The book opens with a young girl dying from what is presumably some kind of bioweapon-esque disease. Her crash is described in vivid living color but one phrase in particular caught me eye: basal writhing. Apparently a very real phenomenon.
From the book, including the fantastically gross part that precedes it:
Then her teeth sank into her lower lip, cutting through the lip, and a run of blood went down her chin and neck. She bit her lip again, hard, with ferocity, and she made a groaning animal sound. This time, the lip detached and hung down. She pulled her lip in, sucked it into her mouth, and swallowed. Now she was chewing again. Eating the inside of her mouth, chewing her lips, the insides of her cheeks. The movement of her teeth was insectile, like the feeding movementsof an insect larva chewing on its food: intense, greedy, automatic -- a kind of repetitive yanking at the tissues of her mouth. Her tongue suddenly protruded. It was coated with blood and bits of bloody skin. She was eating her mouth from the inside.
"She's biting herself!" he yelled. "Help!"
He got his hands around her head and tried to hold her chin steady, but he couldn't stop her teeth from gnawing. He could see her tongue curling and moving behind her teeth. He was begging for help at the top of his lungs. Jennifer was next to him, weeping, crying for help, too. The bathroom door was open, and students were standing in the hallway, looking in, stunned with fright. Most were crying. Several of them had run to call 911.
The girl's body went into a back-and-forth thrashing movement. Then she began to writhe. It was a type of writhing associated with damage to the base of the brain, the midbrain, a knot of structures at the top of the spinal cord. The movements were what is known as basal writhing.
From Merck: Chorea, Athetosis and Hemiballismus
"Chorea is repetitive, brief, jerky, rapid involuntary movements that start in one part of the body and move abruptly, unpredictably, and often continuously to another part. Athetosis is a continuous stream of slow, flowing, writhing involuntary movements. Hemiballismus is a type of chorea, usually involving violent, flinging involuntary movements of one arm."
From Neuroscience Notes: Basal Ganglia, Dr. Stephen Gislason
"There abundant examples of movement disorders that emerge when components of the basal ganglia are damaged. Involuntary movements include tremors (rhythmic, oscillatory movements), athetosis (slow, writhing movements), chorea (abrupt movements of the limbs and facial muscles), ballism (violent movements), and dystonia (persistent postures, grotesque movements and postures)."