Sunday, December 09, 2007

Is the Brain Really Necessary?

This was the question asked by British neurologist John Lorber when he addressed a conference of pædiatricians in 1980. Such a frivolous sounding question was sparked by case studies Lorber had been involved in since the mid-60s. The case studies involve victims of an ailment known as hydrocephalus, more commonly known as water on the brain. The condition results from an abnormal build up of cerebrospinal fluid and can cause severe retardation and death if not treated.

Two young children with hydrocephalus referred to Lorber presented with normal mental development for their age. In both children, there was no evidence of a cerebral cortex. One of the children died at age 3 months, the second at 12 months. He was still following a normal development profile with the exception of the apparent lack of cerebral tissue shown by repeated medical testing. An account of the children was published in Developmental Medicine and Child Neurology.

Later, a colleague at Sheffield University became aware of a young man with a larger than normal head. He was referred to Lorber even though it had not caused him any difficulty. Although the boy had an IQ of 126 and had a first class honours degree in mathematics, he had "virtually no brain". A noninvasive measurement of radio density known as CAT scan showed the boy's skull was lined with a thin layer of brain cells to a millimeter in thickness. The rest of his skull was filled with cerebrospinal fluid. The young man continues a normal life with the exception of his knowledge that he has no brain.

Although anecdotal accounts may be found in medical literature, Lorber is the first to provide a systematic study of such cases. He has documented over 600 scans of people with hydrocephalus and has broken them into four groups:
  • those with nearly normal brains
  • those with 50-70% of the cranium filled with cerebrospinal fluid
  • those with 70-90% of the cranium filled with cerebrospinal fluid
  • and the most severe group with 95% of the cranial cavity filled with cerebrospinal fluid.