This study evaluate the diagnostic accuracy of a simplified clinical algorithm (STANDING) for the differential diagnosis of acute vertigo in the emergency department.

In particular, the investigators want to analyze the sensitivity and specificity of the test for the diagnosis of vertigo of central origin and the reproducibility of the test.

In suspected central vertigo of ischemic origin, a duplex sonography to identify vertebral artery pathology will be performed.

The STANDING test is a structured diagnostic algorithm based on previously described diagnostic signs or bedside maneuvers, the investigators have logically assembled in four sequential steps.

1) Assessment of nystagmus presence (spontaneous vs positional) 2) Assessment of nystagmus direction 3) Head Impulse Test (HIT) 4) Standing (SponTaneous, Direction, hIt, standiNG: STANDING)

1. First, the presence of nystagmus will be assessed with Frenzel goggles in a supine position after at least five minutes of rest. When no spontaneous nystagmus is present in the main gaze positions, the presence of a positional nystagmus will be assessed by the Pagnini test first and then by the Dix-Hallpike test (5). The presence of a positional, transient nystagmus will be considered typical of BPPV.
2. Instead, when spontaneous nystagmus is present, the direction will be examined: multidirectional nystagmus, such as bidirectional gaze-evoked nystagmus (ie, right beating nystagmus present with gaze toward the right and left beating nystagmus present with gaze toward the left side), and a vertical (up or down beating) nystagmus will be considered signs of central vertigo (Video 3).
3. When the nystagmus is unidirectional (ie, nystagmus beating on the same side independent of the gaze direction) we will performed the Head Impulse Test (HIT)(13). When an acute lesion occurs on one labyrinth, the input from the opposite side is unopposed and as a result, when the head is rapidly moved toward the affected side, the eyes will be initially pushed toward that side and, immediately after, a corrective eye movement (corrective "saccade") back to the point of reference is seen. When the corrective "saccade" is present the HIT is considered positive and it indicates non-central AV, whereas a negative HIT indicates central vertigo(14).
4. Patients showing neither spontaneous nor positional nystagmus were invited to stand and gait was evaluated. When objective imbalance was present they were suspected to have central disease.

STANDING will be performed before imaging test. STANDING results will be unknown to the attending emergency physician and to the panel of experts who will establish the final diagnosis at the end of follow-up of three months. The physician who will perform the STANDING will not know patient's clinical data, except those detectable during the STANDING test.

Inclusion Criteria:

• Patients with acute vertigo/unsteadiness

Exclusion Criteria:

• Patients unable to collaborate (patients with severe dementia, bedridden patient)
• Patients unable to follow-up (3 months)
• Patients with terminal disease (3 supposed months of survival)
• Patients with known cervical spine and neck diseases to whom positioning may be dangerous.
• Patients who refuse to participate the study
• Patients with pseudo-vertigo

Consecutive adult patients presenting to the ED of the University Hospital Careggi (AOUC) for vertigo/unsteadiness