Adult Deafness Flashcards
What are the classifications of hearing loss?
Conductive
Sensorineural
Mxed
Describe conductive hearing loss. What are causes of this?
Impaired sound transmission via the external canal and middle ear ossicles to the foot of the stapes
External ear canal obstruction (wax, pus, debris, foreign body, developmental abnormalities)
Otiti media/glue ear
Drum perforation (trauma, barotrauma, infection)
Problems with ossicular chain (otosclerosis, infection, trauma)
Inadequate Eustachian tube ventilation of middle ear - effusion secondary to nasopharyngeal carcinoma
Describe sensorineural hearing loss. What are causes of this?
Results from defects central to the oval window in the cochlea (sensory), cochlear nerve (neural) or rarely, more central pathways
Ototoxic drugs Post infective (measles, meningitis, mumps, flu, herpes, syphilis) Cochlear vasulcar disease Menieres Trauma Presbycusis Acousic neuroma MS
What should you consider if there is unilateral SNHL?
Acoustic neuroma (MRI)
Cholesteatoma
Effusion from nasopharyngeal cancer
What is sudden sensorineural hearing loss?
Loss of 30+dB in 3 continguous pure tone frequencies over 3 days
Hearing loss may be sudden, abrupt or rapidly progressive
Usually unilateral
Causes: Noise exposure Gentamicin/other otxin Mumps Acoustic neuroma MS Storke Vasculitis TB
What is management for sudden SNHL?
Immediate ENT referral
Eamine EAC and TM to exclude wax/effusion
Tuning fork tests
Look for causes: FBC, ESR, U&E, LFT, TSH, autoimmune, clotting, glucose, cholesterol
CXR, MRI, lymph node and nasopharyngeal biopsy
Audiometry
Treat cause
High dose steroids commonly used (presumed inflammatory cause)
Prednisolone
What is otosclerosis? Cause?
New vascular spongy bone is formed around the stapes footplate which leads to its fixation at the oval window and consequent conductive hearing loss.
Autosomal dominant Affects young adults Mostly bilateral 2:1 female 20-40
What are features of otosclerosis?
Conductive deafness Tinnitus Mild transient vertigo Normal tympanic Membrane or Schwarte's sign - pink tinge to the drum (flamingo) due to hyperaemia Positive family history
What is management of otosclerosis?
Hearing aid
Surgery:
Stapedectomy
- surgery is only performed on worse hearing ear, contralateral SNHL is contraindication as a complication of surgery is complete SNHL
What is presbycusis? Investigations?Management?
Age-related bilateral sensorineural hearing loss
High frequency hearing is affected
Can lead to conversational difficulties in noisy environments.
Progresses slowly as sensory hair cells and neurones in cochlea atrophy over time.
Otoscopy - normal no otosclerosis, cholesteatoma, wax
Tympanometry - normal middle ear function with hearing loss
Audiometry - bilateral sensorineural hearing loss
Bloods - normal
Treat with hearing aid
What is the normal range of hearing?
What is mild, moderate, severe and profound hearing loss?
0-140dB
Decibel hearing live is relative to quietest sounds heard with normal hearing.
Normal -10 to 25dBHL Mild: 26-40 dBHL Moderate 41-70dBHL Severe: 71-90 dBHL Profound: >90 dBHL
Low frequencies - vowel sounds
High frequencies - consonants
What drugs are ototoxic?
Aminoglycosides: Streptomycin Vancomycin Gentamicin Choloquine Hydroxychloroquine Vinca alkaloids Furosemide Aspirin
What are symptoms of noise induced hearing loss? Audiometry? Management?
Bilateral symmetrical sensorineural hearing loss
± Tinnitus
Audiometry shows a notch at 3,4 or 6 kHz frequencies - where hearing is worse and then recovery at 8kHz
Reduce risk of occupational exposure
Provide ear defenders
What is acoustic neuroma?
Vestibular schwannoma
Benign subarachnoid tumours that cause local pressure and behave as SOL
Arise from superior vestibular nerve Schwann cell layer
What are features of acoustic neuroma?
CNVIII: Ipsilateral tinnitus, sensorineural deafness due to cochlear nerv compression, veritgo CNV: Absent corneal reflex, numb face VII: Facial palsy
Large tumours may give ipsilateral cerebellar or RICP signs
