Sudden deafness, also known as idiopathic sudden deafness and idiopathic sudden sensorineural deafness, is a sudden sensorineural hearing loss with no apparent cause. Sudden deafness can occur at all ages, with the best age of onset being 50 years old.
Clinical symptoms and diagnostic criteria of sudden deafness
Patients with sudden deafness generally experience sudden onset of unilateral dullness in the ear, often accompanied by tinnitus and/or dizziness. Patients with combined dizziness and tinnitus will usually seek medical attention in a timely manner, while patients with only simple deafness will often think that they are “on fire” and will get better after two days of “resistance” and will not seek medical attention, thus delaying the best time for diagnosis and treatment.
During the consultation, the doctor will inquire about the patient’s symptoms, current medical history, past medical history, personal history, and conduct a routine otologic examination to rule out conductive hearing disorders caused by common causes such as external auditory canal obstruction, tympanic membrane perforation, and otitis media, etc. Then, he will conduct acoustic conductance and pure tone audiometry, and if necessary, conduct auditory brainstem evoked potentials, otoacoustic emissions, auditory steady-state response, speech recognition rate, and CT or MRI of the inner ear internal auditory canal. The diagnosis of sudden deafness, as well as the typology and degree of hearing loss, can be made only after CT or MRI examinations, except for associated diseases that need to be identified. Once the diagnosis is confirmed, immediate treatment is imperative and should not be delayed.
The 2005 diagnostic criteria for sudden deafness of the Chinese Medical Association, Otolaryngology Branch include
1. Sudden onset, which can occur within minutes, hours or 3 days.
2. Non-fluctuating sensorineural hearing loss, which can be mild, moderate or severe, or even total deafness; hearing loss of at least 20dB at at least two connected frequencies; mostly unilateral, occasionally occurring bilaterally at the same time or sequentially.
3.The cause is unknown (no clear cause is found, including systemic or local factors).
4.It may be accompanied by tinnitus and ear blockage.
5.It may be accompanied by vertigo, nausea and vomiting, but not recurrent. 6. There are no symptoms of cranial nerve damage other than the eighth cranial nerve.
Causes of sudden deafness
Studies have shown that inner ear microcirculation disorders, viral infections, immune factors leading to inner ear hair cell dysfunction and damage to the physiological structures of the inner ear are important causes of sudden deafness, and each etiological hypothesis can explain the pathogenesis of some patients, but no single etiological hypothesis can explain all cases, so it is called unknown etiology. Whether it is a microcirculatory disorder in the inner ear or a viral infection or immune factor, it eventually leads to impaired blood supply to the spiral ganglia, cochlear neurons and auditory hair cells in the inner ear, resulting in edema, followed by degeneration and atrophy, causing reduced or even absent inner ear sensory function. Moreover, since the cochlear branch of the vagus artery in the inner ear has no collateral circulation, if the microcirculation is not improved in time to increase the blood and oxygen supply to the spiral ganglia, cochlear neurons and auditory hair cells, it will lead to irreversible damage to the inner ear peripheral receptors and permanent hearing loss.
Systemic systemic therapy for sudden deafness includes.
Drugs to improve inner ear microcirculation, glucocorticoids, neurotrophic drugs, blood viscosity reduction, inhibition of thrombus coagulation, fibrinogen reduction, vasodilator drugs, antioxidants, ion channel blocking therapy, endolymphatic volume reduction, hyperbaric oxygen therapy, antiviral therapy, etc. Local treatment includes: intra-drum chamber administration or cochlear window administration, mainly glucocorticoids.
In view of the complexity of the cause of sudden deafness, the clinical treatment is usually combined with multiple methods.
This is called “cocktail” therapy, such as drugs to improve inner ear microcirculation + glucocorticoids + neurotrophic drugs + hyperbaric oxygen therapy. It is worth noting that glucocorticoids, which are usually feared by patients, have very definite efficacy in the treatment of sudden deafness, with a comparative study showing that the total effective rate of treatment of sudden deafness with glucocorticoids reached 83%, while the total effective rate without glucocorticoids was only 44%. Although viral infection is one of the etiologies of sudden deafness, a large number of prospective, randomized controlled studies have shown that the addition of antiviral drugs to treat sudden deafness does not have better efficacy.
At present, sudden deafness is usually clinically classified into four types, and different treatment regimens are used for different types of sudden deafness, and their therapeutic effects vary greatly.
1.Low-moderate frequency descending type: this type of sudden deafness is thought to be caused by membrane vagus fluid accumulation, and the treatment principles are to improve inner ear microcirculation, glucocorticoids, and endolymphatic volume reduction therapy, etc. This type has the best prognosis.
2.Mid-high frequency drop type: It may be related to hair cell damage, so the treatment principle is recommended to use glucocorticoids, improve inner ear microcirculation, ion channel blockers, neurotrophic drugs, etc. The prognosis of this type is poor.
3.Flat type: Hearing loss below severe level in all frequencies may be caused by inner ear vasospasm, so the treatment principle is mainly to release vasospasm, reduce blood fibrinogen, glucocorticoids, improve inner ear microcirculation treatment, etc. The prognosis of this type is better.
4. Total deafness type: Very severe or more deafness occurs in all frequencies, which may be related to inner ear vascular embolism or thrombosis, often accompanied by vertigo. The treatment principles are thrombolysis, lowering blood fibrinogen, glucocorticoids, improving inner ear microcirculation, etc. This type has the worst prognosis.
Effectiveness of treatment of sudden deafness
The overall efficiency of treatment for sudden deafness is reported in the literature to be between 50 and 80%. There are various factors affecting the outcome of sudden deafness treatment, including disease duration, age, comorbidities, systemic underlying pathology, and lifestyle habits. First, the prognosis of sudden deafness is closely related to the duration of the disease, and the treatment outcome is better for the duration of the disease within 7 days than for the duration of the disease greater than 7 days. One study showed that the total effective rate of treatment was 92% for patients seen within 1 week and 84% for patients seen within 2 weeks. Therefore, patients with sudden onset deafness should be detected as early as possible and treated as soon as possible.
Age is another important factor affecting prognosis.
The total treatment efficiency of sudden deafness in elderly patients is not significantly different from that of young and middle-aged patients, but the healing rate is significantly lower than that of young patients, so early detection and treatment as soon as possible are more required. The prognosis of sudden deafness is significantly related to the presence or absence of vertigo symptoms, and some studies have shown that the outcome of sudden deafness patients with vertigo symptoms is lower than that of sudden deafness patients without vertigo symptoms. Seventy percent of elderly patients with sudden deafness have combined hypertension and diabetes. Patients with sudden deafness with hypertension and diabetes have a higher chance of developing severe deafness than those without underlying pathology, while the treatment effect is the opposite. Sleep disorders, sleep deprivation, and violent mood swings are all relevant factors that can affect the treatment outcome or cause recurrence of symptoms.
Evaluation criteria for the efficacy of sudden deafness.
1.Cured: The hearing threshold of the damaged frequency returns to normal, or reaches the level of the healthy ear, or reaches the level before this disease.
2.Significant effect: The average hearing of the damaged frequency is improved by 30 dB or more.
3.Effective: the average hearing of the damaged frequency is improved by 15~30 dB.
4.Ineffective: the average hearing of the damaged frequency is improved by less than 15 dB. healing rate + significant rate + effective rate = total effective rate.
How people hear sound: 1.
1. Outer ear (auricle, external ear canal): sound passes through the ear canal and “hits” the eardrum.
2. Middle ear (tympanic membrane, auditory tuberosity): sound waves make the tympanic membrane vibrate and push the auditory tuberosity inside the middle ear to move.
3. Inner ear (cochlea): The movement of the auditory tuberosities in the middle ear causes the lymphatic fluid in the cochlea to move, stimulating the hair cells of the inner ear, which convert this movement into bioelectrical signals.
4. Auditory nerve: The electrical signal is transmitted to the auditory center of the brain through the auditory nerve, so that sound is heard.
Classification of deafness and how to protect hearing
Deafness is one of the most common human sensory system defects. 27.8 million people with hearing disabilities exist in China, accounting for 25% of the world’s hearing-impaired population. There are 149 million people over 60 years old in China, and more than 30% of them are suffering from deafness, which has become an important factor affecting the quality of life of the elderly in their later years. After the age of 50, the average hearing level decreases by 1 dB per year, but individual differences are great.
Deafness is classified into three categories: conductive deafness, sensorineural deafness and mixed deafness according to the location of the lesion.
Conductive deafness occurs in the outer ear and middle ear, while sensorineural deafness occurs in the cochlea, auditory nerve, and all levels of the auditory centers, and mixed deafness occurs in both.
The WHO 1997 criteria, classify deafness as follows.
Grade 0 (normal): 25 dB HL or less.
Grade 1 (mild): 26-40 dB HL.
Grade 2 (moderate): 41-60 dB HL.
Grade 3 (severe): 61-80 dB HL.
Grade 4 (very severe): 81 or greater than 81 dB HL.
Conductive deafness can be improved in most cases by clearing the external auditory canal obstruction and surgically reconstructing the middle ear structure, while sensorineural deafness, except for a few diseases such as sudden deafness, is mostly irreversible, so the focus is on hearing conservation and avoiding the various factors that lead to sensorineural deafness.
Common causative triggers include.
1. ototoxic drugs, including aminoglycoside antibiotics, anticancer chemotherapy drugs, tabular diuretics, nonsteroidal anti-inflammatory drugs, macrolide antibiotics, and antimalarial drugs.
2, strong noise.
3, sleep deprivation, sleep disorders.
4, hypertension, diabetes, hyperlipidemia; 5, smoking, alcohol; 6, violent mood swings.