I was a patient of Dr Ron Granot's for nearly three years after my brain injury. He's an experienced neurologist, with a focus on headache and chronic pain conditions as well as neurophysiology. He graduated from the University of New South Wales with a Bachelor of Medicine, Bachelor of Surgery and Medical Science (Medicine and Surgery) in 1999, with First Class Honors and the University Medal. Since I spoke to Dr Granot, the science around the mechanism of botox has changed. Here's a more up to date version from his website.