Thirty years ago, Kerri Walker, now a coordinator for a domestic violence shelter in Phoenix, found herself inexplicably driving down the left side of the road into oncoming traffic. It felt totally normal, she said, recalling how she was oblivious to the danger. Walker escaped an accident that day, but looking back now, it was the first clue she had an undiagnosed brain injury.

At the time, Walker, 51, was in the throes of an abusive relationship, she said. She estimated that over a 2 1/2-year period, she was hit in the head around 15 times -- once with a gun -- and violently shaken.

I had major headaches, and every now and then I would have these moments when I would get dizzy and disoriented, Walker said. But she didn't connect her symptoms to the assaults until a year later, when a doctor at Geauga Medical Center in Ohio diagnosed her with traumatic brain injury, or TBI. When you are in a relationship with that much trauma and violence, you dont know whats physical or whats emotional or mental, she said.

Soldiers returning from war and athletes are regularly diagnosed with TBI -- a complex brain injury caused by a blow or a jolt to the head -- and many subsequently receive support and services for the condition.

But domestic violence survivors have been largely left out of the picture.

On Tuesday, the Sojourner Center, one of the largest U.S. domestic violence shelters and where Walker works in Phoenix, is taking a big step to change that. The center, along with TBI experts at local hospitals and medical institutions, is launching an ambitious program dedicated to the study of TBI in women and children living with domestic violence.

The Sojourner BRAIN (Brain Recovery And Inter-professional Neuroscience) Program will study how common domestic violence-related TBI is, investigate short-term and long-term effects, develop domestic violence-specific tools to screen for head trauma, and provide individualized treatment plans.

These women are falling through the cracks, said Maria E. Garay, the CEO of Sojourner Center who is spearheading the initiative. This is a public health epidemic. The fact that no one is tracking this is, to me, a crime.

Robert Knechtel, the interim director of the BRAIN program, said there is a lack of comprehensive research on TBI in domestic violence survivors. Most of the work has been done with athletes or the military, he said. This is a group that, by extrapolating some numbers, would dwarf the military and the athletes combined.

The first question they hope to answer is what percentage of domestic violence survivors are suffering from TBI caused by domestic violence. By screening women and children at Sojourner -- about 9,000 people are seen at the shelter annually, Knechtel said -- they hope to develop an accurate estimate.

According to a rough calculation by Hirsch Handmaker, a radiologist working with Sojourner and CEO of a nonprofit raising awareness of concussions, as many as 20 million women each year could have TBI caused by domestic violence. If that number bears out, it would mean 6 percent of the population experiences domestic violence-related TBI each year.

Compare that with the Centers for Disease Control and Prevention's estimate that 1.7 million people experience TBI every year, and 2 percent of the population, or 5.3 million Americans, are living with a disability caused by it.

Its obvious -- if someone is a victim of domestic violence, they are going to have a high propensity for head injuries, Handmaker said.