ZHENG Song (not his real name), a university student from Southwest China's Sichuan Province, disturbed by his obssessive thoughts about slaughtering his classmates, underwent neurosurgery last Thursday in the Shanghai Ruijin Hospital.

He returned to his hometown two days after the operation. A good recovery is foreseen if no sign of relapse occurs in the next month.

Doctors from the Shanghai Ruijin Hospital introduced lesions in the neural circuits which controlled his moods. This operation is called MRI-guided capsulotomy for refractory obsessive-compulsive disorder (OCD).

His head was penetrated from above by an electric drill, which cut two small holes - each the size of a nail - in his cerebral hemispheres. A needle was then inserted to make the lesions.

The operation lasted for two hours, with the same period spent on the pre-op evaluation.

The operation attracted considerable attention, with over 20 newspapers and TV stations witnessing the surgery on the spot. It was also broadcast live around the country by CCTV.

Media compared Zheng to Ma Jiajue, a student who murdered four of his room mates in one night of notorious slaughter earlier this year. Zheng himself also made this comparison with Ma, because he could not rid himself of the thought of killing his classmates or making plans for mass murder.

He was diagnosed as suffering from intractable OCD and little improvement in his condition was evident after a year of behavioural therapy and other psychological counselling.

After spending the total savings of his family on an attempted cure, he was asked by the Shanghai Ruijin Hospital to undergo the neurotherapy.

The relevant regions of his brain, lying on the internal capsulum, were identified by high-resolution MRI and lesions were then made by a radiofrequency tool at 80 degrees centigrade for 60 seconds.

Zheng was asked to take certain actions during the operation and he appeared to be very co-operative.

Only a very slight pain was felt in his ears when a monitoring device was inserted. He could talk to the nurse and reporters around him.

A long sleep followed the operation, after which Zheng appeared very talkative.

"No side-effects have been found as of now, such as memory problems, lower IQ performance or emotional shallowness," said Professor Sun Bomin, director of the Centre for Stereotatic and Functional Neurosurgery at the Shanghai Ruijin Hospital.

A long-term follow-up will be undertaken to see whether there are any side-effects from the operation, such as personality alteration or loss of initiative.

"The rate of the success for this operation can reach 80 per cent. It is effective and efficient. But the adverse consequences of capsulotomy must be given careful attention," said Sun.

"The operation is suitable for patients with OCD who are intractable to the mediations, psychotherapy or behahvioural therapy provided by experienced psychiatrists," said Sun.