otology 2

Facial Nerve

1 emerges from the pons 2 CPA (cerebello-pontine angle) 3 internal auditory meatus. 4 medial wall of tympanic cavity. 5 bends backwards at right angle where the geniculate ganglion is situated 6 Passes horizontally, enclosed in fallopian canal, above Oval window. 7 When it reaches the aditus it turns downwards behind the pyramid and continues vertically till it merges from 8 stylomastoid foramen.
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Physiology of Hearing

Sound has two subjective physical properties Frequency (pitch) : hertz (Hz) [Hz - Cycle/sec] Intensity (loudness) : decibel (dB)
Intensity

How We Hear Sounds?

Sound is collected by the pinna and directed into the outer ear canal. Sound makes the eardrum to vibrate. Vibration causes three ossicles to vibrate Vibration setup in the endolymph and perilymph. Vibration is transferred to the snail-shaped cochlea in the inner ear.

Cochlea is lined with sensitive hair cells (cilia) which move when vibrated and cause a nerve impulse to form.
Unfolded cochlea



These impulses travel from cochlea through the cochlear division of vestibulocochlear nerve (8th cranial n.) to the brain.

Transformer Ratio:

Stapes
TM
SURFACEAREA
OSSICULAR LEVER RATIO

Physiology of the Vestibular Apparatus

Balance of the body is maintained by coordination of information from three systems: Vision. Proprioception, i.e. sensation from muscles, joints, tendons and ligaments. Vestibular system.

Vestibular System

Semicircular canals Utricle and saccule.

Utricle and saccule

Respond to linear acceleration. Impulses from the utricle and saccule give information about position of the head in space Initiate reflexes which tend to keep the head in upright position

Semicircular canals

respond to angular (rotatory) acceleration SCC lie at right angles to each other Any rotatory movement will stimulate at least one pair of SCC(R+L). Movement of fluid within SCC will initiates a nerve impulse to travel through vestibular nerve. Sensation of rotation

Symptoms of ear disease

1/ Hearing loss ( Deafness) Is defined as subjective impairment of hearing. Three types; * conductive * sensorineural * mixed

C H L

S N H L
Conductive Hearing Loss Sound appears quieter but it is not distorted. Sounds are well heard when amplified. Paracusis Willisii positive especially otosclerosis The quality of speech is well maintained. Tinnitus usually absent
Sensorineural Hearing Loss Sound quieter and distorted. Sounds ' distortion limits the benefit of amplification.

Paracusis Willisii negative. In severe cases speech becomes indistinct and expressionless because patient does not hear his own voice. Tinnitus present


C H LExternal canal obstruction: cerumen, F.B. polyp, atresia.Perforated eardrum: otitis media, trauma, cholesteatomaOssicular chain fixation: otosclerosis, tympanosclerosisOssicular chain discontinuity car accident, head injury…Fluid in middle ear : secretory otitis media (the most common cause in children)Neoplasm of middle ear SNHL Congenital hearing loss Ototoxic Drugs Aging:(Presbycusis) Infection Cochlear: viral Retrocochlear: meningitis Trauma fracture of base of skull Tumor: cerebellopontine angle tumor vestibular schwannoma Endolymphatic hydrops: Meniere's disease Noise-induced hearing loss Acoustic trauma

2/ Discharge( Otorrhea) 1. Serous or purulent discharge Otitis externa. 2. Mucopurulent discharge, foul smell long duration: chronic suppurative otitis media. 3. Unilateral watery discharge following head injury or aural surgery: CSF otorrhea. (Damage to tegmen tympani) 4. Bloody discharge; due to granulation tissue in chronic suppurative otitis media or due to malignant disease.

3. Pain (Otalgia) Otogenic or primary Non- otogenic or referred otalgia

Otogenic A. External auditory canal trauma (e.g. from cotton bud abuse) auricular haematoma foreign body otitis externa EAC tumour B. Middle ear acute otitis media bullous myringitis chronic suppurative otitis media middle ear tumour
Referred OtalgiaOropharynx (IXth nerve): ■ tonsillitis ■ post-tonsillectomy ■ carcinoma posterior1/3Laryngopharynx (Xth nerve): ■ pyriform fossa tumor-Upper molar teeth,TMJ,parotid gland : impacted wisdom teeth new denture-Cervical spine (C2, C3) pain is often worse at night


4. Tinnitus ■Is a subjective sensation of sound in the ear or head in the absence of any relevant external signals. (Occasionally it is objective e.g. in palatal myoclonus and glomus tumors). ■ Sign of irritation of the cochlea or upper auditory pathways ■ … Ear disease ■ …It is a common symptom of anaemia, thyrotoxicosis, hyperdynamic circulation, renal failure and some intracranial tumors. It may be caused by ototoxic drugs, such as quinine, salicylates and aminoglycocide.

5. Vertigo Is defined as hallucination of movement or subjective sense of imbalance. It can be due to CVS disease, CNS disease or ear disease. Vertigo is considered as a symptom of irritation of the vestibular apparatus.

Vertigo may be central in origin (cerebellum), or peripheral (labyrinth /vestibular nerve). Peripheral lesions : intense vertigo of sudden onset. Nausea and vomiting Central lesions : less intense vertigo Positional changes have less effect, but the patient tends to have more disturbance of gait.

Congenital Abnormality

1. Preauricular sinuses and cysts. 2. Anotia: Complete absence of the pinna. 3. Microtia: Small pinna. 4. Accessory auricles. 5. Atresia of the external auditory meatus. 6. Protruding ear (Bat ear).

Haematoma of the auricle (Haematoma auris)

extravasations of blood under the perichondrium leading to bluish swelling of the auricle.The ear may be slightly tender with a feeling of heat and discomfort.If untreated, the pinna may become distorted and thickened due to replacement of necrosed cartilage with fibrous tissue. A "cauliflower ear" – often seen in wrestlers- may result.

Haematoma of the auricle (Haematoma auris)

Treatment Aspiration or incision and drainage under aseptic precautions followed by firm dressing or suturing of silastic sheets on pinna.

Symptoms History Hearing loss if the FB obstructs the canal Severe irritation and noise in the ear with animate FB Signs: The FB can be seen by otoscopy
Foreign Bodies in the Ear



3. Foreign Body in The Ear
Type of patient: Commonly children Mentally retaded adult Type of FB: Animate FB: Flies, larvae, fleas mosquito,, Inanimate FB: Non vegitable: bead, button, disc battery Vegetable: bean and pea

Types:

Animate FB (flies and larvae) Inanimate FB: vegetable : peas, beans non-vegetable : as buttons and disc battery

Treatment:Animate FB: Kill by alcohol  remove by ear wash or crocodile forceps.Inanimate FB:- Non vegetable: remove by ear wash or instruments BUT PLEASE DO NOT WASH IF THE FB IS DISC BATTERY- Vegetable: Remove by instruments and avoid ear wash because it may swell by water and become more impacted

General anesthesia may be needed in impacted FB and uncooperative children Complications: Injury of the external canal or drum by the FB or during removal
So donn’t wash if:The FB is vegetable The FB is disc battery