I shared your post w/ some others to poke some other brains. Some things to consider:

• While there is no traditional “ear”, there are can still other infections and injuries in that general vicinity which can lead to a rabbit tilting their head due to poor sense of balance, discomfort, compensation, etc.
• There is apparently a nerve on the side of the face that’s very susceptible to causing head tilt/ear inflammation
  • it could be worth doing a basic x-ray to see any obvious abscesses and dental disease (i.e., things not actually related to the ear). Again, other things cause head tilt
• If not done already, testing for EC is a good idea

Generally speaking, it sounds like he’s doing well in the context of the new observation, so it doesn’t sound super urgent.

From both personal experience and review of the general rabbit care community, just keep an open mind. I know when I was neck-deep in recurrent ringworm and respiratory infection episodes w/ one of my rabbits, everything I noticed was instinctively viewed through that frame of mind, so both myself and my vet at the time approached symptoms as such. Fast-forward, I moved, went to a new vet for symptoms, and w/ the different, non-biased set of eyes, we treated for syphilis and it really improved Wick’s overall health. So while you’ve done a lot of reading, research, and financial/time investments in the ear-specific surgeries and literature, it’s very possible this is something completely unrelated and it can be worth exercising cheaper diagnostics to investigate first.

The pulled up face does point to facial nerve (cranial nerverve no 7) involvement. 7 months seem a long time though and your vet seems confident it isnt related to the surgery. Sometimes scar formation can cause more trouble than an original injury -if there ever was injury to the facial nerve.

I think I’d look into ec first of all, since it’s a known cause of vestibular disease. Maybe your vet would be willing to prescribe a course of Panacur without extensive testing? Ec wouldn’t typically affect the facial nerve though, even if ec of course could invade any part of the nervous system. It seems more likely that something is putting pressure on the nerve.

E c is encephalitozoon cuniculi. It’s an intracellular microscopic parasite that’s very common in rabbits. Most rabbits are asymptomatic carriers, but some get ill. Typical findings are head tilt, balance issues and/or hind end paralysis or kidney problems that aren’t due to UTI or sludge. Young buns can get infected already in the womb, a typical sign of that is rapidly progressing cataracts at a young age.

Ec can invade any organ system that has a high bloodflow. There’s still a lot to be known about this parasite. Standard treatment is Panacur (fenbendazole) for 28 days, often in combination with Metacam (meloxicam) to bring down tissue inflammation. Additional meds can be given to help relieve vertigo/ nausea or to improve kidney function (if the kidneys are affected).

A normal x ray can show some tumors. I had a bun that developped a big tumor in his abdomen, that certainly showed on normal x-rays. Buns with suspected uterine cancer often have their lungs x-rayed to look for metastases, because uterine cancers tend to spread to the lungs. I don’t know how good a normal skull x ray would be in your bun’s case.

It could be that your bun’s tilts the head in some sort of “voluntary” effort to compensate for the facial paralysis. Maybe keep monitoring closely for now? It’s a good idea to film the bun so you don’t have to rely on memory. Filming makes it easier to spot more subtle changes.

Bam hit on this a little bit, but another possibility could be permanent damage caused by scar tissue. I had a bunny with permanent facial paralysis from chronic URI’s that eventually migrated to the ear and damaged the nerve. He was treated, of course, but the facial paralysis never resolved.