Positional vertigo is the most common form of vertigo. They represent more than 50% of the causes of consultation for vertigo at the specialist. Most of them are benign, but it should never be forgotten that they can be indicative of more serious pathologies. A positional vertigo persisting  beyond 15 days should be the subject of a consultation with the ENT specialist. Moreover, even if they are benign, he will be able to locate the diseased part of the vestibule and determine the best treatment to accelerate recovery.

As the name suggests, vertigo is influenced by the position of the head in space.

Clinically, they present as brief vertigo, lasting from 30 seconds to one minute, but repeated, sometimes intense, when assuming certain positions: lying down, getting up (risk of confusing with a drop in blood pressure when getting up), turning in bed, leaning the head forward, raising the head

They are sometimes accompanied by nausea or even vomiting (as with seasickness)

The cause is the detachment of a variable quantity of otoliths located in the saccule or utricle, and their migration into one or more semicircular canals.

This image from 

https://pressbooks.umn.edu/sensationandperception/chapter/vestibular-transduction-draft/,

show very well the location of otoliths and their function

When the otoliths are located on one side of the canal, a change in the position of the head to a vertical position will cause a displacement of the otoliths in the canal and stimulate the sensory cells in the cup. This displacement is perceived by the brain, but it does not correspond to reality, leading to a sensory conflict with an erroneous sensation of movement: this is vertigo. 
 

The fall of these otoliths lasts in general 30 seconds and the vertigo stops if one does not change position again. It will start again if you turn your head the other way. 
 

It is a very frequent condition, of which 3 main causes have been documented:

1. traumatic causes,
2. viral causes,
3. vascular causes.

There is also an age-related degeneration, which explains the high frequency of this symptom in the elderly.

Most of the time these vertigoes heal spontaneously in a few weeks. However, they are sometimes incapacitating and require a specialist consultation. Videonystagmoscopy will then enable the affected canal to be determined and manoeuvres adapted to each case to be carried out, which will enable immediate recovery or recovery within 3 or 4 days.

It is important to know that in 40% of cases these vertigoes recur in the 6 months that follow. The repetition of the manoeuvres will allow their healing.

Finally, in the particular case of post-traumatic positional vertigo, recovery is often longer to obtain and recurrences are frequent.

Other positional vertigo exists, with different symptoms, a longer duration, and which do not answer perfectly to this theory. The position of the otoliths in the semicircular canals influences these vertigoes. There are therefore multiple possibilities which require a specialised examination to adapt the liberatory manoeuvres

But if these positional vertigoes are frequent, and in the great majority benign, it should not be forgotten that there are other cases of positional vertigoes, and that they are not always benign. Tumours of the cerebellum, a  unrecognised malformation, labyrinthine fistulas, can lead to positional vertigo.

Positional vertigo that does not resolve in a few weeks should be referred to a specialist.