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Comment by SeanAnderson | Hacker News Reader

I never quite fully grasped the purpose of having patients stay engaged during brain operations. Is it possible to undo a brain incision? If not, what good is it to know a patient's abilities are degraded after having made a cut? Is it just to mitigate compounding unexpected damage?

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You electrically stimulate around the spot with a probe where you’re planning to resect. If the patient can’t perform whatever task you’re evaluating then you know you can’t resect in that area. Generally looking for a 1cm margin between tissue you’re going to resect and a positive stim site.

Can’t undo brain cuts. CNS neurons don’t repair themselves like peripheral neurons or your skin. Generally not cutting glioma brain tumors out per se more likely to use ultrasonic aspiration to suck the tumor out piecemeal. Depends on the tumor though.

Oh, that makes sense. Cool that we can "dry run" explore with electric pulses! Thanks for explaining :)

"dry run" is a great analogy!

Fascinating! What is ultrasonic aspiration and how does it work?

How do you know what task to evaluate?

And what if this was not a saxophone player, but a tennis player? Or both?

The worst is when you're performing brain surgery on a brain surgeon. The operating theater can get really crowded.

Operating theater overflow :)

Okay, this was a good one!

With our brain surgery robot the brain surgeon can definitely perform brain surgery on himself. Or invite a fellow brain surgeon over the phone, well a tablet might work better. Or better VR 3d glasses.

You seem knowledgeable about the topic.

I'm also curious as to the answer to this question [1]. Why does left-handedness make brain surgery slightly more complicated?

1: https://news.ycombinator.com/item?id=33215614

It’s not binary. You go slowly, and stop if it’s starting to impact the behavior you’re observing.

What’s the alternative, knowing that you’re working with a system with unknown specific architecture and whose only way you can get feedback about how you’re doing is via the patient? You can stimulate parts of the brain without damaging it btw. The surgeon just needs to know what that part is specifically.

You don’t make more cuts there

Others have explained, but what I've heard from a brain surgeon on TV: it's extremely delicate and they don't always know how deep they can go, so they probe bit by bit and when they notice it's having an effect they stop. The surgeon I listened to was also a gifted storyteller, it was very very impressive and inspiring. That's really a hell of a job.

Well you can definitely stop cutting deeper if you know something is up!

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