Auditory Brainstem Implant (ABI): An Overview

What Is an Auditory Brainstem Implant?

An Auditory Brainstem Implant (ABI) is a fantastic option for those who suffer from severe hearing loss due to problems with their cochlea or hearing nerve. The ABI produces the impression of sound when these essential auditory system parts are absent or malfunctioning. Bypassing the broken cochlea or hearing nerve, this apparatus directly activates the auditory channels in the brainstem.

Individuals can accomplish more:

• Sensible consciousness.

• Capability to read lips.

• Recognition of sounds, occasionally with word and sentence recognition as well.

What Are the Components of Auditory Brainstem Implant?

There are two components to the implant:

Processor: This portion is worn on the side of the head or above the ear. A microphone built within the processor records ambient noises. The noises are transformed into an electrical signal, then transmitted to the implant. As one sleeps, one should remove the processor.

Internal Implant: This component is implanted by a surgeon and comprises:

• An electrode paddle is the end of a receiver-stimulator that is implanted beneath the skin on the side of the head.

• An electrode paddle is positioned on the surface of the brainstem's cochlear nucleus complex, which is responsible for hearing.

Who Is an Ideal Candidate For an Auditory Brainstem Implant (ABI)?

Originally designed for people with neurofibromatosis 2 (NF2) (malignancies to develop in the nerves, brain, and spinal cord), a rare genetic disorder characterized by the development of tumors along the auditory nerve known as acoustic neuromas, auditory brainstem implants (ABIs) were created.

The removal of these tumors and the associated therapies may cause irreversible harm to the auditory nerve, which could result in significant deafness in both ears. In certain situations, cochlear implants or conventional hearing aids cannot restore hearing.

Sound impulses are transmitted between the inner ear and the brain through the auditory nerve, which plays a crucial role in this process. Sound waves cannot adequately reach the brain when this bridge is broken. By bypassing the injured auditory nerve and directly activating the brainstem, ABIs provide revolutionary technology that enables sound impulses to be transmitted to the brain.

Since their first use for people with NF2, ABIs have proven invaluable in helping those who suffer from severe hearing loss caused by a variety of disorders affecting the auditory nerve or inner ear. These implants are advantageous for those who are:

• Born with an undeveloped auditory nerve (hypoplasia) or without a functioning auditory nerve (aplasia).

• Deafness is brought on by anomalies in the cochlea's shape, inadequate cochlear development (cochlear hypoplasia), lack of inner ear structures (cochlear aplasia), excessive cochlear bone growth (cochlear otosclerosis), or improper cochlear bone development (cochlear ossification).

• Have undergone injury or severance of the auditory nerve, possibly due to temporal bone fractures on both sides of the head.

• Possess other deafness causes for which cochlear implants or traditional hearing aids are insufficient.

• For those suffering from severe hearing loss caused by various underlying disorders impacting the auditory system, assistive brain implants (ABIs) provide a new lease on life and enhanced auditory function.

How Is the Auditory Brainstem Implant (ABI) Inserted?

Pre Surgical Evaluation

What to anticipate before an auditory brainstem implant is as follows:

• Audiologists will assess the hearing with and without hearing aids using behavioral testing.

• Evaluation of communication: A speech-language pathologist may evaluate communication style and language development.

• Electrophysiologic Testing: To assess the degree and location of hearing loss, audiologists will perform tests.

• Imaging Studies: An MRI and CT scan might be performed to examine the cochlea, auditory nerve, and surrounding structures.

• Medical History: The healthcare professional will inquire about the hearing loss and medical history.

• Neuropsychological Assessment: The doctor will assess the capacity and function of the brain.

Surgical Team

A highly skilled surgical team must collaborate during the implantation procedure. Usually, the group consists of a:

• Neurosurgeon: A surgeon of the brain.

• Anesthesiologist: Responsible for controlling pain and preventing movement while doing surgery.

A neurotologist is a board-certified otolaryngologist who specializes in performing surgery on patients suffering from disorders affecting the auditory nerve. An audiologist and an electrophysiologist test the device during the procedure to ensure optimal functionality and help adjust the electrode paddle's placement.

Anesthesia:

To guarantee that the patient is unconscious and pain-free during the treatment, general anesthesia is administered.

Surgical Technique:

To reach the skull and brainstem region, the surgeon creates an incision behind the ear. The precise method may change depending on the patient's anatomy and the surgeon's preference.

• Implantation of Electrode Array: A small electrode array is carefully placed into the brainstem to target certain auditory nuclei involved in sound signal processing. Positioning is essential for the best possible stimulation and sound perception.

• Connection to External Components: After the electrode array is positioned, it is linked to the external ABI system components, which usually consist of an external microphone and speech processor and a receiver-stimulator positioned beneath the scalp.

• Testing and Adjusting: After the ABI components are linked, the surgical team performs intraoperative testing to verify correct device placement and operation. They might also make some preliminary changes to improve hearing.

• Closure: The surgical incisions are shut down when the tests and corrections are finished, and the patient is transferred to a recovery area.

What Are the Advantages of an Auditory Brainstem Implant (ABI)?

While an ABI cannot completely restore normal hearing, it can enhance lip reading skills, awareness, and recognition. The outcomes differ greatly. Compared to adults with NF2 (who have had a prolonged duration of deafness), children who receive an ABI at an early age (after a brief period of deafness) typically exhibit greater word understanding.

Aside from the duration of profound deafness, other variables that may affect the results include the tumor's size and location, involvement in post-operative hearing therapy, and other medical conditions.

Consult the healthcare provider to consider the advantages and disadvantages thoroughly. If they work together, one can decide on health in an informed way.

What Are the Complications of Auditory Implant Surgery?

The likelihood of complications following ABI surgery is minimal, particularly when carried out by a skilled team. The surgical team will review potential postoperative issues and how to handle or treat them. Among the complications are:

• Leaks in cerebrospinal fluid.

• Implant failure occurs when the electrodes shift or the device cannot produce helpful auditory sensations.

• Non-auditory stimulation refers to the uncomfortable stimulation of non-hearing center structures by the device.

• Partial tumor excision.

• Meningitis (inflammation of the membranes lining the brain and spinal cord).

• Facial nerve palsy results in a loss of face mobility due to nerve injury.

• Infection of the wound.

Conclusion

An auditory brainstem implant (ABI) can help people with profound hearing loss. It can also benefit those with a nonfunctioning or missing cochlea (inner ear), auditory nerve from neurofibromatosis 2, acoustic neuroma, or other conditions. With an ABI, one may be able to read lips more easily and experience improved sound awareness. Speak with the healthcare provider to find out if an ABI is a good fit.