Unilateral conductive deafness after head injury is due to all EXCEPT:

Otitis media with effusion (OME) It is also called serous or secretory otitis media (SOM) or glue ear It is simply a collection of fluid that occurs within the middle ear space due to the negative pressure produced by altered Eustachian tube function. This can occur purely from a viral URI, with no pain or bacterial infection, or it can precede and/or follow acute bacterial otitis media. Fluid in the middle ear sometimes causes conductive hearing impairment, but only when it interferes with the normal vibration of the eardrum by sound waves. Over weeks and months, middle ear fluid can become very thick and glue-like (thus the name glue ear), which increases the likelihood of its causing conductive hearing impairment.