Cochlear Implantation
A cochlear implant helps generate sound perception in the brain, and a cochlear implant system has an external and internal part. The external part contains a microphone, a speech processor, a battery, and transmitter, which detects sound from the environment and delivers it into the internal part. The internal device (implanted between the muscle and bone under the ear) receives transmitted signals sent from the external part, and stimulates the cochlea through electrical impulses [51].
Cochlear implantation is frequently referred to as the “treatment of choice” for patients with severe-to-profound sensorineural hearing loss [52]–[54]. Patients must have no anatomical contraindications to be considered for implantation [51]. Absolute indications of cochlear implantation are observed in patients with acute hearing loss after meningitis, deafness and severe visual impairment, and sudden bilateral hearing loss [51].
Cochlear implantation in Pendred Syndrome patients with severe to profound hearing loss results in positive outcomes, with proven benefits in speech perception and speech intelligibility [55]–[57].
Demir et al. concluded that vestibular aqueduct diameter and inner-ear malformations have no impact on audiological outcomes after cochlear implantation [56]. Studies demonstrated that children with SLC26A4 mutations have better outcomes than those with genetically undiagnosed hearing loss, since genetic consequences in Pendred syndrome are in the inner ear, rather than the auditory nerve and central auditory pathways [55], [58]–[60].
Studies support that cochlear implantation should occur before the age of 3.5 years [55], especially in children with fluctuating hearing loss so that speech and language development should not be impaired [61], [62]
One complication of cochlear implantation is the cerebrospinal fluid “gusher”, or the egress of clear fluid upon cochleostomy. However, there are no effects of meningitis or auditory outcomes [63].
Patient with an enlarged thyroid gland (goiter)
3.2 Enlarged Vestibular Aqueduct Treatment
No treatment exists to reduce hearing loss associated with an enlarged vestibular aqueduct. To prevent hearing loss from becoming more severe, patients should avoid head injury by wearing head protection and avoiding situations that lead to extreme, rapid changes in air pressure such as scuba diving or hyperbaric oxygen treatment [63].
Patients who are experiencing vertigo can be treated with anticholinergics or benzodiazepines. These medications are able to modify the intensity of symptoms by suppressing the vestibular aqueduct [64].
Hypothyroidism Treatment
Hypothyroidism refers to thyroid hormone deficiency. Overt hypothyroidism is diagnosed once the thyroid-stimulating hormone (TSH) concentrations are above the reference range (0–4-4–0 mIU/L) and free thyroxine concentrations are below the reference range. Mild and subclinical hypothyroidism is defined once the TSH concentrations are above the reference range and free thyroxine concentrations within the normal range [66].
Symptoms of hypothyroidism include an increase in body-max index, low metabolic rate, fatigue, shortness of breath, muscle weakness, dry skin, hair loss, deterioration of kidney function, and neuropathy. Hypothyroidism has also been reported to cause cochlear dysfunction and decreased hearing [67].
Currently, the preferred treatment for hypothyroidism is levothyroxine monotherapy in solid formulation taken on an empty stomach. The optimal daily dose is 1.5-1.8 μg per kg of bodyweight [54], [68], [69]. Patients with low body weight or older patients will not be able to withstand dose changes, since it can have substantial effects on serum TSH concentrations [67].
The target of treatment is to normalize TSH concentrations and help physical and mental complaints [70]. However, 35-60% of patients do not reach the target range of TSH after treatment due to overtreatment or undertreatment [70], [71]. 6% of patients experience undertreatment (TSH concentrations below 0-1 mIU/L) and 10% experience overtreatment (10-0 mIU/L) [72].
An explanation for persistent complaints after levothyroxine monotherapy could be the treatment itself. This therapy ensures adequate concentrations of circulating thyroxine that is converted to triiodothyronine by deiodination of deiodinase 1 and deiodinase 2. Meanwhile, in euthyroid patients, 20% of circulating triiodothyronine is converted from direct thyroidal secretion [72]–[74].
Another treatment method is using combined levothyroxine-liothyronine therapy. This therapy helps patients with a preference for combination therapy or an improved metabolic profile, however other than that, there are generally no other improved outcomes [75]–[77].