Friday, March 17, 2006

Rationale for leucotomy

I heard some naïve statements on how Egas Moniz conceptualized leucotomy. One story goes that he entered a room where there was a skull on a table; he pointed to one side of the skull and said: here is where we have to pierce.

The idea of treating obsessive psychoses with surgery did not occur suddenly, it was rather the product of long thoughts and search in the literature that started in 1933 and went on during the following two years. Reading about the changes in personality resulting from accidental lesions to the frontal lobes, he concluded that this region was the center of emotions, that it should control the majority of the stimulations originated externally and internally. The data suggested that the frontal lobes are a kind of central hub reached directly or indirectly by most fiber connections. Moreover, because of its larger volume there was a tendency at the time to attribute to the left frontal lobe a particular role in psychic activity.

Based on the histological structure described by Cajal and on the experiments of Pavlov, he thought that obsessive psychoses would dominate all the other psychic activities through reiterated influxes using the same connections. Pavlov obtained in the dog a new pathway resulting from an induced repeated stimulus. Moniz thought that established new circuits could be abolished if the connections to other regions would be severed. He discussed his thoughts with many colleagues and looked for advice whether he should go ahead.

John Fulton several years after the first leucotomies also suggested that “interrupting the vicious circles which form the basis of abnormal states” could successfully treat psychiatric disorders (Jack el-Hai in “The Lobotomist”, John Wiley & Sons, Inc.)

Studies of the brains of patients with schizophrenia indeed suggest altered function in the prefrontal cortex, the brain's organizational center for cognitive function, personality expression, and behavioral control. It is interesting that Torrey’s Washington team found that schizophrenics failed to activate a region within the frontal lobe, technically known as the dorsolateral prefrontal cortex. Torrey said that this seems to imply that schizophrenia is a breakdown of particular areas in the brain in the connections between them, most likely on the brain’s left side. (Tony Dajer in “Divided Selves”, Discover 13(9):38-44; 69, Sep 92)

Brian Kirkpatrick from the University of Maryland School of Medicine in Baltimore has argued that in schizophrenia a flawed brain circuit has possibly been identified, based in part on evidence of impaired frontal and parietal function revealed by PET scans of the thalamic, frontal and parietal areas. (T.M. Powledge in Academy Update, NY Academy of Sciences, June/July 1996)

Moreover, a team from the Albert Einstein College of Medicine in New York found brain abnormalities in schizophrenic children suggesting changes that disrupt the transmission of signals that regulate behavior. The researchers used a sophisticated scanning technique called diffusion tensor imaging. They found abnormalities in white matter of the frontal lobe, which controls emotions and many thinking processes.

A spanish group from the Centros de Investigación Biomédica en Salud Mental headed by Edith Pomarol-Clotet identified structural and functional alterations in the frontal cortex of 32 schizophrenic patients. The work was published in 2010 in the Journal Molecular Psychiatry.

The prefrontal cortex is now considered to be the seat of the most complex and uniquely human activities (G. Miller, Science vol 311, 2006, p. 1851).