THERE ARE FOUR TREATMENT OPTIONS OF OTOSCLEROSIS.

1.        Do nothing: Otosclerosis does not have to be treated.  It is usually advisable to have a hearing test repeated once a year, or more often if hearing lessens.

2.        Hearing aid: Hearing aids are usually effective for conductive hearing loss.

3.        Medical treatment: To date the only proposed medical treatment has been sodium fluoride, which is a dietary supplement, not a drug in association with calcium and vitamin D. Some investigators have also proposed bisphosphonates (e.g. etidronate) as inhibitor agents of bone resorption.

4.        Surgical treatment: Surgery may be useful only in those patients presenting a hearing loss so severe that the bone threshold cannot be evaluated and a gap between air and bone conduction cannot be excluded; in these cases stapes operations can improve hearing to a level that may be useful in hearing aid application. The current standard surgical technique, the stapedectomy, produces excellent hearing result, that remain for many years after the surgery.  This procedure may allow avoidance of hearing aids.  However, it does not help the sensory component of the hearing loss and at best may close the air-bone gap.

MEDICAL TREATMENT

The medical management of cochlear otosclerosis is based on sodium fluoride, in association with calcium and vitamin D; some authors have also proposed diphosphonates as inhibitor agents of bone resorption. The acceptable medical treatment of otosclerosis today continues to be the administration of sodium fluoride in combination with calcium carbonate.

ACTION OF FLUORIDE

Fluoride reduces osteoclastic bone resorption and in creases osteoblastic bone formation.  Cause and Chevance ⁽¹⁾  (1973) suggests in addition, that in otosclerosis there is an antienzymatic action on proteolytic enzymes that are cytotoxic to the cochlea and produce sensorineural deafness Petrovic and Shambauch ⁽²⁾  (1966b) carried out convincing experiments demonstrating that the level of acid phenyl pnosphatase-an enzyme whose level in increased by osteoclastic bone resorption is high in immature otosclerotic bone and much reduced after long-term fluoride therapy.  The uptake of radioactive calcium is a measure of osteoblastic new bone formation and otosclerotic bone shows a greater uptake than normal bone, but if the lesion is immature i.e. active otosclerosis-the uptake is far greater than in the case of an inactive focus or mature otosclerosis.  After long-term therapy with fluorides the uptake of calcium drops sharply, showing a maturation of the focus.

The final evidence that fluoride therapy reduces the enzyme activity of the focus, and so is of value in prevention of sensorineural deafness, is an observation of Causse et al (1989) ⁽³⁾ , that untreated otosclerotic patients, with preoperative progressive sensorineural hearing loss have proteolytic enzymes in the perilymph in a high proportion of cases, but similar patients who have had sodium fluoride treatment rarely show such enzymes in perilymph samples removed during stapedectomy. According to Grayeli AB, et al ⁽¹⁶⁾ , (2003), believe that whether the increased diastrophic dysphasia sulfate transporters (DTDST) activity is a cause or an effect of otosclerosis, it appears to be a specific target for NaF treatment. DTDST is implicated in the regulation of the bone turnover

INDICATIONS FOR SODIUM FLUORIDE THERAPY ⁽⁴⁾

Sodium Fluoride therapy is indicated in the following groups of patients.

1.        Patients with surgically confirmed otosclerosis, which has shown progressive sensorineural deafness disproportionate with age.

2.        Patients with pure sensorineural deafness whose family history, age of onset, audiometric pattern and good auditory discrimination indicate the possibility of cochlear otosclerosis.

3.        Patients with radiological demonstration by polytomography of spongiotic changes in the cochlear capsule.

4.        Patients with positive Schwartze sign.

5.        Pre-operative administration.  When a patient has a focus of otosclerosis which shows activity as evidenced by a positive Schwartze sign, progressive sensorineural hearing loss observed by an audiometry over a period of twelve months, or polytomographic radiological evidence of a demineralized focus in the cochlear capsule, both Shambaugh and Causse ⁽⁵⁾ are of the opinion that a substantial reduction in the vascularity and remodeling of the focus will result from this treatment, Generally the patients with otoscleorosis are followed up by audiometry for one or two years before stapedectomy.  If there is progression of the cochlear component of hearing loss, fluoride therapy is given before operation.

6.         Postoperative treatment:  When patients are found to have an active focus at operation, fluoride therapy is prescribed for two years or more. 

7.        Early stages of otosclerosis:  Colletti and Fiorino ⁽⁶⁾ evaluated the effectiveness of Na F treatment in modifying the natural course of subclinical otosclerosis, as monitored by the stapedius reflex.  The study was carried out on 128 relatives of patients suffering from surgically confirmed footplate otosclerosis.  The diagnosis of subclinical otosclerosis was made on the basis of presence of the on-off effect One group of subjects was treated with NaF in doses ranging from 6-16 according to age.  The treatment lasted 2 years.  A second group served as a control.  Change in stapedius reflex morphology were evaluated at 1, 2, and 5 years from the onset of treatment.  The investigation demonstrated that NaF has a stabilizing effect on early otosclerosis.  This drug, in fact, arrests the disease process in more than 60 percent of ears at the 2-year follow up and in more than 50 percent at 5 years.  A program of secondary prevention of otosclerosis by NaF was suggested.

CONTRAINDCATIONS TO SODIUM FLUORIDE

ΤΗΕRAPY

Sodium fluoride has now been used for 34 years in an effort to slow down or arrest sensorineural hearing nerve deterioration in patients with stapedial otosclerosis or after stapedectomy as well as in patient with pure cochlear otosclerosis.  Extensive clinical experience in thousands, of patients with this therapy has demonstrated its value in arresting previously progressive sensorineural hearing loss.  For a long time there were those who objected to this therapy on the basis that it had not been adequately proven by double-blind, placebo-controlled studies.

But several investigators confirmed on small groups the value of sodium fluoride by double-blind, placebo-controlled studies.

With tissue cultures demonstrated the action of sodium fluoride on bone.  In studies with radioactive strontium it was demonstrated the value of sodium fluoride in promoting maturation of a spongiotic focus ⁽⁷⁾ .  In spite the fact that there is no   reason to hesitate in prescribing this useful, effective, and safe medication to promote maturation of otospongiotic lesions, and thus to slow down or to arrest progression in sensorineural hearing loss Sodium Fluoride treatment has some contraindications.

1.        Patients with chronic nephritis with nitrogen retention.

2.        Patient, with chronic rheumatoid arthritis there may be an increase of the joint symptoms during treatment, which  subside after cessation.

3.        Pregnant or lactating women.

4.        In children before skeletal growth end been achieved.

 5. Allergic to fluoride with induces itching rash

DOSAGE AND ADMINISTRATION OF SODIUM FLUORIDE

According to Scambauch and Glasscock ⁽⁸⁾ .When there is evidence of an active lesion a daily dose of 50mg sodium fluoride has been given for two years.  In a very active case with a positive Schwartze sign the dose is increased to 75mg daily.  When there is evidence of stabilization of hearing, fading of the Schwartze sign and radiological sign of recalcification of the focus, a daily maintenance dose of 16-25mg is given for the rest of the patient' s life. Clinical experience suggests that a somewhat smaller dose of 50 mg daily achieved by taking two capsules with each meal, may be as effective as the larger dose ⁽⁸⁾ .

  Side effects occur about as frequently as with aspirin ; a single very large dose of 5000mg can be fatal and drug should therefore be kept out of the reach of children ⁽⁹⁾ .

Sodium fluoride (Florical, Monocal) used as a dietary supplement contain 8,3 mg.  NaF and 364 mg calcium carbonate combined in a capsule . 24 mg NaF with 1092 mg of calcium carbonate , which is sufficient to supply the necessary calcium for the new bone formation stimulated by the fluoride.

During the winter time, one multivitamin tablet is taken to supply 400 units of vitamin D to ensure intestinal absorption of the calcium.

According to Colleti and Fiorino the dose of 6 to 16 mg of NaF according to age, daily administered for two year is sufficient for the treatment of early cases of otosclerosis . The drug in fact arrests the disease process in more than 60 percent of the ears at the 2-year follow-up and in more that’s 50% at 5 years.

      According to Derks et al (2001)⁽¹⁵⁾ The progress of sensorineural hearing loss (SNHL) in patients with cochlear otosclerosis was compared for 19 patients treated with fluoride for 1-5 years and 22 untreated controls. CT scans of eight patients before and after fluoride treatment were evaluated visually. Fluoride therapy arrested the progression of SNHL in the low (250, 500 and 1,000 Hz) (p < 0.001) and high (2 and 4 kHz) (p = 0.008) frequencies. It seemed to be more effective for the higher frequencies in cases with an initial SNHL of < 50 dB. Fluoride administration for 4 years did not seem to be superior to a shorter treatment period (1-2 years). For six patients followed up after discontinuing fluoride therapy there was minimal deterioration in SNHL. There was no clear relationship between the size and site of otospongiotic lesions on CT and the severity of SNHL. Follow-up with CT evaluation did not provide reliable information as to the efficacy of fluoride therapy.

       Several investigators suggest diphosphonates as inhibitor agents of bone resorption (e g. etidronate). The efficacy of etidronate, was assessed as a treatment for the inner ear symptoms, of otosclerosis in a retrospect, with primary complain of dizziness, hearing loss, tinnitus or Menier's syndrome.

The diagnosis of otosclerosis was based no small-pixel computed tomography of the temporal bones.  Of the 896 patients placed on an etidronate protocol, 545 were followed for more than six months and were analyzed.  The symptomatic response to editronate, as well as audiologic and computerized rotary chair results wore used in the assessment.  In this preliminary    study etidronate appeared to be an effective treatment for the new otologic symptoms of Otosclerosis ⁽⁶⁾ .  Prospective blinded efficacy studies of the bisphosphonates in the treatment of otosclerosis should be unclear taken.