Middle Ear Fluid

bullet Middle Ear is air containing space with small bones called Ossicles. 
bullet When sound hits the Ear drum their vibrations are transmitted via Ossicles to the inner Ear.
bullet Eustachian tube connects the middle Ear with the nose, thereby regulating middle Ear pressure and ventilation when Eustachian tube gets blocked either
  by infection like mucus or by mass like Adenoides.

Other Nasopharyngeal mass .
This hampers middle Ear ventilation, resulting in negative middle Ear pressure, effusion of fluid in middle Ear causes secretory Otitis media.

bullet Decreased hearing.
bullet Fullnes in Ear.
bullet Tinnitus.
bullet Giddiness.

Medical treatment usually cures the condition. Sometimes myringotomy (Incision of Ear drum is required to drain the fluid out.

Ventilator Tubes:
(Grommet) May be required in some cases