Apogeotropic variant of posterior canal benign paroxysmal positional vertigo

Sometimes debris can be located inside the posterior canal close to the common crus, resulting in apogeotropic posterior canal-paroxysmal positional vertigo (APC-PPV), which is characterized by torsional down-beating nystagmus (TDBNy) in the Dix-Hallpike position. The aim of this study was to investigate a differential diagnosis of the anterior canal variant, which is characterized by the same nystagmus direction. We selected 28 patients from among those referred for positional vertigo with TDBNy in Dix-Hallpike position to two Italian Balance Centers from January to August 2014. All of the patients underwent specific physical therapies aimed to cure APC-PPV: liberatory maneuver (LM, n=23) or forced prolonged position (FPP, n=5). All patients were checked within 3 days. The LM was effective in 20 patients: 13 recovered and 7 showed a typical posterior canal torsional up-beating nystagmus (TUBNy). The FPP had a positive outcome in 3 patients: 1 was symptom and sign-free and 2 had typical TUBNy. Thus, the described therapeutic techniques were successful in 82.14% of cases, either recovering the APC-PPV or transforming it into a typical posterior canal form. Both eventualities could allow us to distinguish the apogeotropic posterior canal variant from anterior canal-paroxysmal positional vertigo.