<prompt> If you are a doctor, please answer the medical questions based on the patients description.Today as I was sitting down I felt a pop in the back of my head and then had a dropping sensation visual and physical and was very dizzy for about 20 seconds. I saw the nurse at work and my blood pressure was 13894 which is high for me I am on Lisonopril. I continue to heave a headache but no other symptoms. I went to the doctor today but she had no explanation and recommended an MRI- any thoughts?  <response>: Hello! Thank you for asking on Chat Doctor! Your symptoms could be related to a TIA transient ischemic attack. For this reason, I agree with your doctor on recommending performing a brain MRI. Other tests to consider would be : a Doppler ultrasound of the cervical arteries to examine the blood flow to the brain, a Holder ECG monitoring for possible arrhythmia, blood lipid profile, fasting glucose, kidney and liver function tests and blood electrolytes. In the meantime, I recommend taking baby aspirin daily. Hope to have been helpful! Kind regards, 