Ablative brain surgery

See also: Psychosurgery

Ablative brain surgery (also known as brain lesioning) is the surgical ablation by various methods of brain tissue to treat neurological or psychological disorders. The lesions it causes are irreversible. Ablative brain surgery was first introduced by Pierre Flourens (1774-1867), a French physiologist. He removed different parts of the nervous system on animals and observed what effects were caused by the removal of certain parts. For example, if an animal could not move its arm after a certain part was removed, it was assumed that the region would control arm movements. The method of removal of part of the brain was termed "experimental ablation". With the use of experimental ablation, Flourens claimed to find the area of the brain that controlled heart rate and breathing. [1] 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. Experimental ablation is used in research on animals. Such research is considered unethical on humans, but the effects of brain lesions (caused by accidents or diseases) on behavior can be observed to draw conclusions on the functions of different parts of the brain.[2]

Contents

Uses

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.[3] However, for patients for whom DBS is not feasible, ablation of the subthalamic nucleus has been shown to be safe and effective.[4] DBS is not suitable for certain patients. Patients who suffer from immunodeficiencies is an example of a situation in which DBS is not a suitable procedure. However, a major reason as to why DBS is not often performed is the cost. Because of its high cost, DBS cannot be performed in regions of the world that are not wealthy. In the case of such circumstances, a permanent lesion in the subthalamic nucleus (STN) is created as it is a more favourable surgical procedure.[5]. The surgical procedure is going to be done on the non-dominant side of the brain, a lesion might be favored to evade numerous pacemaker replacements. More so, patients who gain relief from stimulation devoid of any side effects and need a pacemaker change may have a lesion performed on them in the same position. The stimulation parameters act as a guide for the preferred size of the lesion. [6] In order to identify the part of the brain that is to be destroyed, new techniques such as micro electrode mapping have been developed [7].

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.[8]

Psychiatric disorders

Ablative psychosurgery continues to be used in a few centres in various countries.[9] In the US there are a few centres including Massachusetts General Hospital that carry out ablative psychosurgical procedures.[10] Belgium,[9] the United Kingdom,[11] and Venezuela[12] are other examples of countries where the technique is still used. 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.[13] 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.[14]

Methods

Experimental ablation involves the drilling of holes in the skull of an animal and inserting an electrode or a small tube called a cannula into the brain using a stereotaxic apparatus. A brain lesion can be created by conducting electricity through the electrode which damages the targeted area of the brain. likewise, chemicals can be inserted in the cannula which also damages the area of interest. By comparing the prior behavior of the animal to after the lesion, the researcher can predict the function of damaged brain segment.[15] Recently, 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.[16]

References

  1. ^ Carlson, Neil R. (2010). Psychology: The Science of Behaviour. New Jersey, United States: Pearson Education Inc.. pp. 13. ISBN 978-0-205-64524-4. 
  2. ^ Carlson, N.R. (1999). Foundations of physiological psychology (4th ed.). Boston: Allyn and Bacon.
  3. ^ Samii, Ali (2002). "Stereotactic Surgery". American Parkinson Disease Association. http://www.waparkinsons.org/edu_research/articles/Stereotactic_Surgery.html. Retrieved 2008-05-01. 
  4. ^ O. Barlas; H. Hanagasi; M. Emre. "Unilateral Ablative Lesions of the Subthalamic Nucleus in Advanced Parkinson Disease: Long-term Follow-up" (PDF). American Society for Stereotactic and Functional Neurosurgery. http://www.assfn.org/meetings/neuro.pdf. Retrieved 2008-05-01. 
  5. ^ D. Yates. Ablative surgery for Parkinson disease. Nature Reviews Clinical Neurology. 
  6. ^ Siegfried, Jean (November 1998). "Ablative Surgery and Deep Brain Stimulation for Parkinson's Disease.[Review]". Neurosurgery 43 (5): 1014-1015. 
  7. ^ Okun, M. S., & Vitek, J. L. (2004). Lesion therapy for parkinsonʼs disease and other movement disorders. Movement Disorders 19(4), 375-389.
  8. ^ "Stereotactic and Functional Neurosurgery News" (PDF). American Association of Neurological Surgeons. Fall 2007. http://www.assfn.org/society/Fall07newsletter.pdf. Retrieved 2008-05-01. 
  9. ^ a b P.S. Sachdev and X. Chen 2009 Neurosurgical treatment of mood disorders: traditional psychosurgery and the advent of deep brain stimulation Current Opinion in Psychiatry 22(1): 25-31.
  10. ^ Massachusetts General Hospital Functional and Stereotactic Neurosurgery Center.
  11. ^ K. Matthews and M.S. Eljamel 2003 Status of neurosurgery for mental disorder in Scotland British Journal of Psychiatry 182: 404-11.
  12. ^ G. Chiappe 2010 Las Obsesiones se peuden operar. El Universal, 30 March 2010.
  13. ^ Zamiska, Nicholas (November 2, 2007). "In China, Brain Surgery Is Pushed on the Mentally Ill". The Wall Street Journal. 
  14. ^ Zamiska, Nicholas (April 28, 2008). "China Bans Irreversible Brain Procedure". The Wall Street Journal. 
  15. ^ Carlson, Neil R. (2010). Psychology: The Science of Behaviour. New Jersey, United States: Pearson Education Inc.. pp. 105. ISBN 978-0-205-64524-4. 
  16. ^ Gülsoy, M.; et al. (2001). "Er:YAG Laser Ablation of Cerebellar and Cerebral Tissue". Lasers in Medical Science 16 (1). http://www.springerlink.com/content/61pnkwcdr0vwwfdb/. Retrieved 2008-05-01.