SVV Test
                      WHAT IS SUBJECTIVE VISUAL 
VERTICAL DIAGNOSIS TEST 

SVV Test
Millions of people around the world suffer from Vertigo. 
Vertigo arises out of a dis-balance in the inner ear 
nerves, resulting in dizziness, a spinning sensation, loss 
of balance, headache & nausea. 
There are multiple causes for Vertigo; inner ear 
infections or ear diseases such as Benign Paroxysmal 
Positional Vertigo (BPPV), vestibular neuritis & Meniere’s 
disease. 
Due to the nature of the disorder, adequate treatment of 
a patient requires an accurate diagnosis of the exact 
underlying cause of the Vertigo symptoms. 
For the treatment to ultimately be effective, the 
diagnosis has to be accurate, in-depth & authoritative.
It’s a curious fact that most of the symptoms of Vertigo; dizziness, 
nausea, headache, loss of balance; can & do overlap, making it 
difficult for doctors to group the patients in a specific category. 
For this reason, many of the common tests used commonly in clinical 
practice today are unable to determine the exact cause of the 
patient’s Vertigo symptoms.
These tests can’t directly diagnose Acute Vestibular Syndrome(AVS), 
Meniere’s disease, Vestibular Migraine, & many other central nervous 
system problems. 
In the absence of any single diagnostic test, medical practitioners 
often rely on the patient’s recent medical history, immediate 
symptoms & other lifestyle habits to form an eventual differential 
diagnosis. 
Vertigo is generally associated with the peripheral 
Vestibular system, typically a weakness or malfunction of 
the semicircular canals(SCCs) in the inner ear. The 
malfunction occurs in the otolith organs (saccule & utricle), 
which are responsible for upright balance & position. 
The saccule primarily detects vertical acceleration while 
the utricle is responsible for detecting horizontal 
acceleration while standing &/or walking upright. 
Any dysfunction in this otolithic apparatus leads to 
dizziness & loss of balance. 
The Vertigo test that can very accurately measure this 
dysfunction in the otolithic functioning is the 
Subjective Visual Vertical Test. 
There are many medical tests to gauge out the symptoms of 
Vertigo & diagnose patients perfectly. VNG Test for Vertigo & SVV 
Vertigo Test is among the most common diagnostic tests run by 
medical practitioners on Vertigo patients. 
SVV diagnosis test called the Subjective Visual Vertical test is a 
Vertigo diagnosis test that involves an individual’s ability to adjust 
a vertical line in parallel with gravity without any physical or 
visual cues. 
The measurements of the Subjective Visual Vertical Test serve as 
a diagnostic indicator of utricular otolith (dys)function, & can 
many varied forms.
The SVV Diagnosis test can be administered both as inexpensive 
conventional tests, to more evolved & particular clinical tests. 
To accurately measure utricular function in a patient 
suspected of suffering from Vertigo, two tests are used. 
These are Subjective Visual Vertical(Static or Dynamic), 
& ocular vestibular evoked myogenic potential(oVEMP). 
Below, we talk about a list of all the tests conducted as 
part of the SVV Vertigo test. 
Subjective Visual Vertical 
Test(SVV):
The SVV Vertigo Test is a method to test an individual’s 
ability to adjust a vertical line in parallel with gravity in 
the absence of any visual cues. The vestibular organs in 
the inner ear, in particular the utricle of the otolithic 
apparatus, provide the necessary sensory information 
required to perform such a task.
The SVV diagnosis is carried out by showing the patient 
a luminous line in a pitch-dark room, & asking them to 
rotate it in an alignment that is parallel to the direction 
of vertical gravity. 
A healthy patient performs this task with total accuracy & 
has no trouble aligning the horizontal line vertically. Still, in 
case of a patient with a compromised inner-ear Vestibular 
balance system, there is a difference in the alignment.
The SVV, in this case, is determined by measuring the 
deviation of the set angle of the luminous line from the tilt 
angle of the patient’s head. 
When the patient’s head is in an upright position, this tilt 
angle will effectively be zero, as in parallel to gravity. 
The SVV Vertigo test can also be carried out during 
unilateral centrifugation, which involves exclusive 
stimulation to the right or left utricle, depending on the 
direction of origin of the patient’s Vertigo symptoms. 
Listed below are some common 
methods Vertigo specialists use to 
measure a person’s SVV response:
Bucket Test:
The Bucket Test is one of the simplest & most inexpensive 
ways to measure an individual’s SVV response. In this test, 
a bucket is placed on the patient’s head. The bucket 
contains either a line or a rectangular object inside it. The 
test administrator then rotates the bucket over the 
patient’s head until the patient starts to believe that the 
line inside is completely vertical. He/She then records the 
angle of deviation on the back of the bucket. 
This is considered a static test as the subject isn’t moving 
during the test. 
Individuals with a healthy, normal utricular function rotated 
the bucket about 2 degrees of vertical on average, while 
those with vestibular abnormalities rotated the bucket 
about 20 degrees of vertical. 
OVAR Rotating Chair Test 
(clinical):
SVV diagnosis can also be carried out with an OVAR 
Rotating Chair Test. In this, the subject is made to sit on 
a rotating chair in a completely dark room. The chair can 
rotate up to 300 degrees per second while migrating off 
center at 1cm/sec. While they’re rotating, the patient is 
asked to manipulate a laser line reflected on the wall 
using a handheld remote to position the line such that 
the line appears perfectly vertical to them. 
This test is fully controlled at the back-end with 
computer software, & produces extremely accurate 
results. 
Another advantage of this test is that it allows each of 
the patient’s utricle to be tested independently.  
Virtual SVV Vertigo Test with 
Goggles:
This test is perhaps the most technologically enhanced SVV test 
out of all three SVV diagnosis methods. It uses light occluding 
goggles that have a built-in accelerometer along with a 
‘candlesque’ target to test the subject’s utricle responses. 
The subject simply has to move the target inside the simulation 
with a handheld remote, & adjust it to existing vertical gravity 
conditions. 
This simple test can be easily performed even by children. 
An additional advantage this test has over other versions of the 
SVV Vertigo test, is that it can test subjective verticality with the 
subject’s head tilted up to 45 degrees left or right. 
 
In all the three cases, the SVV measurements are determined by 
measuring the degree of deviation from the set angle of the target 
line from the tilt angle of the subject’s head. 
In a static SVV Vertigo test, the subject’s head is at zero 
of fixed degrees of head tilt. A subject with a healthy & 
functional Vestibular System should be able to align their 
target precisely with little to no deviation from zero. 
In a dynamic SVV diagnosis test, the task becomes more 
challenging & a larger deviation angle is recorded for 
subject’s head tilted versus subject’s head in an upright 
position. 
A subject with a properly functioning Vestibular System 
will experience equal stimulation to both utricles when 
the head’s position is upright, & will consequently, 
position the target line very close to zero. 
However, for a subject experiencing acute vestibular 
disease, their head will tilt in the direction of the healthy 
labyrinth which correctly identifies & detects the 
stimulation, while the diseased labyrinth will provide a 
deficit. 
The findings of all tests are recorded by specialized 
software, & can then be utilized by Vertigo specialists to 
formulate a treatment plan for any patient further. 
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