Brain surgery isn't rocket science.
First thing you're going to need is a patient. Preferably one with a brain tumor. If you can't find one with an actual tumor, find someone you don't like, or who's dumb anyway in case something goes wrong. As an aikido teacher I read about once put it very succinctly: sometimes you have to waste a guy to restore harmony to the situation.
That said, feel free to hone your skills on the family pet or any farm animals or rodents you might have hanging around. There will be blood. Once you have enough confidence in your abilities, or are simply reckless and crazy by nature, secure a human patient. Just be aware that he's probably not going to want you to crack open his skull and pull some mass of goo out, even if you tell him it's going to kill him anyway. To quote Woody Allen, again: "The brain? It's my second favorite organ."
If he has a benign tumor and it's growing, you can remove it. If it's a malignant tumor, tell him not to buy any green bananas. (That's neurosurgeon humor – he'll croak before they ripen.) Seriously, if it's a malignant tumor he's going to die anyway, so tell him to take a trip to Vegas and bet everything. And don't let anyone try to trot out the tired existential trope that we're all going to die. We are, but not right away.
Once the patient is ready, it's time to lay him out on the operating table and put him to sleep. Even though the brain has no nerve endings and wouldn't be painful to operate on in theory – busting someone's skull open without anesthesia is not recommended. A combination of inhalation agents and narcotics'll put him under, and then throw a breathing tube down his throat while hooking him up to a ventilator at the same time. Then take a deep breath yourself.
Clamp his brain pan in a Mayfield Head Holder, which is essentially an expensive adjustable shiny-aluminum vise, and then shave it. Draw the outline of the incision on his head with an indelible surgical marker. Do not use the Sharpie you've got in your pocket, because it's not sterile. Which brings up a point worth mentioning now: Beware of hospital cost-cutting measures, as they may result in death. Seriously, we want to do this on the cheap, but we don't want to turn the procedure into an autopsy.
Make the cut, using a Bard-Parker 10-blade knife. You can, in a pinch, use an Xacto with a number 11 blade, but go with the BP if possible. Hack down to bone, and then stop the bleeding by clamping the scalp edges with Rainey Clips. If you don't have any handy, get some. Pliers and/or duck tape won't do the trick.
Drill holes in skull with a cranial perforator – it makes a nice clean quick job of things without overkill i.e. drilling into the brain. Our weapon of choice, so-to-speak, is the Acra-Cut Smart Drill 2000. 4 holes are bored on average, in the corners of the exposure. Then use a Penfield 3 dissector to separate the underlying dura from the skull. Be careful not to shred the dura because it can be extremely thin and brittle. We call this "Old Lady" dura, with affection.
Use a craniotome to saw between the holes in the skull; it's kind of like cutting a light socket outlet in a sheetrock wall. Be neat, and clear as you go I always say. Lift the bone flap off, taking care to separate the remaining dura with your Penfield. Wrap it in anti-biotic sponges, and give it to the sure-handed scrub nurse. If she's got butterfingers and drops it onto the ground, the 5-second rule DOES NOT apply. You will need to soak it in betadine solution, or you could make a new one if you're feeling particularly ambitious. Use a large slab of methylmethacrylate and begin to whittle it down. Oh, I forgot to tell you to check your tee time first since it could take a while, and this isn't something you want to fudge or rush.
Open the dura up, and the elegance of the design of the mind and maybe even the whole wonderful universe will be revealed. As well as the underlying tumor. Hopefully. If it is not revealed, the tumor I mean, then hold up your left hand. No, your LEFT hand. Ok, you had the MRI backwards and are on the wrong side, numbskull! Just kidding – this has never happened to me. Bring over the operating microscope and move it into position. I usually use 10x magnification – this allows me to see what I'm doing without getting too wrapped up and overwhelmed with the details.
If the tumor is soft and suckable, it can easily be removed using a CUSA, which is essentially a small, high-tech vacuum cleaner. If it's hard and recalcitrant, you could spend the next couple of man-hours labouriously cutting every miniscule inch of that unhappiness out. The patient's health care plan will determine the technique used. A comprehensive plan that reimburses the surgeon well will incentivize him to use the proper technique, which means gutting the entire tumor and then carefully dissecting the remaining shell from the brain. This is capitalism at its finest.
If the patient's plan has anything to do with socialism, the surgeon will attach one end of a 10' piece of stout twine to the tumor and the other end to the operating room door, and then have the circulating nurse go out to get everybody coffee. This will remove the tumor swiftly and painlessly (for the surgeon). He can then get in at least 18 holes, if the weather holds.
Assembly is the reverse of dissassembly as the masters of understatement at Chilton told me years ago when I tried to change the piston rings on my CB750/4 – which I will only comment on now by saying that the experience put me in mind of St. Augustine's "humility, method and patience." It became a one-of-a-kind CB750/3 because I had none of the above. The take-away here is: the human body has just enough parts to make it work well, so put them all back where they belong.
In a nutshell this is done by stopping all bleeding, closing the dura, and replacing the bone flap using microplates and screws. Close the scalp in layers – galea first, then skin. Place the dressing on, including a head wrap. Wake patient up, then transfer him to the ICU. Total elapsed time: 4-6 hours. Congratulations, you are now a brain surgeon.