Psychosurgery

Over time, psychosurgical procedures have been created that are more precise and restricted in terms of the amount of brain tissue affected. During the 1950s, a stereotaxic instrument was developed that held the patient's head in a stable position and allowed the more precise manipulation of brain tissue by providing a set of three-dimensional coordinates. Stereotaxic instruments generally consist of a rigid frame with an adjustable probe holder. The instrument is secured on the patient's skull, and in modern psychosurgery is used in conjunction with images of the patient's brain created with brain-imaging techniques. Brain-imaging techniques such as computed tomography and magnetic resonance imaging allow accurate visualization of the brain and precise location of a targeted brain area or lesion. Coordinates of the targeted visual area are then matched with points on the stereotaxic instrument's frame, which has been included in the image. Using these measurements, the attached probe holder's position is adjusted so that the probe will reach the intended area in the brain. Because of individual anatomical differences, surgeons will often electrically stimulate the targeted area observing the effect on a conscious patient in order to verify accurate placement of the probe.

Over the years, neurosurgeons have begun to use electrodes to deliver electric currents and radio frequency waves to specific sites in the brain rather than using various sharp instruments. Compared with the earlier lobotomies, relatively small areas of brain tissue are destroyed with these techniques. Other methods of affecting brain tissue include using cryoprobes that freeze tissue at sites surrounding the probe, radioactive elements, and ultrasonic beams. The most commonly used method today is radio frequency waves.

The more modern restricted psychosurgical procedures usually target various parts of the brain's limbic system. The limbic system is made up of a number of different brain structures that form an arc located in the forebrain. The limbic system seems highly involved in emotional and motivational behaviors. These techniques include destruction of small areas of the frontothalamus, orbital undercutting, cingulectomy, subcaudate tractotomy, limbic leucotomy, anterior capsulotomy, and amygdalotomy. Cingulectomy involves severing fibers in the cingulum, a prominent brain structure that is part of the limbic system. Subcaudate tractotomy was developed in 1964 in Great Britain and uses radioactive yttrium-90 implants to interrupt the signals transmitted in the white matter of the brain. This type of psychosurgery involves a smaller lesion and decreased side effects. The limbic leucotomy was developed in 1973 and combines the subcaudate tractotomy and the cingulectomy. In this surgery, two lesions are created and brain material is destroyed using a cryoprobe or electrode. An anterior capsulotomy interrupts connections in the frontothalamus with electrodes. There seems to be marked side effects associated with this procedure. Amygdalotomy is a type of psychosurgery in which fibers of the amygdala are severed. The amygdala is a small brain structure that is part of the temporal lobe and is classified as being a part of the limbic system. Cingulectomies are now the most common type of psychosurgery procedure used.

Psychosurgery was initially widely accepted without much evidence as to its efficacy and side effects and it has generated a great deal of controversy for many reasons. These include the fact that it involves the destruction of seemingly healthy brain tissue, it is irreversible, and, at least in its earliest procedures, frequently seemed to cause some very harmful side effects. The National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research was created in the mid-1970s to examine research procedures that appeared questionable in the United States. The commission sponsored a number of studies looking at the risks and benefits of psychosurgery. Basically, the Commission concluded that psychosurgery can be highly beneficial for certain types of disorders, but that every procedure should be screened by an institutional review board before it is allowed.

In a review of psychosurgery procedures performed between 1976 and 1977, Elliot Valenstein, in a report for the Commission, concluded that approximately 60-90% of the patients showed a marked reduction in their more severe symptoms, and a very low risk of some of the permanent negative side effects seen in earlier lobotomy procedures. Valenstein primarily looked at more restricted frontal lobe operations and cingulectomy.

Currently, psychosurgery is only performed as a last resort. Most of the psychiatric disorders that were originally treated with psychosurgery, such as schizophrenia and severe depression with psychotic symptoms, are now treated in a more satisfactory manner by drugs. Even current psychosurgical procedures appear beneficial for only a very limited number of patients. It seems that patients suffering severe major depression with physiological symptoms and obsessive tendencies along with agitation and marked tension are most likely to benefit, providing there has been a reasonably stable personality before the onset of symptoms. In rare cases, psychosurgery is performed in patients that show severe violent outbursts and who may cause harm to themselves or others. Used cautiously, these procedures can reduce some of a patient's more disturbing symptoms without producing irreversible negative effects on personality and intellectual functioning.