[pineal]

The neurosurgeon meticulously plans the exact trajectories prior to surgery and we use a combination of software and hardware (Stealth or Brainlab) to ensure we follow the planned path. Of course, complications still occur but are fairly rare, serious or permanent ones even more so.

[polishdude20]

Are they actually piercing into the brain matter or are there gaps in the brain? Does the trajectory avoid actual neurons on the way?

[pineal]

The brain matter is indeed pierced. While “you only use 10% of your brain” is a myth, much of the brain is what we call non-eloquent, meaning it can be damaged or removed without any noticeable effects. Especially when it just means being pierced by a 2-3mm diameter lead. Are there hidden side effects that we are simply unable to recognize? Sure, but with as primitive an understanding of the brain as we currently have, we are forced to rely on a more pragmatic rather than philosophical approach.