Conductive deafness is deafness caused by sound pressure waves not being transmitted to cochlea through normal gas conduction. It is characterized by good speech discrimination, relatively good hearing under noise background and abnormal air conduction of audiogram. However, normal bone conduction can lead to conductive deafness:
(1) The most common cause of cerumen is cerumen blocking the external auditory canal, and the treatment is to remove cerumen by doctors.
(2) Congenital atresia and auricle hypoplasia can be treated by appropriate surgery.
(3) Otitis Media Otitis Media is the most common cause of conductive deafness. The highest incidence rate is among preschool children, which gradually decreases after the age of 6, and some patients become chronic. Repeated attacks can cause hearing loss, generally 20~40dB (decibel), and some can reach 60~70dB.
(4) Pollen allergy with severe allergy can cause external auditory canal obstruction and induce otitis media.
(5) Trauma of external ear or middle ear can cause rupture or perforation of tympanic membrane.
(6) Cholesteatoma
(7) Otosclerosis This is a hereditary bone disease, with air-conduction hearing loss of about 60dB and bone-conduction hearing loss of about 15dB.
2. Sensory nerve deafness
Hearing loss caused by pathological changes in the inner ear or the neural pathway from the inner ear to the brain stem is called sensorineural deafness. The cause can be congenital or acquired, and the drug treatment effect is not good. The auditory characteristics are that it is difficult to recognize different degrees of speech, there is no air-bone conduction gap, and it is difficult to hear clearly in the noise background. If the hearing is not too bad, such patients, especially children, can achieve better results through hearing AIDS and listening and speech training. The causes of sensorineural deafness are:
(1) ototoxic drugs
Excessive use of drugs can cause deafness, such as quinidine, aspirin, streptomycin, kanamycin and gentamicin. It is characterized by hearing loss, dizziness, ear swelling and unstable gait. At present, ototoxic drug poisoning causes the largest proportion of hearing damage in children, about 30%~40%.
(2) Congenital hearing impairment
Congenital sensorineural deafness may be caused by genetic defects or fetal injury during pregnancy, and rubella has the greatest impact on children's hearing in the first three months of pregnancy; Mumps and neonatal infectious diseases may cause inner ear damage; Birth injury, hypoxia or septicemia can lead to deafness.
(3) Acquired deafness caused by bacterial meningitis
If it occurs between/kloc-0 and 2 years old, it can lead to severe deafness, which is the most common cause of acquired severe deafness in the United States in the 1920s.
(4) Meniere's disease (Meniere? S disease)
The disease can cause low-frequency hearing impairment, which can affect all frequencies with the deterioration of the disease, and even cause complete deafness, usually unilateral.
(5) acoustic neuroma
Deafness, usually unilateral, is caused by tumor compressing the eighth cranial nerve trunk between cochlea and brain stem.
(6) Noise-induced hearing loss and acoustic accidents
This kind of deafness is rare among children.
3. Mixed deafness
Patients have both conductive and sensorineural deafness symptoms, and the hearing loss of air conduction is usually greater than that of bone conduction.
4. Central deafness
Pathological changes in the pathway from brain stem to temporal lobe of cerebral cortex can cause central deafness.
(1) organic hearing impairment
It can be caused by infection, such as encephalitis, meningitis, syphilis, multiple sclerosis, cerebrovascular accident, gunshot wound, skull fracture birth injury, brain tumor, etc.
(2) Word hearing impairment (sensory aphasia)
It is characterized by the inability to understand the meaning of words, to speak words and to express ideas in words, which is common in the injury of parietal lobe and temporal lobe.
(3) Congenital aphasia
Some children have great difficulty in learning languages and cannot develop oral expression. It has been found that some of these children have obvious intermediate frequency hearing impairment. 5. Functional deafness (1) Pseudodeafness is common in adults. 2. Mental deafness is common in patients with hysteria.