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.
Describe the pathophysiology of pinna haematoma and its complications?
Pinna well vascularised
Shearing forces = separation of the perichondrium from the cartilage
Results in tearing of the perichondrial blood vessels and haematoma formation
Avascular necrosis of the cartilage and “cauliflower ear”
Name the surgical procedures for the ear studied?
Stapedectomy/Stapedotomy Mastoidectomy Ossiculoplasty BAHA BAHA Attract Middle Ear Implants
What is Otosclerosis?
- Disorder of bone deposition
* Lamellar bone replaced with woven bone
What are the consequences of otosclerosis?
Stapedial footplate fixation
Cochlear otosclerosis
Progressive conductive hearing loss
Distinguish between stapedectomy and stapedotomy?
Stapoidectomy = Removal of Stapes+Replace with full Prosthesis.
Stapedotomy = piston prosthesis in footplate of stapes.
(If the stapes footplate is fixed in position, rather than being normally mobile, then a conductive hearing loss results. There are two major causes of stapes fixation. The first is a disease process of abnormal mineralization of the temporal bone called otosclerosis. The second is a congenital malformation of the stapes. The former has better outcomes from the procedures.
In both of these situations, it is possible to improve hearing by removing the stapes bone and replacing it with a micro prosthesis - a stapedectomy, or creating a small hole in the fixed stapes footplace and inserting a tiny, piston-like prosthesis - a stapedotomy.)
What level of hearing loss is suggestive of ossicular discontinuity? What is a likely cause?
> 30dB
Cholesteatoma
What are the signs and symptoms of cholesteatoma?
SYMPTOMS initially silent Then-hearing loss Discharge( 2nd infection of the of keratin material) Pain
SIGNS
Polyp/granular tissue in attic (Cystic white pearly masses of varying size)
TM perforation
Keratin debris in attic/middle ear
What are the histological features of cholesteatoma?
Histological diagnosis – presence of keratinizing squamous epithelium
What are pathophysiological consequences of cholesteatoma?
Cholesteatomas are invasive & locally destructive
–Local mass effect with pressure erosion
–Produce collagenase- bone resorption
Depending on location & extent of cholesteatoma may cause
–Erosion lateral wall of attic
–Erosion middle ear ossicles
–Erosion of tegmen
–Erosion of facial canal bone
–Erosion of vestibular & cochlear bony capsules
List the different classifications of cholesteatoma?
–Acquired cholesteatoma
–Congenital cholesteatoma
–Cholesteatoma of petrous apex (C/AQ)
What investigations should be performed in suspected cholesteatoma?
–Clinical examination
–PTA (pure tone average/audiometry)
–CT temporal bones
What are the goals of mastoidectomy?
- Goal- eradicate disease
- Provide pt with a safe, dry ear
- Improve or preserve hearing if possible
Name the two types of mastoidectomy
Procedures- Canal wall up (CWU)- air containing mastoid & an external ear are preserved
Canal wall down (CWD) - posterior canal wall is removed and the mastoid is marsupialized into the enlarged ear canal - probably results in worse hearing outcomes and a mastoid cavity which may require lifelong follow-up or later surgical obliteration.
What is a ossiculoplasty?
An ossicular chain reconstruction procedure
What are the two types of ossiculoplasty procedure?
Partial ossicular replacement prosthesis (PORP)
Total ossicular replacement prosthesis (TORP)
Describe the operation of the BAHA?
Sound waves are picked up by the Baha processor
Bypass middle ear function and are delivered directly to the working cochlea in both ears
What are the indications for a BAHA?
Malformation of the ear canal or middle ear
Infection of the ear canal resulting in chronic draining ears
Chronic otitis media
Congenital atresia
Middle ear dysfunction / disease
Sudden hearing loss
Acoustic neuroma
What is the name given to the magnetic BAHA?
BAHA Attract System.
