Sensorineural Hearing Loss: A High-Yield Guide for PLAB 2 Candidates 🎧🧠

Sensorineural hearing loss (SNHL) is a high-yield ENT topic for PLAB 2 and UK clinical practice. The key challenge for candidates is recognizing when hearing loss is an emergency (24-hour referral) versus when it requires an urgent 2-week referral for suspected acoustic neuroma.

This guide summarizes the clinical approach, examination, differential diagnosis, and UK referral pathways.

1. What is Sensorineural Hearing Loss? 🔎

Sensorineural hearing loss (SNHL) occurs when there is damage to:

• The inner ear (cochlea)

• The vestibulocochlear nerve (cranial nerve VIII)

• The central auditory pathways

This differs from conductive hearing loss, where sound cannot properly travel through the external or middle ear.

Key Clinical Clue

SNHL typically presents with:

• Reduced hearing in one or both ears

• Tinnitus

• Difficulty understanding speech

• Poor hearing in noisy environments

2. Sudden vs Gradual SNHL – The Most Important Distinction ⚠️

The timing of hearing loss determines referral urgency in the UK.

Sudden Sensorineural Hearing Loss (SSNHL)

Defined as:

• Rapid hearing loss developing within 72 hours

• Usually unilateral

• Often associated with tinnitus or ear fullness

Why it matters

SSNHL is considered an ENT emergency because early treatment can improve hearing recovery.

UK Management

Patients should be:

🚨 Referred to ENT within 24 hours

Treatment often includes:

• Oral corticosteroids

• Intratympanic steroids

• Urgent audiometry

Typical Causes

Common causes include:

• Viral cochlear inflammation

• Vascular compromise

• Autoimmune inner ear disease

• Idiopathic (most common)

Gradual Sensorineural Hearing Loss

Gradual unilateral SNHL raises concern for structural pathology, especially acoustic neuroma.

These patients require:

⚠️ Urgent referral via the 2-week suspected cancer pathway

3. Acoustic Neuroma (Vestibular Schwannoma) 🧠

An acoustic neuroma, also called vestibular schwannoma, is a benign tumor of the vestibulocochlear nerve (CN VIII).

Although benign, it can compress nearby cranial nerves and brain structures.

Typical Features

The classic presentation is:

• Gradual unilateral sensorineural hearing loss

Other symptoms may include:

• Unilateral tinnitus

• Balance problems

• Facial numbness

• Facial weakness (late stage)

Important Risk Factor

• Neurofibromatosis Type 2 (NF2)

NF2 is associated with:

• Bilateral vestibular schwannomas

Family history of NF2 should raise suspicion.

4. Clinical Assessment in ENT Clinic 🩺

A structured assessment includes:

History

Key questions include:

• Onset – sudden vs gradual

• Duration

• Associated tinnitus

• Dizziness or imbalance

• Ear pain or discharge

• Facial numbness or weakness

• Noise exposure

• Recent infections

• Family history of neurofibromatosis

Understanding the onset pattern is critical because it determines referral urgency.

Examination

1. Otoscopy

Usually normal in SNHL.

This helps rule out conductive causes such as:

• Earwax

• Otitis media

• Tympanic membrane perforation

2. Tuning Fork Tests

These bedside tests help differentiate hearing loss types.

Rinne Test

• Positive (AC > BC) in sensorineural hearing loss

Weber Test

• Sound lateralizes to the normal ear in SNHL.

3. Cranial Nerve Examination

Important in suspected acoustic neuroma.

Assess:

• CN V – facial sensation

• CN VII – facial movement

• CN VIII – hearing and balance

• CN IX/X – gag reflex (large tumors)

4. Balance Examination

Vestibular dysfunction may cause:

• Positive Romberg test

• Unsteady gait

• Past-pointing

5. Key Investigations 🔬

Patients with unilateral SNHL require further evaluation.

Audiometry

A formal hearing test used to confirm:

• Sensorineural vs conductive hearing loss

• Severity of hearing impairment

MRI Internal Auditory Canal

This is the gold standard test to detect:

• Acoustic neuroma

• Other cerebellopontine angle tumors

6. Management of Acoustic Neuroma

Management depends on:

• Tumor size

• Patient symptoms

• Growth rate

• Patient age

Treatment Options

1. Observation ("Watchful Waiting")

Small tumors may be monitored with:

• Periodic MRI scans

• Hearing assessments

2. Radiotherapy

Stereotactic radiosurgery can:

• Stop tumor growth

• Preserve neurological function

3. Microsurgical Removal

Indicated if:

• Tumor is large

• Symptoms are severe

• Tumor is rapidly growing

7. UK Referral Pathways (High-Yield) 🚑

Understanding referral urgency is essential for PLAB and NHS practice.

Condition	Referral Urgency
Sudden SNHL (<72 hours)	🚨 ENT referral within 24 hours
Gradual unilateral SNHL	⚠️ Urgent 2-week referral
Unilateral tinnitus with hearing loss	⚠️ 2-week referral
Bilateral gradual hearing loss	Routine audiology referral

8. Safety Netting Advice

Patients should seek urgent care if they develop:

• Sudden worsening hearing

• Severe vertigo

• Facial weakness

• Facial numbness

• Balance problems

These symptoms may indicate progressive nerve compression.

9. Key PLAB 2 Exam Pearls 🎯

Candidates should remember the following high-yield points:

✔ Sudden SNHL = ENT referral within 24 hours

✔ Gradual unilateral SNHL = suspect acoustic neuroma

✔ MRI internal auditory canal is the diagnostic test

✔ Otoscopy is usually normal

✔ Weber lateralizes to the normal ear in SNHL

✔ Family history of NF2 increases suspicion

Final Takeaway 🧠

Sensorineural hearing loss is a critical ENT presentation because it can represent either:

• A treatable emergency (sudden SNHL), or

• A serious underlying condition such as acoustic neuroma.

Recognizing the pattern of hearing loss and appropriate referral urgency is essential for both PLAB 2 success and safe clinical practice in the UK.