Half Empty Skull

Hey, you have no brain!

You would probably be angry at these starting words of mine if we were face to face, but now you are waiting to see the whole drama. And that's the power of writing than talking.

Jokes apart. Don’t take the starting line seriously. We usually use this "No Brain" to mean fool, having less intelligence, etc. Literally all we know it’s not possible to have a full empty skull. But what about a half-empty skull? Though surprising to hear, few dozens of people are alive without a large part of their brain, half or even less.

Sometimes the half is better than the whole for those who born with malformed brain tissues in one hemisphere. If not treated the rest healthy one may also get damaged by seizure. So to control epilepsy or seizure syndromes a cerebral hemisphere or a portion of it is removed, disconnected, or disabled. It's a rare neurosurgical procedure called Hemispherectomy and done only when all the medications fail, typically in children and occasionally in adults.

MRI of Patients with Hemispherectomy
Source: The Lancet  

The mysterious organ of 1.5kg that we carry doesn’t have lizard DNA(a genetic recipe) or Hydra's interstitial cells for regeneration! It can't regenerate the missing half. Then what do you think? What fills the space? ping pong balls? Doctors experimented with different fillers including ping pong balls before discovering that the area actually fills with the brain's own cerebrospinal fluid.

Now the most important question comes. How can a person live with a half-brain? In fact, having just normal memories and personalities? Indeed our brain has a magical capability to change and adapt. This ability of the brain is called Neuroplasticity, by which we learn new things. The function is powerful enough and fully different from other anatomical systems. Ralph Adolphs, a cognitive neuroscientist at the California Institute of Technology said “If you take any other system that has a number of parts whose functions all depend on one another, like the heart, and you divide it in half, it’s not going to work. You take my laptop and cut it in half, it’s not going to work.” But in the case of the brain, hemispherectomy gives it the opportunity to reorganize and developing itself without ongoing disruption. After taking out the malformed tissues, the other healthy side of the brain takes over some of the functions and responsibilities of the missing half by neuroplasticity.

But there may be some limitations."You can walk, run—some dance or skip—but you lose the use of the hand opposite of the hemisphere that was removed. You have little function in that arm and vision on that side is lost," Johns Hopkins neurologist, John Mark Freeman said. Language, reading, and writing ability are more likely to fully return where visual fields, motor functions are less likely. Notably, the sooner this is done the better the long-term outcomes for children. For instance, typically the left hemisphere develops the language function. If this one is missing or disconnected, the right side can take the responsibility of language function but that’s not possible for the older patients, he/she won't be able to speak as the functions have already been laid down to the left side.

Types of Hemispherectomy 
Source: Sychar

Let's talk about some case studies. In one study Freeman found that children with hemispherectomy can do outstanding results on the academic side once their seizures stopped, "One was champion bowler of her class, one was chess champion of his state, and others are in college doing nicely."

A group of researchers at the California Institute of Technology analyzed the brains of six adults who had undergone hemispherectomy in early childhood to treat epileptic seizures and another six who have both of their hemispheres intact. Everyone's brain activity is measured by the functional  MRI( fMRI). And the comparative result astonished the team. They found that both had a similar connection within the brain network and what is more, high brain connectivity was discovered in the brain of one hemisphere.
Dorit Klienmann, first author of this study said, " When I sit in front of the computer and see these MRI images showing only half a brain, I still marvel that the images are coming from the same human being who I just saw talking and walking and who has chosen to his or her time to research.....You can almost forget their condition when you meet them for the first time." 

Another case study proved that some women were able to smell even though they did not have olfactory bulbs, the lobe of the brain which is concerned with the sense of odor. Scientists thank the extreme plasticity of the developing brain which developed an alternative glomeruli map somewhere else in the brain and but is still undiscovered.

Want to finish with the Romans words, "Rara sunt cara", meaning, Rare is Valuable. Patients with hemispherectomy are rare but their brain capabilities helping us to know more and more about neuroplasticity and opened a widespread platform of research on this topic. So it’s possible you get to know a normal person but find out a half-brain later. Then say to him/her- "Your Brain is Smarter than Ours."

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