2.2. Bases teóricas 1. Embarazo
2.2.3. Complicaciones Maternas en gestaciones de riesgo
While the previous statement holds true that those with only mild hearing loss are often best served by adapting to the deficit rather than purchasing expensive, potentially unhelpful hearing aids, there are certainly patients that will benefit from assistive devices. A moderate to severe hearing loss can produce a large impact on everyday safety, social interaction and employability. These individuals may truly benefit from amplification devices. Technological advances are always being made to improve modem hearing aids with better sound quality, smaller size and some remote controls to change programs for different environments. Recently, totally implantable hearing aids have been introduced so one does not have to worry about the nuisance of a device on the ear and its social implications. An otolaryngology referral is the best practice for the evaluation of hearing aids. Bypassing the otolaryngology specialist leaves the patient at the mercy of the hearing aid dispenser whose business of dispensing hearing aids is an inherent conflict of interest. Guess what-they sell hearing aids and profit directly from the sale.
Ear disorders may lead to deafness, a devastating loss of a primary sense.
Those deaf at birth or in infancy cannot hear anything so, it is nearly impossible to learn the spoken language. Deaf individuals learn by sight; thus, the spoken language is learned as a second language. Lip reading is
Clinical Manual of Otolaryngology
difficult, even for those who become deaf as adults. Hence, signing is the primary communication form for some individuals. There is great debate within the deaf community regarding the social implications of deafness and whether a deaf individual should aim to restore hearing. Some in the deaf community may feel isolated without the ability to hear; when they communicate to the rest of the world, it is through writing or an interpreter. The delayed deaf may miss the pleasures of music and voice of loved ones. Warning sounds used to protect and inform others, such as telephone rings and police sirens are not heard by deaf people. We normally live in a world of noise, a setting to which we are addicted. For those who lose their hearing after previously having it, life may seem lonely and isolated and they would like notrung more than to get their hearing back. On the contrary, some within the deaf community (particularly those with congenital deafness) feel equally strongly that there is nothing 'wrong' that needs to be fixed. There is a feeling that the deaf community is a culture and that effort to violate that culture by forcing the oral language upon it is irreverent.
For those with profound to total sensorineural hearing loss, rehabilitation may be achieved via cochlear implantation. Tills has become a relatively straightforward otologic surgery in which an electrode anay is implanted into the cochlea to provide direct stimulation of the spiral ganglion neurons, whose axons will then cany the signal back to the auditory nuclei in the brainstem. The device consists of an internal receiver and the electrode array. The receiver communicates transcutaneously with an external speech processor via radiofrequency. The external device consists of a behind-the ear processor which looks much like an ordinary hearing aid along with a transmitting coil that magnetically attaches to the receiver through the scalp
(Figures 2.6 to 2.8).
The cochlear implant does not restore normal hearing as it cannot completely replicate the complexity of the innate auditory system. The results of implantation are dependent on several factors, such as thedegree of hearing loss, anatomy of the ear, duration and cause of deafness,
surgical technique and patient motivation. It is ideally suited to two main populations: the prelingually deaf and the progressively deafened who no longer benefit from hearing aid use. When prelingually deafened children are implanted by the age of
2-3
years (a critical threshold for obtaining oral language), completely normal speech can be acrueved in many cases. For those with progressive hearing loss who can no longer carry on a conversation with optimum hearing aids, cochlear implantation can return their ability to talk with their loved ones and impart a tremendous social impact. Cochlear implant technology is continually improving, with devices aimed to improve frequency discrimination and preserve residual low frequency hearing.Figure 2.6: Schematic demonstrating the components of the cochlear implant systems. (1) The behind-the-ear microphone and speech processor which connects to the transmitter on the scalp; (2) The receiver/stimulator package that communicates with
the transmitter by radiofrequency; (3) The electrode array coiled along the contour of
the cochlea; (4) The cochlear nerve which will carry the signal back to the auditory nucleus in the brainstem
Figure 2.7: A frontal radiograph which shows the cochlear implant hardware in situ
Clinical Manual of Otolaryngology
Figure 2.8: A plain radiograph taken with the 'cochlear view' highlighting the tonotopic organization of the cochlea. From this image, it is possible to understand how programming of the cochlear implant will allow frequency discrimination in a fashion similar to the innate auditory system
Bilateral cochlear implants are now becoming rather common. In some settings, prelingually deafened adults are implanted to assist with environmental sound awareness. There is some evidence that cochlear implantation may be a useful tool for those with unilateral deafness and profound tinnitus. The choice of whether to proceed with cochlear implantation requires thorough audiological evaluation and careful discussion with an otologic surgeon. Patients must also keep in mind that success with the device can take months of practice and requires frequent work with their audiologist as well as great personal motivation.
Another recently introduced device for hearing restoration is the bone anchored hearing aid (BAHA). This is indicated for both the treatment of significant conductive hearing loss as well as single-sided deafness. Surgical placement of the device is quite straightforward. A titanium post is implanted into the temporal bone just above and behind the auricle, and an abutment then passes through the skin
(Figures 2.9 and 2.10).
After allowing for a period of osseointegration, a speech processor can then be attached to the abutment (this can be placed and removed as desired). The speech processor will process the environmental sound and then transmit vibration though the titanium implant.In the setting of conductive hearing loss, this vibration will
conduct to the ipsilateral ear to bypass the conductive loss. For a patient with single-sided deafness, the sound will be carried though the calvarium to the contralateral ear and thereby allow perception from the deaf side, eliminating the head-shadow effect that plagues unilateral deafness.There are other services available for the hearing impaired. Society provides training in sign language. It provides interpreters to help communicate
Figure 2.9: The components of the BAHA system. The fixture is screwed into the cortex of the temporal bone where it will osseointegrate. The abutment then attaches to the fixture and serves as a connection for the speech processor device
Figure 2.10: The BAHA system in place behind the ear. The speech processor will produce a vibration that travels through the temporal bone and reaches the cochlea, bypassing the normal conductive system of the middle ear
Clinical Manual of Otolaryngology
and take notes in school. There are vocational rehabilitation programs. Flashing telephone and doorbell signalers are available to help the hearing impaired. Nonetheless, communication is an enormous problem and physicians need to help the deaf individual when called on to do so. More can be learned about the deaf community, by visiting a school for the deaf or by contacting a social service agency that provides services to the deaf community or by contacting the Deafness Foundation.
Otalgia
Otalgia (ear pain) is a common complaint and although the cause is sometimes obvious, it can just as often be obscure. There are a multitude of causes of ear pain and unless a systematic approach is followed, important diagnoses may be missed.
Table 2.3
describes the differential diagnosis for ear pain. These areas noted in Table 2.3 are evaluated by direct examination, palpation, mirror examination, endoscopy, cultures, imaging studies and biopsies. Due to the potential risk of underlying malignancy and the primary care provider's limited ability to completely evaluate the upper aerodigestive tract, those patients with refractory otalgia should be referred to an otolaryngologist for evaluation.Table 2.3: Differential
External auditory canal
• Auricular hematoma
• Foreign body in the ear canal
• Obstructive cerumen/keratosis obturans • Otitis externa
• Malignant otitis externa
• External auditory canal tumor