|Fig. 1: NRC graphic of the Leksell Gamma Knife. (Source: Wikimedia Commons)|
A treatment meant exclusively to address brain disorders, gamma knife surgery is a non-invasive radiosurgery that produces results very similar to that of an actual surgical procedure.  About 200 small beams of radiation are focused on each tumor, lesion, or any other ailment with the goal of mitigating the harmful factors that brought the patient in. This radiation kills cancer cells and shrinks tumors, though each beam is of low intensity so the intervening tissue is left relatively unharmed. The process has 4 steps; the application of the stereotactic frame, image acquisition, dose planning, and the radiation.  See Fig. 1 for an illustrative example of the treatment. It has revolutionized the medical industry because it allows doctors to treat brain ailments without affecting other tissue - which otherwise would be all but impossible.
Gamma Knife treatment is a positive alternative to an invasive procedure for many reasons. For one, there is very little risk borne by the healthy surrounding tissue. This greatly reduces the collateral damage associated with most surgeries.  This treatment accomplishes this feat by attacking the lesion with a high dose of radiation - entirely focused on the area of concern. In addition, gamma knife costs approximately 25%-30% less than traditional neurosurgery. Because it is non-invasive, there is very little discomfort during and after for the patient and the potential for infection and hemorrhaging is completely eliminated.  It also gives patients with inoperable tumors an option for treatment - as they would otherwise not be able to get the help they need. As noted earlier, this radiosurgery was created to provide a safer alternative to neurosurgery.  It is often used to treat a tumor or other harmful growth that is difficult to get to. People who prefer less invasive treatments or who aren't healthy enough to undergo an intense neurosurgical session often opt for Gamma Knife Surgery as well.
It is mainly used to treat 5 different brain disorders: a brain tumor, arteriovenous malformation, trigeminal neuralgia, acoustic neuroma, and pituitary tumors.  The treatment damages a tumor's cells which inhibits them from being able to reproduce - causing the tumor to shrink and eventually die. For AVMs, the treatment destroys the abnormal tangles of arteries and veins and causes the blood vessels to close off over time. Trigeminal Neuralgia is a disorder of the trigeminal nerves.  It causes facial pain delivered in what feels like electric shocks. The nerve pain felt on the face from trigeminal neuralgia is relieved after one treatment of Gamma Knife Surgery. This happens because the radiation kills the nerves so that they can longer send false pain signals to your jaw and facial area. Acoustic Neuroma is a tumor on the nerve of balance and hearing. This can cause hearing loss, dizziness and loss of balance. Radiosurgery attacks the DNA is the tumor's cells which leads to it shrinking.  Finally, radiosurgery addresses pituitary tumors in the same way as the aforementioned tumors. After attacking the tumor's cells, it should shrink and the disruption of the hormone regulation would be rectified. 
© Bryce Marion. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 C. Lindquist, "Gamma Knife Radiosurgery," Semin. Radiat. Oncol. 5, 197 (1995).
 M. Yamamoto, "Gamma Knife Radiosurgery: Technology, Applications, and Future Directions," Neurosurg. Clin. N. Am. 10, 181 (1999).