A Radiographic Analysis of Ventricular Trajectories

doi:10.1016/j.wneu.2012.12.012

World Neurosurgery

Volume 80, Issues 1–2, July–August 2013, Pages 173-178

https://doi.org/10.1016/j.wneu.2012.12.012 Get rights and content

Background

The prevalent method of ventriculostomy placement is via freehand insertion to cannulate the ventricle at a 90° angle to the skull to get ideal placement. Our goal was to test the validity of this practice in patients without midline shift and with normal ventricular size.

Methods

This study was a virtual radiographic analysis of 3-dimensional data of skull and ventricular anatomy. Data were collected using thin-cut (1-mm) computed tomography scans of 101 randomly selected patients with normal ventricular anatomy. Virtual ventriculostomy trajectories were determined for entry from the right and left sides separately, going in at a 90° angle to the skull. Three-dimensional multiplanar reconstructions were performed using Osirix software to see where the catheter would end up within the brain.

Results

In our patient population, the mean bicaudate index was 0.14. Of the 202 perpendicular lines created from Kocher's point into the brain, 67.8% (137) of the virtual lines passed through the ipsilateral frontal horn of the lateral ventricle, 20.8% (42) passed through the contralateral ventricle, and 10.4% (21) did not pass through a ventricular space. A lower bicaudate index also leads to a greater misplacement even with a perpendicular trajectory. Pushing a catheter beyond an entry length of 6.5 cm if no cerebrospinal fluid flow has been obtained will not result in ipsilateral ventricular catheterization.

Conclusions

Our study concludes that not all catheters passed through Kocher's point using a perpendicular trajectory will end up in the ipsilateral frontal horn, and almost 10% of these catheters will be in a nonventricular space. In the instance in which a freehand pass fails to cannulate a ventricle, the safest alternative would be to make only minor adjustments to the perpendicular angle.

Introduction

Ventriculostomy placement is a common neurosurgical procedure used to measure intracranial pressure, drainage of excess cerebrospinal fluid, intraventricular instillation of drugs, and monitoring of carcinomatous and fungal meningitidis. Over the last few decades, the indications for ventricular drainage have expanded to include hydrocephalus, subarachnoid hemorrhage, Reye syndrome, central nervous system bacterial infections, intracranial hemorrhage, intracranial hypertension, and traumatic brain injury (TBI) (7). In the past, ventriculostomies usually were performed on patients who had large ventricles or hydrocephalus. Those performed on patients with small ventricular anatomy were done for elective reasons, and stereotactic equipment could be used with the luxury of time. With the advent of Brain Trauma Foundation guidelines for monitoring patients with severe TBI (2) and the Clot Lysis: Evaluating Accelerated Resolution of Intraventricular Hemorrhage (CLEAR IVH) (3) trial, it has become apparent that several ventriculostomy procedures now need to be performed on patients without hydrocephalus in an emergent manner at the bedside.

Despite all of the data showing a high rate of misplacement with a freehand technique 5, 6, 13, the prevalent method of ventriculostomy placement continues to be via freehand insertion using surface anatomical landmarks. Although extraventricular drain complications have been studied thoroughly, the accuracy of extraventricular drain positioning has been audited only occasionally. Both residents and practicing neurosurgeons admit to frequently using multiple passes and frequent catheter misplacement 10, 11. It is common practice to attempt cannulation of the ventricle at a 90° angle to the skull to get ideal placement in the ipsilateral frontal horn of the lateral ventricle near the foramen of Monro. From the available data, it is apparent that cannulating ventricles in patients with hydrocephalus or with a large bicaudate index (BCI) is easier, with a higher success rate (13). The BCI is defined as the ratio of the width of both lateral ventricles at the level of the heads of the caudate nuclei to the distance between the inner tables of the skull at the same level. Therefore, the challenge of placing ventriculostomy catheters is usually in patients with a small to normal BCI. Our study aims to test the validity of the traditional teaching that in patients with normal ventricular size and no midline shift, the use of the Ghajar guide or of surface landmarks to obtain a perpendicular pass into the ventricle is indeed the best option. We also analyze the previous studies performed that display the current experience regarding the accuracy of ventriculostomy procedures.

Section snippets

Methods

Our study is an analysis of data obtained from virtual radiographic 3-dimensional (3D) skull and ventricular anatomy. No ventriculostomy was performed on real patients. Data were collected using thin-cut (1-mm) computed tomography (CT) scans of 101 randomly selected adult patients with normal ventricular anatomy. Virtual ventriculostomy trajectories were determined for entry from the right and left sides separately, going in at a 90° angle to the skull. A software plug-in was created for the

Results

Data were collected using thin-cut (1-mm) CT scans of the head of 101 randomly selected patients with normal ventricular anatomy. In our patient population, the mean BCI, which is the ratio of the width of both lateral ventricles at the level of the heads of the caudate nuclei to the distance between the inner tables of the skull at the same level, was 0.14. Mean catheter entry length, combined for both left and right sides, was 5.41 cm (SD 0.573, range 3.8 to 7.1 cm).

Ideal ventriculostomy

Discussion

In 1985, Dr. Ghajar described a novel device that allowed catheterization of the ventricles by making a pass perpendicular to the calvarium (4). He reported CSF flow with the first attempt for all patients. A postplacement imaging confirmation was obtained on 11 of the 17 patients, demonstrating ipsilateral frontal horn placement. In 2000, O'Leary et al. (10) also reported use of the Ghajar guide vs a freehand technique and found that although the clinical significance of improved cannulation

Conclusions

Our study is unique in concept and execution. It provides evidence-based recommendations to deal with a common neurosurgical dilemma that accosts multiple practicing neurosurgeons and residents daily and can lead to devastating complications. We provide a simple, cost-effective, and convenient solution that can impact tens of thousands of people annually. An important limitation of our study is its virtual nature, thus eliminating human error. For this reason it would be difficult to compare

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S.L. Bratton et al.
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B.R. O'Neill et al.
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W.A. Friedman et al.
Percutaneous tunnel ventriculostomy: summary of 100 procedures
J Neurosurg
(1980)
J.B. Ghajar
A guide for ventricular catheter placement. Technical note
J Neurosurg
(1985)
D.R. Huyette et al.
Accuracy of the freehand pass technique for ventriculostomy catheter placement: retrospective assessment using computed tomography scans
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There are more references available in the full text version of this article.

Cited by (30)

Ventriculoperitoneal shunt entry points in patients undergoing shunt placement: A single-center study
2024, World Neurosurgery: X
The ventriculoperitoneal (VP) shunt redirects cerebrospinal fluid flow, with the selection of entry points crucial for optimal outcomes. Anatomical landmarks and specific entry points, such as Kocher's, Frazier's, Keen's, and Dandy's points, have been utilized for shunt catheter placement. This study investigates the impact of various entry points on outcomes, particularly the necessity for revision procedures, in patients undergoing VP shunt placement.
In this retrospective cohort study, we analyzed data from patients in our center's database, collected from October 2017 to October 2022. Participants were classified based on ventriculoperitoneal shunt entry points. The study followed STROBE guidelines. Continuous variables were presented as means with standard deviations (SD) and categorical variables as frequencies and percentages. Linear Model ANOVA and Pearson's Chi-squared tests were used for comparisons. Data analysis was conducted using Jamovi software.
Our study included 94 patients who underwent shunt procedures. The patients were categorized into four treatment groups: Dandy point (10), Frazier point (21), Keen point (43), and Kocher point (20).
Our study found no significant differences in age, FOHR, and indication for shunt placement among catheter entry point subgroups. However, gender distribution, catheter length, and catheter tip location significantly varied. The proportion of patients requiring revision surgery varied among the groups, with the highest rate in the Dandy point group and the lowest in the Keen group; however, the difference among the entry groups was insignificant.
Morphometric analysis of Kocher's and Frazier's points in a small sample taken from the South African scaphocephalic paediatric population: A preliminary study
2022, Translational Research in Anatomy
Citation Excerpt :
A ventriculostomy is a routinely used emergency neurosurgical procedure that entails the drilling of a burr hole into the skull and the subsequent catheterization of one of the ventricles of the brain for diagnostic or therapeutic purposes in ICP monitoring and CSF drainage [13,14]. Common indications for emergency ventricular access include hydrocephalus, ICH, subarachnoid and intracranial haemorrhage, and traumatic brain injury [13,15,16]. A ventriculostomy is usually performed freehand using cranial surface anatomical landmarks to identify the optimal entry site for ventricular cannulation [13].
Due to varying cranial morphologies, ventricular access in patients with craniosynostosis using conventional techniques is often a challenge. Although ventricular access may not be frequently required in scaphocephalic patients, it is vital that an ideal location of the access points be established for safe ventricular catheterization. This study aimed to document the morphometry of commonly used ventricular access points, i.e. Kocher's and Frazier's points, within a select South African scaphocephalic paediatric population.
The craniometric dimensions of Kocher's and Frazier's points were measured relative to anatomical and craniometric landmarks on pre-operative computed tomography scans of 24 consecutive patients diagnosed with scaphocephaly between 2014 and 2020. Results were compared against age, sex, population group and the degree of severity of the deformity.
Kocher's point was located between 91.6 mm and 140.0 mm posterior to the nasion, and between 20.5 mm and 34.6 mm lateral to the midline. Statistically significant increases were reported in the mean distance posterior to nasion between patients in the <1 year and older age groups (>1-<9 years) (ANOVA, p < 0.001); and in the mean distance lateral to the midline (ANOVA, p = 0.004), between patients in the <1 year and 3-<6-year (post-hoc, p = 0.002) and 1-<3-year and 3-<6-year (post-hoc, p = 0.030) age groups, respectively. Frazier's point was located between 60.9 mm and 82.8 mm superior to the inion, and 25.9 mm and 41.4 mm lateral to the midline. No statistically significant differences were documented for comparisons by sex, population group and degree of severity in the tested sample.
The study found that the traditional landmarks used for ventricular access can be unreliable in scaphocephalic patients, particularly in those less than one year of age. Parameters measured in the anteroposterior plane were more affected than those measured lateral from the midline. This study provides novel morphometric data for neurosurgical consideration regarding ventricular catheterization procedures in scaphocephalic patients.
Ideal trajectory for frontal ventriculostomy: Radiological study and anatomical study
2022, Clinical Neurology and Neurosurgery
Citation Excerpt :
Until today, no rapid, reliable, practical, and inexpensive method, that could replace freehand ventriculostomy, has been found. [21] Indeed the freehand technique with a perpendicular trajectory to outer cranial table is the most commonly used. [1,7–11,13,17,22,31,32] Althought the anatomical landmarks, needed to establish the perpendicular path, are covered by surgical drapes and, sometimes, difficult to locate during the catheter insertion, therefore, the perfect trajectory toward the target point is challenging to obtain.
Several techniques have been described to improve the accuracy of the freehand procedure for frontal ventriculostomy and reduce complications due to suboptimal placement or misplacement of the catheter tip. To date, none of the available studies have found a reliable, low cost and consistent technique. We aimed to provide a standardized protocol for freehand frontal ventriculostomy.
In the first part of the radiological study, 125 CT scans were used to measure the length of the catheter using 2 right-sided entry points. In the second part, a grid of 24 entry points on the frontal bone was used in 50 CT scans to record the distance from the cranial surface to the Foramen of Monro (FM). Ventriculostomy was performed on six cadaveric heads using a grid of 9 entry points, comparing a 5 ml syringe with the freehand technique to reach the target.
The first part of the radiological study showed a length from the cranial surface to the FM was overall 67,38 ± 1,03 mm. For the second part, the mean length of the 24 selected points was 68,54 ± 2,73 mm without statistical difference. In the anatomical study, the FM was reached 8 times (14.8%) with the syringe vs 31 times (57.4%) with the freehand technique, and the ventricles 43 (79.6%) vs 37 (68.5%). The mean lengths from the skull to the FM were 71.33 ± 4.21 mm.
In this study, we showed the optimal length of a frontal ventricular catheter. We have also demonstrated that the portion of the frontal bone above the superior temporal lines matches a sphere in which the center is the FM.
Orthogonal external ventricular drain (EVD) trajectory from burr holes sited by junior neurosurgical staff is superior to freehand placement: An in-silico model
2021, Journal of Clinical Neuroscience
Citation Excerpt :
The skull and the lateral ventricles are organised in a concentric manner, therefore a tangent drawn to the skull, is also a tangent corresponding to the position of the ventricle. A trajectory perpendicular to this tangent will provide optimal placement of the EVD catheter, as compared to other landmark based methods [2,15–18]. There have been previous attempts to create simple guidance devices to enhance the accuracy of EVD placement using this principle [19,20].
External ventricular drain (EVD) or ventriculostomy placement is one of the most common neurosurgical procedures performed worldwide and is associated with complications including haemorrhage, malposition and infection. Several authors have attempted to define an ideal trajectory for placement, and scalp-mounted guidance devices have been devised to exploit the theoretical ideal orthogonal trajectory from the scalp to the lateral ventricles. However, uptake has been limited due to lack of demonstrated superiority to freehand placement. Previous modelling studies have failed to include a true-to-life sample of patients undergoing EVD insertion and excluded cases with midline shift or non-hydrocephalus indications. Further, none have attempted to model the orthogonal insertion of EVD via actual burr holes placed by junior neurosurgical staff. In our report of 58 cases of frontal EVD insertion in a low-volume Australian neurosurgical unit freehand EVD insertion resulted in acceptable placement in the ipsilateral frontal horn in 62% of cases, any ventricle in 22%, and in eloquent or non-eloquent brain in 16% of cases. The modelled orthogonal trajectory from the same burr holes, using post-procedural computed tomography scans and the S8 Stealth Station (Medtronic), resulted in superior placement; 80% in the ipsilateral frontal horn and 20% contralateral (p = 0.007). There were no significant malpositions associated with the modelled trajectories. In our series, 18% of freehand catheters required multiple placement attempts. In conclusion, our data suggests that an orthogonal trajectory may result in improved EVD positioning compared to freehand placement.
Common Trajectories for Freehand Frontal Ventriculostomy: A Systematic Review
2021, World Neurosurgery
Citation Excerpt :
Gautschi et al.24 performed ventriculostomy on cadaver heads and recorded intraventricular placement in 36 of 52 (69%) cases when adhering to the technique described by Friedman and Vries25 targeting the IMC. Rehman et al.26 described a 67.8% rate of catheterization of the ipsilateral lateral ventricle when passing the catheter perpendicular to the skull and notably only a 10.4% rate of extraventricular placement; the remaining 20.8% catheterized the contralateral ventricle. Park et al.27 radiologically assessed 66 normal CT scans, and evaluated the accuracy of 3 separate targets in the coronal plane; the IMC, CMC, and midpoint between the bilateral medial canthi (MP) against a sagittal trajectory toward the external auditory meatus.
Freehand ventriculostomy is one of the most commonly performed neurosurgical procedures. While a variety of approaches have been described, frontal via Kocher's point is the most common. Multiple trajectories have been described, but no consensus exists as to the most efficacious. Our objective was to assess the literature regarding trajectories for frontal ventriculostomy and their associated success rates and complications.
We performed a systematic review of the literature, querying the PubMed/MEDLINE database with the search term “(EVD OR extra-ventricular drain OR ventriculostomy OR external ventricular drain) AND (hand OR freehand OR bedside)” and reported the characteristics and findings of both simulation and clinical studies according to trajectory and catheter position. Final catheter tip position was graded on the Kakarla scale.
A total of 198 abstracts were screened; 40 full papers were assessed. Sixteen were included, 11 of which were clinical studies and 5 of which were simulation studies. Six studies coronally targeted the ipsilateral medial epicanthus (IMC), 4 utilized an orthogonal trajectory (P), and 1 targeted the naison (N). Ideal placement (Kakarla grade 1) was achieved in 954 of 1391 (68.58%) procedures when the IMC was targeted versus 243 of 354 (70.43%) when P was targeted. Potentially harmful (Kakarla grade 3) placement was observed in 142 of 1391 (10.21%) procedures when the IMC was targeted and 20 of 345 (5.80%) when P was targeted. All 5 simulation studies found the IMC target to be inferior.
The IMC is the most prevalent trajectory for frontal ventriculostomy but no target is demonstrably superior. More robust clinical research is required to determine the optimal trajectory.
Predicting the Ideal Ventricular Freehand Pass Trajectory Using Osirix Software and the Role of Occipital Shape Variations
2020, World Neurosurgery
Cannulation of lateral ventricles via a posterior approach is a common neurosurgical procedure. It is often believed that a single entry and fiducial point applies to all. No importance is given to skull shape variations, which can lead to wrong shunt positions and revisions.
A virtual-reality study was conducted to find the ideal entry point, ideal forehead fiducial point, and ideal angulation of the ventricular catheter and variations in these with changes in skull shapes.
Fifty human cadaveric skulls were used to measure anteroposterior (AP) diameter and width and to classify shape of skulls into 4 types. Hydrocephalus (100 cases) and normal magnetic resonance images (50 cases) were studied from a PACS (Picture Archiving and Communication System) database. An Osirix DICOM Viewer (3.9.4) was used to reconstruct the images and estimate the ideal, 90°, and midline shunt trajectory and correlate the same with AP/width ratios and skull shapes.
Contrary to popular practice, the vertical distance from the inion for ideal trajectory placement was <6 cm and >4 cm in all shapes and ratio groups for hydrocephalus and nonhydrocephalus cases, respectively. As the AP/width ratio increases, the fiducial needs to be placed at a higher distance from the nasion and the distance of the entry point also increased from the inion. A rounder or more dolichocephalic skull dictates a 90° approach to be better, especially as the first pass.
No magical external entry point uniformly applicable for all cases exists. Hence, there is a need to classify skulls according to shapes/ratios and to use a tailored approach for a freehand pass to cannulate the ventricles.

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: Conflict of interest statement: The first author of this article (T.R.) is also the CEO of ARC Surgicals, a company that holds the patent for a ventriculostomy guidance system.

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Peer-Review ReportA Radiographic Analysis of Ventricular Trajectories

Background

Methods

Results

Conclusions

Introduction

Section snippets

Methods

Results

Discussion

Conclusions

Complications of intracranial pressure monitoring in children with head trauma

J Neurosurg

Guidelines for the management of severe traumatic brain injury

J Neurotrauma

A survey of ventriculostomy and intracranial pressure monitor placement practices

Surg Neurol

Percutaneous tunnel ventriculostomy: summary of 100 procedures

J Neurosurg

A guide for ventricular catheter placement. Technical note

J Neurosurg

Accuracy of the freehand pass technique for ventriculostomy catheter placement: retrospective assessment using computed tomography scans

J Neurosurg

Peer-Review Report
A Radiographic Analysis of Ventricular Trajectories