Mumps is a virus infection and the most common cause of acquired unilateral (single sided) deafness in children. The incidence of unilateral deafness in general was 1 for every 20 000 cases in the pre vaccination era.
Nowadays it is reported in less than 1% of cases. Although vaccination for mumps has decreased the incidence dramatically the current true incidence of hearing loss is not known. The hearing loss is usually unilateral, permanent and total. In 5o% of cases vertigo and dizziness can be present. The onset of the hearing loss is usually sudden, starting 4-5 days after the onset. Hearing loss can occur in mild forms of mumps and in patients without parotid gland swelling (parotitis).
The mumps virus spreads via saliva and reaches the inner ear (labyrinth) through the bloodstream. In the inner ear the virus causes a labyrinthitis, damaging the hair cells of the cochlea. It can also damage the vestibular (balance) part of the inner ear.
Meningoencephalitis is another complication of mumps. Meningoenchephalitis can also cause hearing loss due to damage to the vestibulocochlear nerve. Sometimes the cochlea and the vestibulocochlear nerve may be involved.
If your child is diagnosed with mumps it is important to have hearing tests performed as soon as possible and untill 6 weeks after the onset. If at any time after this hearing loss is suspected it should be tested. In young children single sided deafness may go unnoticed for a long time before diagnosed.
There are options to improve hearing in these patients. For incomplete hearing loss a hearing aid may be of benefit. For single sided deafness (SSD), CROS hearing aids, bone anchored hearing systems and cochlear implantations are some of the options. In the rare occurrence of bilateral deafness, bilateral cochlear implants can be considered.
In those patients with single sided deafness the hearing ear should be protected against injury and loud noise exposure. If an infection occurs it should be managed as an emergency.