 There are several causes including a viral or bacterial infection that spreads to the middle ear by way of the eustachian tubes, nasal allergy drainage blocking the sinuses or eustachian tubes, enlarged adenoids also blocking sinuses or eustachian tubes and eardrum rupture. 
There are several causes including a viral or bacterial infection that spreads to the middle ear by way of the eustachian tubes , nasal allergy drainage blocking the sinuses or eustachian tubes , enlarged adenoids also blocking sinuses or eustachian tubes and eardrum rupture .