From the Guidelines
Right vestibular neuritis causes nystagmus to the left side. This occurs because right vestibular neuritis damages the right vestibular nerve, creating an imbalance in vestibular input between the two sides. Normally, both vestibular systems send balanced signals to the brain about head position and movement. When the right side is inflamed and functioning poorly, the healthy left vestibular system becomes relatively overactive. This imbalance causes the eyes to drift slowly toward the damaged right side, followed by a quick corrective movement back to the left (the fast phase of nystagmus). By convention, nystagmus is named according to the direction of this fast phase, so right vestibular neuritis produces left-beating nystagmus. Although the provided evidence 1 focuses on the diagnosis and management of benign paroxysmal positional vertigo (BPPV), the key concept of vestibular imbalance leading to nystagmus is relevant. The evidence does not directly address vestibular neuritis but understanding the principles of vestibular function and dysfunction is crucial for diagnosing and managing various vestibular disorders, including vestibular neuritis. This finding is important for diagnosis and can be observed during clinical examination, particularly when visual fixation is removed. The nystagmus typically resolves over days to weeks as central compensation occurs, even if peripheral vestibular function doesn't fully recover. Key points to consider in the diagnosis and management of vestibular neuritis include:
- Differentiating vestibular neuritis from other causes of vertigo and imbalance, as recommended in the guideline 1.
- Assessing for factors that may modify management, such as impaired mobility or central nervous system disorders 1.
- Considering the role of vestibular rehabilitation in the treatment of vestibular disorders, although the provided evidence 1 specifically addresses BPPV, the principle can be applied broadly.
From the Research
Vestibular Neuritis and Nystagmus
- Vestibular neuritis is characterized by spontaneous horizontal-torsional nystagmus beating away from the lesion side 2.
- The direction of nystagmus in vestibular neuritis is typically away from the affected ear, meaning that if the right vestibular nerve is affected, the nystagmus will beat towards the left side 2, 3.
- In the case of right vestibular neuritis, the nystagmus would beat towards the left side, as the vestibular system tries to compensate for the loss of function on the right side 2, 3.
- However, recovery nystagmus, which is a reversal of spontaneous nystagmus direction, can occur in some cases, beating towards the affected ear 4.
Clinical Features and Diagnosis
- Vestibular neuritis is diagnosed based on clinical features such as abrupt onset of vertigo, spontaneous nystagmus, and abnormal head impulse test 2, 3, 5.
- Diagnostic tests such as the head impulse test, bithermal caloric test, and vestibular-evoked myogenic potential test are used to confirm the diagnosis 2, 3, 5.
- The treatment of vestibular neuritis includes symptomatic therapy, specific drug therapy, and vestibular rehabilitation therapy 5.