Thank you. That's fascinating, I'd never heard of that.
It's not clear from what I can find just how little brain the person had, though. Most descriptions of the case I can find describe the patient as having little to no "cerebral cortex"--I can't tell how much of the rest of his brain the person had.
Also, what there was of the cerebral cortex was a thin layer pressed against the inside of the skull. According to one source, that means the outer layer of the brain, which is most associated with consciousness, may have actually been bigger than in a normal brain.
Anyway, I certainly wouldn't conclude from these cases that the brain is unrelated to consciousness, or that it's been demonstrated that consciousness is not in some way a property of the brain.
This is what John Lorber, the British neurologist that conducted the studies and examinations written about by Lewin, said about this specific case:
"I can't say whether the mathematics student has a brain weighing 50 grams or 150 grams, but it is clear that it is nowhere near the normal 1.5 kilograms."