Stereotactic surgery
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Stereotactic surgery or stereotaxy (not to be confused with the virtuality concept of stereotaxy) is a minimally-invasive form of surgical intervention which makes use of a three-dimensional coordinates system to locate small targets inside the body and to perform on them some action such as ablation (removal), biopsy, lesion, injection, stimulation, implantation, radiosurgery (SRS) etc. "Stereotactic" in Greek (another accepted spelling is "stereotaxic") means "solid ordering".
In theory, any organ system inside the body can be subjected to stereotactic surgery. Difficulties in setting up a reliable frame of reference (such as bone landmarks which bear a constant spatial relation to soft tissues), however, mean that its applications have been limited to brain surgery. Besides the brain, biopsy and surgery of the breast are done routinely to locate, sample (biopsy) and remove tissue. Plain X-ray images (radiographic mammography) and computed tomography can be used to guide the procedure.
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[edit] History
The stereotactic method was first developed by two British scientists in 1908, working at University College London Hospital, Sir Victor Horsley, a physician and neurosurgeon, and Robert H. Clarke, an engineer. The Horsley-Clarke apparatus they developed was used for animal experimentation and implemented a Cartesian (three-orthogonal axis) system. Improved designs of their original device came into use in the 1930s for animal experimentation and are still in wide use today in all animal neuroscience laboratories.
Using the Horsley-Clarke apparatus for human brains was difficult because of the inability to visualize intracranial anatomic detail via radiography. However, contrasted brain radiography (particularly pneumoencephalography and ventriculography) permitted the visualization of intracranial anatomic reference points or landmarks. The first stereotactic devices for humans used the pineal gland and the foramen of Monro as landmarks. Later, other anatomic reference points such as the anterior and posterior commissures were used as intracranial landmarks. These landmarks were used with a brain atlas to estimate the location of intracranial anatomic structures that were not visible in radiographs.
Using this approach between 1947 and 1949, two American neurosurgeons, Ernest A. Spiegel and Henry T. Wycis, and a Swedish neurosurgeon, Lars Leksell, developed the first stereotactic devices that were used for brain surgery in humans. Spiegel and Wycis used the Cartesian coordinate system (also called the translational system) for their device. Leksell's device used the polar coordinate system (also called spherical) that was far easier to use and calibrate in the operating room. The stereotactic localization system was also used by Leksell in his next invention, a device for radiosurgery of the brain. This system is also used by the Gamma Knife device, and by other neurosurgeons, using linear accelerators, proton beam therapy and neutron capture therapy. Lars Leksell went on to commercialize his inventions by founding Elekta.
In 1978, Russell A. Brown, an American physician and computer scientist, invented a simple technique to guide stereotactic surgery using computed tomography.[1] [2] This technique significantly improves surgical precision because computed tomography permits direct visualization of intracranial anatomic detail. The technique uses fiducials to create extracranial landmarks in each tomographic image or section. These landmarks specify the spatial orientation of that section with respect to the stereotactic device. Brown's invention stimulated intense interest in stereotaxy and radiosurgery. It is widely used today in the Brown-Roberts-Wells (BRW) stereotactic system[3] as well as other stereotactic and radiosurgical devices.
The stereotactic method has continued to evolve, and at present uses an elaborate mixture of image-guided surgery using computed tomography, magnetic resonance imaging and stereotactic localization.
[edit] How it works
Stereotactic surgery works on the basis of three main components:
- A stereotactic planning system, including atlas, multimodality image matching tools, coordinates calculator, etc.
- A stereotactic device or apparatus
- A stereotactic localization and placement procedure
Modern stereotactic planning system are computer based. The stereotactic atlas is a series of cross sections of anatomical structure (for example, a human brain), depicted in reference to a two-coordinate frame. Thus, each brain structure can be easily assigned a range of three coordinate numbers, which will be used for positioning the stereotactic device. In most atlases, the three dimensions are: latero-lateral (x), dorso-ventral (y) and rostro-caudal (z).
The stereotactic apparatus uses a set of three coordinates (x, y and z) in an orthogonal frame of reference (cartesian coordinates), or, alternatively, a polar coordinates system, also with three coordinates: angle, depth and antero-posterior location. The mechanical device has head-holding clamps and bars which puts the head in a fixed position in reference to the coordinate system (the so-called zero or origin). In small laboratory animals, these are usually bone landmarks which are known to bear a constant spatial relation to soft tissue. For example, brain atlases often use the external auditory meatus, the inferior orbital ridges, the median point of the maxilla between the incisive teeth. or the bregma (confluence of sutures of frontal and parietal bones), as such landmarks. In humans, the reference points, as described above, are intracerebral structures which are clearly discernible in a radiograph or tomogram.
Guide bars in the x, y and z directions (or alternatively, in the polar coordinate holder), fitted with high precision vernier scales allow the neurosurgeon to position the point of a probe (an electrode, a cannula, etc.) inside the brain, at the calculated coordinates for the desired structure, through a small trephined hole in the skull.
Currently, a number of manufacturers produce stereotactic devices fitted for neurosurgery in humans, as well as for animal experimentation.
[edit] Stereotactic radiosurgery (SRS) in cancer treatment
Stereotactic radiosurgery can successfully treat many different types of tumors, both benign and malignant.[4] The malignant brain tumors treated most often are the "brain metastases" or tumors that have spread to the brain.[5] A study in 2008 by the The University of Texas M. D. Anderson Cancer Center indicated that stereotactic radiosurgery (SRS) and whole brain radiation therapy (WBRT) for the treatment of metastatic brain tumours have more than twice the risk of developing learning and memory problems than those treated with SRS alone. “While both approaches are in practice and both are equally acceptable, data from this study suggest that oncologists should offer SRS alone as the upfront, initial therapy for patients with up to three brain metastases,”[6] Three of the latest radiosurgery treatments, are CyberKnife, Gamma Knife and the Stereotactic Linear Accelerator with Image Guided Radiotherapy, Respiratory Gating, Cone beam CT, Kv Imaging and RapidArc.[7]
[edit] See also
- Cyberknife
- Gamma knife
- Interventional radiology
- Novalis radiosurgery
- Psychosurgery
- Radiosurgery
- Stereotaxic atlas
[edit] Notes
- ^ Brown RA (1979). "A stereotactic head frame for use with CT body scanners". Invest Radiol. 14 (4): 300–4. PMID 385549.
- ^ US patent 4608977 System using computed tomography as for selective body treatment.
- ^ Brown RA, Roberts TS, Osborn AG (1980). "Stereotaxic frame and computer software for CT-directed neurosurgical localization". Invest Radiol. 15 (4): 308–12. PMID 7009485.
- ^ Camphausen KA, Lawrence RC. "Principles of Radiation Therapy" in Pazdur R, Wagman LD, Camphausen KA, Hoskins WJ (Eds) Cancer Management: A Multidisciplinary Approach. 11 ed. 2008.
- ^ John Hopkins - Stereotactic Radiosurgery
- ^ Whole brain radiation ups cancer patients learning, memory problems risk
- ^ Latest radiosurgery treatments
[edit] References
- Robert Levy, A Short History of Stereotactic Surgery, Cyber Museum of Neurosurgery. This is based on
- Patrick J. Kelly, "Introduction and Historical Aspects", Tumor Stereotaxis, Philadelphia: W.B. Saunders Company (1991)
- Philip L. Gildenberg, "Stereotactic Surgery: Present and Past", Stereotactic Neurosurgery, (Editor: M. Peter Heilbrun) Baltimore: Williams and Wilkins (1988)
- Sabbatini, RME: Stereotactic Neurosurgery. In: The History of Psychosurgery. Brain & Mind Magazine, 2, 1997.
- William Regine; Lawrence Chin (2008). Principles of Stereotactic Surgery. Berlin: Springer. ISBN 0-387-71069-8. http://www.springer.com/medicine/surgery/book/978-0-387-71069-3.
[edit] External links
- Tasker RR, Organ LW, Hawrylyshyn P (1976). "Sensory organization of the human thalamus". Applied Neurophysiology 39 (3-4): 139–53. PMID 801856.
- Tasker RR, Hawrylyshyn P, Rowe IH, Organ LW (1977). "Computerized graphic display of results of subcortical stimulation during stereotactic surgery". Acta Neurochirurgica (Suppl 24): 85–98. PMID 335811.
- Stereotactic Apparatus.
- Stereotactic Planning System.
