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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). This appears to result from an imbalance of neuronal input between the left and right inner ears.
Signs and symptoms
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.
Causes
Some cases of vestibular neuritis are thought to be caused by an infection of the vestibular ganglion by the herpes simplex type 1 virus.
This can also be brought on by pressure changes such as those experienced while flying or scuba diving.
Mechanism
In the vestibular system, there are three canals that are semicircular in shape and 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.
Physical therapy
Typical treatments include combinations of head and eye movements, postural changes, and walking exercises. Specifically, exercises that may be prescribed include keeping eyes fixated on a specific target while moving the head, moving the head right to left at two targets at a significant distance apart, walking while keeping eyes fixated on a specific target, and walking while keeping eyes fixated on a specific target while also turning the head in different directions.
The main function behind repeating a combination of head and eye movements, postural changes, and walking is that through this repetition, compensatory changes for the dysfunctions arising from peripheral vestibular structures may be promoted in the central vestibular system (brainstem and cerebellum). VRT works by causing the brain to use already existing neural mechanisms for adaptation, neuroplasticity, and compensation. The vestibular neuritis rehabilitation can improve symptoms or resolve the symptoms which is dependent on each individual.
One study found that patients who believed their illness was out of their control showed the slowest progression to full recovery, long after the initial vestibular injury had healed.
Symptomatic treatment with antihistaminics such as cinnarizine, however, can be used to suppress the symptoms of vestibular neuritis as it spontaneously regresses. Prochlorperazine is another commonly prescribed medication to help alleviate the symptoms of vertigo and nausea.
Mental disorders
Because mood disorders can hamper recovery from labyrinthitis, treatment may also include any co-occurring anxiety disorder or depression. Severe anxiety episodes are usually addressed by short-term benzodiazepine therapy.
Prognosis
Recovery from acute labyrinthine inflammation generally takes from one to six weeks. It is not uncommon for residual symptoms such as dysequilibrium and dizziness to last for a couple of months.
Recovery from a temporarily damaged inner ear typically follows two phases:
- An acute period, which may include severe vertigo and vomiting
- approximately two weeks of sub-acute symptoms and rapid recovery
Epidemiology
The prevalence of vestibular neuritis is approximately 3.5 cases per 100,000 people. Vestibular rehabilitation showed a statistically significant increase in controlling symptoms over no intervention in people who have vestibular neuritis.