Clinical Application of Different Vertical Position Tests for Posterior Canal-Benign Paroxysmal Positional Vertigo-Cupulolithiasis

BACKGROUND: Posterior canal-benign paroxysmal positional vertigo-cupulolithiasis (PC-BPPV-cu) is a new and controversial type of benign paroxysmal positional vertigo (BPPV). At present, there are few relevant clinical studies as to whether the Half Dix-Hallpike test (Half D-HT) induces more obvious nystagmus than the Dix Hallpike test (D-HT) and straight head hanging test (SHH) in patients with PC-BPPV-cu. OBJECTIVES: To investigate the clinical characteristics of PC-BPPV-cu, and analyze the diagnostic significance of the Dix-Hallpike test (D-HT), Half D-HT, and straight head hanging (SHH) test in these patients. METHODS: A total of 46 patients with PC-BPPV-cu were enrolled, and divided into two groups (N = 23): a group A (induction order: D-HT, Half D-HT, SHH) and a group B (induction order: Half D-HT, D-HT, SHH). RESULTS: Among 46 patients with PC-BPPV-cu, the bilateral and unilateral abnormality rates of the disease side were 5 cases and 41 cases, respectively. There were significant differences in the proportion of torsional-upbeating nystagmus and upbeating nystagmus among the three headhanging positions in 46 patients with PC-BPPV-cu (P < 0.001). The slow phase velocity (SPV) of induced nystagmus at half D-HT supine position was slower than D-HT supine position (P < 0.05) and SHH supine position (P < 0.05). The nystagmus latency of D-HT supine position was significantly shorter than half D-HT (P < 0.05) and SHH (P < 0.05). PC-BPPV-cu patients were accompanied by 53.5% semicircular canal paresis, 69.6% audiological abnormalities, 76% cervical vestibular evoked myogenic potential (cVEMP), and 75% video head impulse test (vHIT) abnormalities, the concordance rates of the four detection methods were similar (χ(2) = 0.243, P = 0.970). CONCLUSIONS: The Half D-HT is simple and feasible, but might have a risk of false-negative diagnoses of the torsional-upbeating nystagmus and upbeating nystagmus. The D-HT is still a classic induction method for PC-BPPV-cu. The two complement each other and may aid in the diagnosis of PC-BPPV-cu patients. Future clinical applications of Half D-HT require extensive research to determine its diagnostic efficacy.