The researchers wanted to see if recovery from coma could be improved by stimulating and exercising patients' brains while they were unconscious.
A coma is defined as an unconscious condition in which the patient is unable to open their eyes. When a patient begins to recover from a coma, they progress first to a minimally conscious or "vegetative state," though these states can last anywhere from a few weeks to several years.
Lead author Theresa Pape was inspired to conduct the new study - the results of which are published in the journal Neurorehabilitation and Neural Repair - while working as a speech therapist for coma patients with traumatic brain injuries. Pape observed that patients appeared to respond better to family members than to strangers.
From this, Pape began to wonder if patients' ability to recover might be increased if therapists were able to stimulate and exercise people's brains while they were unconscious.
As part of the randomized, placebo-controlled study, 15 patients with traumatic closed head injuries who were in a minimally conscious state were enrolled to Familiar Auditory Sensory Training (FAST). The 12 men and three women had an average age of 35 and had been in a vegetative state for an average of 70 days before the FAST treatment began.
At the start of the study, Pape and her colleagues used bells and whistles to test how responsive the patients were to sensory information. They also assessed whether the patients were able to follow directions to open their eyes or if they could visually track someone walking across the room.
Magnetic resonance imaging (MRI) was also used to get a baseline impression of how blood oxygen levels in the patients' brains changed while listening to both familiar and unfamiliar voices tell different stories.
The therapists then asked the patients' families to look at photo albums to identify and piece together at least eight important stories concerning events that the patient and their family took part in together.
"It could be a family wedding or a special road trip together, such as going to visit colleges," Pape explains. "It had to be something they'd remember, and we needed to bring the stories to life with sensations, temperature and movement. Families would describe the air rushing past the patient as he rode in the Corvette with the top down or the cold air on his face as he skied down a mountain slope."
Patients were more responsive to unfamiliar voices after 6 weeks of therapy
The stories were rehearsed and recorded by the families and then played to the coma patients for 6 weeks. Following this listening period, the MRI tests were repeated, with blood oxygen levels being taken while the patients listened to their stories being told by familiar and unfamiliar voices.
The MRI recorded a change in oxygen levels when the unfamiliar voice was telling the story, but there was no change from baseline levels for the familiar voice.
Pape says that these findings demonstrate a greater ability to process and understand speech among the patients, as they are more responsive to the unfamiliar voice telling the story: "At baseline they didn't pay attention to that non-familiar voice. But now they are processing what that person is saying.''
At this point in the treatment, the researchers also found that the patients were less responsive to the sound of a small bell ringing than they had been at the start of the study. The team believes that this indicates the patients were now better able to discriminate between different types of audio information and decide what is most important to listen to.
"Mom's voice telling them familiar stories over and over helped their brains pay attention to important information rather than the bell," Pape says. "They were able to filter out what was relevant and what wasn't."
The first 2 weeks were found to be the most important period for treatment and demonstrated the biggest gains. The remaining 4 weeks of treatment saw smaller, more incremental gains.
"This gives families hope and something they can control," Pape says of the treatment, recommending that families work with a therapist to help construct stories that augment the other therapies the patient may be undergoing.
Now, the team is analyzing the study data to investigate whether the FAST treatment strengthened axons - the fibers that make up the brain's "wiring" and transmit signals between neurons.