Otology Flashcards
Otosclerosis, clinically
presents with hearing loss, most often conductive, but can also be sensorineural or mixed, and is frequently bilateral
Clinically, the disease is characterised by periods of remission. These may be long, with occasional flare-ups which can result in rapid deterioration.
Usually, there is minimal or no findings at otoscopy, except in severe cases where cochlear involvement can result in hyperaemia of the cochlear promontory (Schwarze sign)
Hearing loss may be exacerbated by pregnancy
Otosclerosis on imaging
Fenestral:
Stapes—>Oval window, oval window demineralization of fissile ante fenestratrum
http://www.radiologyassistant.nl/en/p49c62abe0880e/temporal-bone-pathology.html#i49c7ea05a31b2
Retrofenestral: Disrupts the normal sharply demarcated homogeneously dense (although not homogeneously thick) border of the cochlear otic capsule. It may be focal or may encircle the whole cochlea
* https://radiopaedia.org/articles/otosclerosis
Otosclerosis types
- Fenestral 80%
- Stapes—>Oval window, oval window demineralization of fissile ante fenestratrum
- TX: Stapedectomy with prosthesis
- Radiology assistant: http://www.radiologyassistant.nl/en/p49c62abe0880e/temporal-bone-pathology.html#i49c7ea05a31b2
- Retrofenestral
- Disrupts the normal sharply demarcated homogeneously dense (although not homogeneously thick) border of the cochlear otic capsule. It may be focal or may encircle the whole cochlea
- https://radiopaedia.org/articles/otosclerosis
CPA Mass DDX
AMEN Acoustic neuroma (80%) Meningioma (10%) Ependymoma (5%) Neuroepithelial cyst (5%)
Vestibular Schwannoma on imaging: MRI characteristics
- T2 shows filling defect w/ increased signal of CSF of CPA-IAC cistern
- small: ovoid filling defect
- Large: “Ice cream on cone” in CPA-IAC
- 0.5% a/w arachnoid cyst
- FLAIR: Increase cochlear signal from increase protein
- GRE/TSE: Microhemorrhage decreased signal foci (common)
- Not seen in meningiomas
- T1: Focal enhancing mass of CPA-IAC cistern centered on porus acustics
Vestibular schwannoma path
- Benign, arises from glial-schwann cell junction.
- Arises from CN8 vestibular portion
- A/w NF2 nonfunctioning mutations in 60% of sporadic VS
- If B/L suspect Neurofibromatosis type 2
- other dx factors of NF2: meningiomas, lenticular opacities, gliomas
Vestibular schwannoma characteristics
- Adults, unilaterally SNHL, tinnitus, headaches, SRT out or proportion to the PTA decrease, facial numbness
- Vertigo uncommon
Vestibular Schwannoma TX
- Translab if no hearing, but spares facial nerve. Post-op CNS leaks common
- Middle cranial fossa if in IAC (best for small)
- offers best chance of retaining hearing and vestibular function
- Retrosigmoid: when CPA or medial IAC component present
- Fractionated or stereotactic radio surgery
Glomus Jugulare
Middle ear mass. Reddish bulge behind TM that blanches with pneumatic otoscopy “brown’s sign”
- aberrant ICA tympanic segment is a normal variant that is on the differential
Paraganglioma
Presents; Tinnitus + hearing loss
Glomus Jugulare presentation
- Pulsatile tinnitus + hearing loss
- Vernet Syndrome
- motor paralysis of CNs IX, X, XI
- Horner Syndrome
- Collet-Sicard Syndrome
- Vernet syndrome + CN XII paralysis
- Vernet Syndrome
Glomus Jugulare CT findings
- Shows moth eaten pattern extending superiorly and laterally toward and sometimes into the hypotympanum
- Must erode through jugular spine to enter middle ear
Glomus Jugulare MRI findings
- Classically shows “salt and pepper”- blood products from hemorrhage or flow voids
- T1: Low
- T2: High
- T1 C+: Intense enhancement
Glomus Jugulare DDX
- Jugular Schwannoma
- Metastasis (multiple myeloma)
- Meningioma
- Jugular bulb thrombosis
- ENdolymphatic sac tumor
Glomus jugulare TX
- Surgery
- Radiation
Unlike non-skull base paragangliomas, radiation actually works for glomus jugulare
Superior Canal Wall Dehiscence Syndrome: Overview and presentation
- caused by dehiscence of the temporal bone overlying the superior semicircular canal
- usually 2/2 trauma or congenital
- discovered by Lloyd Minor (Chair of medicine stanford)
- S/s
- Autophony of same side
- Veritgo
- Tulio phenomenon- sound induced vertigo, nystagmus, nausea usually by everyday sounds
- Pulsatile tinnitus
- Pulse synchronous oscillopsia
- Hyperacusis
Superior Canal Wall Dehiscence Syndrome: Imaging and other dx tests
CT temporal bone, thin cuts
- Other dx:
- Vestibular evoked myogenic potentials
- Videonystamography
Superior Canal Wall Dehiscence Syndrome: TX
surgical resurfacing via middle cranial fossa approach or trans mastoid
Tulio phenomenon
sound induced vertigo, nystagmus, nausea usually by everyday sounds
Perilymphatic Fistula Overview
- Leakage of perilymph from cochlea into middle ear space caused by an abnormal fistula between the two
- usually from ruptured round window. Superior canal wall dehiscence can also cause it
Perilymphatic Fistula S/S and etiology
- Vertigo, imbalance, sudden or progressive SNHL
- Usually 2/2 trauma
- Also caused by rapid increases in ICP
- Also a complication of stapedectomy
- Can be congenital
- Cholesteatoma
Perilymphatic Fistula TX
Tympanostomy is diagnostic and curative
Cochlear Anatomy: 3 chambers (fluid) and membranes separating
Superior- Scala vestibuli (Perilymph) -- Reissner membrane-- Middle- Scala media (endolymph, High K+) -- basilar membrane -- Inferior- Scala tympani (Perilymph)
Organ of corti and dispersion of sound based on frequency
- Organ of corti sits on top of basilar membrane.
- Houses inner and outer hair cells
- Inner hair cells live here (approx 3500)
- can’t regenerate in humans
- Outer hair cells feed back energy to amplify traveling wave up to 65dB
- Membrane is tapered and stiffer on one end allowing for dispersion of sound waves based on frequency
- High frequency=Basal end (narrow, stiff)
- Low frequency=Apical end (Wide, compliant)
Spiral ligament of cochlea function
- Spiral ligament (periosteum of outer wall of the ductus cochlea’s or scala media)
- Upper portion of spiral ligament= Stria vascular
- Produces endolymph
- Upper portion of spiral ligament= Stria vascular
Vertigo DDX
BPPV (short, minutes. Dix-hallpike + and tx: epley)
Meniere’s disease (Idiopathic Endolympathic hydrops)
Labrynthitis
Vestibular migraine
Vestibular schwannoma
Stroke
Rare:
Superior canal wall dehiscence
Perilymphatic fistula
Meniere’s Disease classic S/S
Tinnitus
Fluctuating SNHL
Occasional Episodic vertigo
Aural fullness
Positional Alcohol Nystagmus type I
Alcohol concentration is higher in the blood than in the vestibular system, hence the endolymph is relatively dense
nystagmus to the RIGHT when the RIGHT side of the head is down
Positional Alcohol Nystagmus type II
Alcohol concentration is lower in the blood than in the vestibular system, hence the endolymph is relatively dilute
nystagmus to the RIGHT when the LEFT side of the head is down
Labyrinthitis S/S
Severe vertigo
N/V
Often related to preceeding URI/Flu infections
Labyrinthitis course and TX
Self-limiting
95% of patients will have only one episode
Generally takes 1-6 weeks for acute inflammation to resolve
Then will have 2 weeks of sub-acute symptoms and rapid recovery
TX:
symptomatically: Antihistaminics like Cinnarizine
Prochlorperazine for nausea+vertigo
Glucocorticoids not been shown to be useful
Bezold Abscess
- Acute otomastoiditis complication
- Infection erodes through cortex of mastoid tip and extends into infratemporal fossa
Clinically
- Often impalpable as it is medial to the deep cervical fascia layer enveloping the SCM
- More often seen in Adults as mastoid cortex is thinner
- Complication: IJ thrombosis
