Since this is apparently a thing. This idea actually makes me super sad, but I’ve kind of got a boner for neurosci and neurosurgery especially, so I figured I’d put my time to good use and overanalyze this into something more concrete/scientific than some of the weird symptoms some of the fics out there I’ve seen.
FEEL FREE TO CORRECT ME IF I’M WRONG. All of this argument is based on what I could find in pictures/what I remember of the scene, so I could be totally missing something here. This information is based off my prior knowledge, my textbooks, and various medical articles and journals.
First, let’s look at the actual gun position.
(got this off sherlockoloy, only image I could find without scrolling through 3902 tumblr posts P: )
It’s slightly tilted to the right from what I can see, and notice how it’s obnoxiously straight up and down? Congratulations, Moriarty, you just unguaranteed yourself instant death. It’s vertical enough to not only miss the thalamus and other super-important things like that, but also the lateral ventricles. Think of your brain as an apple, with a few water balloons around the apple, and then surround that with bubble wrap. Moriarty (probably) hit the bubble wrap.
The fact that it’s tilted to the right is actually quite important as well. Hitting the right hemisphere is infinitely better than hitting the left, because most mental disability as a result of traumatic brain injuries (tbi) are most associated with left hemisphere lesions. So that’s another plus.
That being said, I think it’s safe to say he hit the right orbital frontal cortex, which is on the bottom side of the brain, and the right superior frontal cortex, which is on the top of the brain. So that’s entry and exit. It’s also safe to say, because it was so point blank and he fell back, there was not only skull fracturing going on, worsened by his fall, but also the force of the bullet basically created a shockwave that expanded the hole. Now, the size of the shockwave is hard to speculate. I’m going to continue on the assumption that it’s not THAT bad because I’m an optimist, but the lesions can increase up to about 30 times the size of the missile. In which case, worst case scenario the shockwaves are what officially does him in. He’s close enough to the ventricles and the midbrain that a large shockwave could easily do some badass damage. But like I said, optimist alert when it comes to JMo, so let’s continue assuming it’s not that terrifying.
Back to the orbital frontal cortex. Wikipedia says it’s associated with emotion/reward. Patients who come in with penetrative tbi to this area tend to experience “abnormal” sexual behavior afterwards. Usually though, if it’s going to reduce/eliminate sex drive, the lesions have to less-centralized, and Moriarty’s pointing that gun awfully near the midsagittal line. So take “abnormal” as you will, I guess. With the superior frontal cortex, lesions can lead to utilization behavior. Basically, if Sebastian put an empty mug in front of it, he would automatically pick it up and do a drinking action with it for no real reason. This is mostly for left side though.
In terms of speech, that is, again, mostly left side. Right side is more non-verbal, so it’s hard to say if anything would be messed up there, but it’s less likely. For motor skills, to me it looks like he hit the premotor cortex and supplementary motor cortex, so fine motor skills would be problematic. Just grasping would be problematic. Can’t even hold a pencil. Not without a good deal of physical therapy first.
Also, memory-wise, he’d be okay…sort of. Missed the hippocampus, missed the lateral inferoparietal cortex, missed the striatum, missed the diencephalon, did hit the neocortex. So his working memory would have some issues. So performing complex tasks would probably be hard, things like ordering coffee, making tea, engineering a rifle. The thing with memory is that it depends most on the size rather than the place of the lesion. So, if the shockwave wasn’t that big, he probably wouldn’t be too poorly off. If the shockwave was big, then he’d be bummin’. And I’m sure there’s some retrograde amnesia of the actual event of shooting himself. All around the neocortex and frontal lobes are emotional control, though. Right frontal lobe tends to be more “pseudopsychopathic” than previously. I feel bad for Moran now.
Pretty convenient how a lot of the disabilities are associated with left hemisphere issues, and JMo just HAPPENED to shoot himself just to the right enough that it didn’t graze the left hemisphere, but not too far that it didn’t hit any lateral parts and saved himself from those side effects too? Yes. So convenient.
For treatment, after surgery to get out shrapnel/skull fragments, he’d probably be put on anti-seizure meds. Diuretics too so the brain doesn’t swell too much, major side effect being increased piss-taking. And his metabolism would skyrocket. Another complication might be hypertonicity of his muscles, and interestingly enough botulinum toxin has been shown to help that out. Just.. fun fact. It’s had positive signs in studies. And then there’s the shitton of physical therapy.
Quick summary for the tldr; brain damaged JMo would probably have abnormal sexual behavior, pseudopsychopathic behavior (as if he wasn’t already), fine motor impairment, possible memory difficulties.
I’d like to think myself well-researched, though this is based on a lot of assumption on my part. If you have anything to add/would like to correct/would like my sources, feel free to ask.