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A split strap frame applicator for stereotactic frame placement
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Surgical Neurology 68 (2007) 683 – 685 www.surgicalneurology-online.com
Stereotaxis
A split strap frame applicator for stereotactic frame placement Bryan R. Payne, MDa,4, Judy Weber, RNb, Mary S. Payne, MDc a
Department of Neuroscience, Marshall University School of Medicine, Huntington, WV 25755, USA b New Orleans Regional Gamma Knife Center, New Orleans, LA 70115, USA c Department of Neurology, Louisiana State University School of Medicine-New Orleans, New Orleans, LA 70115, USA Received 2 November 2006; accepted 21 December 2006
Abstract
Background: Symmetric and orthogonal placement of stereotactic frames is an important part of many procedures. The authors describe a split strap frame applicator for stereotactic frame placement. Methods: A strap was developed that uses 2 pairs of straps with a common center that support the weight of the frame during screw placement. Ear bars can be used to orient the frame. Results: A retrospective review of the perioperative imaging of 20 patients revealed excellent frame placement with minimal deviation from orthogonal planes relative to the long axis of the head. Conclusion: The orienting usefulness of ear bars during frame placement can be used without the ear bars supporting the weight of the frame with this applicator. D 2007 Elsevier Inc. All rights reserved.
Keywords:
Stereotactic frame; Deep brain stimulation; Stereotactic radiosurgery; Parkinson disease
1. Introduction The use of stereotactic frames has greatly expanded in the past decade owing to the development and refinement of effective procedures for an ever-growing number of indications [1,2]. Although frameless stereotaxy is available in some instances, the use of an affixed frame is necessary in many situations such as gamma knife radiosurgery and may not be preferable in others. The placement of the frame is tailored to the indication for the procedure. In radiosurgical procedures, the frame is usually centered over the target, whereas in movement disorder procedures it is advantageous to have the frame centered over the head and in sharp alignment with the long (anterior-posterior) axis of the skull. When ear bars are used to secure and align the frame during screw placement, sufficient force must be used to bear the weight of the frame. This degree of force in the external auditory canal is generally painful and
Abbreviation: AC-PC, anterior commissure–posterior commissure. 4 Corresponding author. Tel.: 504 920 0839; fax 504 891 9866. E-mail address: [email protected] (B.R. Payne). 0090-3019/$ – see front matter D 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2006.12.062
Fig. 1. The central portion of the strap rests on the patient’s head with Velcro along the exposed surface. On both surfaces of the strap along the split ends, additional Velcro is attached.
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B.R. Payne et al. / Surgical Neurology 68 (2007) 683 – 685
internal auditory canal was visible on both sides in the same image demonstrating no significant yaw. 3. Discussion
Fig. 2. The ends of the strap loop around the ring of the frame on either side of the ear bar assembly and secure to the central portion of the strap on top of the head or the Velcro on the strap ends on the other side.
without adequate and often significant sedation can disrupt this portion of the procedure. Various devices have been used to stabilize the frame during placement. This includes cervical supports [3] and straps from which the frame hangs (Steiner, L, personal communication). A variation of a strap from which the frame hangs is described.
Although many modern stereotactic surgery planning software systems will reconfigure radiographic images along the AC-PC line, frame placement is generally done along this line at an acute angle relative to the axial plane for these procedures. This allows for reproducible target acquisition relative to standard stereotactic atlases that are formatted in orthogonal planes. Also, eliminating axial rotation or yaw relative to the long axis of the head will give similar y and z coordinates in bilateral procedures using similar relationships to the AC-PC line, such as in bilateral subthalamic or thalamic deep brain stimulator placement for Parkinson’s disease or tremor. This is advantageous because it prevents the need to change these coordinates between sides. To center the frame in this fashion while minimizing pain, ear bars can be used in conjunction with this strap. 4. Conclusion The use of a split strap frame applicator allows symmetric and orthogonal placement of the Leksell G stereotactic frame with ear bar assembly use without significant noxious stimuli. References
2. Methods and results The split ends of the strap attach by Velcro to the center of the strap on top of the patients head (Fig. 1). Splitting the 2 ends of the strap down the middle allows use of ear bars to center the frame without bearing the weight of the frame, thus reducing the force needed within the external auditory canal. One half of each end of the strap passes on either side of the ear bar assembly providing support to the frame both in front of and behind the assembly. The ear bars are placed in the external auditory canal to similar depths just deep enough to orient the frame (Fig. 2). To evaluate the effectiveness of this technique, 20 sequential patients undergoing a deep brain stimulation procedure were randomly selected retrospectively and their treatment magnetic resonance imaging scans evaluated. Leksell model G stereotactic frames (Elekta, Inc, Norcross, Ga) and self-tapping titanium screws were used in all procedures. The variance of the x value of the midpoint of the anterior commissure was an average of 1.52 mm from the midline value of the frame of 100 mm (range, 0-5.4 mm). To evaluate the degree of axial rotation along the z axis the y value of the coordinates of the anterior, most border of the internal auditory canal was measured bilaterally for each patient. These values varied from one side to the other an average of 1.09 mm (range, 0-4.6 mm). In all patients, the
[1] Rezai AR, Kopell BH, Gross RE. Deep brain stimulation for Parkinson’s disease: surgical issues. Mov Disord 2006;21(Suppl 14):S197-S218. [2] Hamani C, Neimat J, Lozano AM. Deep brain stimulation for treatment of Parkinson’s disease. J Neural Transm 2006;(70):393 - 9. [3] Kamiryo T, Laws Jr ER. An accurate adjustable applicator for magnetic resonance imaging–based stereotactic procedure using the Leksell G frame. Neurosurgery 1999;45(2):397 - 9.
Commentary The authors describe a simple modification for the standard technique of stereotactic frame application. Although widely used for application of CRW frame (Integra Radionics, Burlington, Mass), velcro straps are not routinely used for Leksell frames (Elekta, Norcross, Ga). The manufacturer of Leksell frame recommends using ear bars for appropriate frame balancing, but many users modified the ear bar application procedure by either using additional ear pads or attaching the magnetic resonance or computed tomography localizer to the frame before the pin insertion. The authors of this short report describe their technique of frame balancing with custom-made straps, and note high accuracy in maintaining the tilt, rotation, and yaw of the final frame position. This strap is used in addition to the
Surgical Neurology 68 (2007) 683 – 685 www.surgicalneurology-online.com
Stereotaxis
A split strap frame applicator for stereotactic frame placement Bryan R. Payne, MDa,4, Judy Weber, RNb, Mary S. Payne, MDc a
Department of Neuroscience, Marshall University School of Medicine, Huntington, WV 25755, USA b New Orleans Regional Gamma Knife Center, New Orleans, LA 70115, USA c Department of Neurology, Louisiana State University School of Medicine-New Orleans, New Orleans, LA 70115, USA Received 2 November 2006; accepted 21 December 2006
Abstract
Background: Symmetric and orthogonal placement of stereotactic frames is an important part of many procedures. The authors describe a split strap frame applicator for stereotactic frame placement. Methods: A strap was developed that uses 2 pairs of straps with a common center that support the weight of the frame during screw placement. Ear bars can be used to orient the frame. Results: A retrospective review of the perioperative imaging of 20 patients revealed excellent frame placement with minimal deviation from orthogonal planes relative to the long axis of the head. Conclusion: The orienting usefulness of ear bars during frame placement can be used without the ear bars supporting the weight of the frame with this applicator. D 2007 Elsevier Inc. All rights reserved.
Keywords:
Stereotactic frame; Deep brain stimulation; Stereotactic radiosurgery; Parkinson disease
1. Introduction The use of stereotactic frames has greatly expanded in the past decade owing to the development and refinement of effective procedures for an ever-growing number of indications [1,2]. Although frameless stereotaxy is available in some instances, the use of an affixed frame is necessary in many situations such as gamma knife radiosurgery and may not be preferable in others. The placement of the frame is tailored to the indication for the procedure. In radiosurgical procedures, the frame is usually centered over the target, whereas in movement disorder procedures it is advantageous to have the frame centered over the head and in sharp alignment with the long (anterior-posterior) axis of the skull. When ear bars are used to secure and align the frame during screw placement, sufficient force must be used to bear the weight of the frame. This degree of force in the external auditory canal is generally painful and
Abbreviation: AC-PC, anterior commissure–posterior commissure. 4 Corresponding author. Tel.: 504 920 0839; fax 504 891 9866. E-mail address: [email protected] (B.R. Payne). 0090-3019/$ – see front matter D 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2006.12.062
Fig. 1. The central portion of the strap rests on the patient’s head with Velcro along the exposed surface. On both surfaces of the strap along the split ends, additional Velcro is attached.
684
B.R. Payne et al. / Surgical Neurology 68 (2007) 683 – 685
internal auditory canal was visible on both sides in the same image demonstrating no significant yaw. 3. Discussion
Fig. 2. The ends of the strap loop around the ring of the frame on either side of the ear bar assembly and secure to the central portion of the strap on top of the head or the Velcro on the strap ends on the other side.
without adequate and often significant sedation can disrupt this portion of the procedure. Various devices have been used to stabilize the frame during placement. This includes cervical supports [3] and straps from which the frame hangs (Steiner, L, personal communication). A variation of a strap from which the frame hangs is described.
Although many modern stereotactic surgery planning software systems will reconfigure radiographic images along the AC-PC line, frame placement is generally done along this line at an acute angle relative to the axial plane for these procedures. This allows for reproducible target acquisition relative to standard stereotactic atlases that are formatted in orthogonal planes. Also, eliminating axial rotation or yaw relative to the long axis of the head will give similar y and z coordinates in bilateral procedures using similar relationships to the AC-PC line, such as in bilateral subthalamic or thalamic deep brain stimulator placement for Parkinson’s disease or tremor. This is advantageous because it prevents the need to change these coordinates between sides. To center the frame in this fashion while minimizing pain, ear bars can be used in conjunction with this strap. 4. Conclusion The use of a split strap frame applicator allows symmetric and orthogonal placement of the Leksell G stereotactic frame with ear bar assembly use without significant noxious stimuli. References
2. Methods and results The split ends of the strap attach by Velcro to the center of the strap on top of the patients head (Fig. 1). Splitting the 2 ends of the strap down the middle allows use of ear bars to center the frame without bearing the weight of the frame, thus reducing the force needed within the external auditory canal. One half of each end of the strap passes on either side of the ear bar assembly providing support to the frame both in front of and behind the assembly. The ear bars are placed in the external auditory canal to similar depths just deep enough to orient the frame (Fig. 2). To evaluate the effectiveness of this technique, 20 sequential patients undergoing a deep brain stimulation procedure were randomly selected retrospectively and their treatment magnetic resonance imaging scans evaluated. Leksell model G stereotactic frames (Elekta, Inc, Norcross, Ga) and self-tapping titanium screws were used in all procedures. The variance of the x value of the midpoint of the anterior commissure was an average of 1.52 mm from the midline value of the frame of 100 mm (range, 0-5.4 mm). To evaluate the degree of axial rotation along the z axis the y value of the coordinates of the anterior, most border of the internal auditory canal was measured bilaterally for each patient. These values varied from one side to the other an average of 1.09 mm (range, 0-4.6 mm). In all patients, the
[1] Rezai AR, Kopell BH, Gross RE. Deep brain stimulation for Parkinson’s disease: surgical issues. Mov Disord 2006;21(Suppl 14):S197-S218. [2] Hamani C, Neimat J, Lozano AM. Deep brain stimulation for treatment of Parkinson’s disease. J Neural Transm 2006;(70):393 - 9. [3] Kamiryo T, Laws Jr ER. An accurate adjustable applicator for magnetic resonance imaging–based stereotactic procedure using the Leksell G frame. Neurosurgery 1999;45(2):397 - 9.
Commentary The authors describe a simple modification for the standard technique of stereotactic frame application. Although widely used for application of CRW frame (Integra Radionics, Burlington, Mass), velcro straps are not routinely used for Leksell frames (Elekta, Norcross, Ga). The manufacturer of Leksell frame recommends using ear bars for appropriate frame balancing, but many users modified the ear bar application procedure by either using additional ear pads or attaching the magnetic resonance or computed tomography localizer to the frame before the pin insertion. The authors of this short report describe their technique of frame balancing with custom-made straps, and note high accuracy in maintaining the tilt, rotation, and yaw of the final frame position. This strap is used in addition to the