Severe spasticity in cerebral palsy child

What’s is best management for severe spasticity in cerebral palsy child (18 years old)
( Baclofen 10 mg BD is not effective)

The several drugs used to treat spasticity in CP, include:

•Oral diazepam (0.01-0.3 mg/kg/day, divided bid or qid), or

•Baclofen (0.2-2 mg/kg/day, divided bid or tid), or

•Dantrolene (0.5-10 mg/kg/day, bid)

Thank you.