18/06/2026
Midsummer in Sweden is just around the corner 🌼🍓
…and let’s be honest, for some, that might come with a drink or two. 🍷
Which makes it a perfect time to talk about something we rarely think about:
Alcohol-induced nystagmus 👀
Alcohol does not just affect behavior. It also directly affects vestibular physiology.
When alcohol enters the bloodstream, it diffuses faster into the cupula than into the surrounding endolymph. This creates a temporary density mismatch, making the cupula relatively lighter than its surroundings and suddenly sensitive to gravity.
The result? A positional nystagmus PAN I
Typically, this presents as a persistent geotropic horizontal nystagmus when the person is lying supine with the head turned to either side, without clear latency and without fatigability.
A few hours later, the situation reverses. As alcohol redistributes and is eliminated unevenly, the cupula becomes relatively heavier than the endolymph and the direction of the nystagmus flips: PAN II
Now, the pattern usually changes to an apogeotropic horizontal nystagmus, again position dependent but in the opposite direction.
Why does this matter clinically?
🔹 It can mimic BPPV but without typical latency or fatigability
🔹 It occurs without otoconia displacement
🔹 It tends to be more persistent rather than clearly paroxysmal
🔹 It highlights how sensitive the vestibular system is to subtle physical changes
For me, this is one of the clearest examples of how physics and physiology interact in the vestibular system. ⚖️
No debris needed. Just a shift in density. A good reminder this Midsummer. 🌿
Not all positional nystagmus is BPPV.
So happy Midsummer, everyone. 🌼🍓
And don’t forget to look your dinner neighbor deep in the eyes and check if there is a PAN I or PAN II nystagmus. 😉