Your question is a good one. I received 41 treatments of radiation along with 7 rounds of chemo, and then 3 months later I underwent a radical neck dissection. The first and last are the likely culprits of my problem. I thought we had found a combination of meds that worked, but it lasted for a short period of time, and "worked" meant that the spikes were lower. Currently, I'm on Lisinopril and Hydrochlorothiazide. I had on hand Hydralazine for severe spikes, but I'm now trying Clonidine to see if it makes a difference. I take those as needed. Hypotension can be a real bear to deal with, but the spikes are what cause the damage. I suspect nocturnal hypertension is why my problem went undiagnosed for so long. Since I've become aware of the need to monitor it, I've learned the spikes are far more frequent than I understood. The remedy for it is to carefully sit up and then cautiously stand to avoid orthostatic hypotension symptoms. Doing so, I can see up to an 80 point drop in my systolic readings. Most of the time the crisis meds can get it under control, but sometimes it can take hours before that happens. Good luck!