| Bone Anchored Hearing Aid |
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Information AboutBone Anchored Hearing Aid |
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USE AND OPERATION Bone anchored hearing aids use a surgically implanted Abutment to transmit sound by direct Conduction Through Bone to the inner ear, bypassing the external auditory canal and middle ear. A Titanium "post" is surgically embedded into the skull with a small abutment exposed outside the skin. A sound processor sits on this abutment and transmits sound vibrations to the external abutment of the titanium implant. The implant vibrates the skull and inner ear, which stimulate the nerve fibers of the inner ear, allowing hearing. The titanium fixture bonds with the surrounding tissue over three to six months after surgery in a process called Osseointegration . The hearing aid can be used once osseointegration is complete, usually three to six months after implantation. Entific's BAHA hearing aids have a patented US Patent 4,498,461. Coupling to a bone-anchored hearing aid {Link without Title} snap-lock coupling which allows it to clip into the abutment. The BAHA is then treated as a regular hearing aid, running on small circular batteries which last approx 6-14 days. The snaplock coupling is designed to detach upon impact as a safety feature to prevent damage to the implant or surrounding tissues. SUITABILITY Bone anchored hearing aids can help:
Bone anchored hearing aids have also been offered successfully to people with bilateral conductive loss due to ossicular disease e.g. otosclerosis and for hearing impairments related to other congenital syndromes such as Down’s Syndrome. In Canada , stage one surgery for BAHA has been implanted into children as young as 13 months at the Hospital For Sick Children in Toronto . Stage two surgery has been done as early as 22 months. For infants, an interim measure young infants can be provided with a BAHA softband allowing them to use a BAHA. This is a tight headband which the infant wears to hold a BAHA against the skull. SURGICAL PROCEDURE In recent years improvements to the surgical procedures have resulted in most patients being able to have a single stage procedure carried out under local, or a short general anaesthetic. Most patients are able to leave hospital within a few hours, or the day after their procedure with many not even requiring analgesia in the following days. Osseointegration is the process of the titanium fixture bonding to the bone. There is a high success rate for osseointegration above 95% according the latest studies in medical journals. Occasionally infection and other problems will prevent osseointegration from being successful. In these cases the patient will be given time to heal and further more cautious attempts at the surgical procedure can be made. In many cases, the surgeon will implant a second "sleeper" receptacle for use should the initial receptor fail or be damaged. Procedure for Very Young Children - Two Stage Operation A double stage procedure is sometimes carried out for small children / babies or other medical reasons. The first stage involves peeling back a small 1cmx1cm section of skin behind the ear, then drilling one or more holes for the fixture. (Some surgeons will place a "sleeper" receptor.) The skin is then grafted back and the child waits for the skull to continue to thicken and for osseointegration to occur properly. After osseointergration (can be 6-8 months) the second stage is performed. The second stage is another surgery in which the "post" is attached, and the skin is grafted around the "post" This will require healing for several weeks, at which point the Baha would be fitted. DANGERS, RISKS, DURABILITY, REPAIRS The titanium screw of the BAHA is screwed from outside into the bone. Because of this open wound, there will always be a risk of infection. Daily care is (may be) required. This consists of using a very soft toothbrush like tool to scrub around the post and skin area to keep it clean and not infected. Daily use of an antibiotic ointment such as Polysporin assists in minimizing infection. Although designed to come off the post should they be contacted, the units are quite fragile if impacted only slightly. Cochlear has a warranty & repair policy. Units requiring repair are sent to Sweden. Cochlear will provide "loaner" units during the repair period. COSTS The cost of the Divino is approximately $4000 USD. Surgery cost can cost as much as $30,000 including the device and can vary depending upon the type and hospital. MANUFACTURERS At present Entific Medical Systems, a Swedish company owned by Cochlear Limited , is the only manufacturer of bone anchored hearing aids. It has registered the acronym BAHA™ as a Trademark Trademark 783134 registered in Sweden on 11.06.2002 {Link without Title} . MODELS There are four types of systems. The Cordelle, Classic, Compact and Divino.
REFERENCES EXTERNAL LINKS
A conference concerning microtia treatment options is sponsored by the Let Them Hear Foundation and held in Palo Alto, California . The conference is always the first Saturday in October. Conference attendees will be able to see presentations on both medpor and rib graft microtia reconstruction, Atresia repair, Prosthetics , jaw distraction and Baha devices.
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