Difference between revisions of "Hearing loss"
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Latest revision as of 15:17, 11 January 2020
- 1 Background
- 2 Clinical Features
- 3 Differential Diagnosis
- 4 Evaluation
- 5 Management
- 6 Disposition
- 7 References
- Sensorineural: involving the inner ear, cochlea, or auditory nerve
- Conductive: any mechanical factor blocking external sound from gaining access to the inner ear; ex: cerumen impaction, middle ear fluid, ossicular chain fixation
- Mixed: both sensorineural and conductive loss
- Should evaluate for recent medication changes, family history of hearing loss, personal history of trauma, recent scuba diving or flying (barotrauma), cold water exposure, onset/progression of hearing loss, high- vs low-pitch loss, history of ear surgeries
- Most common causes: presbycusis (i.e. natural aging of the auditory system), followed by noise-induced hearing loss
- 90% of cases are due to Sensorineural hearing loss, 10% due to Conductive causes
- Most bilateral cases that present gradually are benign. Sudden onset, unilateral hearing loss is more concerning for a serious cause.
- Varies by etiology
Sensorineural (Inner Ear)
- Sudden Sensorineural Hearing Loss (SSHL)
- Infections: (Meningitis, Viral cochleitis)
- Penetrating trauma
- Meniere Disease
- Autoimmune disease
- Multiple Sclerosis
- Cerebrovascular ischemia
- Tumors (Acoustic neuroma, Meningioma)
- Hereditary hearing loss
- Congenital viral infections
- Congenital malformations
- Ototoxic drugs: Aminoglycosides, Erythromycin, Tetracycline, chemotherapeutic agents, high-dose aspirin, phosphodiesterase-5 inhibitors (e.g. sildenafil, antimalarial drugs, Cocaine, Heavy Metals
- Otologic surgery
- Noise exposure
- Outer Ear
- Middle ear
Whispered voice test
Stand at arm’s length behind the patient and block hearing in one ear by occluding the ear canal. Whisper a phrase and ask the patient to repeat it. Test both ears.
- Tone-emitting otoscope: Designed to view the ear canal and TM while emitting three different screening levels at random intervals.
- Place a vibrating tuning fork on the forehead, equidistant to both ears
- If the patient hears the sound equally in both ears, normal hearing or symmetric hearing loss is suspected.
- If sound is heard more in affected ear → consider conductive hearing loss in affected ear
- If sound is heard more in unaffected ear → consider sensorineural hearing loss in affected ear
- A vibrating turning fork is placed on the mastoid bone behind the ear. When the sound is no longer heard, the fork is held near the ear canal.
- If the sound is still present or louder at the ear canal, normal hearing is suspected. (i.e. Air conduction is greater than bone conduction)
- If no sound is heard near the ear canal but the sound was still heard on the mastoid bone, conductive hearing loss is suspected in that ear. (i.e. bone conduction > air conduction)
- Hum test comparable to Weber test in diagnostic accuracy of new onset unilateral conductive hearing loss
- Hum test is conducted by asking the patient to hum and tell you in which ear the humming sounds louder
- In sensorineural hearing loss, humming is louder in the unaffected ear
- In conductive hearing loss, humming is louder in the affected ear
- To evaluate mobility of the TM.
- First, use positive pressure to force air into the EAC to push down the TM.
- Then, release the pressure and the negative pressure pulls the TM outwards.
- Nonmobile = fluid in middle ear, mass in middle ear, stiff/sclerotic TM.
- Hypermobile TM = ossicular chain disruption.
- Movable TM only with negative pressure = blocked Eustachian tube.
Formal audiologic assessment
- Outside scope of ED evaluation
- Performed by an audiologist in a soundproof environment. Air and bone conduction are both tested.
Consideration for these tests should be based on history and physical
- Blood glucose
- CBC to evaluate for anemia or infection
- Thyroid testing
- Serologic testing for Syphilis, Sjögren’s syndrome
- CT scan for unexplained conductive hearing loss
- MRI for sensorineural hearing loss
- ENT evaluation for presbycusis
- Differentiate between conductive and sensorineural hearing loss
- Based on exam findings and imaging.
- For sudden sensorineural hearing (less than 72 hrs):
- Every effort should be made to ensure that conductive hearing loss (eg, ruptured tympanic membrane, or congestion of the middle ear or ear canal) is not present by using a tuning fork. Tinnitus, dizziness, and vertigo are common.
- Head CT not routinely necessary, but may be considered for some patients based on individual charateristics.
- Routine laboratory tests not needed
- ENT providers are encouraged to obtain MRI (outpatient)
- Steroids should be given within 2 weeks of symptom onset (10- to 14-day treatment)
- Do not give antivirals, thrombolytics, or vasoactive substances
- Based on diagnosis
- Ahmed OH et al. Validity of the Hum Test, a Simple and Reliable Alternative to the Weber Test. Ann Otol Rhinol Laryngol. 2018 Jun;127(6):402-405.
- Chandrasekhar, S. S., Tsai Do, B. S., Schwartz, S. R., Bontempo, L. J., Faucett, E. A., Finestone, S. A., … Monjur, T. M. (2019). Clinical Practice Guideline: Sudden Hearing Loss (Update) Executive Summary. Otolaryngology–Head and Neck Surgery, 161(2), 195–210. https://doi.org/10.1177/0194599819859883