Objective: Unexplained dizziness remains a clinical challenge. Our previous studies have shown that unexplained dizziness may be related to patent foramen ovale (PFO). This study aims to explore whether the degree of shunt is correlated with the degree of unexplained dizziness and looking for the possible clinical intervention for patients with unexplained dizziness.
Methods: This study was a large single-center, prospective, controlled study. From March 2019 to March 2022, patients with unexplained dizziness and explained dizziness and healthy controls were recruited. Contrast-enhanced transcranial Doppler sonography (c-TCD) was performed to detect the existence of right-to-left shunt (RLS) and shunt grading. The dizziness handicap inventory (DHI) was completed to evaluate the dizziness. Unexplained dizziness patients with large amount of PFO were volunteered to receive medication treatment and transcatheter PFO closure and followed up six months.
Results: A total of 387 patients (132 unexplained, 123 explained and 132 controls) were enrolled. There was a statistical difference in the RLS grading with three groups (p < 0.001). The Spearman correlation coefficient of RLS grading and DHI scores in unexplained dizziness patients (r =0.122, p =0.163) and explained dizziness patients (r =0.067, p =0.460). In the unexplained group, there were 49 cases with massive grading RLS. Of which 25 patients received percutaneous PFO closure treatment and 24 cases received medication treatment. Followed up six months after treatment, the amount of DHI scores change in patients who received the percutaneous PFO closure was significantly higher than that in the medication treatment group (p < 0.001).
Conclusion: RLS may play an important role in unexplained dizziness. For unexplained dizziness patients, PFO closure may contribute to better outcomes. In the future, large-scale randomized controlled studies are still needed.
Keywords: unexplained dizziness, dizziness handicap inventory, DHI, patent foramen ovale, PFO, right to left shunt, RLS, contrast-enhanced transcranial Doppler sonography, c-TCD