Cochlear Implant Surgery
Listed below is the step by step procedure of cochlear implant surgery:
- What is Cochlear Implant Surgery?
- Why is Cochlear Implant Surgery Required?
- Pre-operative Preparation
- Day Before Surgery
- Procedure Day
- Methods/Techniques of Cochlear Implant Surgery
- Post Procedure
- Risks and Complications
What is Cochlear Implant Surgery?
Cochlear implant surgery is a surgical procedure used to fix an electronic device in order to aid the sense of hearing in an individual. This electronic device is small in nature having a snail shaped tubular body. This procedure is done in people having difficulty in hearing or complete hearing loss due to damaged cochlea.
Cochlear implant consists of two components; namely the inner implant and the external device. The outer device has various parts like microphone, speech processor and a transmitter. The outer device has the following functions:
- The microphone picks the sound from the surrounding environment.
- The speech processor processes these sound signals and arranges it in an order.
- The transmitter will transmit these sound signals to the inner part of the cochlear implant.
The inner implant has various parts like receiver and an electrode system. These parts perform the following functions:
- The receiver collects signals from the transmitter. These sound signals are further converted into electric impulses.
- The electrode system contains a group of electrodes. It is responsible to collect electric impulses from the receiver and pass it to various sections of the auditory nerve.
Why is Cochlear Implant Surgery Required?
Our ears are designed in such a way that certain hair cells collect sound signals and transmit them to the auditory nerve to make your brain understand what you are hearing. However, if these cells are damaged, some or no sound signals can be collected to pass them to your auditory nerve. At such times, cochlear implant Surgery is required. We have already learnt about the working of this implant.
Cochlear implant Surgery has the following benefits that can fulfill many requirements of some patients who have difficulty in hearing:
- If your hearing capability has decreased due to some reason, cochlear implant can increase this ability by improving the functioning of your ear.
- If an individual requires lip reading or sign language, this implant can be considered as a beneficial replacement for such situation.
- Children having difficulty in hearing can use this surgical method for better learning in education and workplace.
- Cochlear implant not only is beneficial for hearing but it also improvises speech skills in patients with hearing disorders
- The implantation of this device also serves as a safety measure. Patients who have difficulty in hearing can hear threats easily from their surrounding environment using a cochlear implant. It becomes really difficult to go to the other side of a road if you have trouble hearing. At such times, hearing implant can be useful.
- People who do not benefit even after using hearing aids will experience improved hearing after cochlear implant surgery.
There are certain tests conducted to know if you are eligible for cochlear implant surgery. Your doctor conducts these tests in order to monitor and learn about the condition of your ear. Based on these tests, your doctor will decide if surgery is the right way to fix your problem or it can be fixed using other treatments. In some cases, these tests show how urgent this surgery is required for the patient.
Evaluation Tests for Hearing Aid
Your hearing capability is tested using an audiogram test. Patients are asked to hear a sound clip which is mainly soundproofed from the noise coming from external sources. As soon as they hear something, they are asked to signal their doctor. The results of this test is drawn in a graphical format. The graph is a pictorial representation of volume and pitch of the sound one's hearing.
Auditory Brainstem Response Testing
Cochlea, which is a part of inner ear collects sound signals that you hear and transmits them to your brain. Auditory brainstem response testing checks for the following:
- Functions of your cochlea and brain
- Ability of your brain to respond to such transmission
- Your conventional response to whatever you hearPresence of any hearing loss because of your cochlea or brain damage
- Deformities in the brain passageways or the auditory nerve
- Quality of hearing
Otoacoustic Emissions (OAEs)
OAEs are sounds that are given away by your inner ear when you hear something. When you hear a certain sound, the hair cells in your ear begin to vibrate. These vibrations generate an inaudible sound which echoes back inside your middle ear. This sound is measured by inserting a small probe into your ear canal.
If your hearing is normal, emissions will be produced. However, if you have decreased or entirely lost your hearing sensation, these emissions would not be produced.
This test also detects various other issues of your ear that include:
- Blockage in outer canal of your ear
- Presence of ear fluid in it's mid-part
- Damage to the hair cells of cochlea
This testing mechanism determines how sharp is your hearing sense even though the sound is very low. Pure-tone testing or pure-tone air conduction hearing test figures out the faintest tones an individual could hear. Your audiologist can use various frequencies of sound, for both high and low pitches and check how well your hearing capability works accordingly. Various sound screening methods are used for the patients to hear and the results are recorded using an audiogram. However, an unilateral loss in hearing (hearing loss of only one ear) cannot be detected through this test.
Speech testing is used hand in hand with the pure-tone testing to get an accurate result. The faintest form of speech is generated that everyone of us are used to hear and correspondingly your hearing capabilities are measured and monitored. Results are recorded in an audiogram.
A speech testing procedure is conducted in a noisy environment. However, for a normal hearing individual, it is very easy to differentiate between what you are hearing and the additional noise coming from the environment (background noise). Patients with hearing loss complain about the background noise as they find it difficult to understand and focus on what they hear.
Tests of the Mid-part of Ear
To monitor your middle ear, your ENT (ear, nose, throat) specialist may require to measure certain parameters. These parameters inform your doctor about the functional aspects of your middle ear. Patients may or may not have middle ear diseases that lead to loss in hearing. To determine all this, tests of the middle ear are conducted.
Various types of middle ear tests include:
The aim of tympanometry includes:
- Detecting ear fluids in the middle part of the ear
- Abnormal condition of your eardrums such as perforation
- Blockages in the ear canal due to wax formation
Acoustic Reflex Measures
The aim of this test is to locate the point within your ear which is responsible to cause hearing issues. Your ear is designed in a way that you respond to any kind of sound you hear. This responding mechanism is called as acoustic reflux. If you hear a loud sound, a small muscle within your ear get contracted. If the behavior of your acoustic reflex is abnormal to louder sound or if it is absent, it indicates that you are having a problem with hearing. Based on the results of this test, your ENT specialist determines the type of hearing loss you have.
Static Acoustic Impedance
This is a test that measures the physical volume of air present with your ear passage. The purpose of this test is to determine the presence of perforated eardrum or, to check the openness of the tubes responsible for ventilation. This test is followed by an audiological evaluation that determines your hearing needs.
Your doctor carries out certain imaging tests to learn about the internal structures of your ear and brain.
Computerized Tomography (CT) Scan
A CT scan provides cross sectional image of the body organ being scanned. Your doctor performs CT scans on both the ears to check whether your cochlear is having a normal shape and structure. Patients who have a history of meningitis may develop a bony growth in the cochlear that may interfere with the insertion of the cochlear implant. Such bone growth can easily be seen on the images generated by a CT scan. Also, CT scanning gives an indication that which ear needs an implantation.
Magnetic Resonance Imaging (MRI)
MRI scan can also be used to determine various structures of your ear. Brain MRI can also be performed in order to learn about the auditory nerve and other brain structures associated and connected with your ear. Abnormalities like blockage, narrowing, etc., in the nerves or blood vessels that connect your brain and ear, may also result in loss of hearing. Such abnormalities may also call for other proprietary treatments along with cochlear implants to aid hearing.
Psychological examination is necessary to check whether you can cope up with the cochlear implant. It determines your behavioral aspects as well as your sensory capabilities and ability by using various methods and techniques. Doctor concludes by these strategies whether you can cope up with such implantation surgery. It will also give you details about your hearing needs.
Physical Examination helps your doctor determine whether your health condition is suitable for the cochlear implantation surgery process. It mainly consists of routine monitoring of your body and health condition. It makes your doctor understand about any other abnormal factors present that may affect your surgical process. Therefore, these tests are mandatory to perform before you undergo cochlear implant surgery.
Day Before Cochlear Implant surgery
Day before surgery involves all the other necessary tests and examinations to see if your physical condition is normal. Various types of tests that might be useful for your surgery are conducted on this day. Given below are the different types of tests and procedures conducted a day before your main cochlear implant process. It is important to fast for few hours before you undergo blood or urine tests.
- Blood Tests
A routine blood test is very important before any kind of surgery. Blood tests can be sub-divided into types that include:
- Blood group: Doctor should know what is your blood group before you undergo any surgery. This is important as the patient may require blood transfusion at any time during or after the surgery.
- Complete blood count (CBC): Blood tests are conducted to measure the count of your Red blood Cells (RBC), White Blood Cells (WBC), Platelets, Haemoglobin, etc.
- Blood sugar level: Blood sugar level should be normal before the surgery. Let your doctor know if you are diabetic.
- Urine Tests: Urine tests are performed to check the presence of any form of infections in your system. Urine samples of patients will be collected and sent to the pathological labs immediately for analysis.
- Electrocardiaogram (ECG) Test: This tests provides information about the electrical activities of your heart.
- Chest X-ray: Chest X-ray gives your surgeon all the information about the working of your lungs and heart. It is also used to get images of the structures of your lungs and heart.
- Liver Function Test (LFT): This tests notifies about the functioning of your liver.
- Kidney Function Test (KFT): Kidney Function Test or Renal Function Test (RFT) tells about the functional working of your kidneys.
Along with the tests mentioned above, there are some other aspects as mentioned below that too need consideration.
- Consent Form: Your surgeon will discuss about the entire procedure of cochlear implantation surgery. He/she will also provide you information about the risks and complications of the surgery. However, you need to sign a consent form if you agree to all the terms and conditions of this surgery.
- Dummy Cochlear Implant: Your doctor may perform a dummy partial implementation of cochlear implant to check if the device is suitable. Earlier he/she may also take the outer and inner measurements of your ear to select the correct size of device being implanted. These measurements are important because the size of the ear of children is different that of an adult or elder individual.
- Other Details: Your doctor will give you all the necessary details to follow on the day of surgery. If fasting is required, your doctor will tell you for how long you should fast before the surgery. Water intake should also be avoided for some period of time before the surgery. Doctor will also ask you to avoid certain medications prior to your surgery. If you are wearing a earing or any kind of ear studs, ensure that you remove it before you come for the operation. Your doctor will inform you about the complete schedule of the operation.
On the day of cochlear implant surgery you should be on time. Right before the main surgical procedure, nurses will create intravenous (IV) lines on your arms and other required body parts.
The side scalp areas around your ear that are about to have an implantation surgery will be shaved off. This reduces the chances of infection around your surgical site. Other necessary patches will be attached to your skin which are then attached through cables to a monitor for monitoring your vital signs.
Local or general anesthesia will be administered into your system through one of these IVs. Drugs and glucose will be administered through other IVs. Once all these arrangements are done, your surgeon begins with the cochlear implant procedure.
Methods/Techniques of Cochlear Implant Surgery
Cochlear implant surgery begins by administering general anesthesia into the patient's body. When general anesthesia starts making its influence, the surgeon begins with the surgery procedure. ENT surgeon will initially make a small cut behind your ear. At the back of your ear is a section of bone called the mastoid bone that contains air spaces. The is a slight hollow portion made in that region to fix the receiver on the skull.
Through the air spaces of the mastoid bone, ENT surgeon drills into the inner ear (cochlea). This process is termed as mastoidectomy. Surgeons use mastoidectomy to view the inner region of your ear without causing any disturbance to your ear drum or ear canal.
Your surgeon makes a slight opening on the internal part of your ear to fit the electrode. The cochleas of most patient can easily hold the electrode completely in place. However, those who are suffering from meningitis, undergo a partial insertion of this electrode onto their cochlear.
While all the components are equipped in place, your doctor will stitch up all the incisions. A cotton bandage is wrapped over your head to prevent bleeding. Cochlear implant surgery takes around three to four hours.
Types of Implants
There are different types of implants that may be equipped on the internal and external sections of your ear. Each of these types serve various purposes in fixing the problem related to your hearing sensation. Your ENT surgeon will decide the best type of implant based on your requirements and need.
Let us differentiate the two main function of the ear.
- Cochlea is highly responsive towards simple tone coming from one place along its length.
- Ear is responsive towards timing of the sound.
Keeping these two important functions in mind, the implanted devices are designed in such a way that they separate various groups of sound. For example, if you hear a sound of low pitch, the implanted device will direct this sound to the section of cochlea which responds to lower pitches. Similarly, sound with high pitch will be sent to its corresponding responsive location of cochlea. This is done by channeling these sounds using electrodes fitted into your cochlea.
On the other hand, cochlear implant device is also improvised in such a manner to cover the timing theory of sound. Such devices collect sound signals from the environment and convert them into pulse to check for better response of cochlea towards various types of pulses.
Audiologists use various permutations and combinations of these devised version of implants to check what works best for each patient. This is mainly done by making adjustments in the design of the implants.
Recovery at the Hospital
Cochlear implant surgery is not an out patient surgery. Therefore, patients are asked to make arrangements for night stay at the hospital after the surgery. Although, one can go home the next day of the post operative period.
Doctor will perform a physical check-up on the day after your surgery. He/she will provide you with medications to ease your pain. Other medications can also be given to prevent any risk from infections and to enhance healing.
Nurses will give you all the instructions and details to follow for a better recovery at home. Schedule of medicines, diet, follow-up appointments and check-ups will also be provided. Complete all the paper work procedure before leaving the hospital.
Recovery at Home
During the earlier days post surgery, you will experience moderate pain. It can be taken care of using pain killers. Do not use any other medicines except those prescribed by your doctor. For example, aspirin which can increase the risk of bleeding.
You may experience dizziness for a few days which goes away within a week. Also, you will be unable to hear clearly during this period. However, do not stress on this function of your ear.
It is very essential to consume healthy meals while your body is healing. Also, it is necessary to create a balance in your body when you consume strong medicines. A healthy diet not only helps in your healing process but is also useful in making your immunity better to fight against the risks and complications occurring out of this surgery.
Other important instructions to follow at home include:
- Eat on time
- Take medicines on time
- Get proper amount of sleep
- Follow all the precautions
- Drink minimum 8 to 10 glasses of water a day
For patients who have had a cochlear implant surgery, it takes around four to six weeks to completely heal the implanted site. After complete recovery from your internal and external wound, your audiologist will schedule an appointment for you to activate your implanted device.
The aim of this appointment is to fit the external components of the ear device. This procedure is followed by programming the external speech processor. A small test will be performed on this speech processor where the patient will be now introduced to a sound clip. This is the first sound that the patient will hear from the implant.
External implanted components are also adjusted to suit the patient's need. Every appointment contains a testing session to check and reach the optimal output for the patient. Also, other diagnostic tests will be conducted along, to check the working of the device as well as other features of your hearing sensations. These tests include, CT scans, MRI scans, Rinne and Weber test, blood tests, etc. Scanning tests help your ENT specialist to get images of the internal parts of your ear in order to detect whether there is any complication.
Follow-up sessions are also conducted to remove your stitches or staples after 10-12 days post surgery. Until then, patients are asked to keep their external wounds dry and regularly apply antibiotic ointments over it for at-least two to three times a day.
You need to follow certain precautions to help your wounds heal faster. Taking precautions is also an important part of your recovery process. For cochlear implant surgery, following are the necessary precautions you must follow:
- Avoid sleeping on the side where surgery was performed.
- Avoid putting pressure on your surgical areas.
- Do not expose your ears to water.
- Keep yourself away from places that include sound louder than normal.
- While combing your hair, avoid any contact with surgical parts.
- Avoid alcohol intake.
- Do not perform vigorous activities for some weeks.
- Avoid driving after consumption of medicines. Pain killers and other medications can relax your body. Most patients experience dizziness after consuming medicines.
- Do not use head phones or any similar kind of ear equipment for few days.
- Avoid smoking.
Risks and Complications
Cochlear implant surgery is a very effective procedure that doctors adapt to solve hearing loss issues. However, there are some common risks and complications associated with it.
Some of the common risks and complications include:
- Reactions due to general anesthesia: The work of general anesthesia is to relax your body and induce sleep. Patients can experience adverse reactions of general anesthesia or other problems caused due to its usage.
- Injury to facial nerve: The facial nerve is present around your middle ear. Its function is to generate muscular movements of the face. This nerve is situated very close to the area of implant. Hence, this nerve is likely to get injured during the cochlear implant surgery. Any injury to this facial nerve can temporarily or permanently weaken your facial movements. Worst case of this nerve damage results into total paralysis of that same side of the face where ear implants were fitted.
- Meningitis: It is a disease causing infections in the internal line of the brain's surface. Change in the form of your ear structure leads to higher risks of meningitis.
- Numbness: Patients may be unable to feel around the areas of surgery. These discomfort might wear off within few weeks.
- Leakage of cerebrospinal fluid: The hollow section created in the cochlea might cause leakage of cerebrospinal fluid from that areas or other internal incisions or holes made during the surgery.
- Leakage of perilymph fluid: The inner part of the ear, i.e., the cochlea, contains a liquid substance called perilymph fluid. This fluid might also leak from the holes created during the surgery.
- Taste disorders: There is a nerve connected to your tongue that is responsible to give you taste sensations. This nerve also travels through the middle ear section where the implantation is conducted. There are chances of this nerve to undergo some kind of damage during the surgery. You will experience greater challenge in tasting any food items if this nerve gets damaged.
- Reparative granuloma: The implanted device is a external foreign material that is placed inside your body. Your body may reject these fittings, causing a localized inflammation around those areas. This condition is called as reparative granumloma.
- Vertigo: Vertigo is a severe attack that causes sudden dizziness. The person having this attack feels as if everything around is spinning or swinging. At such times, keep the patients away from heights.
- Permanent loss of hearing: There can be a possibility that the patients loose their hearing sensation completely.
- Device failure: The implanted device can either fail, dysfunction or break. This makes it necessary for the patient to get the device removed and replaced. However, the chances of device failure is very low as the doctor performs a dummy surgery to monitor its working.
- Infections: Infections can occur around your wounds.
- Blood clots can occur around the surgery areas.
- There can be a collection of fluid near your wounds.
- Tinnitus: Hearing a buzzy sound in your ear.
- Unusual bleeding: Unusual bleeding can occur if your stitches loosen up or there is any other complication.
- Nausea: Patients can experience problems like nausea until they recover completely.
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