This is the most common cause of vertigo
Before we begin let’s recap our anatomy of the inner ear:
Our inner ear has 2 main components: a bony labyrinth (the bony cavity) and a membranous labyrinth (membranous ducts and sacs). The bony labyrinth encases the membranous labyrinth and has 3 distinct components:
- Semicircular canals - containing the semicircular ducts.
- Vestibule - containing the utricle and saccule.
- Cochlea - with scala vestibuli, scala media and scala tympani.
In the utricle and saccule we find maculae which are made of inner hair cells that sense linear acceleration. It is covered in a gelatinous otolithic membrane which is overlayed with calcium carbonate crystals (also known as otoconia, or canaliths or simply ear stones).
In our semicircular ducts, at the junction of the semicircular ducts and the utricle we find bulbous ampullae which contain cupulae that detect angular acceleration.
When stimulated, these inner hair cells depolarise and trigger firing of CN8 (vestibulocochlear nerve) afferent fibres.
Pathophysiology
What happens in BPPV is that an otoconia gets dislodged from the otolithic membrane and ends up in the semicircular ducts (a cupulolithiasis or canalithiasis). It most commonly happens in the posterior semicircular duct. Hence when the patient moves, endolymph will flow abnormally and the detection of movement within the crista ampullaris is misdetected leading to BPPV symptoms.
😷 Presentation
- Brief episodes of vertigo when moving head - vertigo is the sensation that you or the environment around you is spinning. These attacks last for seconds.
- Nausea may be associated.
🔍 Investigations
To perform the Dix-Hallpike manoeuvre:
- The patient will sit upright on a flat examination table, with their head turned 45º to one side. If you want to test the right side, the head is turned to the right, L for L ear.
- The head is supported at 45º while the patient is rapidly lowered until their head is hanging off the end of the table and is extended to about 30º below the level of the table (about 120º from the starting point).
- Watch the patient’s eye closely for 30-60 seconds. A rotary nystagmus should be observed along with the patient feeling symptoms of vertigo.
- The test should be repeated with the head turned 45º to the opposite side.
The rotary nystagmus is observed due to displacement in the posterior semicircular duct. The eye will rotate towards the affected ear (anticlockwise for right ear). If the displacement is located in the anterior or lateral semicircular canals then we will see horizontal nystagmus.
🧰 Management
- Perform the same steps as the Dix-Hallpike manoeuvre (keep the patient upright with head turned 45º to the affected side → keeping them with their head off the edge of the bed while maintained at 45º.
- Rotate their head 90º to the other side (should be at 45º towards the unaffected side now). Have the patient roll onto their side such that their head is now a further 90º towards the unaffected side.
- Have the patient sit up sideways with the legs off the edge of the bed.
- Position the head centrally, flexed at 45º now (chin towards the chest).
- The interval between each step is 30s, waiting for any vertigo or nystagmus to settle
We can also perform Brandt-Daroff exercises which can be done at home:
These involve sitting at the end of the bed, then laying on your side then sitting up again and then laying on the other side. One should repeat the exercises until
