Horizontal apogeotropic
Horizontal-canal BPPV — beats away from the ground (cupula variant).
What the animation does not show. As with the geotropic form, this single-position clip does not localise the affected ear. The weaker-versus-stronger comparison that points to a side is a bedside judgement across both roll positions, not something the animation measures (Bhattacharyya 2017).
Direction-changing horizontal nystagmus on the roll test that beats away from the ground (apogeotropic), the less common cupula-bound variant. Still peripheral — treated with Gufoni or roll maneuvers.
The apogeotropic variant beats away from the ground in each roll position — the mirror of the geotropic pattern. It is usually attributed to particles near or adherent to the cupula rather than free-floating in the canal (Bhattacharyya 2017).
The side inference reverses too. In apogeotropic disease the WEAKER response tends to be with the affected ear down, the opposite of the geotropic rule. Many apogeotropic cases convert to geotropic as particles move, and treatment (a Gufoni or roll maneuver) aims to return them to the canal where they can be cleared (Gufoni; Lempert).
Source: AAO-HNS BPPV clinical practice guideline (Bhattacharyya 2017), which covers the lateral canal; the Gufoni and Lempert maneuvers are named there.