Head position and increased head velocity to optimize video head impulse test sensitivity.

Area of Science:

• Neuroscience
• Ophthalmology
• Audiology

Background:

• The video head impulse test (vHIT) is crucial for assessing vestibular function.
• Understanding how head positioning affects vHIT gain is important for accurate diagnosis.
• Unilateral vestibular loss (UVL) requires precise evaluation methods.

Purpose of the Study:

• To investigate the impact of different head positions on vestibulo-ocular reflex (VOR) gain during vHIT.
• To determine if a modified head position can enhance the sensitivity of vHIT in detecting vestibular deficits.

Main Methods:

• vHIT was performed on 20 healthy controls and 18 patients with UVL.
• Measurements were taken with the head in a neutral (0°) and a 30° downward pitched position.
• Head velocities ranged from 150°/s to 200°/s.

Main Results:

• In controls, the 30° head-down position significantly increased VOR gain in both ears (p < 0.001).
• In UVL patients, the 30° head-down position decreased VOR gain on the diseased side (p = 0.046) and increased inter-ear asymmetry.
• This head position appears to more effectively stimulate the horizontal semicircular canal.

Conclusions:

• A 30° head-down position enhances vHIT sensitivity, increasing gain in healthy individuals and decreasing it in patients with UVL.
• This modified vHIT approach may improve the precision of vestibular function evaluation.
• This technique could help reduce false-negative findings in vHIT assessments.