Ablative brain surgery

Ablative brain surgery is the surgical ablation by burning or freezing of brain tissue to treat neurological or psychological disorders. The lesions it causes are irreversible.

Ablative brain surgery is also often used as an research tool in neurobiology. For example, by ablating specific brain regions and observing differences in animals subjected to behavioral tests, the functions of the removed areas may be inferred.

Parkinson's disease
Surgical ablation has been used to treat Parkinson's disease. In the 1990s, the pallidum was a common surgical target. Unilateral pallidotomy improves tremor and dyskinesia on one side of the body (opposite the side of the brain surgery), but bilateral pallidotomy was found to cause irreversible deterioration in speech and cognition. The thalamus is another potential target for treating tremor; in some countries, so is the subthalamic nucleus, although not in the United States due to its severe side effects. Generally, deep brain stimulation surgery (DBS) is considered preferable to ablation because it has the same effect and is adjustable and reversible. However, for patients for whom DBS is not feasible, ablation of the subthalamic nucleus has been shown to be safe and effective.

Cluster headaches
Cluster headaches have been treated by ablation of the trigeminal nerve, but have not been very effective. Other surgical treatments for cluster headaches are under investigation.

Psychiatric disorders
In the People's Republic of China, surgical ablation was used to treat psychological and neurological disorders, particularly schizophrenia, but also including clinical depression, obsessive-compulsive disorder, and epilepsy. The official Xinhua News Agency has since reported that China's Ministry of Health has banned the procedure for schizophrenia and severely restricted the practice for other conditions.

Methods
Lasers have been shown to be effective in ablation of both cerebral and cerebellar tissue. A laser called Er:YAG, for example, allows great precision in location and size of the lesion and causes little to no thermal damage to adjacent tissue.