U.S. Rep. Gabrielle Giffords' recovery isn't over.

In her new two-minute video, she promises constituents that she will "return and we will work together for Arizona and this great country."

Indeed, with brain injuries there is no set course. There are no rules. Doctors used to talk about plateaus with recovery, but the newer thinking is that the brain can continue to heal.

Medical experts say that as long as she continues her rehabilitation, the 41-year-old Giffords can continue to make progress five, 10, even 30 years from now.

Giffords announced Sunday that she is resigning her congressional seat. She has made tremendous, against-the-odds progress from being shot through the brain in an assassination attempt on Jan. 8, 2011. More than 90 percent of people shot in the brain do not survive.

"I have more work to do on my recovery," Giffords said in her message.

As a result of her injury, she struggles with communication. She also has limited mobility in her right leg and right arm. She was shot through the left side of the brain, a side that typically controls right-sided strength and sensation as well as speech. Those close to Giffords say her personality is intact, as is her understanding. But she suffers from difficulties with speech and language - a condition known as aphasia.

"There is always the ability to improve," Mattie Cummins, executive director of the Brain Injury Association of Arizona, said in an interview Sunday. "This is a lifelong injury-recovery process."

During Giffords' first audio recording to constituents in November, her difficulty speaking more than short sentences was palpable. In her Sunday video message, her sentences are longer, her voice is less staccato.

"Her recovery is unbelievably amazing," Cummins said. "Our community has been grateful for the courage she's had to educate people on the journey of living with brain injuries."

Since she is a federal worker who was injured on the job, Giffords' rehabilitation is covered by workers' compensation through the Federal Employees' Compensation Act, which does not cap the amount of medical benefits that may be paid. She's been in recovery at TIRR (Texas Institute of Rehabilitation and Research) Memorial Hermann Rehabilitation Hospital in Houston since late January of 2011, first as an inpatient and now as an outpatient. She does about six hours of therapy per day - physical, occupational and cognitive.

Her staff and family say Giffords has been disheartened to meet other patients with brain injuries who must stop rehabilitation because they don't have insurance.

Cummins said many patients with brain injuries have insurance coverage for one month only. Other plans cover only physical therapy and not cognitive therapy. Cognitive therapy includes speech rehabilitation.

"She and her family and her office staff have also done a great job being honest about the fact that she has been doing so well compared to others who may have similar injuries because of the access she has to long-term comprehensive rehabilitation, which most people do not have access to," Cummins said.

Giffords' mother told the Star in November that her daughter has befriended skateboarders, football players and a concert cellist - all of them suffering brain trauma. Her congressional office has already begun advocating for better insurance coverage for people with brain injuries, and last month hosted a forum at the Southern Arizona Veterans Health Care Systems in Tucson about traumatic brain injuries.

Whatever she does, Giffords has already been an inspiration to local patients with brain injuries, including 46-year-old John Sabia and 11-year-old Cesar Peña, both of whom were shot through the brain, too. Both have closely followed the congresswoman's progress.

Contact reporter Stephanie Innes at sinnes@azstarnet.com or 573-4134.