Active Head Rotation

16 February 2022
10 mins
Reading

What is the Active Head Rotation test?

The Active Head Rotation Test is useful when you have a bilateral caloric weakness, as it can provide information on the residual function of the vestibular system.

List of tests, including spontaneous nystagmus, gaze, smooth pursuit, random saccade, optokinetic, and VORTEQ active head rotation. For subtests for VORTEQ active head rotation are visible, including horizontal active, horizontal passive, vertical active, and vertical passive.

Figure 1 – License for VE525 and VORTEQ Diagnostic Bundle

 

Performing the test

To begin testing select the first VORTEQ AHR subtest which is Horizontal Active. For active tests the patient will be instructed to move their head to the beat of the metronome while fixating the target which in the default protocol is a black dot on a white screen.

If you haven’t already calibrated in a previous test you would need to calibrate before starting the test. If the eyes were already calibrated in a previous test you are ready to begin and can hit start to begin the first subtest. Make sure the VORTEQ IMU is attached to the goggle and turned on. You will see a message telling you when the sensor is active, and you can begin testing.

Figure 2 – Message showing you the VORTEQ IMU is turned on and you are ready to start testing.

During the test is you will see the head movement shown in yellow, the eyes in red and blue and the gain and phase measurements.

There will be a short practice mode to let your patient get used to the head movements at the speed of the metronome.

Vertical active subtest screen for VORTEQ active head rotation. Empty gain and phase graphs, and a greyed out eye position graph with the words 'Practice mode (5 s)'.

Figure 3 – Practice Mode for Active Head Rotation testing

Horizontal active subtest screen for VORTEQ active head rotation. 81% gain at 1 and 2 hz. 1 degree phase lag at 1 hz. 0 degree phase at 2 hz. Smooth sinusoids for eye position that follow the target position nicely.

Figure 4 – Horizontal Active completed test

You can next perform the test passively where you move the patient’s head for them, or you can move on to the vertical subtests. The vertical subtests are performed with the patient following the metronome while moving their head up and down while fixating the target on the TV. Again, at the end of the test you will see a summary of the data.

Vertical active subtest screen for VORTEQ active head rotation. 75% gain at 1 hz and 68% gain at 2 hz. 5 degree phase lead at 1 hz. 4 degree phase lead at 2 hz. Smooth sinusoids for eye position that fall a bit short of the target position.

Figure 5 – Vertical Active completed test.

 

Results

When you have completed all the subtests you will see a summary plot. You can use the arrows to toggle through multiple pages. The results plotted are similar to the data that is shown in rotation chair testing. You will have a plot for Gain, Phase and Symmetry.

Summary plots for gain, phase, symmetry, and eye position. 84% gain at 1 hz and 83% gain at 2 hz. 5 degree phase lead at 1 hz and 4 degree phase lead at 2 hz. 5% left weakness at 1 hz and 6% right weakness at 2 hz. Eye position tracings follow the target position tracing quite closely.

Figure 6 – Summary plots.

A perfectly normal gain would be 100% and we expect symmetrical responses.

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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