A hypnotherapist (being a certified one myself) should be willing to work with various clients. The issue here is )the person who is receiving the hypnotherapy to be willing to work on the issues at hand. Hypnosis is not mind control and it works best when the client is open to the treatment (like w. any other therapy modality)
My suggestion is to chose a certified hypnotherapist with a Master's degree or above such as a PhD, PsyD, EDD etc. A Medical Doc is not per se required for this unless you have a desire for the provider to be a medical doc in order to address the brain injury component. If you already have a neurologist, see if you could get some good referrals for certified hypnotherapist in your area.
If in the USA, inquire from your mental health insurance carrier if they pay for this treatment (for instance Cigna pays for hypnotherapy) and if your insurance does in deed pays for this service, you may inquire about possible referrals in your area.
Other tips would be to contact the chosen hypnotherapist and see what areas they specialise in. In regard to the brain injury (my thoughts on this as that if the person receiving the hypnosis is functioning at a level of care that allows for this then there is really no "side effects" or risks that I can think of.
Again, hypnosis is never against one's will, it consists of providing verbal inductions to the client when he/she is in a relaxed state and thier brain waves function in Alpha level (which is a state that anyone experiences when relaxed, reading a book, day dreaming, prior to falling or waking up, etc)
I am in the USA andd am not familiar about the credentialing in Canada. I would suggest to use the info below for a start to get more info on possible referrals and best suited provider.
If you can not find a Masters's level provider, look for one with the most clinical hours of experience in the areas in which you seek help.
Hypnosis Help and Information Line: 1-888-686-6163
or this link below for providers in CANADA
Best of Luck.
Please inquire from the therapist what is the average length of treatment (per each category)
Here I've listed some general guidelines applicable :
pain management (6-12 sessions)
smoking cessation (minimum of 3 sessions)
Sessions are going to be spread out (closer to each other initially and then spread out in the following month(s)
The way to make it successful, would be influenced by the willingness to be there and to receive the help (beware of the "honey moon period" when you start to feel better and then think no more sessions are needed. The therapist will make the proper recommendations and then perhaps you could inquire about a sliding scale.
I believe in the mind body connection, have used it w/ clients and in self hypnotic sessions.