Functionally deaf patients can gain normal
hearing with a new implant that replaces the middle ear. The unique
invention from the Chalmers University of Technology has been approved
for a clinical study. The first operation was performed on a patient in
December 2012.
With the new hearing implant, developed at Chalmers in
collaboration with Sahlgrenska University Hospital in Gothenburg, the
patient has an operation to insert an implant slightly less than six
centimetres long just behind the ear, under the skin and attached to the
skull bone itself. The new technique uses the skull bone to transmit
sound vibrations to the inner ear, so-called bone conduction.
“The BCI implant will provide full hearing even to patients born without a middle ear”, says Bo Håkansson.
“You
hear 50 percent of your own voice through bone conduction, so you
perceive this sound as quite natural”, says Professor Bo Håkansson, of
the Department of Signals and Systems, Chalmers.
The new implant,
BCI (Bone Conduction Implant), was developed by Bo Håkansson and his
team of researchers. Unlike the type of bone-conduction device used
today, the new hearing implant does not need to be anchored in the skull
bone using a titanium screw through the skin. The patient has no need
to fear losing the screw and there is no risk of skin infections arising
around the fixing.
The first operation was performed on 5
December 2012 by Måns Eeg-Olofsson, Senior Physician at Sahlgrenska
University Hospital, Gothenburg, and went entirely according to plan.
“Once
the implant was in place, we tested its function and everything seems
to be working as intended so far. Now, the wound needs to heal for six
weeks before we can turn the hearing sound processor on”, says Måns
Eeg-Olofsson, who has been in charge of the medical aspects of the
project for the past two years.
The technique has been designed
to treat mechanical hearing loss in individuals who have been affected
by chronic inflammation of the outer or middle ear, or bone disease, or
who have congenital malformations of the outer ear, auditory canal or
middle ear. Such people often have major problems with their hearing.
Normal hearing aids, which compensate for neurological problems in the
inner ear, rarely work for them. On the other hand, bone-anchored
devices often provide a dramatic improvement.
In addition, the new device may also help people with impaired inner ear.
“Patients
can probably have a neural impairment of down to 30-40 dB even in the
cochlea. We are going to try to establish how much of an impairment can
be tolerated through this clinical study”, says Bo Håkansson.
The toughest challenge has been to make the quadratic implanted loudspeaker sufficiently small, while effective enough.
If
the technique works, patients have even more to gain. Earlier tests
indicate that the volume may be around 5 decibels higher and the quality
of sound at high frequencies will be better with BCI than with previous
bone-anchored techniques.
Now it’s soon time to activate the first
patient’s implant, and adapt it to the patient’s hearing and wishes.
Then hearing tests and checks will be performed roughly every three
months until a year after the operation.
“At that point, we will
end the process with a final X-ray examination and final hearing tests.
If we get good early indications we will continue operating other
patients during this spring already”, says Måns Eeg-Olofsson.
The
researchers anticipate being able to present the first clinical results
in early 2013. But when will the bone-conduction implant be ready for
regular patients?
“According to our plans, it could happen within
a year or two. For the new technique to quickly achieve widespread use,
major investments are needed right now, at the development stage”, says
Bo Håkansson.
Foto: Oscar Mattsson
Two parts – one exterior processor and one implant
The
implant is slightly less than six centimetres long. By a surgical
procedure, it is inserted just behind the ear, under the skin, into the
bone itself. The coil at the upper end operates using magnetic induction
with the outer, visible component, a sound processor that the patient
easily can attach to or remove from the head.
The external sound
processor is held in place using two magnets. The titanium screw
through the skin, used in other techniques, is replaced by an inductive
link that transmits sound from the patient’s surroundings through the
intact skin to an internal receiver. The audio signal is transmitted to a
tiny quadratic loudspeaker anchored to the bone near the auditory
canal. The speaker generates sound vibrations which reach the sensory
organs of the cochlea.
Illustration: Emil Håkansson/Chalmers
Deaf people will gain normal hearing and function
Hearing
impairments are the most common physical disability in the
industrialized world. If the problem originates in the mechanism
required to conduct the sound to the inner ear – for example, in the ear
canal or the small bones in the middle ear – the skull bone can be used
instead. Soon, functionally deaf people will gain normal hearing with
the implant pictured, known as the Bone Conduction Implant (BCI).
“The
implant will be very comfortable and aesthetically attractive. Because
the implant is securely fixed under the skin, the patient won’t need to
be more careful than other people during, for example, outdoor
activities and water sports”, says Professor Bo Håkansson.
Illustration: Boid/Chalmers
Chalmers and Sahlgrenska working
closely together since the 1970s
In
1977, three adult patients had titanium screws inserted into the bone
behind the ear at the Ear Clinic of Sahlgrenska University Hospital.
This was the starting point for close, long-lasting cooperation between
Professor Bo Håkansson, Associate Professor and Ear Specialist Anders
Tjellström and Professor P-I Brånemark, renowned for his concept of
permanently anchoring implants in the bone, known as osseointegrated
implants.
The BAHA (Bone Anchored Hearing Aid) technique has
undergone gradual refinement since then and is today helping more than
100,000 patients worldwide to better hearing – and the number is rising.
The BAHA technique has never gained so much international recognition
as it has today, one success factor being the cross-discipline teamwork
that has been ongoing in Gothenburg without interruption for more than
35 years.
More on the BCI project
In addition
to Bo Håkansson and Måns Eeg-Olofsson, Doctor Sabine Reinfeldt and
doctoral students Hamidreza Taghavi and Karl-Johan Fredén Jansson of the
research team at the Department of Signals and Systems, Chalmers,
together with Associate Professor Anders Tjellström and Joacim Stalfors,
Sahlgrenska University Hospital, and Professor Carina Johansson, of the
Institute of Odontology at Gothenburg University, are involved in the
project.
The research has been financed via funds from Vinnova
(Swedish Research Council for Innovation Systems), the Swedish Research
Council, the Swedish Association of Hard of Hearing People (HRF),
R&D grants from the Regional Board, the Acta Oto-Laryngologica
Foundation, the Stinger Fund, the Gothenburg Medical Society and the
Kristina Stenborg Foundation.
Source:
http://www.chalmers.se/en/
