Symptoms include the following:
- When oxygen to the eye is reduced, people describe the visual effect as a shade being pulled down. People may develop poor night vision. About 35% of TIAs are associated with temporary lost vision in one eye. Although such events are risk factors for future stroke, they pose a lower risk for a stroke and its complications than more widespread TIA symptoms.
- When the cerebral hemisphere is affected, a person can experience problems with speech and partial and temporary paralysis, drooping eyelid, tingling, and numbness, usually on one side of the body. The stroke victim may be unable to express thoughts verbally or to understand spoken words. If the stroke injuries are on the right side of the brain, the symptoms will develop on the left side of the body and vice versa.
- Uncommonly, patients may experience seizures.
Symptoms From Blockage in the Basilar Artery. The other major site of trouble, the basilar artery, is formed at the base of the skull from the vertebral arteries, which run up along the spine and join at the back of the head. When stroke or TIAs occur here, both hemispheres of the brain may be affected so that symptoms occur on both sides of the body. The following symptoms may develop:
- Temporarily dim, gray, blurry, or lost vision
- Tingling or numbness in the mouth, cheeks, or gums
- Headache, usually in the back of the head
- Dizziness
- Nausea and vomiting
- Difficulty swallowing
- Weakness in the arms and legs, sometimes causing a sudden fall
Such strokes usually occur in the brain stem, which can have profound affects on breathing, blood pressure, heart rate, and other vital functions, but does not affect thinking or language.
Speed of Symptom Onset. The speed of symptom onset of a major ischemic stroke may indicate its source:
- If the stroke is caused by a large embolus (a clot that has traveled to an artery in the brain), the onset is sudden. Headache and seizures can occur within seconds of the blockage.
- When thrombosis (a blood clot that has formed within the brain) causes the stroke, the onset usually occurs more gradually, over minutes to hours. On rare occasions it progresses over days to weeks.
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