# Ossicle/Otology
## Otology and Neurotology
### NEUROLOGY REVIEW

Multiple Sclerosis - multiple demyelinated areas in CNS, “remissions” and “exacerbations”, paresthesias AND weakness (most neuro dz is one or the other), EOM’s affected, vertigo, CN7 involvement, internuclear ophthalmoplegia is pathognomonic
Myasthenia Gravis - M>F, eye weakness in 90%, facial weakness in 70%, pharyngeal weakness, nasal regurg, abnl fatiguability of skeletal mm, reflexes preserves, no nystagmus, no vertigo.
Amyotrophic Lateral Sclerosis - hyperreflexia, weakness, mm atrophy, fasiculations and fibrillations (esp tongue), dysarthria, upper and lower motor neuron signs, ocular nuclei spared
Pseudobulbar Palsy - affects motor tracts of brainstem nuclei (Bilat corticobulbar tracts), trouble w/ speech, facial extpression, tongue motion, chewing, swallowing, breathing.
Guillain-Barre - Proximal and distal weakness with paresthesias, areflexia and hypotonia, facial diplegia in 50%, respiratory weakness, ocular weakness
Wallenburg’s Syndrome - PICA thrombosis> Lateral Medullary syndrome. Vertigo, nystagmus, Horner’s, dysphagia, hypotonia, ataxia, decr pain and temp sensation of IPSI face and CONTRA body
Vertebrobasilar Syndrome - vertigo, hemiparesis, dysarthria, vomiting, drop attacks
Migraine - Abort with ergotamine

### FACIAL NERVE

Hemifacial Spasm - Irregular contraction of of side of face. Orbicularis oculi and perioral muscles affected
Blepharospasm - Always bilateral, asynchronous firing with normal rate ~50-70/second
Melkerson's - Recurrent facial paralysis, facial edema, fissured tongue (or furrowed tongue)
Mobius Syndrome - Bilateral congenital facial paralysis with unilateral or bilateral VI palsy
Repairing the Facial Nerve:
EMG - tests voluntary units
Trauma - wait 72 hours after injury for ENOG

### INFECTION AND ITS COMPLICATIONS

Acute Necrotizing OM - β-hemolytic Strep, "sick kids", necrosis of soft tissues and bones of middle ear Acute Mastoiditis - S. pneumo, Strep pyogenes, Staph Otitis Externa - Staph, Fungi including Candida and Aspergillus niger Tuberculous Ear Dz - multiple perforations, oroless discharge, pale granulations, hearing loss out of proportion 11% complication rate after PET placement - otorrhea most common.
Osteoma - singular, large, pedunculated, unilateral, at bony-cartilaginous junction. Exostosis - Most common EAC tumor, bilateral, multiple. Related to cold water (surfers).
Winkler's - Painful nodule @ helix, AV anastomosis, chondrodermatitis nodularis helicus
Complications of AOM (Suppurative):

### AUDIOLOGY QUICKIES

Speed of sound = 300m/s or 1100f/s Velocity = Wavelength x Frequency N dB = 20 x log (P1/P2) Standard Pressure = .0002 dynes/cm2 Resonant Frequency of EAC = 3kHz TM Surface Area = 70-80mm2, pars tensa = 55mm2 Footplate Surface Area = 3.5mm2 Lever Ratio of ossicles = 1.3:1 or 2.5dB Hydraulic Action Mechanical Advantage of TM:Footplate = 17:1 or 25dB Combined mechanical advantage of lever and hydraulic advantages = 22:1 (1.3 x 17)
Speech Recognition Testing (SRT) uses Spondees Discrimination Testing used phonetically balanced phrases Stenger's - when Pure Tone Average does not agree with SRT and descrimination. Performed to detect malingering of unilateral loss. If sound is presented to both ears, patient will deny hearing in the ear with the feigned loss. If sound is presented to the good ear at a suprathreshold level, simultaneous to a louder sound in the questionable ear, a malingerer will localize the sound to his "bad" ear, and therefore deny hearing anything at all.
Masking necessary when AC threshold is 40dB greater than in contralateral ear.
OSHA Sound Exposure Guidelines

### DEAFNESS & SYNDROMES

Rubella - cataracts, cardiovascular abnormalities, retinitis
Cogan's aka nonsyphillitic interstitial keratitis. Vertigo with tinnitus, progressive SNHL. Autoimmune etiology. Rx is Steroids
Syphilis - bilateral asymmetric SNHL with vestibular symptoms (like Meniere's)
EAC Stenosis - normal pinna usually means good middle ear structures. Correct at 4-5y if bilateral >15y if unilateral.
Congenital Hearing Loss 90% are autosomal recessive
Congenital Deafness Syndromes

### VESTIBULAR DISEASE

Utricle - activated by linear acceleration
Acoustic Neuroma (Schwannoma) - Originates from superior vestibular nerve, CNVII displaced anteriorly at IAC. Accounts for 80% of CP-angle tumors.
Otosclerosis - Fluoride may help
Benign Positional Vertigo - rotatory, fatiguable nystagmus, +Dix-Hallpike, Rx: Epley, Singular neurectomy
Labyrinthine Nystagmus - fast AND slow component. Central Nystagmus is usually pendular (without fast/slow component).
Ampullo- or Utriculopedal flow is stimulatory in Lateral SCC, but Ampullofugal flow is stimulatory in posterior and superior SCC.
Meniere's Disease

### TEMPORAL BONE FRACTURE

Longitudinal - 80%
Transverse - 20%
Middle Ear CSF Leaks - Oval window or round window leaks most commonly

### NEUROTOLOGIC ANATOMY
#### Anatomy of the Intratemporal Facial Nerve

VII - The Facial Nerve G1 - First Genu, at the Geniculate Ganglion G2 - Second Genu CT - Chorda Tympani TM - Tympanic Membrane m = Malleus i = Incus C = Cochlea SSCC = Superior Semicircular Canal PSCC = Posterior Semicircular Canal

#### Internal Auditory Canal from medial aspect

BB = Bill's Bar (bony) TC = Transverse Crest, aka Falciform Crest (bony) FN = Facial Nerve (also shown is Nervus Intermedius) SVN = Superior Vestibular Nerve inntervates superior & horizontal canals & utricle IVN = Inferior Vestibular Nerve to posterior canal and saccule CN = Cochlear Nerve
In Radiology, we describe this as "Seven-Up and Coke (Cochlear) Down" follow this link for a picture: http://rad.usuhs.mil/medpix/medpix_image.html?mode=image&imageid=16779&topic_id=2255&quiz=no#top

#### Cochlea in cross section

SV = Scala Vestibuli contains perilymph SM = Scala Media contains endolymph ST = Scala Tympani contains perilymph RM = Reissner's Membrane BM = Basilar Membrane VASC = Stria Vascularis - generates +80-100mV potential in endolymph of Media LIG = Spiral Ligament LIMB = Spiral Limbus contains inner and outer hair cells SG = Spiral Ganglion - cochlear nerve fibers located in modiolus of cochlea