Direction-changing positional nystagmus (DCPN), which refers to the change in the direction of nystagmus with different head positions, is a well-known characteristic of horizontal semicircular canal BPPV. The supine head roll test is commonly used to diagnose horizontal canal BPPV. However, persistent geotropic DCPN observed during this test cannot be explained by the conventional explanations of canalolithiasis or cupulolithiasis. To account for this unique nystagmus, the concept of a “light cupula” has been recently introduced. In this review, we provide an overview of the historical background, clinical features and diagnostic methods, proposed mechanisms, and treatment strategies associated with the light cupula phenomenon based on the available literature to date.

Background/Objectives: Aural toilet using microsuction is a common procedure in ENT clinics, and vertigo is a frequent complaint during this procedure. This study aimed to investigate the characteristics and incidence of microsuction-induced nystagmus and vertigo based on the appearance of the tympanic membrane (TM). Methods: In 85 patients with various TM appearances, microsuction-induced vertigo and nystagmus were assessed. Results: Microsuction elicited nystagmus in 95% (81 of 85) of patients and vertigo in 36% (31 of 85). The nystagmus direction was towards the ipsilateral ear in a bowing position and towards the contralateral ear in a leaning position. The proportion of patients who complained of rotatory vertigo was significantly higher in those with TM perforation, open cavity mastoidectomy, and adhesive otitis media (74%, 26 of 35) compared to those without TM perforation (10%, 5 of 50) (p < 0.001, X² test). Conclusions: Aural toilet using microsuction commonly induces vertigo due to convection in the lateral semicircular canal endolymph caused by the cooling effect. While microsuction-induced nystagmus was observed in most patients, the incidence of vertigo varied depending on the TM condition. Clinicians should closely monitor patients for vertigo during the procedure, and methods to prevent microsuction-induced vertigo should be explored.

Background/Objectives : Aural toilet using microsuction is a common procedure in ENT clinics, and vertigo is a frequent complaint during this procedure. This study aimed to investigate the characteristics and incidence of microsuction-induced nystagmus and vertigo based on the appearance of the tympanic membrane (TM). Methods: In 85 patients with various TM appearances, microsuction-induced vertigo and nystagmus were assessed. Results: Microsuction elicited nystagmus in 95% (81 of 85) of patients and vertigo in 36% (31 of 85). The nystagmus direction was towards the ipsilateral ear in a bowing position and towards the contralateral ear in a leaning position. The proportion of patients who complained of rotatory vertigo was significantly higher in those with TM perforation, open cavity mastoidectomy, and adhesive otitis media (74%, 26 of 35) compared to those without TM perforation group (10%, 5 of 50) (P < 0.001, X² test). Conclusions: Aural toilet using microsuction commonly induces due to convection in the lateral semicircular canal endolymph caused by the cooling effect. While microsuction-induced nystagmus was observed in most patients, the incidence of vertigo varied depending on the TM condition. Clinicians should closely monitor patients for vertigo during the procedure, and methods to prevent microsuction-induced vertigo should be explored.