Cochlear Baha

Baha sound processor

Type	Cochlear Baha 3 sound processor (BP100)
Manufacturer	Cochlear Limited
Country of origin	Sweden. Purchased by Australian company Cochlear in 2005.
Introduced	1977
Website	www.cochlear.com

The Baha is a bone conduction hearing system designed, developed and marketed by Cochlear. When Cochlear bought the Swedish company Entific Medical Systems in 2005, the acronym BAHA was trademarked into Baha, since it is not considered a hearing aid by insurance companies.

The Baha is a semi-implantable percutaneous bone conduction hearing device coupled to the skull by an osseointegrated titanium fixture.^[1] The system transfers sound to the inner ear through the bone, thereby bypassing problems in the outer or middle ear. Candidates with a conductive, mixed or single-sided sensorineural hearing loss can therefore benefit from bone conduction hearing solutions.

Since dr Anders Tjellström at Sahlgrenska University Hospital in Gothenburg, Sweden, implanted and fitted the first patient with a Baha in 1977, an increasing number of clinics around the world offer implantable bone conduction hearing solutions as a method of treatment. More adults and children are implanted with a Baha every year, from only 3 in 1977 to over 75,000 users today.^[2]

Contents 1 History 2 How Baha works 3 Surgery 3.1 Implantation 3.2 Healing 3.3 Osseointegration 3.4 Fitting 4 Candidates and indications 5 References 6 External links

History

Professor Per-Ingvar Brånemark famously discovered osseointegration in the 1950s which allows titanium implants to fuse with human bone. The discovery led to wide use in dental implants. In the mid 1970s Brånemark, together with his ENT colleague Dr Anders Tjellström, glued an Oticon bone vibrator to a snap coupling fitted to a dental implant and then connected it to an audiometer. The patient reported a very high, clear sound. It was obvious that the sound propagated very well through the bones of the maxilla to the inner ear. This became the starting point for the future development of the hearing device Baha together with the titanium implant.^[3]

• In 1977 the very first patient was fitted with a Baha, at Sahlgrenska University Hospital in Gothenburg. The surgery was performed by Dr Anders Tjellström.
• In 1985 Cochlear introduced the first headworn sound processor called the HC-100.
• In 1989 the first Baha bodyworn device was introduced - the NAS HC-220 Superbass.
• In 1993 the headworn processor Baha® Classic was launched.
• In 1996 the Baha® System was cleared by the FDA for use in the USA.
• In 1999 the Baha® System was cleared in USA for paediatric use.
• In 1999 Cochlear launched the powerful bodyworn sound processor Baha® Cordelle II.
• In 2000 the Baha® Compact was introduced.
• In 2001 Baha® System was cleared for use in bilateral fitting in the USA.
• In 2002 the Baha® System was introduced for treatment of Single-Sided Deafness (SSD) in the USA.
• In 2002 the Baha® Softband for children was introduced.
• In 2005 the Baha Divino™ was introduced.
• In 2007 the Baha® Intenso was introduced
• In 2009 Cochlear launched the new technology of the Baha® BP100 sound processor and a Fitting Software to adapt the sound processor to the patient's individual hearing loss.
• In 2010 the new BI300 implant was launched.
• In 2011 the Baha 3 BP110 sound processor was launched. The three components, implant, abutment and sound processor are now called the Baha 3 System.^[4]

How Baha works

The Baha System reroutes the sound by sending it through the bone, bypassing the outer and middle ears, directly to the functioning inner ear through bone conduction.

• Sound waves are created by vibrations. The sound of a person's voice is created by the vibrations of their vocal chords. The sound waves travel through the air like ripples on a pond.
• The Baha sound processor attached to the abutment on the titanium implant in the skull, picks up the sound waves. A computer chip in the processor digitally analyses the sound. The digitally enhanced signal is amplified and converted into vibrations that are sent out of the sound processor.
• The titanium implant receives the amplified vibrations from the sound processor and sends them through the bone directly to the cochlea, bypassing the outer and middle ear. In Baha users with Single-Sided Deafness the implant receives the amplified vibrations and sends them through the bone to the hearing ear, bypassing the non-hearing side.
• The sound vibrations reach the inner ear and cause waves in the fluid of the cochlea. The hair cells convert the fluid movement into electrical signals sent to the hearing nerve.
• The hearing nerve sends the information to the brain as electrical impulses, where they are interpreted as sound.

Surgery

The process involved in getting a Baha is relatively simple. Surgery generally takes place in an outpatient setting, causing minimum disruption and stress. Normal activity can be resumed within a few days.

Implantation

The procedure is minor and often performed in an outpatient facility with local or general anaesthesia. The surgeon prepares a small area behind the ear, 50–55 mm from the ear canal and line with the top of the pinna, removing a small amount of hair follicles. The area (approximately 24 mm in diameter) closest to the abutment will remain hair free. A Baha titanium implant with an abutment will be inserted in the centre of this area. The implant is 4 mm long and the abutment is 6 mm. When surgery is complete, the top of the abutment is on the same level as the skin.

Healing

After surgery, a dressing which should be changed regularly is required. The stitched are usually removed within 10–14 days. Some numbness in the area around the abutment can occur. Most likely this condition is temporary. Once the dressing is removed it is important to keep the abutment area clean using a supplied cleaning brush. Good hygiene is critical to maintaining normal usage of Baha sound processors. Users who are unable to clean the skin themselves need help from family members or caregivers.

Osseointegration

With the improved size and surface of the Baha 3 Implant (BI300) it is no longer necessary to wait 12 weeks after surgery for fitting. Studies show that osseointegration now occurs as early as three weeks after surgery.

Fitting

The Baha sound processor will be fitted at a hearing clinic. A hearing care professional adjusts the sound settings to suit the patient's personal requirements. The sound processor is designed to snap onto the abutment by holding it at a slight angle and put into place with a click. To take it off, place one finger under the device and gently tilt off.

Candidates and indications

In cases where there are complications with the middle ear, or when one ear does not function, sound can't reach its destination. Hearing care professionals agree that for these types of problems Baha is a more effective solution than air conduction devices.^[5]

Candidates for Baha include patients with outer or middle ear problems (conductive hearing loss), middle and inner ear problems (mixed hearing loss) and no hearing at all in one ear (Single-Sided Deafness). In the first two cases, Baha reroutes the sound via the skull to the cochlea. In SSD, Baha transfers the signal directly to the hearing ear, making it possible to perceive sounds from both sides.

There are several other medical indications where Baha can be treated for hearing loss:

• Atresia/Microtia where malformations of the ears cause a conductive hearing loss and sound cannot travel to the inner ear.
• Chronic Otitis Media increases the risk of middle-ear problems that can cause a conductive hearing loss. Conventional hearing aids worn in the ear can be uncomfortable and sometimes impossible to wear when a child has an ear infection. Because Baha doesn't obstruct the ear canal, the discharges associated with chronic ear infections are allowed to dry properly which reduces the risk of recurring problems.
• Cleft lip and palate usually causes middle ear problems since the muscles that open the Eustachian tube lack an anchor to function effectively.
• Down Syndrome children usually face an increased risk of chronic ear infections and neural transmission problems that can cause hearing loss. Especially narrow ear canals are a common condition with Down Syndrome. Baha can be implemented early in life and thus enable Down children to hear and learn language from a young age.
• Treacher Collins syndrome is a very rare genetic disorder resulting in deformities of the skull. Patients are usually born with underdeveloped mandible and maxilla that result in a distorted jaw and eyelids. Hearing loss in Treacher Collins Syndrome is caused by deformed outer and middle ears, therefore the sound cannot reach the functioning cochlea.

References

External links

• Cochlear.com