In the absence of pinna and ear canal, sound cannot enter the external ear or travel to the inner ear. But the BAHA implant bypasses the ear canal and middle ear and conducts sound to the inner ear directly through the skull bone.
Five-year-old Anjali was a stranger to sounds, being born with no external ear or ear canal, organs crucial for sound to be transmitted to the inner ear and processed by the brain. But soon her hearing would be crystal clear, say doctors who implanted a bone anchored hearing aid (BAHA), at a city hospital recently.
In the absence of pinna and ear canal, sound cannot enter the external ear or travel to the inner ear. But the BAHA implant bypasses the ear canal and middle ear and conducts sound to the inner ear directly through the skull bone. The surgery was done by a team of surgeons headed by ENT specialist Jawahar Nagasundaram, from G.Viswanathan Specialty Hospitals.
Anjali’s father, a shrimp exporter from Vishakapatnam approached Dr.Jawahar, a member of the team that performed the first cochlear implant in Chennai four years ago, when the girl was two years old.
A temporary solution in the form of a ‘soft band’ fixed with a BAHA implant, resembling a head band worn by girls, was offered to the child to overcome hearing and speech development problems.
The implant surgery was put off till the child was five years, minimum age for BAHA implant set by Food and Drug Administration, U.S.A. As the implant is fixed by drilling through the bone, bone thickness of three millimetres is mandatory. Additional risk was faced by surgeons as the ear was quite removed from the normal position.
After making an incision above the ear, surgeons used a special drill to bore 3 mm hole, taking caution to avoid touching the brain. The titanium implant handled by a special titanium holder was fixed comfortably in a two-hour procedure.
High clarity hearing
A BAHA sound processor would be fitted after a few months, which is advised to be removed at night to avoid damage to the implant during sleep. Unlike other foreign bodies implanted in the body, titanium is accepted by bone which integrates with the metal in three to six months. The procedure would guarantee high clarity hearing to the child, said Dr.Jawahar.
The congenital defect can be triggered by viral infections or incorrect medication in the first trimester, the period when the ear develops. Though two BAHA implants are ideal, one is the norm due to the prohibitive cost of Rs.2.5 lakh for one implant. The earlier alternative was reconstruction of pinna and canal which has not been entirely successful.
BAHA implants are ideal for single-sided deafness, hearing impairment with chronic ear discharge. They have no utility for people with inner ear defects for which cochlear implants are preferred. Dr.K.Govindaraj, managing director of the hospital, presided.