James Reid has an infectious smile. It's an ear-to-ear grin, exposing a mouthful of pearly whites, and his cheeks turn bright pink.

But it's a smile that mum Sonja will have to see from a computer screen as her five-year-old son receives life-changing surgery in New Jersey.

James has spastic quadriplegia cerebral palsy, epilepsy and hydrocephalus, a blockage to the flow of cerebrospinal fluid. This means James is unable to crawl or stand without support, and can only take assisted steps with great difficulty.

James and dad Don travelled to Overlook Hospital in New Jersey on Friday, where Dr Roy Nuzzo will perform surgery to help with James' contractures, or permanent shortening of the muscle and tendons.

'As you can imagine I'm a bundle of increasing nerves at the moment and I really can't grasp the concept of me not being there with James,” says Sonja. 'But at the same time I know he will be in good hands with my husband, who's an amazing father and the best person for the job.

'I know it's going to be a huge adjustment for James' sister Lily not having her brother and father around for so long and we will be a bit lost back here, but I'm very thankful these days with modern technology we'll be able to keep in touch and see each other's faces almost every day via computer screen.”

The surgery will be followed by a few days of recovery before James receives about a week of intensive therapy in New York. He'll then fly to Croatia's capital city, Zagreb, for a further 10 weeks of therapy.

'With the intensive therapy following surgery it will allow his brain to make new connections and allow him the possibility of a greater range of movement,” says Sonja.

James will celebrate his sixth birthday in Croatia on November 30.

The family from Papamoa have been raising $150,000 for the surgery since last December.

Sonja says they haven't yet raised the full amount, but have enough to cover the surgery and therapy so far.

'Any other funds over and above this would go to as much post-operation therapy as possible in the next year or two. Basically, the more therapy we can do, the better James' chances are for greater movement following surgery.

'The success of surgery is largely dependent on the amount and quality of therapy that will follow so it is really hard to give an exact prediction of outcome.”

To donate, visit www.givealittle.co.nz/cause/TeamJames