Psychosurgery is a term for surgeries of the brain involving procedures that modulate the performance of the brain, and thus effect changes in cognition, with the intent to treat or alleviate severe mental illness.

Currently, the accepted therapeutic approach to most psychiatric disease involves a combination of well-supervised psychotherapy, pharmacotherapy and, in some instances, electroconvulsive therapy. However, despite these modern treatment methods, many patients fail to respond adequately and remain severely disabled. In these patients, surgical intervention might be considered appropriate if the therapeutic result and overall level of functioning could be improved.

In modern neurosurgery  more minimally invasive techniques like gamma knife irradiation and foremost deep brain stimulation have arisen as novel tools for psychosurgery.

Only patients with severe, chronic, disabling and treatment refractory psychiatric illness should be considered for surgical intervention. Chronicity in this context refers to the enduring nature of the illness without extended periods of symptomatic relief

The major psychiatric diagnostic groups as defined by the DSM-III-R that might benefit from surgical intervention include

1.) obsessive compulsive disorder and 2.) major affective disorder (ie. major depression or bipolar disorder).

While many methods have been utilized in the neurosurgical treatment of psychiatric disease, four procedures have evolved as the safest and most effective. These are all performed bilaterally and under stereotactic conditions to allow for precise lesioning of target structures. They include:

1.) Anterior cingulotomy. 2.) Subcaudate tractotomy. 3.) Limbic leucotomy. 4.) Anterior capsulotomy.

Each procedure has different indications, techniques, results and complications which will be discussed in the following sections.

Subcaudate tractotomy

Subcaudate tractotomy was introduced to interrupt white matter tracts between orbital cortex and subcortical structures by placing a lesion in the region of the substantia innominata just below the head of the caudate nucleus. Surgical indications included major depressive illness, obsessive compulsive disorder and anxiety states as well as a variety of other psychiatric diagnoses.

Anterior Cingulotomy

Anterior cingulum is an appropriate target for psychosurgical intervention. These days stereotactic cingulotomy is advocated for intractable pain and in patients with concurrent anxiety-depressive states.  Currently, the surgical indications are treatment refractory major affective disorder, chronic anxiety states, OCD or severe chronic pain.

Limbic leucotomy

Limbic leucotomy combines subcaudate tractotomy with anterior cingulotomy. This procedure was designed to disconnect orbital-frontal-thalamic pathways with the former lesion and interrupt an important portion of Papez's circuit with the latter. Indications for surgical intervention included obsessional neurosis, anxiety states, depression and a variety of other psychiatric diagnoses. This procedure is carried out stereotactically.

Anterior capsulotomy

This  procedure was  aimed  was to interrupt presumed fronto-thalamic connections in the anterior limb of the internal capsule where they pass between the head of the caudate nucleus and the putamen. Clinical indications for capsulotomy initially included schizophrenia, depression, chronic anxiety states and obsessional neurosis.