Facilitatory Maneuver for Posterior Canal BPPV: Unmasking Typical Nystagmus in Dix–Hallpike–Negative Cases — A Multicenter Prospective Study

Background: The Dix–Hallpike test is the gold standard for diagnosing posterior canal benign paroxysmal positional vertigo (pc-BPPV), yet false-negative results occur in up to one-third of clinically suggestive cases, particularly in patients evaluated one week or more after symptom onset. In addition to dispersed otoconial debris, morphological variants of the posterior semicircular canal, such as focal stenoses, curvature irregularities, and non-linear canal profiles may hinder debris mobility and reduce test sensitivity. Objective: To assess whether a facilitatory head flexion maneuver performed in the LARP/RALP plane can unmask typical pc-BPPV nystagmus in patients with negative Dix–Hallpike tests. Methods: Adults with suspected pc-BPPV and bilateral negative Dix–Hallpike tests were enrolled in a multicenter prospective study conducted in Policoro, Matera, and Florence. While in the Dix–Hallpike position, patients underwent a facilitatory maneuver consisting of up to five repeated chin-to-chest flexions aligned with the LARP plane for suspected right pc-BPPV and the RALP plane for suspected left pc-BPPV. Nystagmus was assessed using videonystagmoscopy. When typical posterior canal nystagmus emerged, an Epley maneuver was immediately performed. Results: A total of 190 patients were enrolled. The facilitatory maneuver elicited typical posterior canal nystagmus in 62 patients (32.6%). Positive responses were observed in 20 of 61 patients in Policoro (32.8%), 14 of 40 patients in Matera (35.0%), and 28 of 89 patients in Florence (31.5%). No adverse effects or significant cervical discomfort were reported. Conclusions: This simple, rapid, and low-risk maneuver may serve as an effective diagnostic adjunct in patients with clinically suspected pc-BPPV who test negative on the standard Dix–Hallpike maneuver.