This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cerebrovascular Diseases, Subject name: Surgery
Which of the following is the most common cause of the neurological deterioration in case of cerebrovascular accident? 
Select and explain. 
A. Rebleeding, B. Vasospasm, C. Embolism, D. Hydrocephalus
B: Vasospasm
Answer: B: Vasospasm 
Explanation: Vasospasm Narrowing of the aeries at the base of the brain following SAH occurs regularly. This vasospasm causes symptomatic ischemia and infarction in approximately 30% patients and is the major cause of delayed morbidity or deathQ. Sign of ischemia appear 4-14 days after the hemorrhage, most frequently at about 7 daysQ.