My 5 yr old kindergartner receives Occupational therapy and Speech therapy through our school disrict. His OT incorporates sensory integration therapy as part of his overall treatment.
(We live in California) It was my understanding that as long as a dysfunction interfers with ability to perform in school, it has to be recognized and services provided. Your child is very young and early intervention in sensory integration will work wonders. I would make sure that the diagnosis is correctly stated as he begins his therapy journey with the school district. There are many wonderful books and programs on SI. Check out a book called The Out of Sync Child by Carol Kranowitz, the Alert Program at www.AlertProgram.com, and the Ready Approach at www.atready.com. My son began sensory integration therapy at the age of 2 1/2 and has made great improvements in all areas of sensorymotor skills. Get at good OT who is well entrenched in SI therapy. Good Luck.
Sensory Integration Disorder and Pervasive Developmental Disorder are very different conditions. It is true, though, that there tends to be a large number of children diagnosed with PDD who also display symptoms of SID. Under the guidelines that govern special education laws in this country, sensory integration disorders are recognized as legitimate conditions which can have a profound impact on children's learning capacities.