Head Orientation - Interacoustics EyeSeeCam Instructions For Use Manual

Head Orientation

Two head orientations with respect to the trunk are possible:
1. The head can be either straight (see below Figure 4.5.3-1, left), or
2. it can be rotated by
a. 45 degrees to the right for LARP testing (see below Figure 4.5.3-1, right) or by
b. 45 degrees to the left for RALP testing (not shown).
Figure 4.5.3-1 Vertical Head impulse testing – Two possible orientations of the head-on-trunk and correct straight
gaze in RP canal testing.
It depends on examiner preferences whether the vertical head thrusts are easier to perform with the head
straight or with the head rotated by 45 degrees. For some, testing in the rotated orientation might feel
more natural because the neck anatomy is rotated in pitch only, not in the less usual diagonal direction.
Whichever orientation you opt to use, the correct gaze is always straight along the midsagittal plane.
In order to provide fixation targets for all possible head orientations you can either place additional
external targets at 45 degrees left and right on the wall or you can use the laser as described above in
chapter 4.4.3 ("Display laser during HIT"). You can also adjust the 3D head model settings as described
above in chapter 4.4.2 ("3D Head Modeling") such that you can view it either from the "Top" position, if
you opt for the straight orientation, or from the "Top 45°" position, if you opt for the rotated orientation.
Depending on whether you select the RALP or LARP protocol, the 3D head model will be shown rotated
45 degrees to the left or right, respectively.
For testing in the vertical planes you can select RALP and LARP protocols from the recording menu (right
anterior/left posterior and left anterior/right posterior).
Figure 4.5.3-2 Head impulse testing – vertical canals
D-0101516-E – 2019/03
EyeSeeCam vHIT - Instructions for Use - US Page 32