Rehabilitative Audiology — MCQs
To distinguish between cochlear and post-cochlear damage, which test is done?
Where will be the placement location for Auditory Brainstem Implant?
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?
Which intervention is best in patients operated for bilateral acoustic neuroma for hearing rehabilitation?
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:
The mechanism of hearing and memory, include all, EXCEPT:
Electrode of cochlear implant is placed in:
Which device is depicted below?
All of the following are true about the hearing aid shown in the figure except:
The cough response elicited while cleaning the external ear canal is mediated by stimulation of which nerve?
Rehabilitative Audiology Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: Where will be the placement location for Auditory Brainstem Implant?
- A. Scala tympani
- B. Recess of 4th ventricle (Correct Answer)
- C. IAC
- D. Back of ear
Explanation: ***Recess of 4th ventricle*** - An **Auditory Brainstem Implant (ABI)** is placed on the **cochlear nucleus** in the brainstem, which is anatomically located near the **lateral recess of the fourth ventricle**. - The implant stimulates these nuclei directly, bypassing the damaged auditory nerve in patients who cannot benefit from cochlear implants. *Scala tympani* - The **scala tympani** is the location for electrode placement in a **cochlear implant**, not an auditory brainstem implant. - Cochlear implants stimulate the intact auditory nerve within the cochlea. *IAC* - The **internal auditory canal (IAC)** houses the auditory and facial nerves, but it is not the target site for an ABI. - The ABI is designed for patients whose auditory nerve (which passes through the IAC) is non-functional. *Back of ear* - The "back of the ear" is the general area where the **external processor of a cochlear implant** or a **bone-anchored hearing aid** is typically worn, not the surgical placement site for an ABI. - The ABI's internal component is surgically placed within the cranium.
Question 3: 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 4: Which intervention is best in patients operated for bilateral acoustic neuroma for hearing rehabilitation?
- A. Bilateral cochlear implant
- B. Auditory brainstem implant (ABI) (Correct Answer)
- C. Unilateral cochlear implant
- D. High power hearing aid
Explanation: ***Auditory brainstem implant (ABI)*** - Patients with bilateral acoustic neuromas often suffer damage to both **auditory nerves** during surgery, rendering cochlear implants ineffective. - The **ABI** bypasses the damaged auditory nerves and directly stimulates the **cochlear nucleus** in the brainstem, allowing for sound perception. *Bilateral cochlear implant* - This intervention is suitable when the **auditory nerve** remains intact and functional, which is typically not the case after bilateral acoustic neuroma surgery. - Cochlear implants depend on the integrity of the auditory nerve to transmit electrical signals to the brain. *Unilateral cochlear implant* - Similar to bilateral cochlear implants, a unilateral implant relies on a functional **auditory nerve** on the implanted side. - In bilateral acoustic neuroma, both auditory nerves are usually compromised or sacrificed, making a unilateral implant unsuitable for binaural hearing rehabilitation. *High power hearing aid* - Hearing aids only amplify sound and are effective for **sensorineural hearing loss** where the cochlea and auditory nerve are still functional. - They would not be beneficial in cases where the auditory nerve is damaged or absent, as occurs after bilateral acoustic neuroma removal.
Question 5: 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 6: The mechanism of hearing and memory, include all, EXCEPT:
- A. Spatial Reorganization of synapse
- B. Changes in level of neurotransmitter at synapse
- C. Increasing protein synthesis
- D. Recruitment by multiplication of neurons (Correct Answer)
Explanation: ***Recruitment by multiplication of neurons*** - The **brain's capacity for learning and memory** primarily involves changes in existing neural circuits, not the multiplication of neurons in the adult brain for new information processing. - While neurogenesis occurs in specific brain regions (e.g., hippocampus), it is not a widespread mechanism for acquiring or storing specific memories or the rapid processing involved in hearing. *Spatial Reorganization of synapse* - This refers to the **restructuring of synaptic connections**, which is a crucial mechanism for long-term potentiation and depression, fundamental to learning and memory formation. - Changes in the **number or location of synapses** can alter neural pathways and strengthen or weaken signal transmission. *Changes in level of neurotransmitter at synapse* - Alterations in the **amount of neurotransmitter released** or the **sensitivity of postsynaptic receptors** significantly impact synaptic strength and neuronal communication. - This short-term and long-term modulation is vital for processes like habituation, sensitization, and long-term potentiation, integral to memory and sensory processing. *Increasing protein synthesis* - **New protein synthesis** is essential for the consolidation of long-term memories and for the structural changes underlying synaptic plasticity. - These proteins can range from enzymes that modify synaptic transmission to structural proteins that alter dendritic spine morphology, enabling lasting changes in neural circuits.
Question 7: 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 8: 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 9: All of the following are true about the hearing aid shown in the figure except:
- A. Bypasses the external and middle ear
- B. Osseointegration of titanium fixture takes 2-6 months
- C. Indicated in patients with unilateral profound hearing loss (Correct Answer)
- D. Disadvantage of multi-stage surgery
Explanation: ***Indicated in patients with unilateral profound hearing loss*** - While **bone conduction hearing implants** can be used for **unilateral hearing loss**, they are typically indicated for **single-sided deafness with normal hearing in the contralateral ear** to provide sound awareness to the deaf side. However, in cases of **profound unilateral hearing loss, cochlear implantation** is often the preferred and more effective intervention for direct sound perception. *Bypasses the external and middle ear* - This statement is true; the device shown is a **bone conduction hearing system** (like BAHA), which transmits sound vibrations directly to the inner ear via the bone, thus **bypassing problems in the external auditory canal and middle ear**. - It is effective for **conductive or mixed hearing loss** where the inner ear function is relatively preserved. *Osseointegration of titanium fixture takes 2-6 months* - This statement is true; **osseointegration** is the biological process where the titanium implant fuses with the bone, which typically takes **2 to 6 months** before the external sound processor can be safely attached. - This fusion is crucial for stable and effective **bone sound conduction**. *Disadvantage of multi-stage surgery* - This statement is true; traditional bone conduction implants often require a **two-stage surgical procedure**: one for implanting the fixture and another for attaching the abutment after successful osseointegration. - This involves **multiple clinic visits, recovery periods**, and potential complications associated with two separate surgeries.
Question 10: The cough response elicited while cleaning the external ear canal is mediated by stimulation of which nerve?
- A. The V cranial nerve
- B. Innervation of the external ear canal by C1 and C2
- C. The X cranial nerve (Correct Answer)
- D. Branches of the VII cranial nerve
Explanation: This phenomenon is known as **Arnold’s Reflex** (or the Ear-Cough Reflex). It occurs due to the stimulation of the **Auricular branch of the Vagus Nerve (Arnold’s Nerve)**, which provides sensory innervation to the posterior and inferior walls of the external auditory canal (EAC). ### Why the Correct Answer is Right: When the EAC is stimulated (e.g., during syringing or cleaning with a cotton bud), sensory impulses are carried via the Vagus nerve (CN X) to the nucleus tractus solitarius in the brainstem. This triggers the efferent limb of the cough reflex, leading to an involuntary cough. This is a classic example of a referred reflex where stimulation of a peripheral nerve causes a response in a visceral organ system. ### Why Other Options are Incorrect: * **Option A (V cranial nerve):** The Auriculotemporal branch of the Mandibular nerve (V3) supplies the anterior and superior walls of the EAC. While it carries sensation, it does not mediate the cough reflex. * **Option B (C1 and C2):** The Greater Auricular nerve (C2, C3) supplies the skin over the mastoid and the lateral/lower part of the auricle, not the deep canal associated with this reflex. * **Option C (VII cranial nerve):** The Facial nerve provides minor sensory innervation to the concha and retroauricular area (often involved in Ramsay Hunt Syndrome), but it is not responsible for the cough reflex. ### High-Yield Clinical Pearls for NEET-PG: * **Arnold’s Nerve:** A branch of the Vagus (CN X). * **Vagal Reflexes in ENT:** Stimulation of the EAC can occasionally cause **bradycardia or fainting** (Vaso-vagal syncope) due to the same nerve. * **Hitchelberger’s Sign:** Reduced sensation in the area supplied by the facial nerve in the EAC, seen in Acoustic Neuroma. * **Nerve Supply of EAC (Summary):** 1. Anterior/Superior: V3 (Auriculotemporal). 2. Posterior/Inferior: X (Arnold’s). 3. Concha/Posterior wall: VII (Facial).
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