Dizziness Screening

Eye movement testing

• Spontaneous nystagmus test

  Eye movement is observed without any stimulus applied.

• Gaze-evoked nystagmus test

  With the eyes turned 20–30 degrees up, down, left, and right, the patient fixes on a point about 50 cm ahead for roughly 10 seconds while eye movement is observed.

• Smooth pursuit test

  The patient tracks a single point moving horizontally or vertically, and eye movement is assessed.

• Optokinetic nystagmus testing

  The patient fixes on black lines drawn around them while being rotated at increasing speed, and the resulting nystagmus is recorded.

Detailed vestibular function testing

• Caloric test

  Caloric testing induces dizziness by delivering warm and cool air into each ear, then records eye movement to determine whether the vestibular organ is impaired. Lying on the examination table wearing goggles, air is introduced into the ear canal while eye movement is observed.
  The expected duration is about 15 minutes, though it may vary somewhat with the patient's condition.

• Positional nystagmus test

  This refers to nystagmus that does not appear ordinarily but emerges when the head is tilted into a particular position or angle. Lying supine — or supine with the head hanging over the end of the table — the head is slowly turned to each side, held in position for a set time, and eye movement is then observed.

• Positional nystagmus testing

  Positional nystagmus testing identifies the type of dizziness by observing whether nystagmus appears — and in what form — as head position and posture change. Lying on the examination table wearing goggles, you follow a dot on the ceiling with your eyes. The test proceeds through a variety of head positions: turning the head, sitting up and lying down, and letting the head hang below the edge of the table.
  The expected duration is about 10 to 15 minutes, though it may vary somewhat with the patient's condition.

• Rotational chair test

  With the head tilted 30 degrees forward during or after rotation, the patient is turned side to side at a fixed amplitude and frequency while the resulting nystagmus is compared and measured.

• Head impulse test

  The patient fixes their gaze on the examiner's nose while the examiner turns the patient's head briefly and rapidly from side to side and up and down, observing eye movement. When the vestibulo-ocular reflex is intact, the patient maintains fixation continuously; when the head is turned toward the affected side, a rapid corrective saccade is needed to regain fixation after the turn.

Autonomic and orthostatic testing

• Autonomic testing — tilt table test

  The tilt table test determines directly whether syncope or dizziness originates in the autonomic nervous system. When autonomic responses are exaggerated compared with normal, a sudden change of posture or an excessive response to cardiac medication can transiently lower blood pressure and heart rate, reducing cerebral blood flow and secondarily producing syncope or similar symptoms.
  The test begins lying on a tilt table, which is then slowly raised so the head is above the heart, while the onset of symptoms and changes in pulse and blood pressure are observed. If syncope occurs during the test, or an excessive fall in blood pressure, a drop in pulse, or a change in cerebral blood flow is seen, the result is positive.