What happens if your blood pressure elevated suddenly and severely?

Blood pressure is chronic disease but some time it elevated suddenly and severely which become emergency case which can lead to:

Transient ischemic attack (TIA) or hypertensive encephalopathy leads to memory loss, personality changes, trouble concentrating, irritability, or progressive loss of consciousness.
Stroke either ischemic or hemorrhagic.
Aortic dissection tearing in the artery wall and leakage of the blood inside the wall.
Chest pain angina.
Heart attack.
Pulmonary edema sudden impairment of heart muscle function.
Acute renal failure.
Preeclampsia or eclampsia in pregnant women.

So we have to bring the blood pressure down smoothly to protect your vital organs from damage which is catastrophic event.