If it is medically necessary for you to have the trapezius treated, Botox can definitely be done by either a neurologist or a pain management specialist. Good luck from New York City
Botox is used in small volumes for small muscles (eg face), slightly larger volumes for sweating areas eg armpits and in even larger volumes for larger leg muscles in spasticity. The trapezius is the second largest muscle in the body and I cannot see any benefit to having botox as you would need huge volumes, there will be side effects and you may struggle to maintain your head position!