Abstract
BACKGROUND AND OBJECTIVES:
In conventional freehand frontal ventriculostomy, the Kocher point is the entry point, the external auditory canal is the sagittal target, and the coronal targets include the ipsilateral medial canthus (IMC), the midpoint between the bilateral external auditory meatus (MAM), the contralateral medial canthus (CMC), and the region perpendicular to the skull (P). The aim of this study was to calculate puncture accuracy of the 4 conventional methods to guide clinical selection.
METHODS:
Patient data from thin-slice computed tomography scans were imported, and a 3-dimensional model was reconstructed using software to simulate puncture. The accuracy and puncture depth of the 4 freehand frontal ventriculostomy methods were analyzed.
RESULTS:
From January 1, 2022, to December 30, 2023, 520 patients were screened and 206 were enrolled; 137 (66.5%) participants were males, and 69 (33.5%) were females. The median age of the patients was 64 years (IQR 53-73). The maximal frontal horn width was 21.7-53.7 mm (IQR 34.4-40.0), and the intercanthal distance was 26.0-43.2 mm (IQR 30.7-34.9). Simulating bilateral ventricular puncture, for the IMC trajectory, the puncture accuracy was 13.3% (55/412) [95% CI 10.4-17.0] and the puncture depth was 41.8 ± 4.6 mm. For the MAM trajectory, the puncture accuracy was 74.5% (307/412) [95% CI 70.1-78.5] and the puncture depth was 43.6 ± 4.3 mm. For the P trajectory, the puncture accuracy was 90.5% (373/412) [95% CI 87.3-93.0] and the puncture depth was 49.4 ± 5.9 mm. For the CMC trajectory, the puncture accuracy was 100.0% (412/412) [95% CI 99.1-100.0] and the puncture depth was 47.2 ± 5.2 mm.
CONCLUSION:
Compared with the MAM trajectory, the CMC and P trajectories were more reliable in frontal ventriculostomy, but the P trajectory may enter the contralateral ventricle. The IMC trajectory is not recommended unless the frontal horn is wider than 45 mm or the Kocher point is moved inward.
KEY WORDS: Frontal ventriculostomy, External ventricular drainage, Computer simulation
ABBREVIATIONS:
- CMC
contralateral medial canthus
- IMC
ipsilateral medial canthus
- MAM
midpoint between bilateral external auditory meatus
- P
perpendicular to the skull.
Frontal ventriculostomy is a common neurosurgical procedure. In the United States, 25 000 external ventricular drainage procedures are performed per year.1 Conventional freehand frontal ventriculostomy is performed with the Kocher point as the entry point, the external auditory canal as the sagittal target, and coronal targets, including the ipsilateral medial canthus (IMC),1-7 the midpoint between the bilateral external auditory meatus (MAM),8 the contralateral medial canthus (CMC),9,10 and the region perpendicular to the skull (P).11-14 In the past few decades, literature has reported that the misplacement rates of frontal ventriculostomy range from 8% to 40%,2,15,16 an accuracy of catheter placement between 40% and 80%.4,5,11 But all these accuracy data are from clinical cases, and the accuracy is determined by 3 factors: (1) the accuracy of the puncture method itself, (2) the accuracy of the surgeon's judgment of the target,17 and (3) the number of intraoperative punctures during the operation. Because the accuracy of these punctures was calculated based on computed tomography (CT) images after the operation, in fact, the surgeon could perform multiple punctures before finally entering the ventricle, which improved the accuracy of the punctures. A survey estimated that the average number of punctures per ventriculostomy placement was 1.4 to 2.4.18 Therefore, the accuracy in clinical applications cannot represent the accuracy of the puncture method itself. However, these accuracies are important criteria for neurosurgeons to use when choosing puncture targets, especially for junior neurosurgeons who often feel confused about which puncture target to select after puncture failure.
In our study, we imported CT imaging data into a computer to reconstruct a 3-dimensional (3D) brain model. Simulated puncture was performed on the model to eliminate 2 other factors that could affect the accuracy and to truly reflect the accuracy of each of the 4 traditional puncture methods. The objective of this study was to enable clinical doctors to choose a suitable puncture method based on these accuracies.
METHODS
Patient Data
Brain CT scan data from Jinjiang Municipal Hospital were screened. The inclusion criteria were as follows: (1) age greater than 16 years, (2) the ventricular anatomy should be normal, and (3) CT scan site should contain the coronal suture and bilateral medial canthus. The exclusion criteria were as follows: malformation or defect of the cranial bone.
Ethical approval was obtained for our research registry IBR No. jjsyyxll-2023026 with strict anonymity and confidentiality. All patients consented to the use of their data.
Data Availability
The data are available from the corresponding author upon reasonable request.
Image Acquisition and Model Establishment
The CT data of all patients were obtained from Philips spiral CT machine scans. The scanning range was from the top of the head to the skull base, with a layer thickness of 0.45 mm. The data were imported into 3D Slicer software (3D Slicer 4.11.0, www.slicer.org) for 3D reconstruction, and the skull and head soft tissues were displayed by adjusting different window widths.
Entry Point and Trajectory
The entry point for ventricular puncture was the Kocher point, which is commonly located by using one of the 3 following methods:
Measuring 1 cm anterior to the coronal suture and 2.5 cm lateral to the midline;5,7,19
Measuring 10 mm anterior to the coronal suture in the midpupillary line;20,21
Measuring 10 cm posterior to the nasion and 3 cm lateral to the midline.4,9
The bilateral entry points for this study were defined as 1 cm anterior to the coronal suture and 2.5 cm to the right (left) of the midline (Figure 1A).
FIGURE 1.
A, The bilateral entry point is defined as 1 cm anterior to the coronal suture and 2.5 cm to the right (left) of the midline. B, Plane K, where the entry point and bilateral external auditory canal are located, is defined as the critical plane. C, Position relationship between 4 trajectories, plane K, and the ventricle system (the green model is the ventricle system). The trajectories of all 4 puncture methods are within plane K. D, The relationship between the 4 puncture trajectories and lateral ventricles is shown in plane K. The IMC trajectory is located on the outermost side, with the highest probability of missing the lateral ventricle. The P trajectory is located on the innermost side, with a high possibility of passing through the contralateral ventricle. CMC, contralateral medial canthus trajectory; IMC, ipsilateral medial canthus trajectory; MAM, midpoint between the bilateral external auditory meatus trajectory; P, perpendicular to the skull trajectory.
The trajectories of all 4 conventional frontal ventriculostomy methods are within the Plane K, where the entry point and the bilateral external auditory canal are located (Figure 1B).
The trajectories are as follows:
The IMC trajectory: the line between the entry point and the projection point of the IMC at the line of the bilateral external auditory meatus.
The P trajectory: the line was perpendicular to the skull through the entry point.
The CMC trajectory: The line between the entry point and the projection point of the CMC at the line of the bilateral external auditory meatus.
The MAM trajectory: the line between the entry point and the midpoint of the bilateral external auditory meatus (Figure 1C and 1D).
Evaluation Criteria and Data Collection
The evaluation criteria were as follows: (1) puncture accuracy: the trajectory passed through the ipsilateral ventricle; (2) functional puncture accuracy: the trajectory passed through the ipsilateral ventricle or the contralateral ventricle; and (3) puncture failure: the trajectory did not pass through the lateral ventricle.
The following data were measured: (1) the distance of the trajectory from the outer skull plate to the upper surface of the lateral ventricle, (2) the maximal frontal horn width of the lateral ventricles: the maximal frontal horn width was measured in different axial CT sections. The largest value was selected as the width of the frontal horn of the lateral ventricles, and (3) intercanthal distance. The measurements were conducted independently by 2 people familiar with the software. The data are presented as the average distance measured by these 2 people. If there was a significant difference between the 2 measurements, the data were remeasured under the guidance of a third person.
Statistical Analysis
SPSS V.26.0 software (IBM) was used for the data analyses. A P value <.05 was considered statistically significant. Categorical variables are reported as numbers (%). Continuous data are reported as medians and IQRs. Normally distributed data are presented as the mean ± SD. Intergroup differences were compared using unpaired Mann–Whitney U tests.
RESULTS
Patient and CT Imaging Characteristics
From January 1, 2022, to December 30, 2023, 520 patients were screened and 206 were enrolled (Figure 2); 137 (66.5%) participants were males, and 69 (33.5%) were females. The median age of the patients was 64 years (IQR 53-73). The maximal frontal horn width was 21.7 to 53.7 mm (IQR 34.4-40.0), and the intercanthal distance was 26.0 to 43.2 mm (IQR 30.7-34.9) (Table 1).
FIGURE 2.
Study flowchart. CT, computed tomography.
TABLE 1.
Baseline Demographic and CT Imaging Characteristics of the Patients (n = 206)
| Value | |
|---|---|
| Age, years | 62.1 ± 15.1 (17-95) |
| Sex | |
| Male | 137 (66.5%) |
| Female | 69 (33.5%) |
| Frontal horns width (cm) | |
| 2.0-2.5 | 4 (1.9%) |
| 2.6-3.0 | 9 (4.4%) |
| 3.1-3.5 | 49 (23.8%) |
| 3.6-4.0 | 93 (45.1%) |
| 4.1-4.5 | 34 (16.5%) |
| 4.6-5.0 | 14 (6.8%) |
| 5.1-5.5 | 3 (1.5%) |
| Evans index | |
| ≤0.3 | 135 (65.5%) |
| >0.3 | 71 (34.5%) |
| Intercanthal distance | 32.7 ± 2.9 mm (26.0-43.2 mm) |
CT, computed tomography.
Puncture Accuracy and Depth of the Four Trajectories
In 412 simulated bilateral lateral ventricular frontal horn punctures on 206 models, only the P trajectory entered the contralateral ventricle, whereas the other 3 trajectories did not enter the contralateral ventricle. Therefore, the puncture accuracy and functional puncture accuracy of the other 3 trajectories were the same. The accuracy of the IMC trajectory was 13.3% (55/412) [95% CI 10.4-17.0], and the depth of puncture from the outer skull plate to entry into the lateral ventricle was 41.8 ± 4.6 mm. The accuracy of the MAM trajectory was 74.5% (307/412) [95% CI 70.1-78.5], and the depth was 43.6 ± 4.3 mm. The accuracy of the CMC trajectory was 100.0% (412/412) [95% CI 99.1-100.0], and the depth was 47.2 ± 5.2 mm. The puncture accuracy of the P trajectory was 90.5% (373/412) [95% CI 87.3-93.0], the functional puncture accuracy was 99.5% (410/412) [95% CI 98.2-99.9], and the depth was 49.4 ± 5.9 mm (Table 2, Figure 3).
TABLE 2.
Accuracy of Puncture Through Specified Trajectories and Puncture Depth
| Trajectory | Catheter location | Number (%) | Ventricular frontal horn width: mean ± SD (mm) [95% CI] | Average value of puncture depth: mean ± SD (mm) [95% CI] | P valuea |
|---|---|---|---|---|---|
| IMC | Ipsilateral ventricle | 55 (13.3) | 43.4 ± 5.1 [42.0-44.7] | 41.8 ± 4.6 [40.6-43.1] | |
| Contralateral ventricle | 0(0) | 0(0) | |||
| MAM | Ipsilateral ventricle | 307 (74.5) | 38.4 ± 4.7 [37.9-38.9] | 43.6 ± 4.3 [43.2-44.1] | |
| Contralateral ventricle | 0 (0) | 0 (0) | |||
| P | Ipsilateral ventricle | 373 (90.5) | 37.4 ± 5.0 [36.9-37.9] | 48.5 ± 5.2 [48.0-49.0] | <.001 |
| Contralateral ventricle | 37 (9.0) | 33.4 ± 3.9 [32.1-34.7] | 59.1 ± 3.3 [58.0-60.3] | ||
| CMC | Ipsilateral ventricle | 412 (100) | 37.1 ± 5.3 [36.5-37.6] | 47.2 ± 5.2 [46.7-47.7] | |
| Contralateral ventricle | 0(0) | 0(0) |
CMC, contralateral medial canthus; IMC, ipsilateral medial canthus; MAM, midpoint between bilateral external auditory meatus; P, perpendicular to the skull.
P value represents comparisons of the puncture depth between the ipsilateral ventricle and the contralateral ventricle using a U test.
FIGURE 3.
Puncture accuracy and functional accuracy of 4 traditional puncture methods. CMC, contralateral medial canthus trajectory; IMC, ipsilateral medial canthus trajectory; MAM, midpoint between the bilateral external auditory meatus trajectory; P, perpendicular to the skull trajectory.
Puncture Accuracy and Functional Accuracy of Trajectories With Different Frontal Widths
Regarding puncture accuracy in patients with different frontal horn widths, the accuracy through the CMC trajectory remained 100%. When the frontal horn width was greater than 2.5 cm, the puncture accuracy in the P trajectory remained above 89% and the functional puncture accuracy reached 99.5% (402/404). The accuracy in the IMC and MAM trajectories increased with increasing frontal horn width. The puncture accuracy (Figure 4A) and functional puncture accuracy (Figure 4B) of the 4 puncture methods with different ventricle frontal horn widths are shown in Figure 4. In addition, for the puncture depth, the following result was obtained: P > CMC > MAM > IMC (Figure 4C).
FIGURE 4.
A, Puncture accuracy of the 4 puncture methods for different frontal horn widths; I bars indicate 95% confidence intervals. Compared with the other 3 methods, the puncture method targeting the CMC yielded the best performance, with 100% accuracy with different frontal widths. B, Functional puncture rates of the 4 puncture methods for different frontal horn widths; I bars indicate 95% confidence intervals. The CMC and the P trajectories have a high functional puncture rate with different frontal angle widths, which makes it worth recommending. C, Box diagram describing the characteristics of the puncture depth for the 4 puncture methods, which, based on the median, shows that the puncture depth is P > CMC > MAM > IMC. D, The difference in the puncture depth between the catheter located in the ipsilateral ventricle and the contralateral ventricle was extremely significant (P < .0001). The minimum depth of the ipsilateral ventricular puncture was 30.0 mm, and the maximum depth was 59.8 mm. The minimum depth of the contralateral ventricular puncture was 52.0 mm, and the maximum depth was 65.0 mm. This suggests that when cerebrospinal fluid flow is present at a depth greater than 60 mm, there is a possibility of puncturing the contralateral ventricle. When the puncture depth is greater than 65 mm and no cerebrospinal fluid flows out, the catheter should be withdrawn and the direction should be readjusted to puncture. CMC, contralateral medial canthus trajectory; IMC, ipsilateral medial canthus trajectory; MAM, midpoint between the bilateral external auditory meatus trajectory; P, perpendicular to the skull trajectory.
Comparison of the Puncture Depth Between the Ipsilateral Ventricle and the Contralateral Ventricle
The difference in the puncture depth between the ipsilateral ventricle and the contralateral ventricle was extremely significant (P < .0001); the depth of puncture to the ipsilateral ventricle in 373 patients was less than 60 mm, and the depth of puncture to the contralateral ventricle in 37 patients ranged from 52 to 65 mm (Figure 4D).
DISCUSSION
The purpose of this study was to investigate the accuracy and puncture depth of 4 freehand frontal ventriculostomy methods.
Clinical Puncture Accuracy and Analysis of Frontal Ventriculostomy
External ventricular drainage has a long history of use, with the earliest reports dating back to 1744.22 In the 1880s, the neurosurgeon Theodor Kocher identified the Kocher point, which is currently the most common entry point for placing ventricular catheters.23 The target was the frontal horn of the lateral ventricle. Because the lateral ventricle is not visible, the puncture methods described in the literature have different targets. The puncture accuracy (passing through the ipsilateral ventricle) was 63.7% to 83.1% (Table 3), but which target has a more significant advantage remains unknown. This is because these accuracies were calculated based on CT images after surgery, and when there was no cerebrospinal fluid outflow during the intraoperative puncture, the operator performed another puncture until cerebrospinal fluid outflow. Surgeons rarely abandon the puncture, which ultimately leads to similar puncture accuracies for multiple puncture methods.
TABLE 3.
Clinical Studies Evaluating Accuracy of Puncture Through Specified Trajectories
| Target landmark | Authors | Number | Puncture accuracy (%) |
|---|---|---|---|
| IMC | Huyette et al,5 2008 | 98 | 64.3 |
| Toma et al,3 2009 | 183 | 77.0 | |
| Kakarla et al,4 2008 | 346 | 76.9 | |
| Hsieh et al,19 2011 | 129 | 70.5 | |
| Mizrahi et al,6 2020 | 110 | 80.0 | |
| Pishjoo et al,1 2021 | 100 | 83.0 | |
| P | Lee et al,11 2020 | 77 | 83.1 |
| Foreman et al,13 2015 | 138 | 63.7 | |
| Spadola et al,24 2023 | 50 | 92.0 | |
| Vigo et al,25 2022 | |||
| Nasion | Abdoh et al,26 2012 | 66 | 75.8 |
| MAM | Su et al,8 2021 | ||
| CMC | Fried et al,10 2016 | ||
| Dossani et al,12 2021 | |||
| Krotz et al,27 2004 |
CMC, contralateral medial canthus; IMC, ipsilateral medial canthus; MAM, midpoint between bilateral external auditory meatus; P, perpendicular to the skull.
Owing to different surgeons' subjective perceptions of the location of the target, which also affect the accuracy of puncture, we need to simulate the puncture on CT reconstruction models to eliminate subjective biases and determine the accuracy of various puncture methods themselves.
Comparison of the Accuracy of Four Puncture Methods in Multiple Simulated Puncture Studies
There are 5 simulated puncture studies in the existing literature (Table 4).
TABLE 4.
Evaluation of the Accuracy of Trajectories Used for Simulated Puncture
| Target landmark | Authors | Total number | Catheter location | |
|---|---|---|---|---|
| Ipsilateral ventricle: no. (%) | Contralateral ventricle: no. (%) | |||
| IMC | Muirhead et al, 201221 | 10 | 1 (10) | 0 (0) |
| Raabe et al,28 2018 | ||||
| Enter point 1a | 100 | 0 (0) | 0 (0) | |
| Enter point 2a | 100 | 3 (3) | 0 (0) | |
| Park et al,29 2020 | 122 | 0 | 0 | |
| P | Muirhead et al, 201221 | 10 | 10 (100) | 0 (0) |
| Raabe et al,28 2018 | ||||
| Enter point 1a | 100 | 75 (75) | 14 (14) | |
| Enter point 2a | 100 | 54 (54) | 28 (28) | |
| Vigo et al,25 2022 | 6 | 2 (33.3) | 4 (66.7) | |
| Rehman et al,30 2013 | 202 | 137 (67.8) | 42 (20.8) | |
| CMC | Muirhead et al, 201221 | 10 | 9 (90) | |
| Park et al,29 2020 | 122 | 35 (26.5) | 97 (73.5) | |
| Raabe et al,28 2018 | ||||
| Enter point 1a | 100 | 85 (85) | 14 (14) | |
| Enter point 2a | 100 | 25 (25) | 68 (68) | |
| Nasion | Raabe et al,28 2018 | |||
| Enter point 1a | 100 | 46 (46) | 0 (0) | |
| Enter point 2a | 100 | 86 (86) | 0 (0) | |
| MP | Park et al,29 2020 | 132 | 116 (87.9) | 0 (0) |
CMC, contralateral medial canthus; IMC, ipsilateral medial canthus; MP, midpoint between bilateral medial canthus; P, perpendicular to the skull.
Entry point 1: 1 cm anterior to the coronal suture and 2 cm lateral to the midline; Entry point 2: 1 cm anterior to the coronal suture and 3 cm lateral to the midline.
The first trajectory is aimed at the IMC, which is the most commonly used puncture method in the literature. Michael Amoo et al summarized 40 papers in which 954 (68.58%) of 1391 procedures involved cannulation through the IMC,31 but the puncture accuracy was low. According to the imaging simulation study conducted by Muirhead et al on 10 patients with normal ventricles, 90% of catheter trajectories do not enter the lateral ventricles.21 The study by Raabe C et al on 50 patients with normal ventricles revealed that when the entry point was 1 cm anterior to the coronal suture and 2 cm lateral to the midline, only 3% of trajectories entered the ipsilateral ventricle, and when the entry point was 1 cm anterior to the coronal suture and 3 cm lateral to the midline, no trajectory entered the ventricle.28 The study by Park et al29 on 66 patients with normal ventricles revealed that the accuracy of cannulation was 0%. Our study revealed that the accuracy of the IMC trajectory was only 13.3%. The data do not support that trajectory. However, the clinical application accuracy reported in the literature is 64.3% to 83.0%,1,3-6,17 which may be related to the surgeon's ability to visualize the ventricle. In this study, the target of IMC trajectory was to project IMC onto the line connecting the external auditory canal (Figure 5A). The experienced surgeon might move the projection position of the IMC up near the lateral ventricle to improve the accuracy of the puncture (Figure 5B) or move the Kocher point inward to improve the accuracy of the puncture (Figure 5C). On the other hand, the surgeon might adjust the puncture angle after the first puncture failure and enter the lateral ventricle through multiple punctures, which increased the overall accuracy.32 A survey revealed that 1 surgeon performed as many as 20 punctures before entering the lateral ventricle,18 so it is not recommended that primary neurosurgeons target the IMC.
FIGURE 5.
A, The IMC target is the projection point of the ipsilateral medial canthus on the line connecting the external auditory canal, whereas the CMC target is the projection point of the contralateral medial canthus on the line connecting the external auditory canal. B, Experienced surgeons can improve the accuracy of puncture targeting IMC by moving the projection point upward near the lateral ventricle. This trajectory is close to the MAM trajectory and can achieve an accuracy of approximately 75%. C, Experienced surgeons can move the entry point inward, which can also improve the accuracy of puncture targeting the IMC (from entry point 1 to entry point 2). CMC, contralateral medial canthus trajectory; IMC, ipsilateral medial canthus trajectory; MAM, midpoint between the bilateral external auditory meatus trajectory.
The second trajectory was perpendicular to the skull. Muirhead et al reported that the accuracy of puncture through this trajectory was 100%. Raabe et al reported that when the entry point was 1 cm anterior to the coronal suture and 3 cm lateral to the midline, 75% of trajectories entered the ipsilateral ventricle and 14% entered the contralateral ventricle. The study by Rehman et al30 of 101 patients with normal ventricles revealed that 67.8% of the trajectory entered the ipsilateral ventricle and that 20.8% entered the contralateral ventricle. In our study, 90.5% of trajectories entered the frontal horn of the ipsilateral ventricle and 9.0% entered the contralateral ventricle. The difference in accuracy may be due to different entry points, but overall, the functional puncture accuracy is still around 90%. Therefore, this trajectory is recommended.
The third trajectory is the CMC trajectory, and Muirhead et al revealed that the accuracy of puncture through this trajectory was 90%. Raabe et al reported that 85% of trajectories entered the ipsilateral ventricle and 14% entered the contralateral ventricle, and Rehman et al reported that 85% entered the ipsilateral ventricle and 14% entered the contralateral ventricle. Park et al reported that 26.5% of trajectories entered the ipsilateral ventricle and 73.5% of trajectories entered the contralateral ventricle. In our study, 100% of the trajectories entered the ipsilateral ventricle. The reason for the significant difference in the data compared with the study by Park et al is that Park et al projected the CMC onto plane A, whereas our study projected the CMC onto the line connecting the binaural external auditory canal meatus. This finding indicates that projecting the CMC onto the line connecting the binaural external auditory canal will greatly improve the accuracy of the puncture. This trajectory is the most worthwhile trajectory to use, and this is consistent with the target recommended in the video “Placement of an External Ventricular Drain” published in the New England Journal of Medicine.12
The fourth trajectory is aimed at the midline anatomic marker. Raabe et al revealed that when the entry point is 1 cm anterior to the coronal suture and 2 cm lateral to the midline, with targeting the nasion, 86% of trajectories enter the ipsilateral ventricle and when the entry point is 1 cm anterior to the coronal suture and 3 cm lateral to the midline, only 46% enters the ipsilateral ventricle. Park et al reported that the midpoint of the medial canthus line was the target, with 87.9% entering the ipsilateral ventricle. Our study revealed that when the MAM was the target, 76.0% entered the ipsilateral ventricle.
Our research has shown that the accuracies of the P and CMC trajectory are high. The previous consensus recommended using the Kocher point as the entry point when the ventricular anatomy is normal and a trajectory is perpendicular to the skull or targeting the CMC to provide the highest likelihood of optimal frontal ventriculostomy,27 which is consistent with the findings of this study.
Several Suggestions for Frontal Ventriculostomy
Our study also revealed that only puncture through the P trajectory could reach the contralateral ventricle, with puncture depths of 52 to 65 mm, and that catheters inserted through the P trajectory reached the ipsilateral ventricle, with a puncture depth of less than 60 mm. Therefore, when cerebrospinal fluid flow is present at a depth greater than 60 mm, there is a possibility of puncturing the contralateral ventricle. When the puncture depth is greater than 65 mm and no cerebrospinal fluid flows out, the catheter should be withdrawn and the direction of puncture should be readjusted. In addition, this also suggests that if the ventricles shift to the opposite side, the P trajectory may be worth using. Moreover, we also found that the accuracy of puncture through the CMC trajectory through different frontal horn widths remained stable at 100%, whereas that of puncture through the IMC, MAM, and P trajectories increased as the frontal horn width increased. When the frontal horn width was less than 45 mm, the accuracy of puncture through the IMC was only 8.2% (31/378), and when it was greater than 45 mm, the accuracy through the IMC increased to 73.5% (25/34).
Limitations
There are also several important limitations in this study. First, the results of this study are applicable only to patients with normal lateral ventricular anatomy. Second, the entry point is set only as the Kocher point. If other entry points are used, the accuracy of the puncture will change. For example, the closer the entry point is to the midline, the greater the accuracy of puncture through the IMC.28 Finally, because all the participants were Chinese, there may be differences in other races. For example, the intercanthal distance in Asians is greater than that in Caucasians,33 which results in the IMC trajectory being more external in Asians than in Caucasians, so the puncture accuracy through the IMC trajectory in Asians is lower than that in Caucasians.
CONCLUSION
When the entry point was the Kocher point (1 cm anterior to the coronal suture and 2.5 cm lateral to the midline), compared with the MAM trajectory, the CMC trajectory and P trajectory were more reliable in frontal ventriculostomy, but the P trajectory may enter the contralateral ventricle. The IMC trajectory is not recommended unless the frontal horn width is greater than 45 mm or the Kocher point is moved inward.
Acknowledgments
The authors would like to thank Qinghong Huang, PhD, for his comments on the attached drawing of the article. Author Contributions: Xiaohai Chen: Project design, Data collection, Formal analysis, Writing—original draft, Writing—review and editing. Tengda Chen and Zhangkun Xie: Establish 3D models to simulate puncture, Data collection. Lunshan Xu: Project design and guidance. Zhen Qi: Formal analysis. Xieli Guo: Project guidance. All authors have read and agreed to the final version of the manuscript.
Contributor Information
Tengda Chen, Email: chentengda127@163.com.
Zhangkun Xie, Email: 515891816@qq.com.
Lunshan Xu, Email: xuliu559@163.com.
Zhen Qi, Email: qizhen1203@163.com.
Xieli Guo, Email: xieli_guo1973@163.com.
Funding
This work was supported by the Science and Technology Plan Project of Jinjiang Municipal Hospital (Shanghai Sixth People's Hospital Fujian) [2023LC04].
Disclosures
The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.
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Associated Data
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Data Availability Statement
The data are available from the corresponding author upon reasonable request.