The forthcoming issue of The New Yorker contains a fantastic article by surgeon and writer Atul Gawande about the neurobiology of itching.
The article begins with the extraordinary case of a patient known as M., whose itch, which occurred following an episode of shingles, became so unbearable that one morning she awoke to find that she had scratched through her skull and into her brain while she slept.
Gawande continues with a brief history of theories about itching - it was long considered to be a mild form of pain, but came to be recognized as a distinct sensation, following experimental work and neurologists' examinations of patients who get itchy despite being insensitive to pain.
He then discusses research which suggests that there are sensory neurons that are specialized for relaying itchy sensations to the brain, which appear to be distinct from the fibres involved in detecting hot and cold temperatures or mechanical pressure.
Finally, Gawande discusses 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.
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Reading that blog post made me feel really itchy...
Now I can't wait to get home and read my new New Yorker :D
How do you scratch through a bone that surgeons need a saw to get into?
Good question. I've been wondering that myself.
Where there's a will there's a way.. great article, it's what makes neurology so indispensable and fascinating.
She must have had extremely tough fingernails and/or thin, friable bone in her skull.
Well, there's a Science Magazine article about it, repeating the same story that she itched through her skull, though it doesn't explain how, other than to say she couldn't feel pain because of the effects of the shingles virus.
"'She gave herself frontal-lobe brain damage,' says Anne Louise Oaklander, a neuroscientist and neurologist at Harvard Medical School in Boston, who treated Nilsen and described her case at a recent meeting..."
Crazy.
Perhaps her skull had been softened by infection of the bone (osteomyelitis).
The Science Mag article doesn't say anything about suffering from osteomyelitis, or any other bone degenerative disease.