I first read about this strange condition last night and became fascinated by it. I searched ATS and could only find one single post that mentioned
it.
The info may be out of date and there may be a medical name for it now.

Sitting outside her family's mud hut, near the small town of Lui, Susannah is gripped by a series of brain seizures which force her neck to arch
forwards, down, and then up again.
"We have no clue as what is causing this. It's like a detective novel and a murder mystery, because it's fatal," says Dr Mickey Richer, a tropical
disease specialist from Unicef.
So far, almost 300 children are known to have caught the disease - all in one small region of the country.
Bizarrely, the seizures normally occur when the sufferers start to eat, or when it is particularly cold.
When Dr Richer asks for a bowl of sorghum to be placed in front of Susannah, the "nodding" begins almost immediately, and stop when she has finished
eating.
Curiously, Susannah does not react if she eats unfamiliar food - a chocolate bar for instance.
BBC article and more information
This is extremely strange and interesting. The above mentioned article gives a few theories.
Related Articles:
CBS News
USA Today
Wikipedia
Several theories are given, everything from eating monkeys to biological and chemical weapons. An interesting theory links it to river blindness.
More info on river blindness can be found here:
Onchocerciasis
What I am most interested in is the cases that involve the different food substitutions.

Peter Spencer, an American neurotoxicologist who has investigated the condition for WHO, encountered another 13-year-old girl with a bizarre
variation of the illness.
"I was able to demonstrate with her that she was a regular nodder with local food and by contrast she did not nod when eating a variety of American
food — candy bars or whatever. It was absolutely staggering," he said.
Source: CBS News
That is truly strange.
One article mentions the nodding happens when eating sorghum but stops when eating an unfamiliar candy bar.
I wonder if this isn't caused by a mixture of multiple theories... contaminated river water on crops? ...
[edit on 10-5-2007 by Dulcimer]