You are correct, doctors are reluctant to cut off balance information from the second ear by performing a second nerve section. The reason is that the balance system plays an important role in how your eyes stay focussed on an object. If someone looks at an object and rotates their head side-to-side, the object will stay clearly in focus. This is because the balance system is telling the eyes how much the head has rotated, allowing the eyes to be adjusted exactly to keep the image in the same place. If balance on one side is destroyed, the system will still work using balance information from the one good side. If both balance organs are destroyed, vision may then become blurred when head movements occur. Also, a condition called oscillopsia (a sensation that the visual field is oscillating back and forth) may develop. These problems will always be present (not just as periodic attacks) and may overall be a bigger problem than the vertigo attacks. As an alternative to nerve section surgery, some doctors administer intravenous streptomycin to suppress the balance system in the remaining ear. By titrating the dose, the goal is to suppress the vestibular attacks without totally destroying the entire balance system. The question of whether, and how, to ablate the second labyrinth is controversial, because the outcome for the patient is often not good.