Who is Bhagawhandi from The Man Who Mistook His Wife for a Hat and Other Clinical Tales and what is their importance?

Bhagawhandi's story is one of the most heartbreaking and beautiful of the book. Bhagawhandi is a young Indian girl dying of a brain tumor. The tumor was removed during her early childhood but has returned in her late teens and now the prognosis is not good. Bhagawhandi accepts her fate and seems almost at peace with it as she "suffers" from visions of her beloved India.