ABOHNS Neurotology cheat sheet

Vestibular schwannoma most often arises from the vestibular (inferior) division of CN VIII at the internal auditory canal fundus.

House-Brackmann grade I is normal facial function; grade VI is total paralysis with no movement.

Gadolinium-enhanced MRI is the study of choice for suspected retrocochlear pathology; small intracanalicular tumors may be missed on non-contrast imaging.

Neurofibromatosis type 2 is defined by bilateral vestibular schwannomas; screening MRI is indicated in first-degree relatives.

Cerebellopontine angle tumors: vestibular schwannoma is most common, followed by meningioma and epidermoid cyst.

Audiometric hallmark of retrocochlear disease is disproportionately poor speech discrimination relative to pure-tone thresholds.

Absent or elevated acoustic reflex with normal middle ear function raises suspicion for retrocochlear lesion.

Sudden sensorineural hearing loss is an otologic emergency; treatment within 72 hours improves outcome compared with delayed treatment.

Rinne test: air conduction greater than bone conduction is normal (positive); bone greater than air indicates conductive loss (negative).

Weber test lateralizes to the affected ear in conductive loss and to the better ear in sensorineural loss.

Cholesteatoma is keratinizing squamous epithelium in the middle ear; it is locally destructive and does not spontaneously resolve.

Chronic suppurative otitis media with a marginal or attic perforation raises suspicion for cholesteatoma.

Tympanosclerosis appears as whitish plaques on the tympanic membrane and typically causes conductive hearing loss.

Otosclerosis classically produces progressive conductive loss with a normal tympanic membrane and absent stapes reflex early.

Carhart notch is an apparent bone-conduction dip at 2 kHz seen in otosclerosis that may resolve after stapedectomy.

Vestibular schwannoma and cholesteatoma can both present with unilateral hearing loss, but only cholesteatoma shows middle ear findings.

Translabyrinthine approach sacrifices hearing and is chosen when hearing is nonserviceable or tumor is large.

Middle fossa approach is suited to small intracanalicular tumors with serviceable hearing, preserving cochlear function.

Retrosigmoid approach allows hearing preservation and access to tumors extending into the cerebellopontine angle.

Cerebrospinal fluid leak after translabyrinthine surgery is managed with wound revision, lumbar drain, or fat graft reinforcement.

Facial nerve monitoring is standard in skull base and cerebellopontine angle surgery to reduce iatrogenic injury.

Jugular foramen tumors (glomus jugulare, schwannoma) may present with lower cranial nerve deficits and pulsatile tinnitus.

Preoperative embolization is considered for highly vascular glomus tumors to reduce intraoperative blood loss.

Anterior skull base cerebrospinal fluid rhinorrhea may present with positional clear rhinorrhea and a positive beta-2 transferrin test.

Benign paroxysmal positional vertigo is diagnosed with the Dix-Hallpike maneuver; posterior canal is most commonly involved.

Canalith repositioning (Epley) is first-line treatment for posterior canal benign paroxysmal positional vertigo.

Vestibular neuritis presents with acute prolonged vertigo, nausea, and horizontal nystagmus without hearing loss.

Labyrinthitis is distinguished from vestibular neuritis by accompanying sensorineural hearing loss and tinnitus.

Meniere disease is defined by episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness.

Vestibular migraine is a common cause of recurrent vertigo and often lacks the auditory symptoms of Meniere disease.

Head impulse test is abnormal in peripheral vestibular loss and typically normal in central causes.

Vestibular rehabilitation is effective for unilateral peripheral hypofunction and for persistent postural-perceptual dizziness.

Bell palsy is idiopathic facial paralysis; it is a diagnosis of exclusion after other causes are ruled out.

House-Brackmann grade VI indicates no facial movement; grade II indicates slight weakness noticeable on close inspection.

Corticosteroids within 72 hours of onset improve outcomes in Bell palsy; antiviral agents are added in severe cases.

Ramsay Hunt syndrome is facial palsy with vesicles in the ear canal or auricle, caused by varicella-zoster virus.

Facial nerve decompression is considered in severe Bell palsy with degeneration on electroneuronography, though evidence is debated.

Electroneuronography compares compound action potentials; greater than 90 percent degeneration predicts poor recovery.

Facial nerve schwannoma may present with progressive facial weakness, hearing loss, and a middle ear mass.

Recovery of Bell palsy is favorable in most patients; incomplete recovery may leave synkinesis or hemifacial spasm.

Pure-tone average is commonly calculated from thresholds at 500, 1000, and 2000 Hz.

Speech reception threshold approximates the pure-tone average; word recognition score assesses discrimination.

Sensorineural hearing loss shows air and bone conduction thresholds equally reduced; conductive loss shows an air-bone gap.

Cochlear implant candidacy generally requires severe-to-profound bilateral sensorineural hearing loss with limited speech understanding.

Bone-anchored hearing devices are suited to conductive or mixed hearing loss with a functioning cochlea.

Otoacoustic emissions reflect outer hair cell function and are absent in significant sensorineural hearing loss.

Auditory brainstem response assesses retrocochlear and brainstem function and is used in newborn hearing screening.

Tympanometry: type B flat curve suggests effusion; type C negative pressure suggests eustachian tube dysfunction.

Vestibular schwannoma arises from the vestibular division of CN VIII at the internal auditory canal fundus.

Gadolinium-enhanced MRI is the study of choice for suspected retrocochlear pathology.

Neurofibromatosis type 2 is defined by bilateral vestibular schwannomas.

Cerebellopontine angle tumors: vestibular schwannoma is most common, followed by meningioma and epidermoid.

Retrocochlear disease shows speech discrimination poorer than pure-tone thresholds predict.

Absent acoustic reflex with normal middle ear function suggests retrocochlear lesion.

Sudden sensorineural hearing loss is an emergency; early treatment improves outcome.

Rinne: air greater than bone is normal; bone greater than air indicates conductive loss.

Weber lateralizes to the affected ear in conductive loss and to the better ear in sensorineural loss.

Cholesteatoma is keratinizing squamous epithelium in the middle ear and is locally destructive.

Marginal or attic perforation raises suspicion for cholesteatoma.

Tympanosclerosis appears as whitish tympanic membrane plaques causing conductive loss.

Otosclerosis causes progressive conductive loss with normal tympanic membrane.

Carhart notch is a bone-conduction dip at 2 kHz in otosclerosis.

Translabyrinthine approach sacrifices hearing and suits nonserviceable hearing or large tumors.

Middle fossa approach targets small intracanalicular tumors with serviceable hearing.

Retrosigmoid approach allows hearing preservation and cerebellopontine angle access.

Cerebrospinal fluid leak after translabyrinthine surgery is managed with revision, lumbar drain, or fat graft.

Facial nerve monitoring is standard in cerebellopontine angle surgery.

Jugular foramen tumors may cause lower cranial nerve deficits and pulsatile tinnitus.

Preoperative embolization is considered for vascular glomus tumors.

Benign paroxysmal positional vertigo is diagnosed with the Dix-Hallpike maneuver; posterior canal is most common.

Canalith repositioning (Epley) is first-line for posterior canal benign paroxysmal positional vertigo.

Vestibular neuritis causes acute vertigo and horizontal nystagmus without hearing loss.

Labyrinthitis differs from vestibular neuritis by accompanying sensorineural hearing loss.

Meniere disease: episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness.

Vestibular migraine causes recurrent vertigo often without auditory symptoms.

Head impulse test is abnormal in peripheral vestibular loss and normal in central causes.

Bell palsy is idiopathic facial paralysis and a diagnosis of exclusion.

House-Brackmann grade I is normal; grade VI is total paralysis.

Corticosteroids within 72 hours improve Bell palsy outcomes; antivirals are added in severe cases.

Ramsay Hunt syndrome is facial palsy with ear canal vesicles from varicella-zoster virus.

Electroneuronography: greater than 90 percent degeneration predicts poor recovery.

Facial nerve schwannoma may cause progressive weakness, hearing loss, and a middle ear mass.

Incomplete recovery may leave synkinesis or hemifacial spasm.

Pure-tone average is commonly calculated from 500, 1000, and 2000 Hz.

Speech reception threshold approximates pure-tone average; word recognition score assesses discrimination.

Sensorineural loss: air and bone thresholds equally reduced; conductive loss shows an air-bone gap.

Cochlear implant candidacy generally requires severe-to-profound loss with limited speech understanding.

Bone-anchored devices suit conductive or mixed loss with a functioning cochlea.

Otoacoustic emissions reflect outer hair cell function and are absent in significant sensorineural loss.

Tympanometry: type B flat curve suggests effusion; type C suggests eustachian tube dysfunction.