====== Image-guided stereotactic surgery ======

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A method in neurosurgery for locating points within the brain using an external, three-dimensional frame of reference usually based on the [[Cartesian coordinate system]].
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The term [[stereotactic]] (Greek: stereo = 3-dimensional, tactic = to touch) surgery was initially used in [[animal]]s, and was based on [[atlas]]es of three-dimensional coordinates compiled from [[dissection]]s. The term was then used for surgery performed in humans, usually for [[thalamic]] lesioning to treat [[Parkinsonism]]. 

The [[technique]]s of [[stereotactic surgery]] are utilized in some functional procedures (e.g. [[DBS]]) as well as for biopsies (see [[Stereotactic biopsy]]) [[cyst]] drainage, etc. The term [[stereotactic]] (Greek: stereo = 3-dimensional, tactic = to touch) surgery was initially used in animals, and was based on atlases of three-dimensional coordinates compiled from dissections. The term was then used for surgery performed in humans, usually for [[thalamic]] lesioning to treat [[Parkinsonism]], see [[Parkinson's disease surgery]], where the target site to be lesioned was located relative to [[landmark]]s with intraoperative [[pneumoencephalography]] or contrast [[ventriculography]]. Use of this procedure fell off dramatically in the late [[1960]]s with the introduction of [[L-dopa]] for [[Parkinsonism]]
((Gildenberg PL. Whatever Happened to Stereotactic Surgery? Neurosurgery. 1987; 20:983–987))





===== Indications =====

see [[Stereotactic surgery indications]].

For image-guided [[stereotactic surgery]], in the first part of the procedure, a [[CT]] scan or [[MRI]] (or occasionally, [[angiogram]]) is performed. For increased precision, “[[fiducial]]” markers or a [[stereotactic frame]] is attached to the patient’s head during this image acquisition phase. Acceptable accuracy for [[biopsy]] can often be obtained using high resolution thin cut imaging slices (usually with a 0 angle of the [[gantry]]), and then surface matching algorithms in the guidance system will match the pre-op CT/MRI to the patient’s head. This is not accurate enough for lesion generation or [[electrode placement]]. The second part of the procedure usually takes place in an [[operating room]]. The patient is “registered” with the pre-op images, and then tracking cameras follow the movement of instruments with appropriate attachments to show in “real-time” the location of the instrument with respect to the pre-op image. An important limitation to be aware of is the fact that the pre-op images are “historical” and are not updated as the surgical procedure alters the anatomy of the patient. Even the administration of [[mannitol]] can cause brain shifts that may cause the target of the surgery to move away from its pre-op location by several millimeters
((Bucholz RD, Yeh DD, Trobaugh J, et al. The correction
of stereotactic inaccuracy caused by brain
shift using an intraoperative ultrasound device. In:
Lecture Notes in Computer Science. Berlin:
Springer; 1997. DOI: 10.1007/BFb0029268)).