As we know, our inner ear is made up of a bony labyrinth and a membranous labyrinth. Labyrinthitis occurs when we have inflammation of the membranous labyrinth (semicircular duct, utricle and saccule, cochlear duct).
Pathophysiology
The most common cause of labyrinthitis is a viral URTI. It is rarely due to a bacterial infection but if it is, it is usually secondary to otitis media/meningitis.
😷 Presentation
- Typically in 40-70 year olds.
- Acute onset vertigo - not triggered by movement
- Hearing loss
- Tinnitus
- Spontaneous unidirectional horizontal nystagmus towards unaffected side
- Gait issues - patient falls to affected side
- Typical viral RTI symptoms such as cough, sore throat, blocked nose.
Vestibular neuritis vs labyrinthitis?
In vestibular neuritis, only the vestibular nerve is affected, therefore we have the vestibular issues such as vertigo, gait issues, nausea, however there is no hearing loss. While in labyrinthitis, there is vertigo and hearing loss.
Both will have positive head impulse tests, however.
🔍 Investigations
It is generally a clinical diagnosis, using the history and examination findings to diagnose it. We can do some tests too:
Tests
- Rinne and Weber’s test - positive. Assessing for sensorineural hearing loss.
- Head impulse test - positive. This excludes central causes of vertigo.
🧰 Management
Typically self-limiting (as with most viral infections). However we can manage the dizziness with:
- Prochloroperazine - non-selective dopamine antagonist, blocking the D2 receptor in the CTZ but also the H1 receptor, and ACh antagonism. Less sedating.
- Adverse effects: tardive dyskinesia especially in children.
- Antihistamines (cyclizine, cinnarizine, promethazine) - H1 antagonists in the CTZ.
- Can be quite sedating.
Of course, if it is bacterial antibiotics will be required.
🚨 Complications
- Hearing loss - rare but important, especially after bacterial meningitis.