Covert Saccades
This is an example of head impulse data that exhibits an abnormal vestibular ocular reflex on the
right
side indicated by
the gain response and the catch-up saccades. Looking at the Gain graph the data points are all within the gray range indic-
ating unilateral loss. Note the asymmetry of 56%. The right (abnormal) side is affecting the left (normal) side. The head data
shows well performed head impulses and the eye data shows an inadequate vestibular ocular reflex (A) that does not mir-
ror the head velocities. There are covert catch-up saccades present (B). Catch-up saccades are easier to visualize in the 3D
analysis.
9.10
Hex Plot window
The Hex Plot window provides an overview of the mean gains as well as the 2D analysis graphs for all selected tests. The
tests initially selected are the same as the tests selected in the 2D and 3D Analysis windows.
Mean gains are represented by bars that vary in length according to the mean gain value. The bars are displayed inside a
hexagon. Each side of the hexagon is labeled with a two-letter abbreviation that refers to one of the six semicircular canals:
•
LA (left anterior)
•
RA (right anterior)
•
LL (left lateral)
•
RL (right lateral)
•
LP (left posterior)
•
RP (right posterior)
The outer hexagon represents a mean gain of 1.0. The inner hexagon represents a mean gain of 0.5.
The gain bars are colored according to normative cutoff settings made in the Head Impulse
Options
window. Refer to the
Reference Manual.
Otometrics - ICS Impulse USB
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9 Head Impulse