ANATOMY AND PHYSIOLOGY
The inner ear has three semi-circular canals at right angles to each other. They detect rotational acceleration in all plains. Via nerve reflexes, they keep your eyes fixed on a target despite head movements.
HISTORY
The patients wake up feeling extremely dizzy and nauseous. This lasts a few seconds. Dizziness returns with certain movements, for instance, rolling over in bed. This often resolves spontaneously over a few weeks.
CAUSE
Crystals from the gravity sense organs of the inner ear migrate into these semi-circular canals, resulting in intense vertigo and nausea. In the majority of cases, the cause is not identified, but it may occur post-surgery or post-trauma.
EPIDEMIOLOGY
This is the commonest cause of dizziness, with more than a million cases per year in the US. The incidence rises with increasing age, and there is a female predominance.
CLINICALLY
The basic neuro ENT examination is completely normal. One performs a manoeuvre called a Dix Hallpike. This is diagnostic of posterior semi-circular canal BPPV.
TREATMENT
There are two repositioning manoeuvres, as medication seldom helps. The two manoeuvres are called the Epley and the Semont manoeuvres. These manoeuvres move the crystals out of the semi-circular canals back into the ventricle of the inner ear. There is a greater than 80% success rate with this manoeuvre, but 30% of patients will recur. Surgery is seldom done.