Cerebral Palsy is not a contagious disease, so it will not prevent him from getting a green card.
However, be aware that you will not be able to get state health care (Medicaid) for at least 5 years, and it will be difficult, exorbitant, or impossible to get health insurance for him on your own. So unless you have the qualifications to get a job that provides health benefits for you and your dependent(s), he's probably going to be uninsured for a long time. If he needs frequent medical attention, you may be unable to obtain the care he needs if you don't have tens of thousands of dollars to pay for his care without insurance.