- Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan
Correspondence Address:
Shinya Kobayashi
Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan
DOI:10.4103/2152-7806.102330
Copyright: © 2012 Kobayashi S. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.How to cite this article: Kobayashi S, Ishikawa T, Mutoh T, Hikichi K, Suzuki A. A novel technique for ventriculoperitoneal shunting by flat panel detector CT-guided real-time fluoroscopy. Surg Neurol Int 13-Oct-2012;3:119
How to cite this URL: Kobayashi S, Ishikawa T, Mutoh T, Hikichi K, Suzuki A. A novel technique for ventriculoperitoneal shunting by flat panel detector CT-guided real-time fluoroscopy. Surg Neurol Int 13-Oct-2012;3:119. Available from: http://sni.wpengine.com/surgicalint_articles/a-novel-technique-for-ventriculoperitoneal-shunting-by-flat-panel-detector-ct-guided-real-time-fluoroscopy/
Abstract
Background:Surgical placement of a ventriculoperitoneal shunt (VPS) is the main strategy to manage hydrocephalus. However, the failure rate associated with placement of ventricular catheters remains high.
Methods:A hybrid operating room, equipped with a flat-panel detector digital subtraction angiography system containing C-arm cone-beam computed tomography (CB-CT) imaging, has recently been developed and utilized to assist neurosurgical procedures. We have developed a novel technique using intraoperative fluoroscopy and a C-arm CB-CT system to facilitate accurate placement of a VPS.
Results:Using this novel technique, 39 consecutive ventricular catheters were placed accurately, and no ventricular catheter failures were experienced during the follow-up period. Only two patients experienced obstruction of the VPS, both of which occurred in the extracranial portion of the shunt system.
Conclusion:Surgical placement of a VPS assisted by flat panel detector CT-guided real-time fluoroscopy enabled accurate placement of ventricular catheters and was associated with a decreased need for shunt revision.
Keywords: Cone-beam computed tomography, hydrocephalus, shunt failure, ventriculoperitoneal shunt
INTRODUCTION
Surgical placement of a ventriculoperitoneal shunt (VPS) is the main strategy to manage hydrocephalus. However, the failure rate associated with placement of ventricular catheters remains high. Ventricular catheter placement traditionally involves the identification of external landmarks to determine the catheter entry point and a blind pass via typical trajectories, with the hope that the placement of the catheter is adequate. However, the failure rate of ventricular catheter systems remains as high as 30–40% in the first year,[
The advantage of the posterior approach for VPS placement is the ease of tunneling via a straight path down to the abdomen.[
The use of a hybrid operating room (OR) equipped with radiological examination modalities can facilitate neurosurgical procedures. For example, such systems have enabled intraoperative evaluation with two-/three-dimensional (2D/3D) angiography, fluoroscopic imaging, and soft-tissue cross-sectional imaging,[
Our institution has utilized C-arm-based real-time fluoroscopy and cone-beam computed tomography (CB-CT) in an effort to facilitate a safer and more accurate ventricular catheter placement. This study describes our 3-year experience using this new technique for VPS surgery.
MATERIALS AND METHODS
Patient population
Thirty-nine patients (11 male and 28 female; age range, 44–80 years; mean age, 65.3 years) who underwent VPS surgery with the new technique between June 2008 and May 2011 were enrolled. VPS surgery was performed for 36 patients with normal pressure hydrocephalus after subarachnoid hemorrhage, for one patient with idiopathic normal pressure hydrocephalus, and for two patients with obstructive hydrocephalus (in one patient after surgery for angioblastoma and another patient after intracerebral hemorrhage;
As a comparison, we analyzed 37 patients (13 male and 24 female; age range, 21–83 years; mean age, 64.4 years) who underwent VPS surgery via conventional methods using the standard external landmarks[
The surgical outcomes and the rate of complications were compared between the two patient groups.
Novel surgical technique
Our hybrid OR has a newly designed, multipurpose radiolucent surgical table with a special radiolucent head clamp system and a digital subtraction angiography (DSA) system with a biplane C-arm. For image viewing, there are seven flat-display monitors equipped for biplane angiographic imaging and 3D imaging. During surgery, the monitor can be easily repositioned to assist visualization. In addition to the apparatus for conventional 2D and 3D DSA, a newly developed C-arm CB-CT imaging system (Dyna CT, Siemens, Germany) has been installed. This advanced device provides bone and soft-tissue images. The high-resolution 3D image data set was reconstructed using the OR 3D Workstation.[
Surgery was performed with patients under general anesthesia. Patients were placed in this supine position with his/her head rotated to the contralateral side, and the neck was extended with a roll placed under the shoulder. A carbon head clamp adapter and a carbon Mayfield head clamp were used. To reduce artifacts made when C-arm CB-CT imaging was performed, the position of the head pins and the spring of the Mayfield head clamp were kept as far as possible from the expected planes for ventricular catheter placement.
First, copper markers were placed on the glabella and on the conventional entry point of the posterior approach (6 cm above and 3 cm lateral to the inion) as external landmarks, and C-arm CB-CT imaging was performed to provide reconstructed axial, sagittal, and coronal images. The actual point for burr hole, the direction for catheter insertion, and the depth of the catheter was determined based on these images [
Figure 1
(a) Planning CB-CT produces three-dimensional surgical planes (axial, coronal, and sagittal) and a three-dimensionally reconstructed image, which helps determining the site of the burr hole and the direction and depth for catheter insertion. (b) External copper markers placed on the glabella and the conventional entry point can be detected with planning CB-CT to allow correction of the true external landmark relative to the external copper maker based on visual inspection
Next, the surgical field was disinfected and draped, and a burr hole was made in the appropriate position. Under fluoroscopic imaging, the ventricle was punctured along the planned trajectory until the tip of the ventricular catheter reached the target position in the anterior horn. Visual corrections regarding the direction of the puncture and catheter insertion were made using a virtual plane constructed by the points of puncture and target as well as the plane parallel to the flat-panel detector [
Figure 2
(a) Virtually constructed planes (a and b) cover the points of puncture and the expected final position of the catheter tip. Plane (a) is consistent with the fluoroscopic image. Plane (b) is vertical to plane. (a) The intersection of the planes indicates the appropriate direction for catheter insertion (arrow). (b) Fluoroscopic image during catheter insertion. Accurate direction and depth for catheter insertion (yellow line) is overlaid on the fluoroscopic image. (c) Intraoperative image. The operator punctures the ventricle, referring to the fluoroscopic guidance
Finally, C-arm CB-CT imaging was performed to confirm that the ventricular catheter was situated in an appropriate position [
RESULTS
Among the 37 patients undergoing the conventional VPS technique, 11 (29.7%) ventricular catheters were placed inappropriately; 9 were placed in the contralateral anterior horn, 1 was placed in the ipsilateral inferior horn, and 1 was placed in the prepontine cistern. In the follow-up period described (mean 28 months, median 12 months, range 1–81months), four (10.9%) revision surgeries have been necessary; two ventricular catheters required revision because of misplacement or proximal obstruction, one peritoneal catheter was revised because of distal obstruction; and one entire shunt system was removed because of infection [
Using the new technique, all 39 consecutive ventricular catheters were placed accurately, with the tip of each catheter placed at the target point in the ipsilateral anterior horn. We have not experienced any ventricular catheter failures during the follow-up period (mean 14 months, median 12 months, range 1–48 months). Two (5.1%) patients developed shunt obstruction in the extracranial portion of the shunt system; one required revision of the peritoneal catheter, and the other required reconnection of the shunt valve to the peritoneal catheter [
Representative case
A 57-year-old woman developed normal pressure hydrocephalus after subarachnoid hemorrhage. She underwent VPS surgery, in which the ventricular catheter was inserted through the right occipital region using the technique described. The tip of the ventricular catheter was placed at the exact target in the anterior horn, and the VPS system has worked well [
Figure 4
(a) CT scan of a 57-year-old woman who developed normal pressure hydrocephalus after subarachnoid hemorrhage is shown. The ventricles are enlarged and are associated with periventricular lucency. (b) CT after surgery. The tip of the ventricular catheter was placed at the exact target in the anterior horn, and ventricle size returned to normal
DISCUSSION
The complication rate of VPS surgery ranges from 30% to 40%,[
Endoscopic- and navigation-assisted shunt techniques have been used to facilitate more accurate shunt placement. Villavicencio et al.[
In terms of navigation-assisted techniques, Azeem et al.[
The present study demonstrated that accurate catheter placement was associated with a decrease in the incidence of proximal shunt failure, although this study had a relatively short follow-up period. This study also demonstrated that VPS placement under flat panel detector CT-guided real-time fluoroscopy enabled accurate catheter placement. In addition, this technique makes it possible to reveal and arrange the position of the ventricular catheter intraoperatively. The patient receives some amount of irradiation through CB-CT, but the amount of radiation associated with CB-CT for VPS surgery is similar to that associated with a single CT scan, which is within the safe range for adult patients. Artifacts from pins and coils in the Mayfield head clamp can compromise the quality of the CB-CT image; thus, modifications of the materials may be necessary to improve the diagnostic value of this modality.
CONCLUSIONS
The present study demonstrated the utility of flat panel detector CT-guided real-time fluoroscopy for accurate placement of ventricular catheters during VPS surgery. Accurate shunt placement with this novel technique may help reduce the early shunt revision rate.
ACKNOWLEDGEMENTS
We thank Kaoru Sato and Keita Narita for their invaluable support in the acquisition of radiological and intraoperative data.
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