Acute Vestibular Syndrome Symptoms 

Vertigo is the primary symptom of AVS. With vertigo, you feel like you or the environment around you is moving or spinning. Other symptoms include:

• Balance problems, including trouble walking
• Dizziness
• Involuntary eye movements (nystagmus)
• Severe nausea and vomiting

AVS symptoms usually start quickly and continue uninterrupted for 24 hours or longer. This pattern contrasts with other vestibular balance disorders, such as benign paroxysmal positional vertigo (BPPV) and Meniere’s disease, in which symptoms come and go.  

Causes of Acute Vestibular Syndrome

The causes of AVS include:

• Vestibular neuronitis: This condition is an inflammation of the eighth cranial nerve in your brain. The eighth cranial nerve relays information between your inner ear and brain and helps control hearing and balance. Vestibular neuronitis is likely the result of a virus, such as herpes simplex virus (HSV), that stays dormant (hides) in the nerve and suddenly becomes active.
• Stroke: A stroke occurs when a blood vessel in your brain becomes blocked (ischemic stroke) or ruptures (hemorrhagic stroke). AVS is usually associated with an ischemic stroke at the base of your brain in the brainstem or cerebellum. 

A careful assessment is essential to diagnose AVS and identify the underlying cause. Your clinician will ask about your medical history and symptoms, including when symptoms began and how long they have lasted.

Your evaluation may also include vestibular diagnostic tests to check the function of your inner ear and eyes. Your eyes play an important role in maintaining balance. Information from your inner ears helps your eyes remain focused when you move your head. Inner ear problems may cause involuntary or abnormal eye movements or affect your ability to focus.

Vestibular diagnostic tests include:

• Audiogram: Assesses how well you hear loud and soft sounds at different frequencies
• Electronystagmography (ENG) and videonystagmography (VNG): Checks your eye movements
• Rotary chair test: Determines whether your brain or inner ear is causing dizziness
• Vestibular evoked myogenic potential (VEMP): Evaluates the function of the vestibular organs and nerves
• Video head impulse testing (vHIT): Assesses how well your eyes and ears work together

Your clinician may also perform tests to determine whether your symptoms are due to vestibular neuronitis or a stroke. The most effective test is a HINTS (head impulse, nystagmus, and test of skew) exam, which includes three tests to evaluate your eye movements.

Other signs of a stroke your clinician may look for include:

• Neurological symptoms: Typical symptoms of stroke include weakness on one side of the body or face, headache, double vision, difficulty speaking, and lack of coordination. The presence of these symptoms suggests a stroke, but their absence doesn’t necessarily rule it out. People with stroke-related AVS may not have any other stroke symptoms.
• Stroke risk factors: Stroke is more common in people with high blood pressure, high cholesterol, diabetes, family history of stroke, obstructive sleep apnea, atrial fibrillation, or smoking. The presence of risk factors may suggest stroke, but it is not conclusive. 

CT and MRI imaging are usually not very effective tools for identifying vestibular neuronitis or stroke in people with AVS, especially within the first 48 hours of symptoms.