Otoscopy
Written by Dr.ChrisOtoscopy: The inside of the external auditory canal is examined conve-niently using a head mirror, light source and ear speculum. The examination may also be done by using a battery or electric Oto-scope. This gives some magnification and is useful in examining children, infants and for bedside examination of patients, but any manipulation with an […]
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HYPERACUSIS (PHONOPHOBIA)
Written by Dr.ChrisHYPERACUSIS (PHONOPHOBIA): This term is applied to a condition when the subject complains of increased sensitivity to sounds.
The sounds appear as uncomfortably loud to the patient. This phenomenon occurs in cases suffering from stapedius muscle paralysis as after supra stapedial lesions of facial nerve paralysis and in cases of congential syphilis.
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TULLIO PHENOMENON
Written by Dr.ChrisTULLIO PHENOMENON: This term is applied to a condition where the subject gets attacks of dizziness or/vertigo by loud sounds. The vertigo is due to stimulation of ampullary cristae by the sound waves.
The phenomenon may occur in patients having labyrinthine fistulae, and in those who have undergone fenestration operation.
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RefFerred Otalgia
Written by Dr.ChrisThe ear itself being normal, otalgia maybe a symptom of lesions affectitous anatomical sites in head and neck. The external ear is supplied by 5th and 10th cranial nerves. These nerves also supply various structures-rtfEiad aid neck. Similarly 9th cranial nerve besides supplying the middle ear is also sensory to 1—-zicin-ions of oropharynx and base […]
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EARACHE (OTALGIA)
Written by Dr.ChrisEARACHE (OTALGIA): The pain in the ear may be due to lesions, in the ear itself or due to the conditions in the surrounding areas (referred otalgia).
The earache due to the lesions of the ear itself include:
a) External ear
(i) Furunculosis
(ii) Impacted wax or foreign body
(iii) Perichondritis
(iv) Diffuse otitis externa
(v) Otomycosis
(vi) Myringitis Bullosa
(vii) Ramsay Hunt’s Syndrome
(viii) Traumatic lesions within the external auditory canal.
(b) Middle […]
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EAR DISCHARGE (OTORRHOEA)
Written by Dr.ChrisEAR DISCHARGE (OTORRHOEA): Discharging ear is a common manifestation of an ear disease. The discharge is commonly due to middle ear pathalogy but may also be due to the infections of external audio canal. The discharge may be serous, mucoid, muco purulent, purulent, blood stained, or watery.
Serous discharge is found in allergic otitis externa. Muco purulent […]
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Hearing Loss and Deafness are not the Same
Written by Dr.ChrisHearing Loss and Deafness are not the Same
Hard of Hearing:A person is said to be hard of hearing if he or she has hearing loss which can be helped by medical and/or surgical treatment, or has learned speaking naturally as partially hearing child or adult. Rehabilitation measures like providing amplification (hearing aid), speech and auditory […]
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Deafness or Hearing impairment
Written by Dr.ChrisDeafness or Hearing impairment is an important otological symptom. It may be unilateral or bilateral. The various points to be asked are:
1. Onset: Whether onset was gradual or sudden. Sudden deaf¬ness may be after headinjuries, blast injuries, viral infections and vascular causes etc.
2. Duration: Deafness which is present since birth may be due to genetic causes, due […]
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Distortion in the ear
Written by Dr.ChrisDistortion in the ear: There are several forms of sound distortion to which ear, in com¬mon with other acoustic devices, is subjected. These are:
1. Frequency distortion: The “preferential’ transmission of certain frequencies as compared with others. It occurs when the secondary system into which the sound is transmitted from the primary system cannot reproduce all frequencies […]
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The efferent cochlear system
Written by Dr.ChrisThe efferent cochlear system: Within the auditory nerve there have been found some 500 cen¬trifugal fibres coursing from the brain stem to the hair cells. Ana¬tomical studies show that they originate in the superior olivary nucleus. About 1/5th of them are of homolateral origin and the remainder from the opposite side. Rasmussen has defined sev¬eral […]
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Summation potentials or S.P.
Written by Dr.ChrisSummation potentials or S.P.: This also results from acoustic stimulation and consists of a change in E.P. which’ may be in the positive or the negative sense (S.P.± & SP-) unlike C.M. it does not follow the actual instantaneous values of the sound stimulus, but is proportional to the r.m.s. (root mean square) acoustic pressure.
S.P. […]
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The cochlear microphonics or C.M.
Written by Dr.ChrisThe cochlear microphonics or C.M.: This is the main compo¬nent and confers upon the cochlear potentials. It has 2 element C.M. 1. which is oxygen dependent and is abolished by oxygen lack or by death of the individual, and C.M. 2.about 10% of the whole, which can still be elicited for several hours after total […]
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Auditory nerve action potential
Written by Dr.ChrisThe auditory nerve action potential or A.P. which consists of an aggregate of the action potentials of the individual nerve fibres. These potentials are similar to those of other nerves e.g. a spike discharge preceded by a latent period and followed by a refractory period.
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Sensorineural mechanism of hearing
Written by D C MorganSensorineural mechanism of hearing: Once the sound waves are transmitted, foot plate of stapes causes movement of cochlear fluids It produces a wave which cause displacement of the basilar membrane. The organ of corti gets stimulated and results in generation of cochlear microphonics.
The nerve impulses (action potentials) are carried to the central connection.
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Functions of mastoid cellular system
Written by D C MorganFunctions of mastoid cellular system
The functions of cellularity of mastoid is not very clear. It may serve following functions:
(i) Air reservior for the middle ear cavity. -
(ii) Insulating chambers protecting the labyrinth from temper¬ature variations.
(iii) May provide resonance to sound.
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