1. Modification of Laser Alignment of Cranial X-Rays Intraoperatively
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Modification of Laser Alignment of Cranial X-Rays Intraoperatively
Pamela Tebebi
Peter Konrad, MD, Ph.D (Advisor)

2. Functional Stereotactic Neurosurgery
Stereotaxy is technique used in surgery for directing an electrode to a specific locus in the brain
Intracerebral site is selected for destruction, stimulation, or physiological monitoring
Diseases associated: movement disorders (including Parkinson's Disease, tremor, and torticollis), epilepsy, pain and spasticity

3. Deep Brain Stimulation (DBS) for Movement Disorders
A surgical procedure whereby electrodes are permanently implanted in particular parts of the brain and continuous stimulation administered by a small electric unit (generator) that is implanted under the skin of the chest
Goals of DBS are to improve the control of movement on the side opposite the stimulator by modifying the brain cells in area of interest
Depending on the type of movement disorder, this may result in loss of tremor, loss of rigidity, loss of dyskinesia or dystonia
Risk of DBS
Most serious is bleeding into the brain causing headache, paralysis, coma, or death
Infection (10%)
Malfunction of stimulator
Movement of the electrode

4. Current Device for DBS Many surgeon use CRW frame
Stereotactic frame is fixed in the skull and the stimulating electrode is driven through a burrhole
Can only be aligned once
Does not provide an accurate X-ray laser sighting alignment system for the comparison of the electrode stimulation site to the final site of the implant so as to verify that the implant is at the designated site
Cosman-Roberts-Wells (CRW) apparatus; Photo from R. Galloway, R Maciunas. Stereotactic Neurosurery. Biomedical Engineering, Vol 18(3), 1990.

5. New Technology in DBS: mT Platform System
Developed by Frederick Haer & Co. (FHC), Inc (specialize in metal and glass microelectrode, needles and instrumentation for cellular research)
microTargeting Platform System requires no stereotactic frame or image guidance system
Vanderbilt is the first and only institution in the nation testing the device
microTargeting (mT Platform) Platform System; Photo provided by FHC

6. New Technology in DBS: mT Platform System
mT Platform is design from importing CT and MR scans of the head into the mT Platform Planning and Design Software
Software allows neurosurgeon to design custom fixture based on the target, entry, references points, and etc.
Software virtually build the Platform in place on patient, including trajectory and target
microTargeting (mT Platform) ; Photos provided by FHC

7. New Technology in DBS: mT Platform System
If virtual representation is satisfactory, data file is send to FHC for fabrication of Platform
No method for alignment
Does not provide an accurate X-ray laser sighting alignment system for the comparison of the electrode stimulation site to the final site of the implant so as to verify that the implant is at the designated site
microTargeting (mT Platform) Platform System; Photo provided by FHC

8. Project Goal
Design an accurate sighting system by means of laser sighting alignment for intraoperative X-rays taken of brain stimulator implants

9. Proposed Alignment Device
Mount an aiming tube to a rectangular platform that is attached to a leg on mT Platform
Aiming tube is parallel to mid-sagittal plane
Center of tube is normal to mid-sagittal plane

10. Problem & Soloution to Proposed Alignment Device
PROBLEM: Too expensive for FHC to modify the software interface to allow attachment of alignment device to leg
Legs are based on a component that is loaded once and copied to other two position
Changing one leg would result in complete redesign
SOLUTION by FHC: Modify software to create a component for second hub

11. Alignment Device Requires modification of the mT Platform
Requires modification of of the software model file written by FHC
Modification is less expensive
Both hubs point to the target site, and hub with tube is parallel to mid-sagittal plane
Image provided by FHC

12. Alignment Device : components
Image provided by FHC
Aiming tube for X-ray with cross hair on both ends is attached to second hub
Image provided by FHC
mT Platform with second hub on the fixture

13. Alignment Device Fixture has its mounting
surface surface parallel to the
mid-sagittal plane
Fixture has its center on a line
normal to the mid-sagittal
plane and extending from the
target point
Allows for a sagittal view
through the aiming tube
Image provided by FHC

14. Alignment Device
When cross hairs at the ends of the tube are in line in the image, C-arm is aligned with predicted target point
Beam of the C-arm passes through the tube pointed at target point
All calculations and localization is done by mT Platform Planning and Design Software with out neurosurgeon having to align tube
Image provided by FHC

15. Sample X-ray Image Stimulation site Implantation site
Stimulating electrode
Implantation site
Stimulation site
Stimulation site Implantation site

16. Tolerance Target site area: 4X6mm
Allowable distance implant can be from site of stimulation: 0.5mm
If implant is placed more than 0.5mm from targeted stimulation result in no stimulation or undesirable side effects

17. Technology: Alignment Device
First of its kind; ~48 procedures/year
Vanderbilt University is the first institution to consider this new approach
Helpful tool for neurosurgeon; feel more comfortable about accurately placing the stimulating implants
X-ray is useful in lawsuits and beneficial to insurance company to verify correct placement of implant to stimulation site by neurosurgeon

18. Market Size Neurosurgery: -tool for neurosurgeon
Medical and Research Institution:
-prevent lawsuits
-receive better insurance coverage

19. Device Status Prototype model will be provided by FHC
Once completed the alignment device will be tested on patients here at Vanderbilt

20. Acknowledgements Peter Konrad, MD, Ph.D (Vanderbilt University)
Ron Franklin, Senior Engineer (Frederick Haer & Co.)
Chris Koa, MD, Ph.D (Vanderbilt University)
Robert Galloway, Ph.D (Vanderbilt University)
John Song, MD (Vanderbilt University)

21. References
Surgery for Deep Brain Stimulation, Anderson MA, RN. Vanderbilt University Medical Center, Jan (pamphlet)
microTargeting Platform System incorporating STarFix guidance. User Manual A989-02, FHC, Inc, 2001.
Galloway RL, Cleary K, Peter T. Image Guided Procedures 2001 A Snapshot View. July
Galloway RL, Macinus RJ. Stereotactic Neurosurgery. Biomedical Engineering, Vol. 18(3), pp , 1990.
Stereotactic Neurosurgery. Concepts in Neurosurgery. Heilbrum MP, Ed., Baltimore: William & Wilkins, Vol. 2., 1988.
Movement Disorder Surgery. Progress in Neurological Surgery. Lozano AM, Ed., New York: Karger, Vol. 15, 2000.
Shrivastava, RK, Germano IM. Deep Brain Stimulation for the Treatment of Parkinson’s Disease. Contemporary Neurosurgery, Vol.. 23(16), Aug 15, 2001.