I have suffered from PCS after a mTBI in October of 2011. My neurologist finally suggested that I try Botox for my chronic headaches after exhausting all other medical and non-traditional (acupuncture, biofeedback, etc.) therapies. He modified my diagnosis, since at the time Botox injections were only approved by insurance companies for migraine headaches. I have had two series of 30 injections (about 6 units), spaced 12 weeks apart. The treatments help with severity of my headaches, but not the frequency is which has been constant for 24 months. After the first series, my relief lasted approx. 10.5 weeks. After the second series, approx. 9 weeks. I'm not due for my third series until next Friday and the last two weeks have been miserable, with elevated pain levels, light sensitivity, fatigue and minor cognitive impacts. Has anyone else had this experience with Botox and the diminished longevity of effectiveness? It's basically the only thing that has given me relief and if the effectiveness continues to wane, I'm not sure where to turn.