Implantable Hearing Devices — MCQs
A female patient presents with hearing loss. Rinne test results show Rinne negative at 256 Hz and 512 Hz, while Rinne positive at 1024 Hz. Based on these findings, what is the expected air conduction and bone conduction gap?
To distinguish between cochlear and post-cochlear damage, which test is done?
What is a specific indication for the use of a Bone-Anchored Hearing Aid (BAHA)?
A patient presents with vertigo, tinnitus, and head tilt. He underwent myringoplasty for the safe type of chronic suppurative otitis media (CSOM) 6 months back. What is your diagnosis?
Cochlear implants are primarily indicated for which of the following conditions?
A child aged 3 yrs, presented with severe sensorineural deafness was prescribed hearing aids, but showed no improvement. What is the next line of management:
Which of the following is the most common morbidity associated with Meniere's disease?
Electrode of cochlear implant is placed in:
Which device is depicted below?
Positive Rinne test is seen in -
Implantable Hearing Devices Indian Medical PG Practice Questions and MCQs
Question 1: A female patient presents with hearing loss. Rinne test results show Rinne negative at 256 Hz and 512 Hz, while Rinne positive at 1024 Hz. Based on these findings, what is the expected air conduction and bone conduction gap?
- A. 30-45 dB
- B. 15-30 dB (Correct Answer)
- C. 45-60 dB
- D. >60 dB
Explanation: ***15-30 dB*** - The pattern of **Rinne negative at 256 Hz and 512 Hz** combined with **Rinne positive at 1024 Hz** is characteristic of a **mild to moderate conductive hearing loss** with an air-bone gap in the **15-30 dB range**. - In this range, the conductive component is sufficient to cause Rinne negativity at lower frequencies where bone conduction is more efficient, but at higher frequencies (1024 Hz), the gap narrows and air conduction becomes relatively better, resulting in a positive Rinne test. - This frequency-dependent pattern indicates the air-bone gap is **closing at higher frequencies**, typical of mild conductive losses. *30-45 dB* - An air-bone gap of **30-45 dB** represents a **moderate conductive hearing loss** where Rinne test would remain **negative across all frequencies** including 1024 Hz. - At this magnitude of conductive loss, bone conduction would still significantly exceed air conduction even at higher frequencies. - The transition to Rinne positive at 1024 Hz would NOT occur with this degree of hearing loss. *45-60 dB* - This represents a **moderate-severe conductive hearing loss** with a substantial air-bone gap. - Rinne test would be **strongly negative across all tested frequencies** without exception. - The large gap would prevent any frequency from showing air conduction superiority. *>60 dB* - This indicates a **severe to profound conductive hearing loss** with a very large air-bone gap. - Rinne test would be **markedly negative at all frequencies**, with bone conduction dramatically exceeding air conduction. - Air conduction may be barely perceptible or absent at this level of loss.
Question 2: To distinguish between cochlear and post-cochlear damage, which test is done?
- A. Auditory brainstem response (ABR) (Correct Answer)
- B. Impedance audiometry
- C. Pure tone audiometry
- D. Electrocochleography (ECochG)
Explanation: ***Auditory brainstem response (ABR)*** - This test evaluates the integrity of the **auditory pathway from the cochlea through the brainstem**, making it excellent for differentiating between cochlear (sensory) and post-cochlear (retrocochlear/neural) lesions. - Abnormalities in wave latencies or interpeak intervals suggest **retrocochlear pathology** (e.g., acoustic neuroma), while normal ABR responses despite hearing loss point towards cochlear damage. - ABR records **five characteristic waves (I-V)** representing neural transmission from the auditory nerve through the brainstem. *Impedance audiometry* - Primarily assesses the **middle ear function**, including the eardrum and ossicles, by measuring **tympanic membrane compliance** and **acoustic reflexes**. - It does not directly evaluate the function of the **cochlea or the retrocochlear pathways**, making it unsuitable for this differentiation. *Pure tone audiometry* - Measures a person's **hearing sensitivity** at different frequencies and provides information on the **degree and type of hearing loss (conductive, sensorineural, or mixed)**. - While it identifies sensorineural hearing loss, it cannot pinpoint whether the damage is **cochlear or retrocochlear** within the sensorineural category. *Electrocochleography (ECochG)* - Records **electrical potentials generated by the cochlea and auditory nerve** in response to sound, including **cochlear microphonics, summating potentials, and compound action potentials**. - While it evaluates cochlear function and is useful in diagnosing **Meniere's disease** and **auditory neuropathy**, it does not adequately assess the **integrity of the brainstem auditory pathways** needed to differentiate retrocochlear lesions.
Question 3: What is a specific indication for the use of a Bone-Anchored Hearing Aid (BAHA)?
- A. Bilateral conductive hearing loss
- B. Unilateral sensorineural hearing loss
- C. Congenital canal atresia (Correct Answer)
- D. Conductive hearing loss due to other causes
Explanation: ***Congenital canal atresia*** - **Congenital canal atresia** represents a classic, specific indication for BAHA because the ear canal is congenitally absent or severely stenosed, making conventional hearing aids impossible to fit or ineffective. - BAHA bypasses the absent ear canal entirely by transmitting sound vibrations directly to the **cochlea through bone conduction**, providing an ideal solution for this anatomical abnormality. *Bilateral conductive hearing loss* - While BAHA can be used for conductive hearing loss, **conventional hearing aids** are typically the first-line treatment when ear canals are intact and functional. - Bilateral cases often benefit from traditional amplification devices or **surgical correction** of the underlying conductive pathology before considering BAHA. *Unilateral sensorineural hearing loss* - BAHA is commonly used for **single-sided deafness (SSD)** to route sound from the deaf ear to the hearing ear via bone conduction using the **CROS principle**. - However, this indication is less specific than congenital canal atresia, as other treatment options like **conventional CROS hearing aids** may also be considered. *Conductive hearing loss due to other causes* - This option is too **broad and non-specific** as it encompasses many different etiologies of conductive hearing loss. - Many other causes of conductive hearing loss have **alternative treatments** such as surgical repair, conventional hearing aids, or medical management, making BAHA a secondary consideration.
Question 4: A patient presents with vertigo, tinnitus, and head tilt. He underwent myringoplasty for the safe type of chronic suppurative otitis media (CSOM) 6 months back. What is your diagnosis?
- A. Paget disease
- B. Labyrinthitis
- C. Vestibular schwannoma
- D. Perilymphatic fistula (Correct Answer)
Explanation: ***Perilymphatic fistula*** - The combination of **vertigo**, **tinnitus**, and **head tilt** occurring after a **myringoplasty**, even for a safe type of CSOM, suggests a perilymphatic fistula. - Myringoplasty can occasionally involve trauma to the **oval or round window**, leading to a direct communication between the inner ear (perilymph) and the middle ear, causing these symptoms. *Paget disease* - This is a **bone remodeling disorder** that primarily affects the skull, pelvis, and long bones, leading to bone pain and deformities. - While it can cause hearing loss (due to otosclerosis) and a sense of imbalance, it does not typically present with the acute onset of **vertigo** and **tinnitus** following ear surgery. *Labyrinthitis* - **Labyrinthitis** is an inflammation of the inner ear, typically caused by a viral infection, leading to sudden, severe **vertigo**, **nausea**, and often **hearing loss** or **tinnitus**. - While the symptoms of vertigo and tinnitus are present, the history of recent myringoplasty makes a **structural compromise** like a perilymphatic fistula a more specific diagnosis than generalized inflammation. *Vestibular schwannoma* - Also known as an acoustic neuroma, this is a **benign tumor** on the eighth cranial nerve, causing **gradual unilateral hearing loss**, **tinnitus**, and **imbalance**, but rarely sudden, intense vertigo unless very large. - The presentation with a history of myringoplasty and acute symptoms makes a **spontaneous structural defect** more likely than a slowly growing tumor.
Question 5: Cochlear implants are primarily indicated for which of the following conditions?
- A. Sensorineural deafness (Correct Answer)
- B. Conductive deafness
- C. Mixed deafness
- D. Absent pinna
Explanation: ***Sensorineural deafness*** - **Cochlear implants** are prosthetic devices that electrically stimulate the **auditory nerve**, bypassing damaged hair cells in the **cochlea**. - They are primarily indicated for individuals with **severe to profound sensorineural hearing loss** who do not benefit adequately from conventional hearing aids. - This is the gold standard indication for cochlear implantation in both adults and children. *Conductive deafness* - **Conductive hearing loss** occurs when sound waves cannot reach the inner ear due to problems in the outer or middle ear (e.g., **otosclerosis**, **perforated eardrum**). - This type of hearing loss is typically treatable with **hearing aids**, surgery, or bone-anchored hearing systems, as the inner ear and auditory nerve are still functional. *Mixed deafness* - **Mixed hearing loss** involves elements of both **conductive** and **sensorineural hearing loss**. - While a profound sensorineural component might eventually warrant a cochlear implant, initial treatment often focuses on addressing the conductive component first, or using hearing aids for both aspects. - Not the **primary** indication for cochlear implants. *Absent pinna* - An **absent pinna** (microtia or anotia) represents a developmental anomaly of the external ear, primarily affecting **cosmetics** and potentially causing **conductive hearing loss** if the ear canal or middle ear structures are also affected. - It does not indicate the need for a **cochlear implant**, as the inner ear and auditory nerve may be perfectly healthy.
Question 6: A child aged 3 yrs, presented with severe sensorineural deafness was prescribed hearing aids, but showed no improvement. What is the next line of management:
- A. Conservative
- B. Fenestration surgery
- C. Stapes mobilisation
- D. Cochlear implant (Correct Answer)
Explanation: ***Cochlear implant*** - For **severe sensorineural deafness** where conventional hearing aids provide no benefit, a cochlear implant is the most effective next step for restoring hearing. - A cochlear implant directly stimulates the **auditory nerve**, bypassing damaged hair cells in the cochlea, which is crucial for severe sensorineural hearing loss. - In children aged **12 months to 5 years**, early cochlear implantation is critical for optimal **speech and language development**. *Conservative* - This typically refers to observation or non-invasive treatments like hearing aids, which have already failed in this case. - Continuing a conservative approach would delay effective intervention for severe deafness, potentially impacting the child's **speech and language development**. *Fenestration surgery* - This is a surgical procedure primarily used for some types of **conductive hearing loss**, especially **otosclerosis**, by creating an opening in the bony labyrinth. - It is not indicated for **sensorineural deafness**, as the problem lies with the inner ear or auditory nerve, not the sound conduction pathway. *Stapes mobilisation* - This procedure aims to restore mobility to the **stapes bone** in cases of **otosclerosis**, a form of conductive hearing loss where the stapes becomes fixed. - It is not appropriate for **sensorineural hearing loss**, where the primary issue is damage to the inner ear's sensory cells or the auditory nerve.
Question 7: Which of the following is the most common morbidity associated with Meniere's disease?
- A. Permanent hearing loss (Correct Answer)
- B. Secondary development of a craniopharyngioma
- C. Chronic otitis media
- D. Chronic otitis externa
Explanation: ***Permanent hearing loss*** - **Meniere's disease** is characterized by episodes of **vertigo**, **tinnitus**, ear fullness, and fluctuating hearing loss, which often progresses to permanent hearing loss over time. - The recurrent episodes of **endolymphatic hydrops** cause cumulative damage to the **cochlea** and **vestibular apparatus**, leading to irreversible sensorineural hearing loss. *Chronic otitis media* - This is an **infection** and **inflammation of the middle ear**, typically leading to tympanic membrane perforation or cholesteatoma. - It is distinct from Meniere's disease, which is a disorder of the **inner ear** with no direct pathological link to middle ear infections. *Chronic otitis externa* - This condition involves **inflammation of the external ear canal** and is usually caused by bacterial or fungal infections. - It is an outer ear condition and bears no etiological or symptomatic relationship to the inner ear pathology of Meniere's disease. *Secondary development of a craniopharyngioma* - A **craniopharyngioma** is a benign brain tumor arising from Rathke's pouch cells, typically located near the **pituitary gland**. - There is no known direct association or increased risk of developing a craniopharyngioma in patients with Meniere's disease.
Question 8: Electrode of cochlear implant is placed in:
- A. Horizontal semicircular canal
- B. Scala media
- C. Scala tympani (Correct Answer)
- D. Scala vestibuli
Explanation: ***Scala tympani*** - The electrode array of a **cochlear implant** is carefully inserted into the **scala tympani** of the cochlea. - This placement allows the electrodes to directly stimulate the **spiral ganglion neurons**, bypassing damaged hair cells and transmitting electrical signals to the auditory nerve. *Horizontal semicircular canal* - The **horizontal semicircular canal** is part of the **vestibular system**, responsible for sensing angular head movements, not hearing. - Placing an electrode here would cause **vestibular dysfunction** and would not restore hearing. *Scala media* - The **scala media** (cochlear duct) contains the **organ of Corti** and **endolymph**, which has a high potassium concentration. - Inserting an electrode here would damage the delicate structures essential for natural sound transduction and could lead to electric potential imbalances. *Scala vestibuli* - The **scala vestibuli** is filled with **perilymph** and receives sound vibrations from the stapes. - While it's adjacent to the scala tympani, the **scala tympani** offers a safer and more direct path for optimal electrode insertion with less trauma to the sensory structures.
Question 9: Which device is depicted below?
- A. Cochlear implant (Correct Answer)
- B. Auditory brainstem implant (ABI)
- C. Bone anchored hearing aid (BAHA)
- D. Hearing aid
Explanation: ***Cochlear implant*** - A cochlear implant is an **electronic medical device that replaces the function of a damaged inner ear (cochlea)** and provides sound signals directly to the brain - On imaging (X-ray, CT, or skull radiograph), it appears as a **characteristic circular receiver-stimulator device** under the skin behind the ear with an **electrode array extending into the cochlea** - The **internal receiver has a distinctive appearance** with visible magnets and electrode contacts, making it easily identifiable on radiographic images - Used for patients with **severe to profound sensorineural hearing loss** who do not benefit from conventional hearing aids *Auditory brainstem implant (ABI)* - An ABI **bypasses both the cochlea and auditory nerve**, directly stimulating the **cochlear nucleus in the brainstem** - On imaging, the electrode array would be located at the **cerebellopontine angle** near the brainstem, not in the cochlea - Reserved for patients with **absent or non-functional auditory nerves** (e.g., bilateral vestibular schwannomas, neurofibromatosis type 2) *Bone anchored hearing aid (BAHA)* - A BAHA consists of a **titanium implant osseointegrated into the skull bone** behind the ear with an external sound processor - On X-ray, only the **small titanium fixture/abutment** would be visible in the mastoid bone, without any cochlear or intracranial components - Works by **bone conduction**, transmitting sound vibrations directly to the inner ear, bypassing the outer and middle ear - Used for **conductive hearing loss, mixed hearing loss, or single-sided deafness** *Hearing aid* - A conventional hearing aid is a **completely external electronic device** that amplifies sound - It would **not be visible on X-ray or CT imaging** as it contains no implanted components - Simply amplifies sound for individuals with mild to moderate hearing loss
Question 10: Positive Rinne test is seen in -
- A. Wax impacted ear
- B. Presbycusis (Correct Answer)
- C. CSOM
- D. Otosclerosis
Explanation: ***Presbycusis*** - A **positive Rinne test** indicates that **air conduction is better than bone conduction (AC > BC)**, which is normal. - In presbycusis, which is a **sensorineural hearing loss**, the inner ear is affected. While hearing is impaired, the *relationship between air and bone conduction remains normal*, thus a positive Rinne test is maintained. *Wax impacted ear* - This causes a **conductive hearing loss** by obstructing the ear canal. - In conductive hearing loss, **bone conduction is better than air conduction (BC > AC)**, resulting in a **negative Rinne test**. *CSOM* - **Chronic Suppurative Otitis Media (CSOM)** involves infection and perforation of the tympanic membrane and/or damage to ossicles. - This leads to **conductive hearing loss**, where **bone conduction is better than air conduction**, resulting in a **negative Rinne test**. *Otosclerosis* - This condition involves **abnormal bone growth** in the middle ear, particularly around the stapes footplate, leading to fixation. - It causes a **conductive hearing loss**, characterized by **bone conduction being better than air conduction**, meaning a **negative Rinne test**.
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