If the symptoms persist it certainly is a stroke not TIA. TIA stands for transient ischemic attack, transient meaning symptoms disappear inside an hour. At times CT might miss the lesion especially if performed inside the first 12 hours or if stroke is in certain brain areas. An MRI would be advisable to confirm the diagnosis. Of course there is a chance of a second stroke. What we can do is determine what caused the stroke and after identifying the culprits take preventive measures to lower the risk on a re-occurrence. We can t make that risk disappear but we can drastically reduce it. In order to do that we have to identify the causes first (treatable ones, old age is a risk factor which can t be cured). There are many of them, they can t be all listed here, and they are not tested for at the same time in all people. Usually it s started with the most common ones, like heart issues, high blood pressure, diabetes, smoking, high cholesterol, obesity. If the patient has none of these risk factors it can be investigated for other more rare issues. So treatment consists treating these factors appropriately and either an antiaggregant like aspirin or an anticoagulant like warfarin (both blood thinning products, the choice depends on the type and causes of stroke).