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In India Otosclerosis is one of the commonest causes of deafness with an intact ear drum. When sound waves fall upon the ear drum, it vibrates. These vibrations are transmitted by a chain of 3 mobile bones called ossicles in the middle ear from the drum to the inner ear.
Otosclerosis is a microscopic abnormal growth of bone in the walls of the inner ear. This abnormal growth causes the stapes bone (also called the "stirrup") to become immobile or "fixed". Normally the stapes vibrates freely to allow the transmission of sound to the inner ear, but when it cannot move, it prevents sound waves from reaching the inner ear fluids, and hearing is impaired.
Otosclerotic bone sometimes involves other structures of the inner ear, thereby affecting the nerves of the inner ear. When this occurs it also causes a distortion or difficulty in understanding the speech of others, regardless of how loudly they talk.
Otosclerosis affects only the ears and involves both ears usually one after another. It occurs in both men and women but women are usually affected slightly more frequently. This is a disease of the early middle age and thus affects people in the prime of life. Pregnancy is known to aggravate the situation. Otosclerosis tends to be familial, but there is no pattern to its heredity.
- Stapedial Otosclerosis : Usually otosclerosis involves the stapes or stirrup bone, the third bone of hearing in the middle ear. This bone rests in a small hollow, the oval window, in intimate contact with the inner ear fluids. This bone is attached to its surroundings by an elastic tissue, the stapedio-vestibular ligament, which allows the free vibration of the stapes while preventing the fluids of the inner ear from leaking out. Fixation of this third bone is called stapedial otosclerosis and is usually correctable by surgery. This enjoys a high success rate of over 96%.
- Cochlear Otosclerosis :
When otosclerosis spreads to the inner ear, a sensorineural hearing impairment may result due to interference with the nerve function. This nerve impairment is called cochlear otosclerosis, and once it develops it is permanent.
On occasion the otosclerosis may spread to the balance canals and may cause episodes of unsteadiness. The amount of hearing loss due to involvement of the stapes and the degree of nerve impairment present can be determined only by careful hearing tests.
- Medication : There is no medical cure for this disease. In certain selected cases medication (Sodium Fluoride) may help prevent progress. However the benefit is not quantifiable. Ear drops cannot help.
Tinnitus develops due to involvement of the delicate nerve endings in the inner ear by the otosclerotic focus. Since the nerve carries sound, this irritation is manifested as ringing, roaring or buzzing. It is usually worse when the patient is fatigued, nervous or in a quiet environment.
Following the successful stapes surgery, tinnitus is often decreases, usually in proportion to the hearing gain. However this does not always happen, and sometimes the intensity of the tinnitus remains unchanged. This is because of involvement of the nerve.
- Medical Treatment : There is no local treatment to the ear itself or any medication that will improve the hearing in persons with otosclerosis, although in some cases medication may be helpful in preventing further loss of hearing.
- Surgical Treatment : An operation that replaces the damaged stapes by one of the techniques described below is recommended for patients with otosclerosis who are candidates for surgery. This operation is performed under local anesthesia, so the patient is fully conscious and therefore the hearing restoration, which is usually immediate, can be measured by audiometry (intra-operative audiometry) The ear is then closed and the patient requires a short period of hospitalization. The patient can go home the very next day and the convalescence period is usually less than a week.
TECHNIQUES USED FOR SURGERY
1. The Direct Piston Technique (Fig.-A)The eardrum is turned forward and the immobile stapes removed using instruments, a drill, or a laser.
A 0.7 mm hole is made in the footplate and a 0.6 mm diameter Teflon—or titanium piston is inserted connecting the incus to the hole. The eardrum is then replaced to its normal position.
The Teflon piston-is self lubricating and it does not adhere to the body tissues, so continued growth of the Otosclerotic focus on the foot-plate cannot fix itself to the side of piston and prevent vibration.
It is essential that the diameter of the hole and the length of the piston should be accurate to within 1/8 of a mm. If the piston has been cut too short, the Otosclerotic focus can grow underneath the piston and cause late conductive deafness. If it has been cut too long or if the hole is made too big, late nerve deafness due to leakage of inner ear fluid may occur (Perilymph Fistula).
2. The Piston with Vein interposition Technique (Fig.-B)A 0.8 mm hole is made in the footplate covered with a vein graft and a 0.4 mm diameter piston is used to connect the vein-graft to the Incus. The advantage of this is the formation of an immediate and durable oval window seal so the inner ear fluids cannot leak out.
3. Posterior-Crus on Perichondrium Technique (Fig.-C)The entire footplate is removed from the oval-window, which is then covered with perichondrium and the Posterior crus of the stapes is used to connect the Incus to the Oval-window. The problem of late nerve deafness due to a long piston can never arise in this technique because the patient's own posterior crus can never be too long. However very active Otosclerosis may invade and ossify the Perichondrium causing late conductive deafness. if this should happen it is still possible to use the piston.
4. Cartilage on Vein Technique (Fig.-D)The Tragal-cartilage is used instead of the Posterior crus to connect the Incus to the Vein covering the Oval-window.
All these techniques have their own advantages and disadvantages. A good stapes-surgeon should be able to use all these techniques with equal ease. In order to get all the advantages of the various techniques it is advisable to use one technique on the first ear and another technique on the second ear.
In our clinic, we prefer to use the Teflon piston with vein interposition technique as the method of choice, as it has the maximum margin of safety as well as the best hearing results.
The Piston with Vein Interposition Technique.A 0.8 mm. hole is drilled in the footplate, covered with a vein graft, and a 0.4 mm T. P. is used.
The vein forms the stapedio-vestibular interface. The moving surface is 0.8mm in diameter, which is very good for sound transmission.
- You get an immediate seal.
- Adhesions from the lenticular process to the promontory are prevented as the promontory is covered with intima.
- You cannot use an overlong piston, as the vein will get invaginated into the oval window and the appearance will warn you.
- The moving surface is 0.8 mm, so you get better hearing than with a 0.4 mm piston.
- In case of sudden movement due to a loud sound or barotrauma, you will not get a dead ear, as the 0.4 mm piston will not hit the saccule or the utricle (Fig.1A and 1B).
In any operation, the emphasis is on :1. an accurately made 0.8 mm hole. If there is excessive footplate removal, even if a vein or perichondrium interposition is used, late bulging of the blue membrane, which is directly proportional to the extent of footplate removal, will inevitably give late S.N. loss due to a fistula.
2. A perfect measurement of the length of the piston; if the piston is too short, late conductive hearing loss will result as the hole made in the footplate will re-close. If the piston is too long, permanent sensori-neural (nerve) hearing loss will result, irrespective of whether a vein or soft tissue has been put around the piston.
Clinical application :We use this technique as far as possible as we feel that there is a greater margin of safety due to the vein.
The stapes prosthesis allows sound vibrations to again pass from the eardrum to the inner ear fluids. The hearing improvement obtained is usually immediate & permanent.
The patient may return to work in 1 week usually, depending upon occupational requirements. Patients should not drive a car or 2-wheeler for at least 1 week after surgery. Air travel is permitted after 7-10 days.
Hearing Improvement Following Stapedectomy :Hearing improvement may or may not be noticeable at surgery. The hearing fluctuates following surgery, in a few hours after operation due to swelling in the ear. Improvement in hearing may be apparent within 3 weeks of surgery. Maximum hearing, however, is obtained in approximately three months.
The degree of hearing improvement depends on how the ear heals. In over 96% of patients the ear heals perfectly and hearing improvement is as anticipated. In some, the hearing improvement is only partial or temporary. In these cases, the ear usually may be re-operated upon with a good chance of success.
In less than 1% of the cases, the hearing may be further impaired due to the development of scar tissue or infection.
In less than 0.5% complications in the healing process may be so great due to blood vessel spasm, irritation of the inner ear, or a leak of inner ear fluid (fistula), that there is severe loss of hearing in the operated ear, to the extent that one may not be able to benefit from a hearing aid in that ear.
When further loss of hearing occurs in the operated ear, head noise may be more pronounced. Unsteadiness may persist for some time. For this reason, the poorer hearing ear is usually selected for surgery.
However these complications are extremely rare.
Complications, Risks & Sequelae of Stapedotomy
Vertigovertigo is normal for a few hours following stapes surgery and nausea and vomiting may occur. Some unsteadiness is common during the first few postoperative days; dizziness on sudden head motion may rarely persist for several weeks. On very rare occasions, dizziness is prolonged.
Taste Disturbance and Mouth DrynessTaste disturbance and mouth dryness is not uncommon for a few weeks following surgery. In 5% of the patients, this disturbance may be prolonged.
Loss of HearingFurther hearing loss develops in 2% of the patients due to some complications in the healing process. In less than 1% this hearing loss is severe and may prevent the use of an aid in the operated ear.
TinnitusShould the hearing be worse following stapedectomy, tinnitus (head noise) likewise may be more pronounced.
Eardrum PerforationA perforation (hole) in the eardrum membrane is an unusual complicationand usually is due to an infection. Fortunately, should this complication occur, the membrane may heal spontaneously. If healing does not occur, surgical repair (myringoplasty) may be required.
Weakness of the FaceA very rare complication of stapedectomy is temporary weakness of the face. This may occur as the result of an abnormality or swelling of the facial nerve. . It develops in less than 0.5%
Q: If my initial result was good and the problem recurred, can I be re-operated?Yes, provided that the loss of hearing is conductive.
An audiogram will reveal the nature of the hearing loss.
Generally, conductive loss is treatable, whereas sensori-Neural loss cannot be restored.
Re-operation can be performed, and in most cases an excellent result can be obtained. However, the risk in revision operation is slightly higher. This differs from a case-to-case basis, and the individual risk should be discussed with the treating surgeon.
Sensori-neural loss following surgery is mostly due to aPERILYMPH FISTULA.
Q: What is a perilymph fistula?It is the leakage of perilymphatic fluids (fluids of the inner ear) due to non- closure of the opening made in the stapes footplate.
Causes of Perilymph Fistula
- Long piston
- Large hole
- Pulled in by adhesions from lenticular process to raw promontory
- Pushed in by Acoustic trauma / Barotrauma
N. B. : A Gusher will not cause a fistula if the operation has been performed according to the principles outlined above.
A fistula by itself does not cause deafness. If you do a direct piston operation, do not seal & reflect the drum back, an Intra operative audiogram will show good hearing though there is a fistula till an endosteal membrane forms.
Diagnosis of a Perllymph FistulaApart from the usual methods of presentation which are well known, we would only like to emphasize the necessity of comparing the bone conduction of the operated with the bone conduction of the unoperated ear at follow-up.
Bone conduction of the operated ear has fallen below B.C. of unoperated ear after an initial good result.It is well known that the cochlear function of the unoperated ear deteriorates faster than that of the operated ear quite apart from the Carhart correction. This probably is due to disuse, as cochlear otosclerosis and presbyacusis should normally have similar effects on both sides. If at any time we see an audiogram where the B.C. of the operated ear after an initial good result drops below the b.c . of the unoperated ear on long term follow-up, we would explore for fistula.
At surgery, the piston must be removed and if the endothelial tube surrounding the piston is isolated on dry gelfoam under high magnification, a drop of perilymph can be identified emerging from it.
The commonest cause of a fistula and late S.N. loss is a long piston.The piston should project no more than 0.2 mm into the vestibule. This accuracy is only possible with the small 0.4 mm or medium 0.8 mm fenestra technique as you have the edge of the footplate as a reference point for judging the piston length. Even if the initial measurement is perfect, the piston can be pulled in by contraction of fibrous adhesions from the lenticular process to the promontory.
The second cause of fistula is inadvertent excessive footplate removal.If a large part of the footplate is hooked out, the rounded edge of the oval window makes this grade of accuracy of measurement very difficult. Late bulging of the blue membrane which forms, which is directly proportional to the extent of footplate removal, will almost inevitably result in late S.N. loss due to a fistula even if soft tissue interposition has been used. So, in case of inadvertent total/subtotal footplate removal, a direct piston technique with or without soft tissue interposition is contra-indicated.
Please note that what you put around the piston whether it is gelfoam or connective tissue is not material, as the perilymph leak that develops is submucosal.
In our clinic in such rare cases we cover the oval window with vein or perichondrium and use a cartilage connection from the incus to the oval window or the posterior crus of the stapes.
Hearing Aids & OtosclerosisIf the patient refuses surgery in spite of being a suitable candidate for surgery, he should benefit from a properly fitted hearing aid. If the patient has otosclerosis and is not suitable for stapes surgery, occasionally the patient may benefit from a properly fitted aid. However, otosclerosis is a progressive disease, and worsening of the ear is to be expected. The rate of progress of disease cannot be predicted.
Medications :Please inform our staff 1 week in advance if you are taking the following medications:
- Pain killers & anti-inflammatory drugs including Brufen, Combiflam
- Anti-platelet agents such as Disprin or Clopidogrel
- Anti-epileptic medications
- Anti-diabetic medications
- Anti-hypertension medications
- Anti-depressants or psychiatric medications
If you have any doubts regarding your medications, please show your personal physician this list or call us.
Do not take any aspirin containing medication including cold formulas for at least one week prior to surgery. These compounds have a tendency to decrease the average clotting capacity and increase bleeding during surgery. Crocin or Calpol may be used instead as it does not have these untoward effects.
Smoking and alcoholSmoking and alcohol significantly increases the risk of complications, bleeding and wound healing problems. Therefore, DO NOT SMOKE for at least two weeks before and six weeks after surgery . This also applies to second hand smoke; therefore do not stay in the room with cigarette smokers.
DO NOT DRINK ALCOHOL for at least 1 week before and 1 week after surgery.
Pre-operative LabsPreoperative blood investigations must be obtained and reviewed prior to surgery. You will be asked to visit the hospital where you will meet with the doctors.
Soap for BodyUse Dettol soap (over-the-counter antibacterial skin cleanser) in the shower instead of soap for three days prior to surgery.
Shampoo your hair and wash your face on the morning of the operation.
DO NOT OIL YOUR HAIR.
In case you are having a throat operation, please brush your teeth.
In case you are having a nose operation, males should trim their moustache.
Notification of IllnessesNotify our office promptly if cold, fever, or any illness appears before surgery. Call in any allergies, medications, or conditions which you may have forgotten to tell us about.
The Night Before SurgeryDo not eat or drink anything after midnight the night before surgery. This includes gum, chocolate, milk, tea, coffee and water.
If you are diabetic and take insulin you will be instructed how to take your medication and discuss this with your anesthesiologist during the preoperative visit.
FAILURE TO COMPLY WITH THESE INSTRUCTIONS MAY RESULT IN CANCELLATION OR DELAY OF YOUR OPERATION.
IF YOU HAVE ANY DOUBTS OR QUESTIONS, PLEASE CONTACT US FROM 4:00PM TO 11:00PM ON ANY WORKING DAY.