Wednesday, June 25, 2008
The neuroscience of itching

I know I do it. I itch my scalp without even thinking about it. Then I'll realize I'm doing it and be irritated with myself.

Atul Gawande says there are sensory neurons that are specialized for relaying itchy sensations to the brain, which appear to be distinct from the fibers involved in detecting hot and cold temperatures or mechanical pressure.

He explains how research into itching and phantom limb syndrome have led to a new theory of perception, according to which, the brain generates a "best guess" about the world around us and about the sensory information impinging upon us.

So what does this mean? Why do we itch? What could the cause be? Clearly we can't all just have bad and/or dry skin, right?

Other causes of the itchiness can be hyperthyroidism, iron deficiency, liver disease, and cancers like Hodgkin's lymphoma. Sometimes the syndrome is very specific. Persistent outer-arm itching that worsens in sunlight is known as brachioradial pruritus, and it's caused by a crimped nerve in the neck.

Though scratching can provide momentary relief, it often makes the itching worse. Dermatologists call this the itch-scratch cycle. Ah yes, the scratch cycle, I know about this.

How do you explain the "phantom itch" that amputees feel even though they know the limb is no longer there? Doctors will tell you there is nothing wrong. Some people are told they are OCD. Let me tell you right now, leave those idiots, they are throwing excuses out at you to get you to be quiet. They don't know what is wrong and "educated guessing" will not find the root of the problem, you will still be itchy.

I don't have the answers and as I have said before, I'm not a doctor. I do believe the mind is a powerful tool and manipulator. You can make yourself feel bad, you can make yourself feel itchy, this doesn't mean you're crazy. This means you need to find new ways to cope with these sensory feelings.

But how? This I don't know.

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7:56 AM
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