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)
Causes to consider with otorrhoea
- Otitis externa
- Acute otitis media
- Cholesteatoma (rare but important)
- Chronic otitis media
Watery otorrhoea could be…
Eczema of ear canal, CSF
Purulent otorrhoea could be…
Acute otitis externa, furunculosis
Mucoid otorrhoea could be…
CSOM with perforation
Bloody otorrhoea could be…
Trauma, acute OM, carcinoma
Foul smelling otorrhoea could be…
CSOM cholesteatoma
Causes of conductive hearing loss
- External canal obstruction- wax, pus, debris, foreign body, developmental abnormalities
- Ear drum perforation- trauma, infection
- Ossicular chain problems- otosclerosis, trauma, infection
- Eustachian tube dysfunction- effusion secondary to nasopharyngeal carcinoma
Causes of sensineural hearing loss
- Ototoxic drugs
- Post-infective- meningitis, mumps, measles, herpes, syphilis
- Meniere’s disease
- Trauma
- Presbyacusis
Vertigo lasting for seconds could be…
BPV, cervical spondylosis, postural hypotension
Vertigo lasting for hours could be…
migraine, menier’s, labrynthitis
Vertigo lasting for days could be…
Central cause - eg brainstem vesibular nuclei, cerebellum etc
Vertigo causes
Peripheral: Meniere’s Disease, BPV, Labyrinthitis, vestibular failure Central: acoustic neuroma, MS, head injury, inner ear syphillus, migraine Drugs: gentamicin, loop diuretics, metronidazole, co-trimoxazole Miscellaneous: cholesteatoma
Causes of tinnitus
Hearing loss Presbyacusis Head injury Noise induced Otosclerosis Meniere’s disease Acoustic neuroma, MS Loop diuretics- Furosemide Stress
What is otosclerosis?
Where the vascular spongy bone replaces normal lamellar bone of optic capsule origin, potentially in oval window which fixes the stapes foot plate. Bone around the base of the stapes becomes thickened and eventually fuses with the bone of the cochlea It is the commonest cause of progressive deafness in young adults. 75% have tinnitus.
Presentation of otosclerosis
Normally appear in late adult life with conductive deafness, tinnitus and vertigo.
Management of otosclerosis
Medical - hearing aid Stapedectomy - only on worst ear
What is a patch myringoplasty?
A procedure in which some material is used to cover the perforation in an effort to encourage the body’s normal healing process to close the hole. Only useful for very small perforations.
What is a tympanoplasty?
Performed through an incision behind the ear (postauricular incision). Fascia is harvested from a muscle above the ear to repair the perforation. The eardrum is elevated like a trap door and the fascia patch is slipped behind the eardrum to cover the hole. The eardrum is then laid back in its natural position over the patch.
Describe mastoid surgery/indications
• Mastoid bone contains a number of air spaces the largest of which is called the antrum, which connects with the air space in the middle ear. This means that disease in the middle ear can extend into the mastoid bone. • Most commonly done for cholesteatoma. • Bone covering the infection within the mastoid cells is removed. Sometimes the mastoid cavity is left opn into the ear canal, but sometimes the mastoid cavity is closed with bone, cartilage or muscle from around the ear.
Describe path of facial nerve
Facial nerve arises in the medulla, emerges between the pons and medulla , the facial nerve passes through the posterior fossa and runs through the middle ear before emerging from the stylomastoid foramen to pass into the parotid gland.
Causes of facial palsy
- Brainstem tumours
- Strokes
- Multiple sclerosis
- Cerebellopontine angle lesions (acoustic neuroma, meningitis)
- CVA Intratemporal
- Otitis media; cholesteatoma
- Bell’s
- Middle ear infection Infratemporal
- Parotid tumours;
- Trauma leading to complete palsy is an indication for urgent CT Others
- Lyme disease
- Sarcoid
- Diabetes/polyneuritis of Bell’s palsy
Difference between bells and facial palsy
LMN can paralyse all of one side of the face, but in UMN the forehead muscles and closing eyes may still work. • A lower motor neurone lesion occurs with Bell’s palsy, whereas an upper motor neurone lesion is associated with a cerebrovascular accident. Will occur on the lower half of the face on the contralateral side of the lesion • A lower motor neurone lesion causes weakness of all the muscles of facial expression • Bell’s palsy is a 7th nerve event in isolation. Saliva production, mucous membrane, lacrimal production, Taste anterior 2 thirds of tongue. Muscles of facial expression BELL’S IS THE CAUSE OF 70% OF FACIAL PALSIES BELL’s IS LMN SO ALL OF ONE SIDE IS PARALISED – reassurance can be given that it is not a CVA.
Tests in facial palsy
• Glucose (diabetic neuropathy?) • Lyme disease serology • Examine parotid for lumps • Examine ears to exclude cholesteatoma • Any head trauma? • MRI – space occupying lesion, MS, temporal bone fracture, CVA
