Suppression head impulse paradigm test–retest reliability
Mayada Abdelsalam ElsherifAbstract
Background:
The suppression head impulse test (SHIMP) is a clinical tool used to assess vestibulo-ocular reflex (VOR) function and vestibular compensation. This study aimed to evaluate the test–retest reliability of VOR gain and anti-compensatory saccade parameters measured using the SHIMP protocol in individuals with and without vestibular impairment.
Methods:
A total of 42 participants (18 males, 24 females; mean age: 45.7 ± 16.2 years) were enrolled in the study, among whom 8 presented with vestibular loss, 3 had bilateral vestibular loss, and 5 had unilateral vestibular loss (4 left-sided and 1 right-sided). All patients with vestibular impairment were evaluated during their subacute phases. All participants underwent the SHIMP test twice within a short time interval of 15 min. The test–retest reliability of VOR gain, asymmetry percentage, and anticompensatory saccade characteristics (amplitude and latency) was analyzed using the intraclass correlation coefficient (ICC) and Bland–Altman plots.
Results:
The VOR gain for the right and left lateral planes and the VOR asymmetry percentage demonstrated good to excellent reliability (ICC >0.75). Covert saccades on the left side also exhibited good agreement between measurements. For overt saccades, the amplitude of the anticompensatory saccades exhibited good reliability, whereas the latency did not.
Conclusion:
Both VOR gain and the amplitude of overt anticompensatory saccades represent highly reliable measures when evaluated using the SHIMP paradigm. Consequently, observed variations in these parameters reflect underlying vestibular dysfunction rather than test–retest variability or methodological artifact inherent to the SHIMP protocol.