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INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul Aziz University Riyadh, Saudi Arabia

INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

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Page 1: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

INNER EAR CONDUCTIVE

HEARING LOSS

Prof. Hamad Al MuhaimeedProf. Yousry El Sayed

Dr. Abdulrahman RabahDr. Abdulrahman Essa

Department of ORLKing Abdul Aziz University

Riyadh, Saudi Arabia

Page 2: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Cochlea prefers 2 functions:

1 )Transmission of sound energy = oval window to basilar membrane

2 )Transduction of the mechanical )acoustic) energy) --> electrical )neural energy) = organ of corti

Page 3: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

• Lesion of hair cells --> SNHL

• Lesions in scala vestibuli, helicotrema, scala tympani, or basilar membrane --> CHL

– Inner ear CHL will be characterized by absent RWR + normal contra- lateral stapedial reflex

Page 4: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 1:

–10 year old boy – Lt. hearing loss – No history of trauma, infections, -ve family history of HL – Otoscopy: NAD – Tuning fork test: +ve Rt.; -ve Lt. = Weber --> Lt.

Page 5: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 1: (cont.)

–PTA – Tympanometry: Ipsilateral stapedial reflex absence Lt., present Rt. > Contralateral - St. reflex was elicited in Lt. – C.T. scan Temporal bone: Normal cochlea, cochlear aqueduct, no signs of cholesteatoma

Page 6: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 1: (cont.)

– Provisional diagnosis: Ossicular disruption medial to neck of the stapedius – Lt. tympanotomy: • intact & mobile ossicles • normal footplate movement • RW reflex -ve

– ABR: conductive nature of HL

Page 7: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 2:

–20 year old girl – Progressive Lt. HL for 5 years – No hx of ear discharge, tinnitus, vertigo or trauma – Otoscopy: NAD – Tuning fork test: Consistent with Lt. CHL – PTA – Tympanometry: Contralateral St. reflex was elicited in Lt.

Page 8: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 2: (cont.)

– C.T. scan : NAD– Lt. tympanotomy: NAD + -ve RWR– ABR: Hearing threshold is 80 dBHL with shifting of wave latency

Page 9: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Case 3:

– 38 year old man– Bil. HL with tinnitus for 2 years– No hx of ear discharge, vertigo or trauma– Otoscopy: NAD– Rinne: -ve bilaterally Weber test is central– PTA– Tympanometry– Rt. Tympanotomy: NAD + -ve RWR– CT scan: NAD

Page 10: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

History

The concept of inner ear CHL has beenproposed as early as 1960s by Gloris &Davis, Nixon & Glorig )stiffness of thecochlear partition.

Shea: Inner ear CHL occurs in 1:700pts. with otosclerosis.

Page 11: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion

– Lesion of the external & middle ear affecting the sound conduction or/and the transformer functions --> CHL

– Lesions affecting hair cells [transduction] --> SNHL

– Lesions affecting scala vestibuli, helicotrema, scala tympani, or basillar membrane )sound conduction)--> CHL

Page 12: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion )cont.)

You should exclude: – Inorganic deafness – SNHL with shadow bone conduction

Diagnosis of CHL in the 3 cases hasbeen confirmed by: 1) Repeated tuning fork test 2) PTA with masking 3) ABR 4) Stapedial reflex

Page 13: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion: )cont.)

Surgical exploration had excluded anymiddle ear abnormalities includingcongenital cholesteatoma.

Consequently, CHL is most likely dueto an anatomic or functional lesion inthe cochlea proximal to the sensorypart )hair cells).

Page 14: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion )cont.)

Possible causes of inner ear CHL:

1) Abnormal perilymp pressure - Cremers et al, 1983

2) Stiffness of the basilar membrane - Nodal, 1979

This is more reasonable to cause HL in 3 cases.

Page 15: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Causes:

– The 1st case is probably due to congenital cause since birth while the others may be acquired.

– The elevated bone conduction threshold seen in some frequencies may be inter- preted as mixed HL secondary to affection of the hair cells by the same aetiological agent.

Page 16: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion )cont.)

Bone conduction threshold is NOTjust a measure of hair cell function.

Some disorders may falsely enhancethe bone conduction while others mayfalsely decrease it e.g. Carhart effect.

- Dirks, 1985

Page 17: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion: )cont.)

– Diagnosis & treatment of CHL due to external or middle ear abnormalities are well documented. It includes clinical, audiological, radiological examinations.

– Diagnosis of inner ear CHL is a difficult task.

Page 18: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Causes:

The 1st two young pts. showed unilateral HLwhile the 3rd case )38 yr) showed bil. HL

– Is the main lying pathology in all cases the same?

– Is this pathology progressive that involved the other side as the age advances?

Page 19: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion: )cont.)

The anatomic correlate to inner earCHL is not completely understood.

Probably the functional loss is due toimpairment of the vibration of thebasillar membrane as a result ofabnormality in the scala vestibuli,helicotrema, & scala tympani orbasillar membrane.

Page 20: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Discussion )cont.)

Positive contralateral stapedial reflex:

1) Fractured crurae of the stapedes

2) Ossicular disruption with presence of soft tissue connection between stapes and incus.

Page 21: INNER EAR CONDUCTIVE HEARING LOSS Prof. Hamad Al Muhaimeed Prof. Yousry El Sayed Dr. Abdulrahman Rabah Dr. Abdulrahman Essa Department of ORL King Abdul

Inner Ear Conductive HL

Conclusion:

Three cases of mainly CHL thought to be dueto derangements of the sound conductionfunction of the inner ear.

The pathophysiology is not clear due toinaccessibility of the cochlea for clinicalexamination and lack of histopathologicalstudies. More studies are needed to clarifythis matter.

These pts. need to be followed to see theprogress of inner ear pathologies.