically, leading to a hemorrhagic stroke, a life-threatening condition in which uncontrolled bleeding inside the brain destroys brain cells. Sometimes, however, an aneurysm develops a small pinhole leak before a major rupture occurs. Doctors call this a sentinel bleed, as it is often a precursor to a serious, life-threatening stroke. If a sentinel bleed is preceded by warning signs, doctors may be able to treat it and prevent a major rupture from occurring.
Sudden, Severe Headache
The primary symptom of a leaking brain aneurysm is the sudden onset of a severe headache. Mayo Clinic researchers report that this is often the only symptom of a leaking aneurysm. There is typically no obvious cause for the pain, and patients may describe the pain as the worst they have ever experienced. This headache is often the only reported symptom of a leaking brain aneurysm, and patients may attempt to ignore it and wait for it to pass, a potentially deadly decision, as the Journal of the American Heart Association has reported that up to 60 percent of patients who experience these headaches go on to experience a massive brain hemorrhage.
Sensitivity to Light
Patients experiencing a leaking brain aneurysm may be sensitive to light. Sentinel headaches are often located in one specific spot in the brain, typically behind one eye. Light may exacerbate the headache, causing patients to seek out a dark room.
Visual Disturbances
A growing aneurysm may put pressure on brain tissues or nerves, often the optic nerve, changing the behavior of the affected eye. Patients may report double vision or blurred vision in one eye.
Drooping Eyelid or Dilated Pupil
Sometimes, observers will be able to see physical changes in the eye most affected by the leaking aneurysm. These may include a drooping eyelid or suddenly dilated pupil.
