Otology - Basic concepts + anatomy Flashcards
Describe anatomy of early (working outwards in)
Pina lobe - ear canal - tympanic membrane - MIDDLE EAR - malleus, stapes, incus - INNER EAR - cochlea - semimembranous canal
Describe what can be seen on otoscopy
Pars flaccida, pars tens, lateral process of malleus, light reflex. Note that only 1/4 of the eardrum can be seen on ophthalmoscope. Look for handle of males to orientate.
Define otalgia
Ear pain (external and middle ear)
Define otorrhoea
Ear pus (external ear)
What is tinnitus?
Perception of sound (inner ear - cochlea)
What is vertigo?
Hallucination of movement (inner ear- vestibule)
What is impedance audiometry?
Varying the pressure in the external ear canal, the compliance (i.e. the mobility) of the eardrum may be calculated by the degree of sound reflected from a probe tone
What is electric response audiometry?
Evoked potential in 8th nerve, brainstem or auditory cortex recorded by using skin electrodes following acoustic stimulation of the cochlea
What is otoacoustic emissions?
Assess function of the cochlea by recording sound vibration produced by outer air cells in the cochlea. Most commonly used in neonatal screening.
Hearing assessment in young children
Birth - 6 months: electric response audiometry 6-12 months: distraction test 2 years: conditioning/cooperation test Headphones not used until 3-4 years
What is a pure tone audiogram?
Most commonly used method to assess hearing. Subjective test - identifies hearing thresholds. Examier and patient in contact via a microphone and headset respectively. Patient presses button if sound is heard.
What is tympanogram/audiometry?
Measures energy transmission through middle ear. Measure of tympanic membrane compliance involving middle ear and ear canal pressure. Normal ear will show bell shaped curve but if there is fluid in the ear it flattens the curve. Negative pressure will pull it to the negative side.
Name some ototoxic mediations
Gentamicin (aminoglycopeptides) Chemotherapy drugs- especially Cisplatin Quinine Aspirin- can cause reversible sensineural hearing loss NSAIDs Macrolides Loopdiuretics
Name some of the ear related causes that cause otalgia
- Otitis externa,
- Necrotising OE
- Otitis Media (Acute)
- Glue ear
- Trauma, foreign body
- Bullous myringitis
Name some referred causes of otalgia
- TMJ Dysfunction- tender over TMJ, worse with eating
- Teeth-dental disease (auriculo-temporal branch of trigeminal nerve)
- Herpes zoster i.e. Ramsay-Hunt (sensory branch of facial nerve)- supplies lateral surface of drum
- Throat e.g. tonsillitis or base of tongue (tympanic branch of glossopharyngeal)
- Larynx e.g. carcinoma (Auricular branch of vagus)
- Neck and cervical discs e.g. cervical spondylosis/arthritis (great auricular nerve)