LAUSR

This study assessed cardiovascular control during Head‑Down Neck Flexion (HDNF) in a group of patients suffering from total bilateral idiopathic vestibular loss (BVL) for 7 ± 2 years. Nine adult patients (age 54 ± 6 years) with BVL were recruited. Calf blood flow (CBF), mean arterial pressure (MAP), heart rate (HR) were measured with eyes closed in two lying body positions: ventral prone (VP) and lateral (LP) on the left side. Vascular resistance (CVR) was calculated as MAP/CBF. The HDNF protocol consisted in passively changing the head position: head up (HU) ‑ head down (HD) ‑ HU. Measurements were taken twice at each head position. In ventral position CBF significantly decreased in the HD 3.65 ± 0.65 mL.min‑1.100mL‑1 vs HU 4.64 ± 0.71; p < 0.002, while the CVR in the VP significantly raised in the HD 31.87 ± 6.93 arbitrary units vs 25.61 ± 6.36 in HU; p < 0.01. In the LP no change in CBF or CVR was found between the two head positions. MAP and HR presented no difference between HU and HD in both body positions. Age of patients did not significantly affect the results. Decrease in CBF of the BVL patients was similar to the decrease observed with the same HDNF protocol in normal subjects. This suggests a sensory compensation for the lost vestibular inputs that could originate from the integration of inputs from trunk graviceptors, proprioceptive and cutaneous receptors. Another possibility is that HDNF vascular effect is evoked mostly by non-labyrinthine sensors.