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.

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:
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.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.
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.
16 comments:
Thank you for this excellent post - clearing out such things is really necessary (and very helpful in internet discussions:).
You might be interested that Chase Britton's actual mother commented on Steven Novella's post you mentioned - I believe they are now in contact, so I hope we will see some more details on this very interesting case.
There is one example of previous case of person without cerebellum. http://www.ncbi.nlm.nih.gov/pubmed/19843649 It is definitely not something never seen before.
I pretty much had the exact same thought process as you. I thought, "what the hell kind of neurologist would call someone without a cerebellum a 'vegetable'?!?!" Then read the bit about the pons, and thought, "huh, that's odd". And so forth.
Presumably he has no pons in the sense that, lacking cerebellar projections, his pons is no longer the sticky out bit at the top of the brainstem. Since he apparently has cranial nerve function and connections with his spinal cord he must have something where the pons usually is.
pj: Right. Though it's hard to tell without seeing the scans so it's hard to tell. There are a few brief glimpses of some in the video but not much.
The case is remarkable, as a human story, and the video is moving. I'm just concerned that they felt the need to try and make it into a medical mystery as well.
Doctors (medical) are usually wrong. I bet you Chase will eventually see, walk etc. so this is a medical miracle. Just because there's a name for the condition with possible explanations like neuroplasticity doesn't make it any less extraordinary or less than a mystery. What is misleading are selective facts. But you can't expect much from mainstream journalism. Priority is to sell a story, generate hits, controversy, express a discrete political agenda, swerve the masses to who knows.
"Imagine if you had no mouse and had to move the cursor with a pair of big rusty iron levers"
On my computer, the cursor can be moved by the cursor keys. I have had to do this when a mouse failed and it is indeed awkward.
My impression of the cerebellum is that it is a sequencer, like a music sequencer but for muscle contractions rather than notes of music. A movement such as taking a step is like a theme that you can call up ready-made, instead of having to compose it from scratch every time.
I seem to recall an article in Science back in the mid-70s about a student at either Oxford or Cambridge who was found to have very little in the way of a cortex. Basically, he was in an experiment for some completely different reason where the did a scan of his brain and found that he was all ventricles with a thin layer of cortex around the outside, yet he was a mid-level performing student. I think the article was called something like: Is your brain really necessary?
Should have just bothered to look it up, I got the particulars wrong, but the overall description was correct. Here is the URL:
http://www.sciencemag.org/content/210/4475/1232.full.pdf
So controlling a body without a cerebellum is a bit like controlling a cursor with a big pair of rusty iron levers: i.e you could eventually learn to compensate
and you would be able to compensate by making continuous minor adjustments to your movements using your...... cerebellum.
is this analogy a tad circular perhaps?
that's a very circular analogy you use for the function of a cerebellum.
Anonymous: OK, fair point. Without a cerebellum I think you have to learn to control your movements "manually", as it were, i.e. with your cortex, which is not designed to do that.
The cortex is designed to learn lots of things, but movement learning is normally "outsourced" to the cerebellum. And possibly other aspects of learning that we're still discovering.
If you have to do it "in house", it's much harder.
"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."
I experience this whenever I try to play first person shooters on consoles.
likewise when i'm drunk. i swear i can do anything. then you wake up next to a baboon with something smeared across your face oh blimey.
Your interpretations might quite be true yet it is definitely perplexing that such sever hypoplasia can be present.
I'm sure you'd have read the studies by Andre Goffinet's lab about the mouse lacking any connections between the cortex and thalamus and yet being able to perform all motor activities.
Similarly, an experiment in the late 70s showed that a monkey with a lesion in the spinal cord could still climb cages and hold things etc (things presumed it couldn't do).
So there's something really mind-boggling about this. Sure we can all say its plasticity at play...but the magnitude of plasticity required for this far exceeds those achieved in any experiment.
The only way you can be skeptic is if you ask to read the scientific report instead of a journo's article.
The functions of the cerebellum have been overstated by neuroscientists, largely because the cortex is difficult to study and mice have approximately the same cerebellum as we have. Whenever you see an overlap between us and the rodents studied in the lab, you will see all sorts of advanced, human-like functions attributed to the rodent/human common structure. The cerebellum does not mediate emotion. The cerebellum only mediates motor procedure memories to the point of smoothing the motions. The major motor patterns are stored and mediated by the cortex. The apraxias represent defects of the cortical systems. At least 50% of the frontal lobes are devoted to the mediation of motor patterns. Fortunately, numerous cases of agenesis of the cerebellum suggest that the cortex and the basal ganglia can compensate for the lack of a cerebellum. I wonder how many people are now walking around without a cerebellum and don't even know what they are missing. I think the medical staff were all misquoted so that the journalist could emphasize the "amazing wonder" of the story and get attention. I notice that many of the comments in the blog are reactions to the news reports rather than scientific papers. I wonder how much of our scientific knowledge is just bits and pieces of what journalists report.
Hi, I have no experience with missing cerebellum - just wanted to tell you that I was thinking about you. Seems like its one thing after another - things really will calm down eventually.
Post a Comment