Minimum Stimulus Strategy: A step-by-step diagnostic approach to BPPV

Abstract

Benign Paroxysmal Positional Vertigo (BPPV) is among the most common vestibular disorders, characterized by brief vertigo spells triggered by head position changes with abrupt onset and rapid decrease. BPPV is ascribed to otoconial matter dislodged from utricular macula and attached to the cupula of the affected semicircular canal (cupulolithiasis) or free-floating within its lumen (canalolithiasis). According to the vestibulo-ocular reflex pathophysiology, each cupular deflection, either exciting or inhibiting the corresponding ampullary afferents, generates the contraction of specific extraocular muscles couples leading to pathognomonic nystagmus. The Upright BPPV Protocol (UBP) is a diagnostic approach to BPPV conducted in the sitting position slowly bending the patient's head along the spatial axes, aiming to move canaliths by gravity within the involved semicircular canal, under continuous nystagmus monitoring by video-Frenzel goggles. UBP starts with the evaluation of pseudo-spontaneous nystagmus in the primary gaze position and continues with the upright Head Pitch Test (uHPT) by forward and backward head bendings along the pitch plane. The uHPT can indicate whether horizontal or vertical semicircular canal is involved. If horizontal canal is suspected, the upright Head Roll Test (uHRT) usually provides the diagnosis of the involved side and arm by tilting the patient's head rightward and leftward along the roll plane. Conversely, canalolithiasis involving the posterior semicircular canal can be diagnosed with the uHPT alone. Nevertheless, if necessary, the diagnostic sensitivity can be increased by head movements along the right anterior - left posterior (RALP) and left anterior - right posterior (LARP) canal planes (uRALP/uLARP test). Following the UBP, most BPPV form can be diagnosed in upright position, allowing clinicians to proceed immediately with proper physical treatment and avoiding unpleasant maneuvers to patients.

Keywords: BPPV; Canalithiasis; Minimum Stimulus Strategy; Upright protocol; Vertigo.