Neurotology — MCQs

Q: Which of the following is the earliest symptom of acoustic neuroma?

Deafness. ***Deafness*** - **Unilateral progressive sensorineural hearing loss** is the earliest and most common presenting symptom, occurring in **90-95% of patients** as the initial manifestation of acoustic neuroma. - This occurs due to compression and dysfunction of the **cochlear portion of the vestibulocochlear nerve (CN VIII)** as the tumor grows from the internal auditory canal. - The hearing loss is typically **gradual and progressive**, often beginning in the high-frequency range before affecting speech frequencies. *Tinnitus* - **Tinnitus** (ringing in the ear) is very common and often accompanies the early hearing loss, but it is rarely the sole presenting symptom. - It occurs in approximately 60-70% of patients, usually **concurrent with or following** the onset of hearing loss. - When present alone, it is caused by irritation of the **auditory nerve fibers** before significant compression. *Vertigo* - **True vertigo** (spinning sensation) is relatively uncommon as an initial symptom, occurring in only 10-20% of patients at presentation. - Most patients experience **mild imbalance or disequilibrium** rather than severe vertigo due to slow tumor growth allowing vestibular compensation. - Results from involvement of the **vestibular portion of CN VIII**. *Facial weakness* - **Facial weakness** is a **late symptom**, occurring when the tumor has grown large enough (typically >2-3 cm) to compress the **facial nerve (CN VII)** in the cerebellopontine angle. - The facial nerve is anatomically separate and less susceptible to early compression compared to the vestibulocochlear nerve.

Q: Findings of BERA in vestibular schwannoma are:

Increased I-V interpeak latency. ***Increased I-V interpeak latency*** - A **vestibular schwannoma** (acoustic neuroma) compresses the auditory nerve, leading to delayed neural conduction through the brainstem auditory pathway. - This delay is reflected as a **prolonged I-V interpeak latency** (normally <4.4 ms), which is the most sensitive and characteristic BERA finding for retrocochlear pathology. - The **I-V interval** measures the time from the cochlear nerve (wave I) to the inferior colliculus (wave V), and prolongation indicates a lesion along this pathway. *Normal interpeak latency I-III and I-V* - This finding would suggest **normal conduction** times through the auditory pathway. - In a vestibular schwannoma, the interpeak latencies, particularly the **I-V interval**, are typically prolonged (>4.4 ms) due to the slow conduction caused by the tumor. *Absent wave V* - While wave V can be absent or poorly formed in severe cases of hearing loss or large tumors, it is **not the most sensitive early finding**. - **Increased I-V interpeak latency** is a more sensitive indicator of retrocochlear pathology, even before complete loss or absence of wave V occurs. *Normal latency in waves I-V* - Normal interpeak latencies would indicate a **healthy auditory nerve** and brainstem function. - This would effectively rule out a **vestibular schwannoma**, which characteristically interferes with neural transmission, causing prolongation of the I-V interpeak interval.

Practice by Chapter

Vestibular System Anatomy and Physiology

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Vestibular Testing

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Benign Paroxysmal Positional Vertigo

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Ménière's Disease

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Vestibular Neuritis

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Labyrinthitis

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Acoustic Neuroma

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Other Cerebellopontine Angle Tumors

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Facial Nerve Disorders

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Skull Base Surgery

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Cochlear Implantation

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Vestibular Schwannoma Management

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