Sensorineural Hearing Loss

Presbycusis

N.B. Most common cause of hearing loss.

Presents with bilateral, symmetrical loss of high-frequency hearing over many years. The factors affecting it’s onset and severity are genetics, noise exposure, smoking, HTN, DM, and PVD.

Managed with Hearing aids or Hearing tactics.

Noise-induced

Noise can cause hearing loss in 2 ways:

• One-time exposure to an intense ‘impulse’ sounds OR

• Continuous exposure to loud sounds over an extended period of time e.g. machinery, gunfire, loud music

The noise leads to a Temporary Threshold Shift (TTS), which is a brief hearing loss that occurs after noise exposure and completely resolves with rest. If repeated episodes of it, it can lead to a permanent threshold shift.

Drug-induced

Ototoxic medications:

• Aminoglycosides – Progressive loss of hair cells, affecting high frequency first, as well as vestibular organs (dizziness/imbalance)

• Loop diuretics – Temporary, yet rapidly reversible hearing loss due to oedema in the stria vascularis

• Macrolides – Temporary

• Antimalarials e.g. Quinine, Chloroquine

Acoustic Neuroma (Vestibular Schwannoma)

This is a benign, slow-growing tumour from overproduction of Schwann cells. It grows at the Cerebellopontine Angle, leading to asymmetrical/unilateral SNHL, tinnitus, and dizziness. If large enough, it can cause facial (CNVII) symptoms; forehead won’t be spared as it it’s a LMN palsy.

If it occurs bilaterally, it indicates Neurofibromatosis type II.

An MRI is used for diagnosis and check-up 6 monthly if the mass is < 40mm. If larger than this, surgery is done.

sed by an Acoustic neuroma (aka vestibular shwanomma).

Labyrinthitis

Presents with Acute Vertigo, associated with HL, Tinnitus, and Ear fullness, and is usually associated with a viral URTI.

Diagnosis is mainly clinical, but it's important to rule out the central causes of acute vertigo e.g. stroke, with a Head Impulse Test. A positive result (corrective saccade seen) here indicates a peripheral cause i.e. labyrinthitis or vestibular neuronitis.

Management:

• Acute - Prochlorperazine, Antihistamine for N+V symptoms

• Prophylactic – Betahistine

Meniere’s Disease

Due to endolymphatic hydrops (build-up in inner ear), leading to recurrent attacks of vertigo lasting 12-24 hours with unilateral hearing loss, tinnitus, and ear fullness.

The disease progresses in stages:

• Early stages – Vestibular/cochlear symptoms may occur in isolation. Hearing loss (low frequency) and tinnitus recede fully

• After 1-2 years – Complete set of symptoms

• Late stages – Progressive deterioration of hearing

Managament:

• Acute - Prochlorperazine, Antihistamine for N+V symptoms

• Prophylactic – Betahistine

Sudden Sensorineural HL (SSNHL)

Defined as 30dB+ hearing loss > 3 consecutive frequencies within 72 hours, w/o any obvious cause. Usually has a unilateral (95%) presentation, with 30-65% having a spontaneous recovery. A bilateral presentation is a lot less common with a lower chance of any recovery, therefore is an emergency.

Management - Treat underlying cause, Steroids