Labyrinthitis is inflammation of the labyrinth, a maze of fluid-filled channels in the inner ear. Vestibular neuritis is inflammation of the vestibular nerve (the nerve in the ear that sends messages related to motion and position to the brain). Both conditions involve inflammation of the inner ear. Labyrinths that house the vestibular system sense changes in the head's position or the head's motion. Inflammation of these inner ear parts results in a vertigo (sensation of the world spinning) and also possible hearing loss or tinnitus (ringing in the ears). It can occur as a single attack, a series of attacks, or a persistent condition that diminishes over three to six weeks. It may be associated with nausea, vomiting, and eye nystagmus.

The cause is often not clear. It may be due to a virus, but it can also arise from bacterial infection, head injury, extreme stress, an allergy, or as a reaction to medication. 30% of affected people had a common cold prior to developing the disease. Either bacterial or viral labyrinthitis can cause a permanent hearing loss in rare cases. This appears to result from an imbalance of neuronal input between the left and right inner ears.

The main symptoms are severe vertigo and nystagmus. The most common symptom of vestibular neuritis is the onset of vertigo due to an ongoing infection or trauma. The dizziness sensation that is associated with vertigo is thought to be from the inner ear labyrinth. Rapid and undesired eye motion (nystagmus) often results from the improper indication of rotational motion. Nausea, anxiety, and a general ill feeling are common due to the distorted balance signals that the brain receives from the inner ear system. Other common symptoms include tinnitus, ear ache, and a feeling of fullness in the ear.

Some people will report having an upper respiratory infection (common cold) or flu prior to the onset of the symptoms of vestibular neuritis; others will have no viral symptoms prior to the vertigo attack.

Some cases of vestibular neuritis are thought to be caused by an infection of the vestibular ganglion by the herpes simplex type 1 virus. However, the cause of this condition is not fully understood, and in fact, many different viruses may be capable of infecting the vestibular nerve.

Acute localized ischemia of these structures also may be an important cause. Especially in children, vestibular neuritis may be preceded by symptoms of a common cold. However, the causative mechanism remains uncertain.

This can also be brought on by pressure changes such as those experienced while flying or scuba diving.

In the vestibular system, there are three canals that are semicircular in shape that input sensory clues. These canals allow the brain to sense rotational motion and linear motion changes. The brain then uses the sensory input clues and the visual input clues from the vestibular system to retain balance. The vestibulo-ocular reflex retains continuous visual focus during motion which is also the vestibular system's purpose during activity.