Advanced Dix-Hallpike

15 February 2022
10 mins
Reading

The Advanced Dix Hallpike test has two additional features that provide significant improvements over the standard Dix Hallpike test. The new features are:

  1. 3D Head Model Guide
  2. Torsional Nystagmus Analysis

 

Calibration

To perform the test, you must first calibrate the eyes in the software. This allows the algorithm to identify the iris and track the movements of the eyeball.

First select the Advanced Dix Hallpike Protocol from your existing protocols drop down menu.

List of tests, including: random saccade, saccadometry, optokinetic, dix hallpike, dix hallpike advanced, lateral head roll, positional, and caloric. For dix hallpike advanced, left and right are available options, with left highlighted in yellow.

Figure 1 – Test Menu

Make sure the VORTEQ sensor is turned on. Then select the calibration option.

Calibration selection for VORTEQ sensor. The following is displayed: 120 seconds, start button, calibration button, center imu button, and a message which says: 'Head sensor is connected. Ready!'.

Figure 2 – Calibration Selection

Once in the calibration menu you can perform 2 tasks:

  1. Calibrate the torsion eye tracker
  2. Calibrate the eyes to the visual targets

First calibrate the torsional eye tracker. Have the patient fixate a target in front of them.

Images of right and left eyes. For both eyes, a small cross is at the center of the pupil, encircled by a white circle. The tracking area for the right eye is 62 pixels, and 59 pixels for the left eye. A button is available labeled 'Auto Detect'. To the left there are four options available: start calibration, torsion, use default calibration, and advanced settings.

Figure 3 Torsional Tracker Calibration

Use the Auto Detect button to identify the appropriate iris tracking area. If the white tracking circles are not encompassing enough of the iris you can use the manual slider adjust bars to make small adjustments. When you are satisfied that the tracker is stable around the eyes then use the “Set Reference” button to finish the calibration.

Images of right and left eyes. For both eyes, a small cross is at the center of the pupil, encircled by a white circle. The tracking area for the right eye is 61 pixels, and 58 pixels for the left eye. A button is available labeled 'Auto Detect'. To the left there are two options available: set reference and close.

Figure 4 Set Reference to complete Torsion calibration.

Next calibrate the eyes to the TV monitor. Instruct the patient to hold their head still and look at each of the 5 targets.

Right and left eyes displayed, with five green checkmarks below for the following positions: center, left, up, right, and down. Visible as an almost perpendicular cross relative to the center dot in a graph below.

Figure 5 Video Eye Calibration

 

Performing the test

Once the system is calibrated you are ready to begin testing. During testing remind the patient to keep their eyes as wide open as possible. It is important to have good visibility of the iris. You will use the 3D Head Model to guide you through the appropriate head/body positions for the Dix Hallpike test.

  1. Step 1 is to turn the patient’s head 45 degrees towards the side you will be
  2. Step 2 is to lay the patient down with the head hanging 10

The black bar represents the head movement and when the head is in the correct position the shaded area will turn green. Once you have reached the first position you can immediately begin the second position.

3D image of a head, with semicircular canals displayed for both ears. The x-axis ranges from right to left, and the y-axis ranges from down to up. A green shaded area on both axes displays where to point the head, and a black marker indicates whether the patient's head is pointed correctly. Both black markers are in the green region, and the 3D head is pointing accordingly. In this instance, to the left and down.

Figure 6 3D Head Model Guide

Once the patient is in the correct position with both step 1 and step 2 highlighted in green you can begin the data recording by pressing the start button or start on the remote control.

Figure 7 Start the test

The eye recording will begin once you hit start and will continue to run for the preset time or until you hit continue, which will then prompt you to sit the patient up again. You should record at least 10 seconds of eye movements after the patient returns to sitting position to see if any nystagmus that was present in the supine position reverses direction when you sit the patient upright.

Counter is down to 109 seconds from 120, visible by a portion of the circle around marked yellow. There are five options available: continue, stop, add time, add note, and fixation manual.

Figure 8 Continue test with patient sitting up.

 

Results

After the test is completed you will see the data graphed for the horizontal and vertical eye movements and the torsional eye movements. A red diamond will appear if BPPV is detected.

Results for eye position, average slow phase velocity, and torsion velocity are displayed in separate graphs. BPPV is detected, indicated by a red diamond.

Figure 9 Advanced Dix-Hallpike results screen.

For further assistance, if needed, please refer to the Instructions for use and Additional Information manuals.


Presenter

Michelle Petrak
Michelle Petrak, Ph.D., is the Director of Clinical Audiology and Vestibular Research for Interacoustics. Her primary role is development and clinical validation of new technologies in the vestibular and balance areas. She is located in Chicago where she is a licensed private practice clinical audiologist at Northwest Speech and Hearing (NWSPH). Dr. Petrak received her doctorates in Electrophysiology (1992) and Biomolecular Electronics (1994) from Wayne State University and her Masters in Audiology in 1989. Her special areas of expertise include vestibular and balance assessments and management of the dizzy patient. Dr. Petrak is involved with new innovative product developments, clinical evaluations of new protocols, and publishing, teaching, and training on the management of patients with dizziness. She continues to lecture extensively nationally and internationally, and she has numerous articles published in the hearing industry journals. She also participates on the committees for several doctoral students as support for the research projects.

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