I have dysphonia treated wit botox every 3/4mts until nw.botox only lasted 7 weeks /voice aphonic nw.will i need a higher dose?is it gtn worse?

Depends on type: There are two major types of Botox for spasmodic dysphonia (adduction, abduction) and your Botox treatment does depend on the type. If your Botox is lasting less time than usual, it may be the your dysphonia is worsening and need a stronger dose. Dysphonia can worsen in times of stress and can wax and wane. So a higher dose at a time does not mean that you destined to have a higher dose forever.

Possible: On occasion variation in response can be due to tolerance requiring higher doses but there are many other possible causes such as preparation techniques, inadequate refrigeration, diffusion variation, etc. It may be best to first try the same dose and then go from there. There are other manufacturers of botulinum toxin as well including Dysport and xeomin (incobotulinumtoxin a).