@Izzy78 - Inner ear infections are usually caused by a virus that blocks fluid from draining from the ears. The fluid collects and then starts to grow bacteria.
You're right that it is more common in kids than in adults. I have read one of the main reasons that babies get more ear infections is because when they are fed lying down, the fluid can collect in their ears easier.
I would assume that since labyrinthitis is caused by ear infections babies are more likely to get it.
I'm wondering if there are instances when long term damage to someone's hearing or balance can happen. What would cause this?