Vestibular neuronitis or labyrinthitis

Vestibular neuronitis is the second most common cause of vertigo, and is caused by inflammation of the vestibular nerve, usually due to a viral infection. The acute, spontaneous symptoms of vertigo will usually subside after 48-72 hours, although motion sensitivity can be prolonged for up to 12 weeks.

Unlike BPPV, movement of the head and “positioning” is not the trigger for the problem, however, head motion is likely to enhance symptoms. It is likely with vestibular neuronitis that there is a recent history of upper respiratory infection, although this is not always obvious. Somebody suffering from vestibular neuronitis can feel overwhelmed with a continual sense of spinning, and will also often present with associated, one-sided neck pain.

The inflamed nerve (seen in the diagram, in yellow) is unable to transport information from the inner ear (of one side) to the brain, making it difficult for the brain to equalize between left and right. Without accurate information from both vestibular systems, the brain cannot understand where the head is positioned in relation to the environment, and therefore the patient can feel an illusionary sense of spinning or motion.

In the acute stage, it is useful for the head and eyes to be specifically positioned in a way which minimizes symptoms. Plasticity of the brain allows it to eventually re-arrange itself in a way which compensates for the nerve dysfunction, reducing symptoms of vertigo.

Therefore, vestibular rehabilitation therapy is aimed at enhancing the effectiveness and speed at which these compensatory mechanisms take place. Rehabilitation involves movements of the head whilst the eyes remain focused on a fixed target, called gaze-stability exercises. It is important that these exercises are a “challenge” for the brain, since it is the challenge which drives neuroplastic adaptation.

Vestibular labyrinthitis is also a condition in which there is loss of nerve function of the inner ear, however, in this condition, the causative infection can be viral OR bacterial. The main difference with labyrinthitis vs. neuronitis is that labyrinthitis sufferers experience a change in hearing along with the other symptoms of neuronitis. In some cases, the hearing loss can be permanent, depending on the type of infection.