Hearing impairment

Introduction Hearing impairment refers to a structural defect of the auditory organ due to congenital or acquired causes, or a partial or total disorder of the function, resulting in difficulty in listening or recognizing the sound. Sound waves have different amplitudes and frequencies. The amplitude is the peak pressure change of the sound wave, and the frequency is the number of times the sound wave changes periodically every second. Compared to the same kind, a creature that loses its ability to sense sound at certain frequencies, or cannot hear a lower amplitude sound, may indicate that the creature is suffering from hearing impairment.

Cause

Due to congenital or acquired causes, the structural defects of the auditory organs, or some or all of the obstacles to the function of the hearing, make it difficult to listen or recognize the sound. Most hearing defects are acquired conductive hearing loss, with otitis media and its sequelae. related. Almost all children have experienced mild to moderate, intermittent or persistent hearing loss caused by otitis media. Repeated episodes or severe infections can lead to permanent defects. The most susceptible to otitis media are those with cranial facial abnormalities (such as cleft palate), immunodeficiency (such as infants with temporary hypogammaglobulinemia), and exposure to environmental risk factors (such as swallowing, day care). Boys are more susceptible to otitis media than girls.

an examination

Related inspection

Otolaryngology CT examination of newborn hearing screening

Ordinary hearing tests require subjective responses to the sounds heard, but are not suitable for very small children, because this method requires the child's cooperation. Here are a few examples of children's hearing tests.

Middle ear impedance and acoustic reflection test

Check the condition of the middle ear of infants and young children.

Otoacoustic emission (OAE)

This test can be done quickly without the active cooperation of children, so it is often used for newborn hearing. If you want to get the activity of hair cells when the inner ear is stimulated by sound, you need to test when the child is quiet or asleep.

Brain stem evoked potential (ABR)

This test is based on sound stimulation to detect brain waves, and does not require active coordination by children. But it is longer than the otoacoustic emission test. The test results are very useful for children's choice of hearing aids. Therefore, the test takes a long time, so it is best to test while the child is sleeping. Brain stem evoked potential is a more accurate guest observation method. The patient is painless during the test and is not affected by the patient's subjective will and state of consciousness, but needs to be completely relaxed, or in a state of sleep, anesthesia or coma. Subject's age, gender, body temperature, medication, mental state, test environment, filtering range, and electrode location all have an impact on ABR.

Multi-frequency steady-state evoked potential (ASSR)

This test is an objective hearing test with frequency characteristics, which has been gradually applied in recent years. Clinical application with auditory brainstem evoked potentials provides a direct basis for early diagnosis and early hearing compensation of deafness. Generally, in 95% of cases, the difference between the infant hearing threshold and the behavioral listening threshold predicted by ASSR is within 20 dB. The more severe the hearing, the closer the relationship between the ASSR threshold and the behavioral audiogram. A number of studies have demonstrated that ASSR can accurately test the hearing of younger infants and children, while increasing the accuracy of hearing aids for infants.

Behavioral Hearing Test (BOA)

Hearing can be checked for children from 6 months to 3 years old.

Differential diagnosis

1. Acoustic neuroma: more common in adults, patients with slow onset, progressive hearing loss, sensorineural deafness, no recurrence; often have other symptoms of cranial nerve damage.

2. Brain stem lesions: vascular and tumor lesions of the brain stem, persistent vertigo symptoms, often nystagmus, hearing loss and other signs of nervous system.

3. Cochlear nerve drug toxicity damage: more common in children, causing cochlear nerve damage more drugs, but the extent and location of various drugs for cochlear nerve damage are not the same, some are biased in the cochlea, and some are biased in the vestibule, Or both.

Streptomycin sulfate and gentamicin mainly affect the vestibule, dihydrostreptomycin, neomycin, kanamycin, and vancomycin affect the cochlea. Among them, neomycin affects the most severe cochlea, and sulfa drugs can cause hearing. Decreased and tinnitus, but if vestibular symptoms occur, hearing impairment will be difficult to recover. Salicylic acid drugs can cause hearing loss in patients who are overdose or drug allergic, mainly degeneration of cochlear spiral ganglion cells, and the degree of damage is lighter. Easy to recover.

4. Cholesteatoma is a benign tumor that often occurs in untreated otitis media patients, but also congenital. Cholesteatoma can lead to necrosis of the ossicular chain and conductive hearing loss. Infection and closure of the middle ear can also lead to structural damage to the auditory bone. The long-term pathological process of the incus is the most common influencing factor and can result in significant conductive hearing loss.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.