From a conventional maneuver to a mechanical repositioning procedure for torsional-vertical down beating positioning...

To explore, using numerical simulations, the biomechanical behavior of otoconia during the Garaycochea maneuver in torsional-vertical down-beating positioning nystagmus (TVP-DBNy) associated with benign paroxysmal positional vertigo (BPPV), and to propose a modified maneuver designed for execution under controlled conditions compatible with a mechanical-repositioning-chair (MRC).

A high-resolution three-dimensional micro-computed tomography (μCT) reconstruction of a human membranous labyrinth was used to simulate TVP-DBNyrelated conditions. The main clinical scenarios producing TVP-DBNy where included: short-arm of the posterior canal (PC); distal portion of the long-arm of the PC; and a contralateral anterior canal (AC). Endolymphatic flow was modeled using the Navier-Stokes equations, and otoconia of different sizes (5-20 μm) were introduced as Lagrangian particles. Two maneuver protocols were simulated: the original Garaycochea maneuver and a modified sequence simulated under idealized, controlled conditions consistent with MRC-based execution.

The original maneuver did not consistently promote otoconial transport toward the utricular macula across all simulated scenarios. The modified maneuver resulted in trajectories that favored otoconial progression toward the utricle under the specific kinematic conditions simulated, with limited displacement observed for the smallest particles.

The simulations suggest that symptom improvement after the standard maneuver may be associated with scenarios in which most particles remain near the utricular side of the horizontal ampulla. The proposed modification provides mechanistic insight into possible personalized repositioning strategies but should be interpreted as exploratory and hypothesis-generating, conditional on the modeled conditions, rather than as evidence of clinical superiority.