3. Ear Disorders 2 Flashcards
What is conductive hearing loss?
Transmission of sound is blocked any where before the middle ear.
(Oxford) Impaired sound transmission via the external canal and middle ear ossicles to the foot of the stapes.
What is sensorineural hearing loss?
(Oxford) Defects central to the oval window in the cochlea (sensory), cochlear nerve (neural) or, rarely, more central pathways. Ototoxic drugs (eg streptomycin, vancomycin, gentamicin, chloroquine and hydroxychloroquine, vinca alkaloids), postinfective (meningitis, measles, mumps, flu, herpes, syphilis), cochlear vascular disease, Ménière’s (p554), trauma, and presbyacusis are all sensorineural.
How is hearing loss tested and localised clinically?
Rinne Test (Loss) combined with the Weber Test (Localisation
How is the Rinne Test performed?
(Oxford) Hold a vibrating tuning fork so that the prongs and auditory canal lie on the same line, testing air conduction (AC). Then place the vibrating stem on the mastoid for bone conduction (BC). Ask “Which is louder?”
Rinne negative: BC > AC. This occurs with conductive deafness >20dB, but also severe sensorineural hearing loss (SNHL)—ie a false –ve Rinne: the other cochlea picks up the sound by bone conduction. Using a Barany noise box to mask the other ear during the test prevents this.
How is the Weber Test performed?
(Oxford) With the vibrating tuning fork on the vertex, forehead or upper incisors(!), ask the patient which ear the sound is heard in. Sound localizes to the affected ear with conductive loss (>10dB loss), to the contralateral ear in SNHL, and to the midline if both ears are normal (or if bilateral sensorineural loss).
What are the testing features of normal hearing?
Rinne Test: Air > Bone
Weber Test: Midline
What are the testing features of sensorineural hearing loss?
Rinne Test: Air > Bone
Weber Test: Normal Ear
What are the testing features of conductive hearing loss?
Rinne Test: Bone > Air
Weber Test: Affected Ear
In an audiogram which line denote the right ear?
Red Line with Round Circles
Red, Round = Right
List the main external ear pathologies?
Otitis Externa
Canal Atresia (Congenital)
Exostosis
List main Middle Ear Pathologies
Acute Otitis Media Otitis Media Effusion Chronic Otitis Media Cholesteatoma Ossicular Discontinuity Otosclerosis
What is exostosis?
Irritation from cold wind and water exposure causes the bone surrounding the ear canal to develop lumps of new bony growth which constrict the ear canal. Where the ear canal is actually blocked by this condition, water and wax can become trapped and give rise to infection.
What are the features of Exotosis?
- Common in swimmers
- Deep in EAC
- Usually multiple
- Can interfere with skin migration
- Can cause CHL
(Oxford) These are smooth multiple bilateral swellings of the bony canals and said to represent local bony hypertrophy from cold exposure, eg in aquatic sports. Symptoms: none, so long as the lumen is sufficient for sound conduc- tion (so they are often picked up incidentally). When they hinder migration of wax or debris, or when they occlude the canal to cause conductive deafness, surgical removal is indicated
What is an Osteoma?
Osteoma is a solitary bony growth that is most commonly attached to the tympanosquamous suture line;
Usually single
Not as problematic as exostosis
What are the two congenital disorders of the external ear studied and with what are congential disorders of the ear often associated with?
Canal atresia ( a failure of canalization) or stenosis (narrowing) Often coexist with ossicular chain deformity (outer and /or middle ear deformities) Patients with auditory canal stenosis are at high risk for ear canal cholesteatoma formation.
