Deaf Toddler Has Second Brainstem Device Surgery to Help Him Hear

— -- A deaf toddler who underwent surgery to have a radical auditory device implanted into his brainstem to help him hear is showing vast improvement after undergoing the surgery a second time, his doctors said, giving new hope that the device could one day be a common treatment option for deaf children.

Alex Frederick, a 2-year-old boy from Washington Township, Mich., was just 17 months old when Dr. Daniel Lee from Massachusetts Eye and Ear Infirmary and a team of specialists from Massachusetts General Hospital, both located in Boston, implanted a device called an Auditory Brainstem Implant, or ABI, into Alex’s brain last year.

Alex was born with little to no hearing and the ABI acts as a kind of "digital ear." It's made up of a small antenna that is implanted on the brainstem so that it can pick up signals from a tiny microphone worn on the ear and relay them back inside as electrical signals that reach the area of the brain associated with interpreting sound.

An Italian surgeon named Dr. Vittorio Colletti pioneered the use of the device and implanting procedure in children -- previously the device had been used as a common approach for treating adults with brain tumors. The device is currently not approved by the U.S. Food and Drug Administration, but is undergoing a series of clinical trials to win approval. Alex was selected as a participant in one of these trials last year. “Nightline” has followed him and his parents on their months-long journey throughout the process.

WATCH: Deaf Toddler's Journey to Hearing for First Time

Alex's first surgery was a success, but a few weeks ago, the toddler fell and hit his head on a table. The impact broke the speech processor and damaged the surgically implanted plate in his skull that holds the device in place, doctors said.

On July 2, Alex underwent a five-hour "revision" surgery at Massachusetts General to have the entire device re-implanted. His team of doctors successfully replaced the broken ABI with a new one, in the same location on the left side of his brainstem, and Alex seems to be improving quickly.

“The responses looked encouraging. That could be associated with stimulation of the first brainstem implant," Dr. Lee told "Nightline" today. "In order for brain development to continue it needs to be stimulated whether it is through sight or through hearing, through sound. In the case of the ABI, the device is electrically stimulating the path of sound in the brain, which means that the neural network can continue to mature. A mature network of the auditory pathway is associated with better responses.”

WATCH: Alex The Day After His Recovery from Second ABI Surgery

Alex returned home just four days after the second surgery and his parents remain optimistic.

He is "alert and playing with toys less than 48 hours after surgery completion,” Alex’s father Phil Frederick told “Nightline” over email. “Not trying to jinx things but he is healing faster than last time.”

“We are just so happy right now and excited things are looking up,” he added.

At the time of Alex's first surgery in November 2013, he was the youngest person in the United States to receive the ABI device and is one of a very few pediatric patients in the world to undergo ABI revision surgery. Worldwide, about 10 children are known to have had the device re-implanted.

Since the procedure on children is still new, Dr. Lee said he and the rest of Alex's surgical team discussed whether to re-implant Alex's device in the same location, or try to place it around his other ear.

“The decision was not so clear, as far as whether you implant the same ear and encounter scarring, which would make the surgery difficult, or consider doing an ABI on the other ear, which has not been implanted yet," Dr. Lee said. "In the end we decided to attempt replacing the first ABI because it was working well and because the experience of one particular ABI surgeon, Dr. Colletti, was that revising these ABI’s is possible if done carefully. We went ahead after much deliberation to do the ABI on the same side."

Alex was born two months prematurely, weighing just four pounds and four ounces at birth. He spent the first month of his life in the neonatal intensive care unit of St. John Hospital in Detroit. Scans later showed that Alex had a heart condition, his vision was compromised and he was deaf.

When Alex was 1 year old, his parents tried for a cochlear implant, a 40-year-old technology that uses electrodes to stimulate auditory nerves. The surgery commenced, but was halted mid-operation when it became evident it would not work due to the irregular structure of Alex's inner ear. The scar from that failure is still evident behind his right ear.