The vestibulocochlear nerve, also known as cranial nerve XIII, is a special sensory nerve with two nerve branches. The vestibular branch of the nerve aids in balance control, allowing the individual to ascertain their spatial positioning and maintain upright posture. The cochlear branch helps the brain detect sound, through vibrations in special nerve endings called hair cells.
When this nerve is damaged, the individual's ability to hear or to maintain equilibrium can be compromised. A number of factors can cause damage to the vestibulocochlear nerve.
An article written by V. Danielidis and other scientists from the Department of Otorhinolaryngology at the School of Medicine at Democritus University in Greece and published in the journal "Audiology & Neuro-ontology" states that "hearing impairment is a well-known consequence of closed head injury." A head injury resulting in a skull fracture can damage the vestibulocochlear nerve. This nerve exits from the brain though the temporal bone, where it passes into an opening called the internal acoustic meatus before dividing into its two branches. Damage to the temporal bone could result in damage to the vestibulocochlear nerve, and hearing and balance could be negatively impacted.
Ear infections can damage the sensory nerve ending of the vestibulocochlear cochlear nerve, which are called hair cells. Middle ear infections, called otitis media, are the most common form of ear infection. Vestibular neuronitis is an infection that inflames the vestibular portion of the eighth cranial nerve, leading to balance disorders. KidsHealth notes that mumps, measles and chickenpox can also contribute to damage to the ear.
It's well known that exposure to loud noise, either suddenly or over time, can cause hearing loss. Prolonged, excessive noise can kill the nerve endings in the inner ear, causing permanent damage, according to the American Academy of Otolaryngology. Damage to the nerve endings can cause hearing loss or tinnitus, a condition commonly described as "ringing in the ears".
Tumors of the brain or skull could damage the acoustic or vestibular branches of the vestibulocochlear nerve.
Acoustic neuroma is a benign growth that the New York Times Health Guide says is believed to be caused by genetic factors. This tumor can also appear in the vestibular portion of the nerve, and can be referred to as a vestibular schwannoma. Hearing loss, balance disorders and tinnitus are common symptoms of acoustic neuroma. It is treated by surgery or radiation therapy, or, in cases where the condition has remained asymptomatic, it is sometimes left alone and observed via MRI scans for any further growth.
- New York Times Health Guide: Acoustic Neuroma
- American Academy of Otolaryngology: Noise and Hearing Protection
- KidsHealth: Balance Disorders
- Kids Health: Hearing Impairment
- "Audiology & Neuro-ontology"; Short-term Pathophysiologic Changes and Histopathologic Findings of the Auditory Pathway After Closed Head Injury; V. Danielidis et. al.; 2007