User:Forsakendaemon/Audiology
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Audiology (from Latin [audīre] Error: {{Lang}}: text has italic markup (help), "to hear"; and from Greek -λογία, -logia) is a branch of science that studies hearing, balance, and related disorders.[1]: ix In a clinical setting, audiology is concerned with the diagnosis, assessment, and rehabilitation of disorders of the auditory and vestibular systems. [2]: 1–3
The practitioners of audiology are called audiologists. Audiologists may specialise in diagnostics, rehabilitation, or research, and may focus on hearing or balance. Some audiologists specialise in working with newborns, young children, patients with additional disabilities, or those with implantable devices such as cochlear implants and bone conduction hearing implants.
Auditory Audiology[edit]
Auditory audiology is that part of audiology concerned with the measurement of hearing, diagnosis of hearing disorders, and the rehabilitation of hearing loss. It is often associated with the provision of hearing aids, cochlear implants, or other hearing devices. It may be practiced by audiologists or audiometrists (a profession concerned with the measurement of hearing and the rehabilitation of hearing loss).
Diagnostics[edit]
A variety of tests may be used to assess hearing function. These tests may be subjective, requiring a behavioural response from the patient under investigation, or objective, measuring an automatic physiological response in the auditory system.
A full and accurate case history should be taken, which may inform which diagnostic tests are to be undertaken, explain the results of these tests, or suggest medical referral.
Common subjective tests used to assess hearing function are pure tone audiometry (and its variants play audiometry, visual response orientation audiometry, and behavioural observation audiometry), and speech audiometry, including both word and sentence tests. These tests present a stimulus to the patient (such as a pure tone, noise burst or speech) and require the patient to respond to the presence or content of the stimulus. Behavioural tests test the function of the auditory system as a whole, as they rely on the patient hearing and processing a sound before responding to it.
Objective tests used to assess auditory system function include impedance tests and electroacoustic tests. Impedance tests measure the movement of the tympanic membrane, and include tympanometry, acoustic reflex testing, and otoacoustic emmission measurements. Electroacoustic tests measure the electrcal signals in the auditory system elicited by acoustic stimuli, and include electrocochleography, auditory brainstem response, auditory steady-state response, and cortical acoustic evoked potentials. These tests may be able to identify the location of problems within the auditory system, as they do not require the entire auditory pathway to function to elicit a response.
Diagnostic information obtained through testing may suggest one of various disorders of the auditory system, including sensorineural hearing loss, conductive hearing loss, cholesteatoma, vestibular schwannoma (acoustic neuroma), or auditory neuropathy. If a medically relevant diagnosis is suspected, the patient should be referred to an otolaryngologist, neurologist or other medical specialist.
Rehabilitation[edit]
Rehabilitative auditory audiology focuses on the rehabilitation of a diagnosed hearing loss and associated disorders, including tinnitus.
A programme of auditory rehabilitation is generally designed to achieve one or more goals, which are set by the clinician and the patient. Once goals have been identified, and expectations discussed, options for rehabilitation will be presented to the patient. This may include fitting and verification of hearing aids, cochlear implants, or other hearing devices, communication training, and counselling to come to terms with the hearing loss or tinnitus.
Hearing aids are programmed by connecting them to a computer, and adjusted to provide a prescribed amount of sound output. Several prescription formulae exist. The amount of gain can be verified against the prescription through Real Ear Measures or in a hearing aid test chamber.
Cochlear implants are fitted in a similar way, although as the output is not sound the fitting cannot be verified in the same way. The procedure of setting up the voltage output of a cochlear implant processor is called mapping.
Communication training refers to activities designed to equip the patient and their communication partners with skills necessary to cope effectively with the hearing loss. It addresses functional issues with hearing that are not solved through the provision of hearing devices, such as residual difficulty hearing in background noise or on the telephone. It may involve various activities, including discussing good communication practice with communication partners, practicing the identification of strateges to deal with intrusive background noise in social situations, or training a patient to use a telephone effectively.
The rehabilitation programme may also be functionally assessed, by performing speech audiometry or through self-report questionnaires. These measurements are intended to ensure that any auditory rehabilitation programme achieves the goals identified by the patient and clinician, improving the patient's quality of life.
Vestibular Audiology[edit]
Vestibular audiology refers to the diagnosis, measurement, and mangement of vestibular disorders and related disorders of balance function. Due to the connected nature of the cochlea and vestibulum, as well as the similarities in function of their sensory cells, vestibular testing is often performed in concert with auditory testing.
Diagnostics[edit]
A variety of tests may be used to measure the fuction of the various components of the vestibular system, including the semicircular canals, otolithic organs (utricle and saccule), vestibular nerve, and vestibular nuclei.
Vestibular tests generally induce a change in one or more of the semicircular canals or otolithic organs, and then measure the effect of his change via the eyes (vestibulo-ocular reflex) or sternocleidomastoid (SCM) muscle (vestibulo-collic reflex). Ocular effects may be seen as nystagmus, and detected by electronystagmography or videonystagmography. Effects in the SCM may be detected using electrodes that record the electrical activity of the muscle.
Changes may be induced by the introduction of heat or cold to the ear canal (as in caloric reflex testing), using a loud sound (as in cervical vestibular evoked myogenic potential (cVEMP) testing), using a mechanical tap on the head (as in ocular vestibular evoked myogenic potential (oVEMP) testing), or by mechanically rotating the body as in the Dix-Hallpike test.
As much vestibular testing relies on proper function of the oculomotor system, tests of eye movement may also be undertaken, including a horizontal gaze nystagmus test, and tests of smooth pursuit and saccade ability.
Vestibular testing may assist with the diagnosis of particular kinds of disease, such as benign paroxysmal positional vertigo, Meniere's disease, vestibular neuronitis, labyrinthitis, or perilymph fistula.
If a disorder is suspected, referral will generally be made to an otolaryngologist or neurologist for further investigation (such as an MRI or CT scan) or drug treatment.
Rehabilitation[edit]
Treatments prescribed by an audiologist vary due to the different locations and severities of vestibular insufficiency. They may include head and eye movements, postural changes, and walking exercises aimed at alleviating symptoms and training the vestibular system to compensate for the insufficiency.
Actvities may include keeping the eyes fixated on a specific target while moving the head or walking, moving the head right to left to shift eye focus between two targets a significant distance apart, and walking while keeping eyes fixated on a specific target while also turning the head in different directions.[3]
By repeating a combination of head and eye movements, postural changes and walking, the central vestibular system (brainstem and cerebellum) will strengthen pathways associated with weaker peripheral function, restoring overall vestibular function and redcing symptoms. [3]
Disorders of the vestibular system may present with auditory symptoms, such as hearing loss and tinnitus, and so rehabilitation of the vestibular symptoms may not be sufficient to improve quality of life. In these cases, auditory reabiltation should be pursued concurrently.
Existing content to be edited[edit]
- ^ Gelfand, Stanley A. (2009). Essentials of Audiology (3 ed.). New York: Thieme Medical Publishers, Inc. ISBN 978-1-60406-044-7. Retrieved 17 March 2015.
- ^ Stach, Brad (2010). Clinical Audiology: An Introduction (2 ed.). Clifton Park, New York: Delmar. ISBN 978-0-766-86288-3. Retrieved 17 March 2015.
- ^ a b Walker, MF (January 2009). "Treatment of vestibular neuritis". Current treatment options in neurology. 11 (1): 41–5. doi:10.1007/s11940-009-0006-8. PMID 19094835.