Wednesday, February 16, 2011

Boy Without A Cerebellum...Has No Cerebellum

A reader pointed me to this piece:
Boy Without a Cerebellum Baffles Doctors
Argh. This is going to be a bit awkward. So I'll just say at the outset that I have nothing against kids struggling with serious illnesses and I wish them all the best.


The article's about Chase Britton, a boy who apparantly lacks two important parts of the brain: the cerebellum and the pons. Despite this, the article says, Chase is a lovely kid and is determined to be as active as possible.

As I said, I am all in favor of this. However the article runs into trouble is where it starts to argue that "doctors are baffled" by this:

When he was 1 year old, doctors did an MRI, expecting to find he had a mild case of cerebral palsy. Instead, they discovered he was completely missing his cerebellum -- the part of the brain that controls motor skills, balance and emotions.

"That's when the doctor called and didn't know what to say to us," Britton said in a telephone interview. "No one had ever seen it before. And then we'd go to the neurologists and they'd say, 'That's impossible.' 'He has the MRI of a vegetable,' one of the doctors said to us."

Chase is not a vegetable, leaving doctors bewildered and experts rethinking what they thought they knew about the human brain.

They don't say which doctor made the "vegetable" comment but whoever it was deserves to be hit over the head with a large marrow because it's just not true. The cerebellum is more or less a kind of sidekick for the rest of the brain. Although it actually contains more brain cells than the rest of the brain put together (they're really small ones), it's not required for any of our basic functions such as sensation or movement.

Without it, you can still move, because movement commands are initiated in the motor cortex. Such movement is clumsy and awkward (ataxia), because the cerebellum helps to coordinate things like posture and gait, getting the timing exactly right to allow you to move smoothly. Like how your mouse makes it easy and intuitive to move the cursor around the screen.

Imagine if you had no mouse and had to move the cursor with a pair of big rusty iron levers to go left and right, up and down. It would be annoying, but eventually, maybe, you could learn to compensate.

From the footage of Chase alongside the article it's clear that he has problems with coordination, albeit he's gradually learning to be able to move despite them.

Lacking a pons is another kettle of fish however. The pons is part of your brainstem and it controls, amongst other things, breathing. In fact you (or rather your body) can survive perfectly well if the whole of your brain above the pons is removed; only the brainstem is required for vital functions.

So it seems very unlikely that Chase actually lacks a pons. The article claims that scans show that "There is only fluid where the cerebellum and pons should be" but as Steven Novella points out in his post on the case, the pons might be so shrunken that it's not easily visible - at least not in the place it normally is - yet functional remnants could remain.

As for the idea that the case is bafflingly unique, it's not really. There are no less than 6 known types of pontocerebellar hypoplasia caused by different genes; Novella points to a case series of children whose cerebellums seemed to develop normally in the womb, but then degenerated when they were born prematurely, which Chase was.

The article has had well over a thousand comments and has attracted lots of links from religious websites amongst others. The case seems, if you believe the article, to mean that the brain isn't all that important, almost as if there was some kind of immaterial soul at work instead... or at the very least suggesting that the brain is much more "plastic" and changeable than neuroscientists suppose.

Unfortunately, the heroic efforts that Chase has been required to make to cope with his disability suggest otherwise and as I've written before, while neuroplasticity is certainly real it has its limits.

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