耳鼻喉科Otolaryngology topic eight: Inner ear diseases

Inner ear diseases

1. Neurologic pathway:

-- spiral ganglion--> cochlear nucleus-->bilateral superior olive (pons) -->inferior colliculus (midbrain) -->medial geniculate body (thalamus) -->auditory cortex

2. Detect rotation

-- angular: semicircular canal--> crista angularis 

-- linear: vestibule--> utricle ─ /saccule │, -> macula , contain otoliths

3. BPPV

-- most common vestibule disease

-- caused by otoliths floating to posterior semicircular canal, may automatically return

-- diagnosis: Dix-Hallpike test (45°, quickly lay down pt.)

-- symptoms: latency 1~5 secs, duration <30 secs, fatigability(+), nystagmus toward the ground (geotropic), clockwise when left BPPV

-- treatment: Epley maneuver

4. Vestibular neuritis

-- DO NOT affect hearing, otherwise consider labyinthitis

-- sudden onset vertigo

-- last days to weeks, full recover in 3~6 months

-- mostly non-recurrent

-- check electronystagmographic testing(ENG) with head thrust, caloric stimulation...

-- treatment: vestibular depressant, hydration, antiemetics, corticosteroids, vestibular nerve resection, rehabilitation 
-- DDx:  Ménière’s disease, vestibular schwannoma, cerebellar infarction

5. Ménière’s disease

Triad
-- sudden onset dizziness, lasting for hours
-- tinnitus
-- fluctuating hearing loss and dysacusis

-- 20~40 y/o female
-- endolymphatic cochlear hydrops (overproduction, re-aborption↓, obstruction) 
-- diagnosis: definite, possible or certain case
-- tools: otoscopy, auditory brainstem response(ABR),  electrocochleography(ECochG), vestibular findings

Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762

-- treatment: similar, antihistamine(Betahistine)/ BZD, restrict salt/caffeine/nicotine/alcohol, Ca2+↓(clinnarizine), destruction(surgery or Gentamycin)

6. Audiogram
-- normal: 125- 8000Hz, at least 25dB
-- hearing loss: conduction, sensorineural, mixed
-- acute symptoms of hearing injury: pain, muffled, tinnitus 
-- audiometric hallmark: early stage--> drop in  3-6 kHz(4kHz), high pitch

7. Tinnitus
-- subjective
-- objective (hemangioma, muscle cramping)
-- mind drug use:  aspirin, diuretics, quinidine, NSAID

8. Ototoxicity
-- usually bilateral
-- aminoglycosides (streptomycin), cisplatin...

9. Sudden sensorineural hearing loss

333 rule
-- loss 30 db↑
-- 3 continuous frequency
-- progress within 3 days

-- no specific etiology, may be related to virus, vessel contraction induced ischemia, membrane rupture, autoimmune

-- treatment: vasodilators (no for BP), corticosteroids

10. Cerebellopontine angle tumors (CPA tumor); benign
-- vestibular schwannomas (78%)
-- unilateral hearing / vestibular problem
-- most sensitive/ specific test: auditory brainstem response (ABR)
-- must-do image: MRI
-- surgery if >3cm, or nerve compression (CN7, 8)