In the older child or teenager with established maladaptive habits, the task is to create new, more useful ways of using the hand(s). This is still possible, but it takes more work. If the tone is high, you should consult with your physician and ask to see a spasticity management team. The team is important, as the best results often involve more than one modality or intervention. I have found that many are hesitant to go forward with what is actually needed to improve the hand use and I really do not understand this position. Goggle “cerebral palsy hand images” and look at the hands of older people who did not have these treatments. Why would you not take advantage of techniques that have been shown to work? Please read this blog. (Quick Fixes for 2014 – Stabilize the Wrist and Thumb) With the right support, function improves.
If the hand is still fisted over the age of about 6 years, it is not going to improve without significant help. I think part of the problem is that therapy is offered to children in defined age periods. The Birth to 3y Early Intervention therapist rarely sees the dislocated wrist of the teenager. In many regions of the world, there is little access to spasticity management, multiple forms of support, ranging from Kinesiotape to firm splints, or innovative therapy programs like Constraint Induced Movement Therapy (CIMT). CIMT has now had more than 20 positive randomized controlled trials in children that all showed improved function. To get the best from intensive brain retraining like CIMT, you have to have a hand and wrist that can respond. This is a very useful book. Handbook of Pediatric Constraint-Induced Movement Therapy (CIMT): A Guide for Occupational Therapy and Health Care Clinicians, Researchers, and Educators It is available on Amazon and I think every therapy center should have at least one copy. Ask your therapist and when they get it, then read it yourselves. Find out about this technique and learn to do the modified home programs yourself.