Cochlear Implants — MCQs
Which of the following would be the most appropriate treatment for rehabilitation of a patient, who has bilateral profound deafness following surgery for bilateral acoustic schwannoma?
A female patient presents with mild conductive hearing loss (CHL) and tinnitus. Based on the pure tone audiometry (PTA) shown in the image, what is the most likely diagnosis?
Which device is depicted below?
Identify the device shown in the image below:
Cochlear implants are primarily indicated for which of the following conditions?
Which of the following interventions is least appropriate for an 8-year-old boy with bilateral sensorineural hearing loss?
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 devices typically requires the most stringent safety protocols before MRI scanning?
Electrode of cochlear implant is placed in:
Which of the following tests is used to differentiate between cochlear and retrocochlear hearing loss?
Cochlear Implants Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following would be the most appropriate treatment for rehabilitation of a patient, who has bilateral profound deafness following surgery for bilateral acoustic schwannoma?
- A. Bilateral cochlear implant
- B. Unilateral cochlear implant
- C. Brainstem implant (Correct Answer)
- D. Bilateral high powered digital hearing aid
Explanation: ***Brainstem implant*** - A **brainstem implant** is the most appropriate treatment when the auditory nerve has been damaged or destroyed, as can occur during bilateral acoustic schwannoma surgery. - This device bypasses the cochlea and auditory nerve by directly stimulating the **cochlear nucleus** in the brainstem, allowing sound perception. *Bilateral cochlear implant* - A **cochlear implant** requires an intact auditory nerve to transmit signals from the cochlea to the brain. - In this scenario, bilateral profound deafness post-surgery for acoustic schwannoma often implies damage to both **auditory nerves**, rendering cochlear implants ineffective. *Unilateral cochlear implant* - Similar to a bilateral cochlear implant, a **unilateral cochlear implant** relies on the functionality of at least one auditory nerve. - Since the patient has **bilateral profound deafness** following bilateral surgery, the auditory nerves are likely compromised on both sides, making even a unilateral implant unsuitable. *Bilateral high powered digital hearing aid* - Hearing aids amplify sound and rely on the presence of residual hair cell function in the **cochlea** and an intact auditory pathway. - Profound deafness indicates severe damage to the inner ear or auditory nerve, which hearing aids cannot overcome as they only provide *amplification*, not direct neural stimulation.
Question 2: A female patient presents with mild conductive hearing loss (CHL) and tinnitus. Based on the pure tone audiometry (PTA) shown in the image, what is the most likely diagnosis?
- A. Ménière's disease
- B. Otosclerosis (Correct Answer)
- C. Ototoxicity
- D. Noise-Induced Hearing Loss (NIHL)
Explanation: ***Otosclerosis*** - The audiogram shows a **conductive hearing loss** with a notable **Carhart notch** (bone conduction dip at 2000 Hz), which is characteristic of otosclerosis. - The patient's symptoms of **mild CHL** and **tinnitus** are consistent with the presentation of otosclerosis, a condition involving abnormal bone growth in the middle ear. *Ménière's disease* - This condition primarily causes **sensorineural hearing loss**, often fluctuating and affecting low frequencies initially, along with **vertigo, tinnitus, and aural fullness**. - The audiogram indicates **conductive hearing loss**, not sensorineural, and **vertigo** is not mentioned as a primary symptom. *Ototoxicity* - Ototoxicity typically results in **sensorineural hearing loss**, often bilateral and affecting high frequencies first. - The audiogram demonstrates **conductive hearing loss**, and there is no information about exposure to ototoxic medications. *Noise-Induced Hearing Loss (NIHL)* - NIHL is characterized by **sensorineural hearing loss**, typically with a **notch at 3000-6000 Hz** (most commonly 4000 Hz notch) on the audiogram. - The audiogram reflects **conductive hearing loss**, and the specific pattern does not match that of NIHL.
Question 3: 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 4: Identify the device shown in the image below:
- A. Cochlear implant (Correct Answer)
- B. Transcranial magnetic stimulation
- C. Vagus nerve stimulation
- D. Deep brain stimulation
Explanation: ***Cochlear implant*** - The image displays the external components of a **cochlear implant**: a **speech processor** worn behind the ear connected to an external transmitter that sends signals to an implanted receiver. - This device is designed to provide a sense of sound to individuals with **severe-to-profound hearing loss** by directly stimulating the auditory nerve. *Transcranial magnetic stimulation* - This therapy involves a **coil placed on the scalp** that delivers magnetic pulses to stimulate nerve cells in the brain, typically for depression or migraines. - It does not involve ear-worn components or internal surgical implants of the type seen in the image. *Vagus nerve stimulation* - This involves a device surgically implanted under the skin in the chest, with wires connected to the **vagus nerve** in the neck. - It is used to treat epilepsy and depression and does not have external components positioned around the ear or on the head as depicted. *Deep brain stimulation* - This neurosurgical procedure involves implanting electrodes into specific areas of the brain, connected to a pulse generator (similar to a pacemaker) implanted in the chest. - It is primarily used for movement disorders like Parkinson's disease and does not feature external ear-worn components visible in the image.
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: Which of the following interventions is least appropriate for an 8-year-old boy with bilateral sensorineural hearing loss?
- A. Adenoidectomy with grommet insertion (Correct Answer)
- B. Hearing aid
- C. Cochlear implant
- D. Preferential sitting in the classroom
Explanation: ***Adenoidectomy with grommet insertion*** - This procedure addresses **conductive hearing loss** (e.g., due to **otitis media with effusion**), while the boy has **sensorineural hearing loss (SNHL)**. - **Grommet insertion** (tympanostomy tubes) is used to improve middle ear ventilation and drain fluid, which is irrelevant for SNHL. *Hearing aid* - A **hearing aid** amplifies sound and is a common and appropriate intervention for **sensorineural hearing loss**, especially for mild to severe cases. - It can significantly improve a child's ability to hear and develop speech. *Cochlear implant* - A **cochlear implant** is appropriate for children with **severe to profound sensorineural hearing loss** who do not benefit sufficiently from hearing aids. - It directly stimulates the auditory nerve, bypassing damaged parts of the inner ear. *Preferential sitting in the classroom* - This is a simple and effective **accommodative strategy** to improve a child's listening environment and is appropriate for any degree of hearing loss. - It helps the child to better hear the teacher and participate in classroom discussions.
Question 7: 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 8: Which of the following devices typically requires the most stringent safety protocols before MRI scanning?
- A. Prosthetic cardiac valves
- B. Insulin pump
- C. Cochlear implants
- D. Automatic Cardioverter-defibrillators (Correct Answer)
Explanation: ***Automatic Cardioverter-defibrillators*** - **Implantable cardioverter-defibrillators (ICDs)**, while increasingly MRI-conditional, require stringent protocols due to potential for **heating, lead damage, and inappropriate pacing/shocks**. - Detailed device interrogation, programming to asynchronous modes or MRI mode, and continuous monitoring are often required to mitigate risks and ensure patient safety. *Prosthetic cardiac valves* - Most modern **prosthetic cardiac valves** (both mechanical and bioprosthetic) are **MRI-conditional** or **MRI-safe** and generally do not pose significant risks. - They are typically made of non-ferromagnetic materials, reducing concerns about displacement or heating. *Insulin pump* - External insulin pumps are generally considered **MR-unsafe** and must be **removed from the patient** before entering the MRI scan room. - While removal is a safety protocol, they don't involve complex internal electronic interactions in the same way an implanted ICD does, making their protocol simpler (remove and resume). *Cochlear implants* - Many **cochlear implants** are now **MRI-conditional**, but they often require specific protocols such as removing the external processor and sometimes applying a head bandage to secure the implant. - Older models or certain configurations may still be considered MR-unsafe due to potential for magnet displacement or device damage.
Question 9: 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 10: Which of the following tests is used to differentiate between cochlear and retrocochlear hearing loss?
- A. Recruitment
- B. Threshold tone decay test
- C. Evoked response audiometry (Correct Answer)
- D. SISI test
Explanation: **Evoked response audiometry** - **Evoked response audiometry (ERA)**, specifically **Auditory Brainstem Response (ABR)** or **Brainstem Evoked Response Audiometry (BERA)**, is the gold standard for differentiating between cochlear and retrocochlear hearing loss. - ABR measures electrical activity from the auditory nerve and brainstem in response to sound, allowing for differentiation between **cochlear pathology** (normal ABR latencies with hearing loss) and **retrocochlear pathology** (prolonged interpeak latencies, absent waves, or abnormal waveform morphology suggestive of auditory nerve or brainstem lesion). - Classic findings in retrocochlear lesions include prolonged I-V interpeak latency or absent Wave V. *SISI test* - The **Short Increment Sensitivity Index (SISI) test** assesses the ability to detect small (1 dB) increments in sound intensity superimposed on a continuous tone. - A **high SISI score (>70%)** indicates **cochlear dysfunction** due to recruitment phenomenon, while a **low score (<20%)** may suggest retrocochlear pathology. - However, it does not directly differentiate between cochlear and retrocochlear lesions with the same specificity and sensitivity as ABR. *Threshold tone decay test* - The **Tone Decay Test (TDT)** measures the ability to sustain the perception of a continuous pure tone presented at or near threshold level. - **Significant tone decay (>30 dB in 60 seconds)** suggests **retrocochlear pathology** due to auditory nerve fatigue, making it useful for screening. - While helpful, it is less precise, sensitive, and specific than ABR for definitive differentiation and may have false positives. *Recruitment* - **Recruitment** is an abnormal growth in the perception of loudness, where a small increase in sound intensity leads to a disproportionately large increase in perceived loudness. - It is a classic sign of **cochlear hearing loss**, particularly associated with outer hair cell damage (sensory hearing loss). - Its presence confirms cochlear pathology but its absence does not confirm retrocochlear lesions, making it less reliable as a differentiating test compared to ABR.
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