Comparative analysis of endoscopic third ventriculostomy trajectories in pediatric cases

Zsolt Zador MD, PhD, MRCS(Eng)1,3, David J. Coope MBChB, BSc, PhD, FRCS(Neuro Surg)1,2,3, and Ian D. Kamaly-Asl MD, MBChB, FRCS(SN)1
View More View Less
  • 1 Department of Pediatric Neurosurgery, Royal Manchester Children’s Hospital, Manchester;
  • | 2 Wolfson Molecular Imaging Centre, The University of Manchester, Manchester; and
  • | 3 Department of Neurosurgery, Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Salford, United Kingdom
Free access

OBJECT

Endoscopic third ventriculostomy (ETV) has become a widely used method for CSF diversion when treating obstructive hydrocephalus. There are multiple recommendations on the transcortical ETV entry points, and some are specifically designed to provide a trajectory that avoids displacement to the eloquent periventricular structures. However, the morphology of the ventricular system is highly variable in hydrocephalus, and therefore a single best ETV trajectory may not be applicable to all cases. In the current study, 3 frequently quoted ETV entry points are compared in a cohort of pediatric cases with different degrees of ventriculomegaly.

METHODS

The images of 30 consecutive pediatric patients with varying degrees of ventriculomegaly were reviewed. Three-dimensional models were created using radiological analysis of anatomical detail and preoperative MRI scans in order to simulate 3 frequently quoted ETV trajectories for rigid neuroendoscopes. These trajectories were characterized based on the frequency and depth of tissue displacement to structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus. The results are stratified based on ventricle size using the frontal horn ratio (FHR).

RESULTS

Eloquent areas were displaced in nearly all analyzed entry points (97%–100%). Stratifying the data based on ventricle size revealed that 1) lateral structures were more likely to be displaced in cases of intermediate ventriculomegaly (FHR < 0.4) using all 3 trajectories, whereas 2) the fornix was less likely to be displaced using more posteriorly placed trajectories for severe ventriculomegaly (FHR > 0.4). Allowing for minimal (2.4 mm) tissue displacement, a more posterior entry point was less traumatic for severe ventriculomegaly.

CONCLUSIONS

There is no single best ETV trajectory that fully avoids displacement of the eloquent periventricular structures. Larger ventricles require a more posteriorly placed entry point in order to reduce injury to the eloquent structures, and intermediate ventricles would dictate a medial entry point. These results suggest that the optimal entry point should be selected on a case-by-case basis after incorporating ventricle size.

ABBREVIATIONS

ETV = endoscopic third ventriculostomy; FHR = frontal horn ratio.

OBJECT

Endoscopic third ventriculostomy (ETV) has become a widely used method for CSF diversion when treating obstructive hydrocephalus. There are multiple recommendations on the transcortical ETV entry points, and some are specifically designed to provide a trajectory that avoids displacement to the eloquent periventricular structures. However, the morphology of the ventricular system is highly variable in hydrocephalus, and therefore a single best ETV trajectory may not be applicable to all cases. In the current study, 3 frequently quoted ETV entry points are compared in a cohort of pediatric cases with different degrees of ventriculomegaly.

METHODS

The images of 30 consecutive pediatric patients with varying degrees of ventriculomegaly were reviewed. Three-dimensional models were created using radiological analysis of anatomical detail and preoperative MRI scans in order to simulate 3 frequently quoted ETV trajectories for rigid neuroendoscopes. These trajectories were characterized based on the frequency and depth of tissue displacement to structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus. The results are stratified based on ventricle size using the frontal horn ratio (FHR).

RESULTS

Eloquent areas were displaced in nearly all analyzed entry points (97%–100%). Stratifying the data based on ventricle size revealed that 1) lateral structures were more likely to be displaced in cases of intermediate ventriculomegaly (FHR < 0.4) using all 3 trajectories, whereas 2) the fornix was less likely to be displaced using more posteriorly placed trajectories for severe ventriculomegaly (FHR > 0.4). Allowing for minimal (2.4 mm) tissue displacement, a more posterior entry point was less traumatic for severe ventriculomegaly.

CONCLUSIONS

There is no single best ETV trajectory that fully avoids displacement of the eloquent periventricular structures. Larger ventricles require a more posteriorly placed entry point in order to reduce injury to the eloquent structures, and intermediate ventricles would dictate a medial entry point. These results suggest that the optimal entry point should be selected on a case-by-case basis after incorporating ventricle size.

ABBREVIATIONS

ETV = endoscopic third ventriculostomy; FHR = frontal horn ratio.

Endoscopic third ventriculostomy (ETV) has emerged as an alternative method of CSF diversion alongside the placement of ventriculoperitoneal shunts.18–20 ETV has been primarily advocated as an aqueductal bypass procedure for obstructive hydrocephalus,12 but its application has now expanded to treating hydrocephalus of nonobstructive etiologies1,5,8 with an overall success rate ranging from 68.5% to 83% in large mixed series.1,2,13,23 Parallel to these high success rates, a recent review demonstrates an overall complication rate of 8.5%, permanent morbidity of 2.4%, and mortality of 0.21% for ETVs.3 In addition to the conceptual advantage of hardware-free CSF diversion, ETV presents the option of acquiring tissue biopsy if needed.15,16,25 ETV also benefits from a potentially better cost effectiveness9,11,12 and shorter surgical time compared with the placement of ventriculoperitoneal shunts.

A safe and successful ETV requires good surgical visualization and atraumatic neuroendoscope passage through the foramen of Monro in order to access the floor of the third ventricle. These factors depend on the ETV trajectory, which is predefined by the bur hole entry site used. The most frequently described ETV entry sites are either 3 cm lateral to the midline and 1 cm anterior to the coronal suture 1,13,14 or located at a point 3 cm lateral to the midline along the coronal suture.20 Recent morphometric studies recommend placing the bur hole more posteriorly (approximately 1 cm behind the coronal suture and 3 cm away from the midline) in order to grant an atraumatic trajectory through the foramen of Monro that is aimed straight at the floor of the third ventricle.4,6 However, the ventricle dimensions in hydrocephalus are highly variable,6,7,17 which translates into diverse anatomical relationships between the floor of the third ventricle and the foramen of Monro. This observation is reinforced by the broad data range reported for the individual entry points of atraumatic trajectories.4,6,14,15 It is therefore likely that there is no “single best” ETV trajectory that avoids all tissue breaches, and the ETV entry point needs to be adjusted according to the ventricle morphology. To test this hypothesis, we used radiological analysis of anatomical detail to analyze 3 ETV entry points in 30 pediatric cases with different degrees of ventriculomegaly.

Methods

The patients were originally identified and data were collected as part of an ETV audit approved by the Clinical Audit Department of Royal Manchester Children’s Hospital. We created an anonymized database of 30 consecutive pediatric patients between the ages of 6 months and 16 years with varying degrees of ventriculomegaly who underwent treatment for newly diagnosed hydrocephalus. Patients with ipsilateral supratentorial mass lesions were excluded. Preoperative MRI scans were reconstructed, reviewed, and analyzed using the Brainlab iPlan workstation (software version 3.0). This software allows the creation and adjustment of the ETV trajectory in 3 dimensions. We used the “probe view” function to visualize the proximity to the adjacent structures at each point on the planned trajectory, and we could further scrutinize the intersection of this trajectory with key anatomical structures.

Assessment of Ventriculomegaly

We used the frontal horn ratio (FHR) as described by Hahn and Rim10 to assess the ventricular dimensions. This parameter is calculated as the ratio between the interfrontal distance (maximum distance between the lateral edges of the frontal horns) and the internal diameter of the skull at the same location (Fig. 1D).

FIG. 1.
FIG. 1.

Comparative analysis of ETV trajectories. A: Entry points for the 3 trajectories plotted over a representative 3D surface reconstruction: the precoronal point is 3 cm to midline and 1 cm anterior the coronal suture (1); the coronal point overlies the coronal suture and is 3 cm away from midline (2); and the posterior coronal point is 3 cm to midline and 1 cm behind the coronal suture (3). The arrows indicate the coronal suture that is visible on the 3D reconstruction on both the sagittal (B) and axial (C) views. D: FHR was computed according to the methods of Hahn and Rim as the ratio of the interfrontal distance (a) to the internal diameter of the skull at the same location (b). Figure is available in color online only.

Assessment of the Conventional ETV Entry Points and Trajectories for Rigid Neuroendoscopes

Our study was designed for rigid neuroendoscopes. Flexible neuroendoscopes provide greater maneuverability and potentially reduce the extent of tissue displacement. However, neuroendoscopy performed using rigid neuroendoscopes is the most widely used modality at this time, and the majority of our existing experience is derived from this technique. Only right-sided trajectories were considered. The coronal suture and the midline were identified in all cases either on the 3D surface reconstruction and/or using planar scan views (Fig. 1A–C). Three entry points were analyzed: 1) the precoronal point, which is 3 cm lateral to the midline along the coronal suture and 1 cm anterior to the coronal suture1,13,14; 2) the coronal point, which is 3 cm lateral to the midline along the coronal suture20; and 3) the posterior coronal point, which is 3 cm lateral to midline and 1 cm posterior to the coronal suture coronal point.4,6,22 These landmarks were clearly distinguished from one another by multiple case series.4,6,13,14,20 Furthermore, the concept of identifying different cranio-metric points accurately by relying on the coronal suture is well established in the literature.22

During ETV, the neuroendoscope is passed under direct vision and the eloquent structures are avoided. However, at the stage of third ventricular fenestration, the neuroendoscope is passed beyond the foramen of Monro and the operator loses direct visualization of its surrounding structures, thereby potentially displacing them while accessing the target area. Therefore, the ETV trajectory for a rigid neuroendoscope was simulated as a straight line between the entry points and the ETV fenestration site (the floor of the third ventricle just anterior to the mammillary bodies) (Fig. 2B and C). The depth of the intersection with the anatomical structures was used to simulate the extent of tissue displacement caused by the rigid neuroendoscope. Displacement was categorized as 1) “anterior displacement,” which included displacement to the fornix, or 2) “lateral displacement,” which included displacement to the caudate nucleus, genu of the internal capsule, or thalamus. The diameter of the rigid neuroendoscope was incorporated into our simulations by assigning the trajectory a width of 4.5 mm (Fig. 2B–E). We recorded both the frequency and the depth of tissue displacement (Fig. 3; Tables 1 and 2).

FIG. 2.
FIG. 2.

An example of an ETV trajectory through the coronal point is shown. A: Three-dimensional surface reconstruction demonstrating the coronal suture (arrows), ETV entry point, and trajectory. B and C: Probe view of the same trajectory in the sagittal (B) and coronal (C) projections. D and E: Representative axial cuts demonstrating tissue displacement for the trajectory. Anterior displacement to the fornix on the axial view at the level of the foramen of Monro (D). The level of this cut is marked by the interrupted line shown in panel B. Lateral displacement to the caudate nucleus on the axial view (E). The level of this axial cut is through the lateral ventricle body, as indicated by the interrupted line shown in panel C. Figure is available in color online only.

FIG. 3.
FIG. 3.

Comparative analysis of ETV trajectories in patients with intermediate (A–C) or severe (D–F) ventriculomegaly. The graphs depict the depth of tissue displacement to the anterior (the fornix) and lateral structures (the caudate nucleus, genu of internal capsule, or thalamus) for each of the 30 cases. The dots in each graph represent no displacement to the neuronal tissue, the dotted line marks the adjusted threshold of 2.4 mm, and the shaded area (red) indicates displacement greater than 2.4 mm. Figure is available in color online only.

TABLE 1.

Frequency of tissue displacement to eloquent periventricular structures by the different ETV trajectories in patients with intermediate (FHR < 0.4) or severe (FHR > 0.4) ventriculomegaly

DisplacementDisplacement Frequency*
Precoronal PointCoronal PointPosterior Coronal Point
FHR<0.4 (n = 18)
 Anterior50%44.4%66.7%
 Lateral94.4%94.4%88.9%
FHR >0.4 (n = 12)
 Anterior100%75%50%
 Lateral0%0%33.3%

Precoronal point: 3 cm lateral to midline and 1 cm anterior to the coronal suture. Coronal point: 3 cm lateral to midline along the coronal suture. Posterior coronal point: 3 cm lateral to midline and 1 cm posterior to the coronal suture. Anterior displacement: displacement to the fornix. Lateral displacement: displacement to the caudate nucleus, genu of internal capsule, or thalamus.

p < 0.05 (Fisher exact test with the Freeman-Halton modification).

TABLE 2.

Tissue displacement to eloquent periventricular structures by the different ETV trajectories in patients with intermediate (FHR < 0.4) or severe (FHR > 0.4) ventriculomegaly

DisplacementDisplacement Depth (mm)P Value*
Precoronal PointCoronal PointPosterior Coronal Point
FHR <0.4 (n = 18)
 Anterior4.27 ± 1.852.85 ± 0.963.51 ± 1.610.17
 Lateral2.98 ± 1.62.64 ± 1.043.68 ± 1.520.1
FHR >0.4 (n = 12)
 Anterior3.44 ± 1.762.75 ± 1.751.51 ± 0.390.07
LateralNoneNone1.6 ± 0.73<0.001

ANOVA.

Data Analysis

Cases were stratified based on the ventricle dimensions into groups with FHR > 0.4 (“severe ventriculomegaly”) or FHR < 0.4 (“intermediate ventriculomegaly”). The simulated displacement of the neuronal structures was analyzed for each trajectory using the Student t-test, chi-square test, 1-way ANOVA, or Fisher exact test with the Freeman-Halton modification.

Results

Patient Population

The cohort consisted of 19 male and 11 female patients, the average age was 7.66 ± 4.59 years (range 9 days to 16 years), and various degrees of ventriculomegaly were noted. The most common diagnosis was posterior fossa neoplasm (22 of 30 patients), including medulloblastoma, ependymoma, and meningioma, followed by primary CSF circulation abnormalities (8 of 30 patients).

Stratification of Cases Based on Ventricle Size

The average FHR was 0.38 (range 0.24–0.57), and we empirically stratified the cohort into severe (FHR > 0.4; n = 12) or intermediate ventriculomegaly (FHR < 0.4; n = 18).

Assessment of the Ventricular Entry Points

The results for the frequency and depth of displacement to the eloquent structures are presented in Tables 1 and 2, respectively, and are summarized in Fig. 3. Initial analysis showed that there was no difference between the virtual tissue displacements for each trajectory without stratification by ventricle size (p = 0.09 and p = 0.4 for anterior and lateral displacement, respectively). We found that the anterior and/or lateral periventricular structures were displaced to some extent by all 3 ETV trajectories in 97% to 100% of cases.

We next stratified the results into severe (FHR > 0.4) and intermediate ventriculomegaly (FHR < 0.4), as summarized in Fig. 3 on the scatterplots. The analysis yielded the following results.

Displacement Frequency

Intermediate Ventriculomegaly

The 3 trajectories were associated with displacement frequencies between 44.4% and 66.7% for anterior structures and 94.4% and 88.9% for lateral structures, with no statistical differences between trajectories (Fig. 3; Table 1).

Severe Ventriculomegaly

The displacement frequencies to the anterior structures were significantly less for trajectories through the posterior coronal point (50%) compared with the precoronal (100%) and coronal points (75%; p < 0.05). There was no displacement to the latter structures for any of the trajectories, except for the posterior coronal point in 33% of cases (p < 0.05).

We observed a high frequency of lateral displacement in patients with intermediate ventriculomegaly. On further testing, this proved to be significantly greater than the displacement frequency for the lateral structures in patients with severe ventriculomegaly (0%–33.3% vs 94.4%– 88.9%) for all 3 trajectories (p < 0.01). These findings suggest that a more medial entry point would potentially be less traumatic for intermediate ventriculomegaly, as larger ventricles seem to accommodate a more lateral trajectory.

Displacement Depth

Intermediate Ventriculomegaly

The displacement depths are summarized in Table 2. There was no significant difference between trajectories for anterior (p = 0.17) or lateral (p = 0.1) displacement.

Severe Ventriculomegaly

There was a trend toward reduced anterior displacement for the posterior coronal point (p = 0.07) compared with other trajectories. The lateral displacement depth was 1.6 ± 0.73 mm for the posterior coronal point compared with no displacement in the remaining trajectories (p < 0.001).

To further interpret these results, we incorporated the compliance of the neuronal structures to surgical manipulation by introducing a threshold for tissue displacement at the level of the foramen of Monro. We adopted 2.4 mm as the “safe” tissue displacement based on 2 case series (22 patients total), where ETVs were performed in combination with a biopsy through the same bur hole without procedure-related complications.16,25 Our results are summarized in Fig. 3 and Table 3. Direct comparison of the 3 trajectories without incorporating ventricle sizes showed no difference in the adjusted displacement to the anterior (p = 0.36) or lateral structures (p = 0.94). When stratifying for ventriculomegaly, for intermediate ventricles there was no difference in the frequencies of tissue displacement when comparing the precoronal (Fig. 3A and D), coronal (Fig. 3B and E), and posterior coronal points (Fig. 3C and F; anterior displacement, p = 0.44; lateral displacement, p = 0.82). In severe ventriculomegaly, only the posterior coronal point provided a trajectory with no tissue displacement above the threshold for both the anterior and posterior structures (Fig. 3F; Table 3; p < 0.005).

TABLE 3.

Comparative analysis of the frequency of tissue displacement greater than 2.4 mm for the different ETV trajectories

Displacement*Displacement Frequency
Precoronal PointCoronal PointPosterior Coronal Point
All ventricle sizes
 Anterior50%33%30%
 Lateral33%40%40%
FHR <0.4 (n = 18)
 Anterior38.9%27.8%50%
 Lateral55.6%66.7%66.7%
FHR >0.4 (n = 12)
 Anterior66.7%41.7%0%
 Lateral0%0%0%

Displacement threshold of 2.4 mm.

p < 0.005 (Fisher exact test with the Freeman-Halton modification).

Discussion

We tested the applicability of 3 frequently quoted ETV entry points using radiological analyses of anatomical detail in a cohort of 30 consecutive pediatric cases with different degrees of ventriculomegaly. Our results show there is no single best trajectory for a rigid neuroendoscope that avoids any neuronal tissue displacement in every case. For intermediate ventriculomegaly (FHR < 0.4) the lateral periventricular structures were displaced more frequently than in severe ventriculomegaly, which suggests a more medial trajectory for smaller ventricles could potentially be less traumatic. Of the 3 trajectories studied, the posterior coronal entry point (as recommended by Duffner et al.6 and Chen and Nakaji4) offered the least amount of tissue displacement for cases with relatively large ventricles (FHR > 0.4).

ETV is stratified as a low-risk procedure; however, there are well-recognized complications attributed to injuring the eloquent structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus.3 These structures are adjacent to the foramen of Monro—the narrowest section of the ETV trajectory—and after passing the neuroendoscope into the third ventricle they are no longer visible to the operator. Therefore, subsequent manipulation of the neuroendoscope during fenestration can displace and injure these structures. To minimize this risk, multiple studies recommend an optimal entry point that allows atraumatic passage of the neuroendoscope in order to reach the floor of the third ventricle.4,6,14–16 The first set of studies found that the average entry point was approximately 3 cm lateral and 1 cm anterior to the coronal suture.14 Other authors proposed a more posterior entry point, averaging approximately 3 cm lateral and 1 cm posterior to the coronal suture.4,6 These studies also show that the atraumatic entry point varies considerably between individual cases. The locations range between 12.5 and 18.1 mm to 42.22 and 44.4 mm for the distance from the midline and 16.1 and 30.6 mm anterior to 35.8 and 46.5 mm posterior to the coronal suture.4,6 Knaus at al. reported similar variance in the mean optimal ETV entry point in 48 pediatric patients (119.7 ± 26.4 mm posterior to the nasion and 20.5 ± 11.5 mm lateral to the midline).15 In parallel to this broad data range, there is significant anatomical variance in ventricular morphology in patients with hydrocephalus, as shown by a series of radiological analyses of anatomical detail.6,7,17 Duffner et al. analyzed the MRI appearances of the lateral and third ventricles in patients with hydrocephalus with special consideration to ETV. Their data show highly variable ventricular dimensions: the height and width of the lateral/third ventricle varied 2- to 3-fold, and the distance from the cortex to the lateral ventricle ranged between 5.4 and 34.6 mm.6 Gammal et al.7 characterized the MRI appearances of patients with normal, atrophic, and hydrocephalic brains. They reported a range of 12 to 30 mm for the corpus callosum-fornix distance compared with 0 to 8 mm for normal and 0 to 15 mm for atrophic brains. The volumes of the third and fourth ventricles in patients with hydrocephalus related to subarachnoid hemorrhage were reported to range up to 6-fold.17 This anatomical variability preempts the findings of our study: there is no single universal working trajectory that could be applied to every surgical case given the highly diverse configuration of the periventricular structures.

The concept of “1 trajectory fits all” has been tested by accessing the ipsilateral anterior horn when using Kocher’s point as the entry point21 (which corresponds to the precoronal point in our study). Only a subset (67.5%) of the ventricular trajectories passed through the frontal horn, and as a result the study recommended small adjustments on a case-by-case basis. Compared with anterior horn ventriculostomy, the ETV has a longer working trajectory, thereby giving rise to a greater degree of cumulative errors, e.g., displacing the eloquent structures. This is in accordance with our results, showing that none of the 3 ETV entry points tested would grant a fully atraumatic trajectory to the floor of the third ventricle.

The translational value of ETV simulations for assessing clinical outcome is traceable in the literature.15,16,25 These studies used preoperative computer-assisted planning16 or intraoperative neuronavigation25 to determine the extent of virtual tissue displacement at the level of the foramen of Monro, which was then correlated with postoperative complication. We adopted the mean tissue displacement of 2.4 mm quoted in these studies, which was associated with no intra- or postoperative complications and an ETV success rate of 86.7% to 100%.16,25 Displacement values below this threshold are less likely to have clinical consequences, which explains why there is a relatively low complication rate for ETV3 despite the high frequency of tissue displacement shown in our study. A suboptimal ETV trajectory, however, can also translate to restricted surgical access and limited visualization, thereby resulting in 1) suboptimal fenestration and consequently stoma failure and 2) intraoperative bleeding from the neurovascular structures, which forces the procedure to be abandoned. The degree of tissue shift appears to be a good indicator of cumulative errors that impact not only the safety but also the success of the procedure. Ultimately, the concept of “individualized” ETV entry points that minimize tissue displacement requires prospective clinical studies for verification. We are in the process of designing these trials using our recently developed operative planning tool.24

Conclusions

Our results show that none of the 3 frequently described ETV trajectories are universally applicable to cases with different degrees of ventriculomegaly. Allowing for a relatively small amount of tissue displacement, the posterior coronal entry point grants the most optimal trajectory for larger ventriculomegaly. However, any degree of tissue displacement may be associated with bleeding or suboptimal visualization, thereby triggering a series of cumulative errors for the procedure. Therefore, ultimately our results suggest individual adjustments should be made to the entry site based on ventricle size in order to optimize procedure safety and success.

Author Contributions

Conception and design: all authors. Acquisition of data: Zador. Analysis and interpretation of data: Zador, Coope. Drafting the article: all authors. Critically revising the article: Zador, Kamaly-Asl. Reviewed submitted version of manuscript: Zador. Approved the final version of the manuscript on behalf of all authors: Zador. Statistical analysis: Zador. Study supervision: Kamaly-Asl.

References

  • 1

    Amini A, & Schmidt RH: Endoscopic third ventriculostomy in a series of 36 adult patients. Neurosurg Focus 19:6 E9, 2005

  • 2

    Bognar L, , Markia B, & Novak L: Retrospective analysis of 400 neuroendoscopic interventions: the Hungarian experience. Neurosurg Focus 19:6 E10, 2005

    • Search Google Scholar
    • Export Citation
  • 3

    Bouras T, & Sgouros S: Complications of endoscopic third ventriculostomy. J Neurosurg Pediatr 7:643649, 2011

  • 4

    Chen F, & Nakaji P: Optimal entry point and trajectory for endoscopic third ventriculostomy: evaluation of 53 patients with volumetric imaging guidance. J Neurosurg 116:11531157, 2012

    • Search Google Scholar
    • Export Citation
  • 5

    Cinalli G, , Salazar C, , Mallucci C, , Yada JZ, , Zerah M, & Sainte-Rose C: The role of endoscopic third ventriculostomy in the management of shunt malfunction. Neurosurgery 43:13231329, 1998

    • Search Google Scholar
    • Export Citation
  • 6

    Duffner F, , Schiffbauer H, , Glemser D, , Skalej M, & Freudenstein D: Anatomy of the cerebral ventricular system for endoscopic neurosurgery: a magnetic resonance study. Acta Neurochir (Wien) 145:359368, 2003

    • Search Google Scholar
    • Export Citation
  • 7

    Gammal TE, , Allen MB Jr, , Brooks BS, & Mark EK: MR evaluation of hydrocephalus. AJR Am J Roentgenol 149:807813, 1987

  • 8

    Gangemi M, , Maiuri F, , Buonamassa S, , Colella G, & de Divitiis E: Endoscopic third ventriculostomy in idiopathic normal pressure hydrocephalus. Neurosurgery 55:129134, 2004

    • Search Google Scholar
    • Export Citation
  • 9

    Garton HJ, , Kestle JR, , Cochrane DD, & Steinbok P: A cost-effectiveness analysis of endoscopic third ventriculostomy. Neurosurgery 51:6978, 2002

    • Search Google Scholar
    • Export Citation
  • 10

    Hahn FJ, & Rim K: Frontal ventricular dimensions on normal computed tomography. AJR Am J Roentgenol 126:593596, 1976

  • 11

    Hellwig D, , Grotenhuis A, & Tirakotai W: A cost-effectiveness analysis of endoscopic third ventriculostomy. Neurosurgery 52:15061508, 2003

    • Search Google Scholar
    • Export Citation
  • 12

    Hellwig D, , Grotenhuis JA, , Tirakotai W, , Riegel T, , Schulte DM, , Bauer BL, & Bertalanffy H: Endoscopic third ventriculostomy for obstructive hydrocephalus. Neurosurg Rev 28:138, 2005

    • Search Google Scholar
    • Export Citation
  • 13

    Jenkinson MD, , Hayhurst C, , Al-Jumaily M, , Kandasamy J, , Clark S, & Mallucci CL: The role of endoscopic third ventriculostomy in adult patients with hydrocephalus. J Neurosurg 110:861866, 2009

    • Search Google Scholar
    • Export Citation
  • 14

    Kanner A, , Hopf NJ, & Grunert P: The “optimal” burr hole position for endoscopic third ventriculostomy: results from 31 stereotactically guided procedures. Minim Invasive Neurosurg 43:187189, 2000

    • Search Google Scholar
    • Export Citation
  • 15

    Knaus H, , Abbushi A, , Hoffmann KT, , Schwarz K, , Haberl H, & Thomale UW: Measurements of burr-hole localization for endoscopic procedures in the third ventricle in children. Childs Nerv Syst 25:293299, 2009

    • Search Google Scholar
    • Export Citation
  • 16

    Knaus H, , Matthias S, , Koch A, & Thomale UW: Single burr hole endoscopic biopsy with third ventriculostomy-measure-ments and computer-assisted planning. Childs Nerv Syst 27:12331241, 2011

    • Search Google Scholar
    • Export Citation
  • 17

    Knol DS, , van Gijn J, , Kruitwagen CL, & Rinkel GJ: Size of third and fourth ventricle in obstructive and communicating acute hydrocephalus after aneurysmal subarachnoid hemorrhage. J Neurol 258:4449, 2011

    • Search Google Scholar
    • Export Citation
  • 18

    Kulkarni AV, , Drake JM, , Kestle JR, , Mallucci CL, , Sgouros S, & Constantini S: Endoscopic third ventriculostomy vs cerebrospinal fluid shunt in the treatment of hydrocephalus in children: a propensity score-adjusted analysis. Neurosurgery 67:588593, 2010

    • Search Google Scholar
    • Export Citation
  • 19

    Kulkarni AV, , Drake JM, , Kestle JR, , Mallucci CL, , Sgouros S, & Constantini S: Predicting who will benefit from endoscopic third ventriculostomy compared with shunt insertion in childhood hydrocephalus using the ETV Success Score. J Neurosurg Pediatr 6:310315, 2010

    • Search Google Scholar
    • Export Citation
  • 20

    O’Brien DF, , Javadpour M, , Collins DR, , Spennato P, & Mallucci CL: Endoscopic third ventriculostomy: an outcome analysis of primary cases and procedures performed after ventriculoperitoneal shunt malfunction. J Neurosurg 103:5 Suppl 393400, 2005

    • Search Google Scholar
    • Export Citation
  • 21

    Rehman T, , Rehman Au, , Ali R, , Rehman A, , Bashir H, & Ahmed Bhimani S, et al.: A radiographic analysis of ventricular trajectories. World Neurosurg 80:173178, 2013

    • Search Google Scholar
    • Export Citation
  • 22

    Ribas GC, , Yasuda A, , Ribas EC, , Nishikuni K, & Rodrigues AJ Jr: Surgical anatomy of microneurosurgical sulcal key points. Neurosurgery 59:4 Suppl 2 ONS177ONS211, 2006

    • Search Google Scholar
    • Export Citation
  • 23

    Sacko O, , Boetto S, , Lauwers-Cances V, , Dupuy M, & Roux FE: Endoscopic third ventriculostomy: outcome analysis in 368 procedures. J Neurosurg Pediatr 5:6874, 2010

    • Search Google Scholar
    • Export Citation
  • 24

    Zador Z, , Coope DJ, & Kamaly I: Optimal cranial entry point for third ventriculostomy in pediatric patients. Br J Neurosurg 27:560, 2013. (Abstract)

    • Search Google Scholar
    • Export Citation
  • 25

    Zhu XL, , Gao R, , Wong GK, , Wong HT, , Ng RY, & Yu Y, et al.: Single burr hole rigid endoscopic third ventriculostomy and endoscopic tumor biopsy: what is the safe displacement range for the foramen of Monro?. Asian J Surg 36:7482, 2013

    • Search Google Scholar
    • Export Citation
  • View in gallery

    Comparative analysis of ETV trajectories. A: Entry points for the 3 trajectories plotted over a representative 3D surface reconstruction: the precoronal point is 3 cm to midline and 1 cm anterior the coronal suture (1); the coronal point overlies the coronal suture and is 3 cm away from midline (2); and the posterior coronal point is 3 cm to midline and 1 cm behind the coronal suture (3). The arrows indicate the coronal suture that is visible on the 3D reconstruction on both the sagittal (B) and axial (C) views. D: FHR was computed according to the methods of Hahn and Rim as the ratio of the interfrontal distance (a) to the internal diameter of the skull at the same location (b). Figure is available in color online only.

  • View in gallery

    An example of an ETV trajectory through the coronal point is shown. A: Three-dimensional surface reconstruction demonstrating the coronal suture (arrows), ETV entry point, and trajectory. B and C: Probe view of the same trajectory in the sagittal (B) and coronal (C) projections. D and E: Representative axial cuts demonstrating tissue displacement for the trajectory. Anterior displacement to the fornix on the axial view at the level of the foramen of Monro (D). The level of this cut is marked by the interrupted line shown in panel B. Lateral displacement to the caudate nucleus on the axial view (E). The level of this axial cut is through the lateral ventricle body, as indicated by the interrupted line shown in panel C. Figure is available in color online only.

  • View in gallery

    Comparative analysis of ETV trajectories in patients with intermediate (A–C) or severe (D–F) ventriculomegaly. The graphs depict the depth of tissue displacement to the anterior (the fornix) and lateral structures (the caudate nucleus, genu of internal capsule, or thalamus) for each of the 30 cases. The dots in each graph represent no displacement to the neuronal tissue, the dotted line marks the adjusted threshold of 2.4 mm, and the shaded area (red) indicates displacement greater than 2.4 mm. Figure is available in color online only.

  • 1

    Amini A, & Schmidt RH: Endoscopic third ventriculostomy in a series of 36 adult patients. Neurosurg Focus 19:6 E9, 2005

  • 2

    Bognar L, , Markia B, & Novak L: Retrospective analysis of 400 neuroendoscopic interventions: the Hungarian experience. Neurosurg Focus 19:6 E10, 2005

    • Search Google Scholar
    • Export Citation
  • 3

    Bouras T, & Sgouros S: Complications of endoscopic third ventriculostomy. J Neurosurg Pediatr 7:643649, 2011

  • 4

    Chen F, & Nakaji P: Optimal entry point and trajectory for endoscopic third ventriculostomy: evaluation of 53 patients with volumetric imaging guidance. J Neurosurg 116:11531157, 2012

    • Search Google Scholar
    • Export Citation
  • 5

    Cinalli G, , Salazar C, , Mallucci C, , Yada JZ, , Zerah M, & Sainte-Rose C: The role of endoscopic third ventriculostomy in the management of shunt malfunction. Neurosurgery 43:13231329, 1998

    • Search Google Scholar
    • Export Citation
  • 6

    Duffner F, , Schiffbauer H, , Glemser D, , Skalej M, & Freudenstein D: Anatomy of the cerebral ventricular system for endoscopic neurosurgery: a magnetic resonance study. Acta Neurochir (Wien) 145:359368, 2003

    • Search Google Scholar
    • Export Citation
  • 7

    Gammal TE, , Allen MB Jr, , Brooks BS, & Mark EK: MR evaluation of hydrocephalus. AJR Am J Roentgenol 149:807813, 1987

  • 8

    Gangemi M, , Maiuri F, , Buonamassa S, , Colella G, & de Divitiis E: Endoscopic third ventriculostomy in idiopathic normal pressure hydrocephalus. Neurosurgery 55:129134, 2004

    • Search Google Scholar
    • Export Citation
  • 9

    Garton HJ, , Kestle JR, , Cochrane DD, & Steinbok P: A cost-effectiveness analysis of endoscopic third ventriculostomy. Neurosurgery 51:6978, 2002

    • Search Google Scholar
    • Export Citation
  • 10

    Hahn FJ, & Rim K: Frontal ventricular dimensions on normal computed tomography. AJR Am J Roentgenol 126:593596, 1976

  • 11

    Hellwig D, , Grotenhuis A, & Tirakotai W: A cost-effectiveness analysis of endoscopic third ventriculostomy. Neurosurgery 52:15061508, 2003

    • Search Google Scholar
    • Export Citation
  • 12

    Hellwig D, , Grotenhuis JA, , Tirakotai W, , Riegel T, , Schulte DM, , Bauer BL, & Bertalanffy H: Endoscopic third ventriculostomy for obstructive hydrocephalus. Neurosurg Rev 28:138, 2005

    • Search Google Scholar
    • Export Citation
  • 13

    Jenkinson MD, , Hayhurst C, , Al-Jumaily M, , Kandasamy J, , Clark S, & Mallucci CL: The role of endoscopic third ventriculostomy in adult patients with hydrocephalus. J Neurosurg 110:861866, 2009

    • Search Google Scholar
    • Export Citation
  • 14

    Kanner A, , Hopf NJ, & Grunert P: The “optimal” burr hole position for endoscopic third ventriculostomy: results from 31 stereotactically guided procedures. Minim Invasive Neurosurg 43:187189, 2000

    • Search Google Scholar
    • Export Citation
  • 15

    Knaus H, , Abbushi A, , Hoffmann KT, , Schwarz K, , Haberl H, & Thomale UW: Measurements of burr-hole localization for endoscopic procedures in the third ventricle in children. Childs Nerv Syst 25:293299, 2009

    • Search Google Scholar
    • Export Citation
  • 16

    Knaus H, , Matthias S, , Koch A, & Thomale UW: Single burr hole endoscopic biopsy with third ventriculostomy-measure-ments and computer-assisted planning. Childs Nerv Syst 27:12331241, 2011

    • Search Google Scholar
    • Export Citation
  • 17

    Knol DS, , van Gijn J, , Kruitwagen CL, & Rinkel GJ: Size of third and fourth ventricle in obstructive and communicating acute hydrocephalus after aneurysmal subarachnoid hemorrhage. J Neurol 258:4449, 2011

    • Search Google Scholar
    • Export Citation
  • 18

    Kulkarni AV, , Drake JM, , Kestle JR, , Mallucci CL, , Sgouros S, & Constantini S: Endoscopic third ventriculostomy vs cerebrospinal fluid shunt in the treatment of hydrocephalus in children: a propensity score-adjusted analysis. Neurosurgery 67:588593, 2010

    • Search Google Scholar
    • Export Citation
  • 19

    Kulkarni AV, , Drake JM, , Kestle JR, , Mallucci CL, , Sgouros S, & Constantini S: Predicting who will benefit from endoscopic third ventriculostomy compared with shunt insertion in childhood hydrocephalus using the ETV Success Score. J Neurosurg Pediatr 6:310315, 2010

    • Search Google Scholar
    • Export Citation
  • 20

    O’Brien DF, , Javadpour M, , Collins DR, , Spennato P, & Mallucci CL: Endoscopic third ventriculostomy: an outcome analysis of primary cases and procedures performed after ventriculoperitoneal shunt malfunction. J Neurosurg 103:5 Suppl 393400, 2005

    • Search Google Scholar
    • Export Citation
  • 21

    Rehman T, , Rehman Au, , Ali R, , Rehman A, , Bashir H, & Ahmed Bhimani S, et al.: A radiographic analysis of ventricular trajectories. World Neurosurg 80:173178, 2013

    • Search Google Scholar
    • Export Citation
  • 22

    Ribas GC, , Yasuda A, , Ribas EC, , Nishikuni K, & Rodrigues AJ Jr: Surgical anatomy of microneurosurgical sulcal key points. Neurosurgery 59:4 Suppl 2 ONS177ONS211, 2006

    • Search Google Scholar
    • Export Citation
  • 23

    Sacko O, , Boetto S, , Lauwers-Cances V, , Dupuy M, & Roux FE: Endoscopic third ventriculostomy: outcome analysis in 368 procedures. J Neurosurg Pediatr 5:6874, 2010

    • Search Google Scholar
    • Export Citation
  • 24

    Zador Z, , Coope DJ, & Kamaly I: Optimal cranial entry point for third ventriculostomy in pediatric patients. Br J Neurosurg 27:560, 2013. (Abstract)

    • Search Google Scholar
    • Export Citation
  • 25

    Zhu XL, , Gao R, , Wong GK, , Wong HT, , Ng RY, & Yu Y, et al.: Single burr hole rigid endoscopic third ventriculostomy and endoscopic tumor biopsy: what is the safe displacement range for the foramen of Monro?. Asian J Surg 36:7482, 2013

    • Search Google Scholar
    • Export Citation

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 375 112 28
PDF Downloads 399 94 23
EPUB Downloads 0 0 0