A Whakatāne girl was on the family trip of a lifetime in the United States when she suffered a head injury and now faces potentially life-changing brain damage.

Alyssa Ledbetter, 11, was swimming with her cousins and brother when she came out of the water complaining of a severe headache, neck pain, blurry vision and numbness in her legs.

She was rushed to hospital whereafter brain surgery doctors determined Alyssa had two arteriovenous malformations in the frontal cortex of her brain.

Open surgery was not possible because of the risk of permanent brain damage, leaving gamma knife radiosurgery the only other option.

A Givealittle page has been set up to assist Alyssa and the family with her recovery and surgery, which they say is not performed in New Zealand, with the closest option Sydney, Australia.

"Alyssa is our young, lovable and exuberant 11-year-old daughter," her father Dave said.

"She has always been a healthy and active child who loves hip-hop dancing, various sports including field hockey, swimming and surf-lifesaving with her family."

During the incident on July 21, as Alyssa emerged from the water they knew from the symptoms it was likely a spinal or head injury, her father said.

They got her to the lifeguard tower, where a doctor picnicking nearby assisted.

However, Alyssa's condition deteriorated abruptly and seriously.

She lost control of her bodily functions and began to have uncontrollable seizures.

Her blurred vision worsened, she couldn't recognise the people in the room, called out for her parents, then began to fall in and out of consciousness.

They called an ambulance and she was rushed to hospital.

The family knew it was bad, but the doctor said if she didn't get to hospital ASAP she could end up with permanent and irreversible brain damage.

She was taken into surgery immediately where they drilled through her skull to relieve the pressure and drain the fluids.

The quick responses by all involved proved crucial, her father said.

She remained in the intensive care unit while her brain slowly healed.

Once discharged from hospital, she would have to complete outpatient treatment before being cleared to return to New Zealand.

She would then have to wait at least three to six more months for her brain to heal sufficiently before she could undergo the gamma knife surgery.

The family is facing numerous medical expenses. Including the cost of the surgery, ongoing CT and MRI scans, medications and various travel and accommodation expenses will be necessary.

There could also be ongoing expenses for speech and language or physical therapy.