BAHA.Words
-- BAHA in Baltimore: How John Niparko Inserts a Bone-Anchored Hearing Aid --
“It’s not pretty,” Dr. John Niparko declared, smiling and plucking purple gloves from his fingers after a successful surgery. “There’s a lot more blood here when I do it than you would typically see in a BAHA procedure. But I get the job done.”
Niparko – famous worldwide for his cochlear implant work, including implantation of Heather Whitestone, America’s first deaf beauty queen – is head of the Listening Center at The Johns Hopkins Medical School. The Baltimore physician performs about 10 bone anchored hearing aid (BAHA) surgeries a year. And even though, as Niparko said, the BAHA procedure has been considered “simple enough to be pulled off in the office,” it is indeed complex.
This hidden complexity has left room for the reknown Hopkins surgeon to customize the way he approches insertion of bone anchored hearing aids. Niparko inserts them differently than most otolaryngologists across the nation, which has yielded him greater success, as measured by the fact that only 5% of his patients return for replacements.
“That’s a tremendously low rate,” said Steve Hazard, manager of CochlearTM, one of only three companies to make cochlear implants and other hearing devices. Hazard had come all the way from Colorado, Cochlear’s headquarters, to photograph the surgery in Baltimore the day that I observed. At each step of the way, Hazard took pictures of Niparko’s signature moves for a much-needed medical manual that his company will distribute to surgeons around the world.
“In a BAHA surgery, it all comes down to detail,” explained Dr. Marc Eisen, the young doctor who had worked alongside Niparko to perform his very first BAHA procedure the February morning that I visted the Hopkins Outpatient Center. “There is this feeling out there among other surgeons that the BAHA procedure is simple,” he continued. “This is because there are really no vital structures -- like facial nerves -- put at risk. Also, the steps sound simple: raise up the skin, thin the skin, drill a pilot hole, place the device, and place the thinned skin down over it. And in the short-term, these steps work well.”
Niparko doesn’t just think short-term, however. “What I learned working with him,” Eisen said, “is that for long-term success of a bone anchored hearing aid, three details matter: the size of the skin flap, its thinness, and the angle at which you place the part of the hearing aid that’s outside the head. These details are not well described in the BAHA literature.”
Bone anchored hearing aids work through bone conduction, one of two ways – the second being air – that sound is conducted to the inner ear. The cochlea, the part of the inner ear which receives the sound and converts it to the electrical signals that the brain can understand, is still functional in BAHA recipients, unlike in cochlear implant patients, for example. Therefore, the job of a BAHA is simply to get the sound to the cochlea, and it does so by enhancing the already naturally occurring transmission of sound to the bone.
Bone anchored hearing aids benefit people who cannot wear traditional air conduction hearing aids – placed in the outer ear – due to outer or middle ear deformities. People with microtia, a disease in which the outer ear is either severely deformed or entirely absent, as well as patients with chronic ear infections, inflammation, and astresia – the absence of the ear canal – are good candidates.
And as far as which hearing device – air or bone – improves hearing to a greater extent, “there is no clear cut winner,” Eisen said. However, the advantages of the BAHA are several-fold in the right situation. In cases of a patient with severe, unilateral deafness, for example, a conventional hearing aid offers little benefit, but the BAHA, explained Eisen, “seems to route the sound to the good ear, giving the patient some benefit of binaural (two-ear) hearing.”
Hearing via a bone anchored device involves a three-part system. A small box called a processor is attached to a screw that is drilled into the skull, behind the ear. The screw attaches to the third part of the hearing aid, a titanium implant. Both the implant and the screw must be inserted surgically, as I watched Niparko and Eisen do. And while the implant is lodged below the skin flap, the screw – meant to stay completely in the bone – is drilled into the skull afterwards. At 3 or 4 millimeters deep, the screw is not at risk of penetrating to the other side of the bone or piercing the dura, the fibrous coat which protects the brain. “This would be a sure route for meningitis,” Eisen explained.
Over time – about three months after the surgery – the titanium implant naturally integrates with the skull bone in a special process known as osseointegration. During this process, the implant bonds with the surrounding bone tissue, making a direct structural and functional connection. This lets vibrations from the sound processor be transmitted via the bone to the cochlea, on the other skull’s other side. The long term success of Baha rehabilitation is based on titanium’s unique ability to integrate with tissue and on the fact that an active bond between tissue and implant is created at the molecular level, such that the implant is not only accepted but also incorporated within the bone.
After successful osseointegration, the final part, the sound processor is attached to the screw. At this point, sound vibrations can be picked up from the air and travel through the screw to the implant, which vibrates. This initiates vibrations within the skull and inner ear, and these vibrations stimulate the nerve fibers of the cochlea directly, allowing hearing.
Patients who receive BAHAS are typically happy. Few of them, studies site, prefer their old hearing aids, and the majority report increased comfort and function. This wasn’t always the case for bone conduction hearing aids, however; “If you simply saw the old ones,” Eisen explained, “you would immediately have your answer as to why people found them uncomfortable. They weren’t implants, but headbands that held the hearing aid tightly against the skull someplace. They were also cumbersome and noticeable.”
Unlike the old bone conduction hearing aids, BAHAs do require surgery, but it is typically a short, minimally invasive procedure, lasting not much more than 30 minutes. As I observed in February though, Niparko takes his time, performing a BAHA in an hour, from start to finish.
“This process should take about 15 minutes – in and out,” joked a young resident in the operating room as he pulled on his face mask moments before the surgery. But he was wrong; Niparko – a tall, lean man with a careful eye – takes longer than average, and this is just one aspect of his BAHA surgery strategy that strays from the norm.
For starters, the size of skin flap made at the initial incision is larger -- that of an orange versus a ping pong ball – when Niparko is at the helm. “I don’t mind taking time to make the larger cut,” Niparko explained to Hazard, as the man watched, and took shot after shot.
Incision size is crucial; sufficient subcutaneous tissue – or fat – needs to be removed from under and around the skin flaps so that once the screw is drilled into the skull, it is less likely to be disrupted by creeping tissue. This tissue, though only millimeters in thickness, often grows back and pushes the screw out of line.
On the day of the surgery, Niparko spent calculated time using a pick to pull thin lumps of yellow, fatty tissue from under perimeter skin flaps of his large incision. After pulling an especially wide tissue lump from the patient’s head, Niparko plucked a ruler from the pocket of his green standard-issued Hopkins scrubs: “4 inches!” he said, commenting on its diameter. The tissue was so large that when the nurse dropped it in on a steel table nearby, it made a thud loud enough for me – on the other side of the room – to clearly hear.
Beyond incision size, the second detail Niparko focuses on is the angle of processor attachment. “I’ve never heard a better insight into the success of this surgery,” Hazard commented, after hearing Niparko explain his emphasis on a drilling the screw, perfectly straight, into the skull to avoid complications with the processor. Apparently, it does not function as well when it touches skin – when it’s angled up or down because of bad screw alignment, in other words. That’s because if the processor touches flesh, its vibrations are dampened, making the transfer of those vibrations – from processor to screw to implant – less efficient. “Remember,” Eisen reminded me later, “it is all about physics. No electrical stimulation like a cochlear implant.”
Eisen explained that surgeons do not use a device to measure the angle at which they enter the skull. “We just have our line of sight to guide us. This is why it’s important for the surgeon to anchor his arms.” As Eisen drilled the screw 4 millimeters deep into patient’s skull that day, Niparko loomed over him and lectured on angles. “Don’t let it be anything but 90 degrees,” he said. Meanwhile, Hazard watched closely, seemingly amazed at what I found to be a simple idea.
Niparko then did something which captivated all in the room. To determine how well the screw was affixed to the skull, he bent low to the patient’s head and hit the screw with a small metal pole. He listened carefully to the pitch generated. “A sharper ring should mean more solid fixation,” Eisen later explained. Niparko was dissatisfied with the high pitched ring that chirped quickly in the silent room, and he instructed Eisen to turn the screw again. To make it tighter.
Then Niparko tapped, listened, and -- still dissatisfied -- asked Eisen for yet another twist of the screw. After the final turn of screw into skull, Niparko was happy with the high pitch ting generated from careful insertion.
“Niparko’s strategy is great,” Hazard said. “Especially because he cuts a large flap when making the incision. Larger than most and large enough so that the tissue around the BAHA implant doesn’t become an issue and push the implant out of line. This takes more time and most surgeons won’t do it. They cut small flaps. Or they do a dermatrome. But Niparko doesn’t care. He’s takes his time and makes a big cut.”
By paying attention to tissue removal and drilling angle, then, Niparko has customized the BAHA surgery. His signature moves have yielded him success about which the world will hear with the coming of Hazard’s manual. Surely, Niparko’s patients will hear of it, too.
.MGW.
“It’s not pretty,” Dr. John Niparko declared, smiling and plucking purple gloves from his fingers after a successful surgery. “There’s a lot more blood here when I do it than you would typically see in a BAHA procedure. But I get the job done.”
Niparko – famous worldwide for his cochlear implant work, including implantation of Heather Whitestone, America’s first deaf beauty queen – is head of the Listening Center at The Johns Hopkins Medical School. The Baltimore physician performs about 10 bone anchored hearing aid (BAHA) surgeries a year. And even though, as Niparko said, the BAHA procedure has been considered “simple enough to be pulled off in the office,” it is indeed complex.
This hidden complexity has left room for the reknown Hopkins surgeon to customize the way he approches insertion of bone anchored hearing aids. Niparko inserts them differently than most otolaryngologists across the nation, which has yielded him greater success, as measured by the fact that only 5% of his patients return for replacements.
“That’s a tremendously low rate,” said Steve Hazard, manager of CochlearTM, one of only three companies to make cochlear implants and other hearing devices. Hazard had come all the way from Colorado, Cochlear’s headquarters, to photograph the surgery in Baltimore the day that I observed. At each step of the way, Hazard took pictures of Niparko’s signature moves for a much-needed medical manual that his company will distribute to surgeons around the world.
“In a BAHA surgery, it all comes down to detail,” explained Dr. Marc Eisen, the young doctor who had worked alongside Niparko to perform his very first BAHA procedure the February morning that I visted the Hopkins Outpatient Center. “There is this feeling out there among other surgeons that the BAHA procedure is simple,” he continued. “This is because there are really no vital structures -- like facial nerves -- put at risk. Also, the steps sound simple: raise up the skin, thin the skin, drill a pilot hole, place the device, and place the thinned skin down over it. And in the short-term, these steps work well.”
Niparko doesn’t just think short-term, however. “What I learned working with him,” Eisen said, “is that for long-term success of a bone anchored hearing aid, three details matter: the size of the skin flap, its thinness, and the angle at which you place the part of the hearing aid that’s outside the head. These details are not well described in the BAHA literature.”
Bone anchored hearing aids work through bone conduction, one of two ways – the second being air – that sound is conducted to the inner ear. The cochlea, the part of the inner ear which receives the sound and converts it to the electrical signals that the brain can understand, is still functional in BAHA recipients, unlike in cochlear implant patients, for example. Therefore, the job of a BAHA is simply to get the sound to the cochlea, and it does so by enhancing the already naturally occurring transmission of sound to the bone.
Bone anchored hearing aids benefit people who cannot wear traditional air conduction hearing aids – placed in the outer ear – due to outer or middle ear deformities. People with microtia, a disease in which the outer ear is either severely deformed or entirely absent, as well as patients with chronic ear infections, inflammation, and astresia – the absence of the ear canal – are good candidates.
And as far as which hearing device – air or bone – improves hearing to a greater extent, “there is no clear cut winner,” Eisen said. However, the advantages of the BAHA are several-fold in the right situation. In cases of a patient with severe, unilateral deafness, for example, a conventional hearing aid offers little benefit, but the BAHA, explained Eisen, “seems to route the sound to the good ear, giving the patient some benefit of binaural (two-ear) hearing.”
Hearing via a bone anchored device involves a three-part system. A small box called a processor is attached to a screw that is drilled into the skull, behind the ear. The screw attaches to the third part of the hearing aid, a titanium implant. Both the implant and the screw must be inserted surgically, as I watched Niparko and Eisen do. And while the implant is lodged below the skin flap, the screw – meant to stay completely in the bone – is drilled into the skull afterwards. At 3 or 4 millimeters deep, the screw is not at risk of penetrating to the other side of the bone or piercing the dura, the fibrous coat which protects the brain. “This would be a sure route for meningitis,” Eisen explained.
Over time – about three months after the surgery – the titanium implant naturally integrates with the skull bone in a special process known as osseointegration. During this process, the implant bonds with the surrounding bone tissue, making a direct structural and functional connection. This lets vibrations from the sound processor be transmitted via the bone to the cochlea, on the other skull’s other side. The long term success of Baha rehabilitation is based on titanium’s unique ability to integrate with tissue and on the fact that an active bond between tissue and implant is created at the molecular level, such that the implant is not only accepted but also incorporated within the bone.
After successful osseointegration, the final part, the sound processor is attached to the screw. At this point, sound vibrations can be picked up from the air and travel through the screw to the implant, which vibrates. This initiates vibrations within the skull and inner ear, and these vibrations stimulate the nerve fibers of the cochlea directly, allowing hearing.
Patients who receive BAHAS are typically happy. Few of them, studies site, prefer their old hearing aids, and the majority report increased comfort and function. This wasn’t always the case for bone conduction hearing aids, however; “If you simply saw the old ones,” Eisen explained, “you would immediately have your answer as to why people found them uncomfortable. They weren’t implants, but headbands that held the hearing aid tightly against the skull someplace. They were also cumbersome and noticeable.”
Unlike the old bone conduction hearing aids, BAHAs do require surgery, but it is typically a short, minimally invasive procedure, lasting not much more than 30 minutes. As I observed in February though, Niparko takes his time, performing a BAHA in an hour, from start to finish.
“This process should take about 15 minutes – in and out,” joked a young resident in the operating room as he pulled on his face mask moments before the surgery. But he was wrong; Niparko – a tall, lean man with a careful eye – takes longer than average, and this is just one aspect of his BAHA surgery strategy that strays from the norm.
For starters, the size of skin flap made at the initial incision is larger -- that of an orange versus a ping pong ball – when Niparko is at the helm. “I don’t mind taking time to make the larger cut,” Niparko explained to Hazard, as the man watched, and took shot after shot.
Incision size is crucial; sufficient subcutaneous tissue – or fat – needs to be removed from under and around the skin flaps so that once the screw is drilled into the skull, it is less likely to be disrupted by creeping tissue. This tissue, though only millimeters in thickness, often grows back and pushes the screw out of line.
On the day of the surgery, Niparko spent calculated time using a pick to pull thin lumps of yellow, fatty tissue from under perimeter skin flaps of his large incision. After pulling an especially wide tissue lump from the patient’s head, Niparko plucked a ruler from the pocket of his green standard-issued Hopkins scrubs: “4 inches!” he said, commenting on its diameter. The tissue was so large that when the nurse dropped it in on a steel table nearby, it made a thud loud enough for me – on the other side of the room – to clearly hear.
Beyond incision size, the second detail Niparko focuses on is the angle of processor attachment. “I’ve never heard a better insight into the success of this surgery,” Hazard commented, after hearing Niparko explain his emphasis on a drilling the screw, perfectly straight, into the skull to avoid complications with the processor. Apparently, it does not function as well when it touches skin – when it’s angled up or down because of bad screw alignment, in other words. That’s because if the processor touches flesh, its vibrations are dampened, making the transfer of those vibrations – from processor to screw to implant – less efficient. “Remember,” Eisen reminded me later, “it is all about physics. No electrical stimulation like a cochlear implant.”
Eisen explained that surgeons do not use a device to measure the angle at which they enter the skull. “We just have our line of sight to guide us. This is why it’s important for the surgeon to anchor his arms.” As Eisen drilled the screw 4 millimeters deep into patient’s skull that day, Niparko loomed over him and lectured on angles. “Don’t let it be anything but 90 degrees,” he said. Meanwhile, Hazard watched closely, seemingly amazed at what I found to be a simple idea.
Niparko then did something which captivated all in the room. To determine how well the screw was affixed to the skull, he bent low to the patient’s head and hit the screw with a small metal pole. He listened carefully to the pitch generated. “A sharper ring should mean more solid fixation,” Eisen later explained. Niparko was dissatisfied with the high pitched ring that chirped quickly in the silent room, and he instructed Eisen to turn the screw again. To make it tighter.
Then Niparko tapped, listened, and -- still dissatisfied -- asked Eisen for yet another twist of the screw. After the final turn of screw into skull, Niparko was happy with the high pitch ting generated from careful insertion.
“Niparko’s strategy is great,” Hazard said. “Especially because he cuts a large flap when making the incision. Larger than most and large enough so that the tissue around the BAHA implant doesn’t become an issue and push the implant out of line. This takes more time and most surgeons won’t do it. They cut small flaps. Or they do a dermatrome. But Niparko doesn’t care. He’s takes his time and makes a big cut.”
By paying attention to tissue removal and drilling angle, then, Niparko has customized the BAHA surgery. His signature moves have yielded him success about which the world will hear with the coming of Hazard’s manual. Surely, Niparko’s patients will hear of it, too.
.MGW.
posted by Meagan G at
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