What is Subjective visual vertical diagnosis test

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What is Subjective visual vertical diagnosis
test
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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 Menieres 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.

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• Its 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 patients
  Vertigo symptoms.
• These tests cant directly diagnose Acute
  Vestibular Syndrome(AVS), Menieres disease,
  Vestibular Migraine, many other central nervous
  system problems.
• In the absence of any single diagnostic test,
  medical practitioners often rely on the patients
  recent medical history, immediate symptoms
  other lifestyle habits to form an eventual
  differential diagnosis.

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• 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.

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• 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 individuals 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.

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• 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.

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Subjective Visual Vertical Test(SVV)

• The SVV Vertigo Test is a method to test an
  individuals 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.

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• 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 patients head.
• When the patients 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 patients Vertigo symptoms.

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• Listed below are some common methods Vertigo
  specialists use to measure a persons SVV
  response

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Bucket Test

• The Bucket Test is one of the simplest most
  inexpensive ways to measure an individuals SVV
  response. In this test, a bucket is placed on the
  patients head. The bucket contains either a line
  or a rectangular object inside it. The test
  administrator then rotates the bucket over the
  patients 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 isnt
  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.

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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 theyre 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 patients utricle to be tested
  independently.

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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 subjects 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 subjects
  head tilted up to 45 degrees left or right.
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• 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 subjects head.

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• In a static SVV Vertigo test, the subjects 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 subjects head tilted versus
  subjects head in an upright position.
• A subject with a properly functioning Vestibular
  System will experience equal stimulation to both
  utricles when the heads position is upright,
  will consequently, position the target line very
  close to zero.

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• 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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• Thanks