Cine phase-contrast MR images failed to predict clinical outcome following ETV

The Predictive Role of Early Postoperative Magnetic Resonance Imaging After Endoscopic Third Ventriculostomy

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is a treatment option for obstructive hydrocephalus; reported success rates vary. We investigated immediate postoperative magnetic resonance imaging to evaluate the role of imaging parameters associated with outcomes.

METHODS

Retrospective chart review was performed on patients undergoing initial ETV between 2005 and 2019. Patients with preoperative and postoperative magnetic resonance imaging with follow-up>one year were included. The following were noted: changes in subarachnoid cerebrospinal fluid, third ventricle diameter, bowing of the third ventricle floor, and postoperative flow void. Kaplan-Meier survival methods were used to assess ETV success and univariable and multivariable Cox proportional-hazards models were fitted to assess factors contributing to ETV success.

RESULTS

Fifty-eight subjects were included. Nineteen (32.8%) experienced failure within one year; individually, no single imaging parameter predicted success. However, all cases of failure had no identifiable flow void. Any postoperative radiological change was not consistently associated with decreased odds of failure. Obstructive hydrocephalus treated with ETV demonstrated significantly better ETV success than patients treated with nonobstructive hydrocephalus. Interobserver reliability was moderate for 2 of the radiological variables and substantial for 1 of the radiological variables.

CONCLUSIONS

Individually, none of the qualitative radiologic parameters measured in our study predicted ETV success. Absence of a flow void predicted ETV failure, but additional studies are needed to determine its true negative predictive value. Inability to clarify which specific parameter predicts success reflects the limited role of immediate postoperative imaging in influencing clinical management.

Comparative Outcome Analysis of Endoscopic Third Ventriculostomy and Ventriculoperitoneal Shunt Surgery in Pediatric Hydrocephalus: An Experience of a Tertiary Care Center

Background  Endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt surgery (VPS) are used for the surgical management of pediatric hydrocephalus. There is controversy regarding the safety and efficacy of these procedures according to age, etiologies, and type of hydrocephalus.

Objective  The purpose of this study was to compare the outcomes and complications of ETV and VPS in pediatric hydrocephalus and to evaluate the better procedure.

Material and Methods  We retrospectively analyzed the pediatric hydrocephalus cases that were operated by ETV and VPS at our department from June 2016 to June 2019. Data were analyzed with respect to the etiology of hydrocephalus, age, and gender of the patients. We compared the outcomes (success and failure) depending on age at surgery, etiology, and type of hydrocephalus, complications at 12 months of follow-up. Fisher's exact test and chi-square test were applied to test the significance of difference.

Results  There were 195 pediatric hydrocephalus cases, which were operated by ETV ( n  = 43; 22.05%) and VPS ( n  = 152; 77.95%). The mean age of the cases was 53.63 ± 60.24 (ranged 0.5–204 months) in the ETV group and 53.44 ± 54.10 (ranged 0.3–210 months) in the VPS group. The male-to-female ratio was 1.41:1 in the ETV group and 1.21: 1 in the VPS group. Overall, ETV had successful outcomes in 30(69.77%) cases and VPS in 102(67.11%) cases at 12 months of follow-up. The complication rates were found in 7 (16.28%) cases in the ETV group and 38 (25.0%) cases in the VPS group. At initial 0.5 months of follow-up, ETV required revisions in 6 (13.95%) cases and VPS in 15 (9.87%) cases.

Conclusion  Although the success and failure of both the procedure vary according to the age at surgery, etiology and type of hydrocephalus, and complications, and failure rates on follow-up, there were no statistically significant differences between the two surgical groups in respect to these variables.

Endoscopic Third Ventriculostomy - A Review

BACKGROUND

Endoscopic third ventriculostomy (ETV) has become a proven modality for treating obstructive and selected cases of communicating hydrocephalus.

OBJECTIVE

This review aims to summarize the indications, preoperative workup, surgical technique, results, postoperative care, complications, advantages, and limitations of an ETV.

MATERIALS AND METHODS

A thorough review of PubMed and Google Scholar was performed. This review is based on the relevant articles and authors' experience.

RESULTS

ETV is indicated in obstructive hydrocephalus and selected cases of communicating hydrocephalus. Studying preoperative imaging is critical, and a detailed assessment of interthalamic adhesions, the thickness of floor, arteries or membranes below the third ventricle floor, and prepontine cistern width is essential. Blunt perforation in a thin floor, while bipolar cautery at low settings and water jet dissection are preferred in a thick floor. The appearance of stoma pulsations and intraoperative ventriculostomography reassure stoma and basal cistern patency. The intraoperative decision for shunt, external ventricular drainage, or Ommaya reservoir can be taken. Magnetic resonance ventriculography and cine phase-contrast magnetic resonance imaging can determine stoma patency. Good postoperative care with repeated cerebrospinal fluid drainage enhances outcomes in selected cases. Though the complications mostly occur in an early postoperative phase, delayed lethal ones may happen. Watching live surgeries, assisting expert surgeons, and practicing on cadavers and models can shorten the learning curve.

CONCLUSION

ETV is an excellent technique for managing obstructive and selected cases of communicating hydrocephalus. Good case selection, methodical technique, and proper training under experts are vital.

Assessment of third ventriculostomy patency with the 3D-SPACE technique: a preliminary multicenter research study

OBJECT

The goal of this study was to determine the value of the 3D sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) technique in the evaluation of endoscopic third ventriculostomy (ETV) patency.

METHODS

Twenty-six patients with ETV were examined using 3-T MRI units. Sagittal-plane 3D-SPACE with variant flip-angle mode, 3D T1-weighted (T1W), and 3D heavily T2-weighted (T2W) images were obtained with isotropic voxel sizes. Also, sagittal-axial plane phase-contrast cine (PC)-MR images were obtained. The following findings were evaluated: diameters of stoma and third ventricle, flow-void sign on 3D-SPACE and PC-MR images, integrity of the third ventricle on heavily T2W images, and quantitative PC-MRI parameters of the stoma. Obtained sequences were evaluated singly, in combination with one another, and all together.

RESULTS

The mean area, flow, and velocity values measured at the level of stoma in patients with patent stoma were significantly higher than those measured in patients with closed stoma (p < 0.05). There was significant correlation among PC-MRI, 3D-SPACE, and 3D heavily T2W techniques regarding assessment of ETV patency (p < 0.001). The 3D-SPACE technique provided the lowest rate of ambiguous results.

CONCLUSIONS

The 3D-SPACE technique seems to be the most efficient one for determination of ETV patency. The authors suggest the use of 3D-SPACE as a stand-alone first-line sequence in addition to routine brain MRI protocols in assessing patients with ETV, thereby decreasing scan time and reserving the use of a combination of additional sequences such as PC-MRI and 3D heavily T2W images in suspicious or complex cases.

Infundibular Recess Angle Reduction After Endoscopic Third Ventriculostomy: Does It Reflect Clinical Success?

BACKGROUND

Although the ventricular size is significantly reduced after endoscopic third ventriculostomy (ETV) in most successfully treated patients, ventricular size reduction is not always seen after a successful ETV. Practical and reliable radiologic parameters are still needed to assess the clinical success of an ETV.

METHODS

We retrieved the clinical and radiologic data of patients who underwent an ETV. Patients with the following criteria were included: (1) preoperative magnetic resonance imaging studies available, (2) postoperative magnetic resonance imaging studies done within the first 2 postoperative weeks, and (3) the infundibular recess clearly visible on preoperative and postoperative sagittal magnetic resonance imaging. Preoperative and postoperative measurements of the angle of the infundibular recess of the third ventricle were performed on midsagittal T1-weighted, T2-weighted, fast imaging employing steady-state acquisition, or constructive interference in steady state images.

RESULTS

The extent of reduction of the infundibular recess angle predicted the clinical outcome of ETV during the early postoperative period with a high degree of accuracy. The average reduction was about 48% in successful procedures versus only 15% in failed procedures.

CONCLUSIONS

The degree of reduction of the angle of the infundibular recess of the third ventricle correlated with the amount of third ventricular decompression after ETV. Most importantly, such a reduction was noted to occur during the early postoperative period when radiologic changes are less pronounced. Assessment of change in infundibular recess angle measurement is easy to perform and may prove helpful in cases with no clear-cut clinical evidence of success of ETV.

Quantitative analysis of intraspinal cerebrospinal fluid flow in normal adults

The present study quantitatively analyzed intraspinal cerebrospinal fluid flow patterns in 19 normal adults using fast cine phase-contrast magnetic resonance imaging. Results showed increased downward flow velocity and volume compared with upward flow, and the average downward flow volume of intraspinal cerebrospinal fluid decreased from top to bottom at different intervertebral disc levels. Upward and downward cerebrospinal fluid flow velocity reached a peak at the thoracic intraspinal anterior region, and velocity reached a minimum at the posterior region. Overall measurements revealed that mean upward and downward flow volume positively correlated with the subarachnoid area. Upward peak flow velocity and volume positively correlated with spinal anteroposterior diameter. However, downward peak flow velocity and volume exhibited a negative correlation with spinal anteroposterior diameter. Further flow measurements showed that flow velocity in upward and downward directions was associated with subarachnoid anteroposterior diameter, respectively. The present experimental results showed that cerebrospinal fluid flow velocity and volume varied at different intraspinal regions and were affected by subarachnoid space area and anteroposterior diameter size.

An innovative approach to investigate the dynamics of the cerebrospinal fluid in the prepontine cistern: A feasibility study using spatial saturation-prepared cine PC-MRI

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An innovative sat-pulse based cine PC-MRI to investigate complex CSF dynamic.

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Compared to conventional sequence and validated in the PPC of hydrocephalus patients.

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No compromise neither on temporal nor on spatial resolution.

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Compared to conventional exam: the PPC has same area but lower flow stroke volume.

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It contributes to a better follow-up of patients with altered CSF circulation.

Purposes

Accurate measurements of the cerebrospinal fluid that flows through the prepontine cistern (PPC) are challenging due to artefacts originating from basilar artery blood flow. We aim to accurately quantify cerebrospinal fluid (CSF) flow and stroke volume in the PPC, which is essential before endoscopic third ventriculostomy.

Materials and methods

We developed a new PC-MRI sequence prepared with Hadamard saturation bands to accurately quantify CSF flow in the PPC by suppressing the blood signal in the surrounding vessels. In total, 28 adult hydrocephalic patients (age 59 ± 20 years) were scanned using conventional PC-MRI and our developed sequence. CSF was separately extracted from the PPC and the foramen of Magendie, and flow (min and max) and stroke volume were quantified.

Results

Our modifications result in a complete deletion of signal from flowing blood, resulting in significantly reduced CSF stroke volume (Conv = 446 ± 113 mm³, Dev = 390 ± 119 mm³, p = 0.006) and flow, both minimum (Conv = −1630 ± 486 mm³/s, Dev = −1430 ± 406 mm³/s, p = 0.005) and maximum (Conv = 2384 ± 657 mm³/s, Dev = 1971 ± 62 mm³/s, p = 0.002) compared with the conventional sequence, whereas no change in the area of interest was noted (Conv = 236 ± 65 mm², Dev = 249 ± 75 mm², p = 0.21).

Conclusions

Accurate and reproducible CSF flow and stroke volume measurements in the PPC can be achieved with sat-band prepared cine PC-MRI.

Usefulness of intraoperative magnetic resonance ventriculography during endoscopic third ventriculostomy

BACKGROUND

Endoscopic third ventriculostomy (ETV) is the preferred method for the treatment of noncommunicating hydrocephalus. The different success rates of ETV indicate the difficulties in predicting the success of this procedure.

OBJECTIVE

To show the usefulness of intraoperative ventriculography performed by the low-field 0.15-T magnetic resonance imager Polestar N20 during ETV.

METHODS

The study was conducted in 11 patients with noncommunicating hydrocephalus caused by tumors or cysts of the third ventricle (n = 5), nontumoral stenosis of the sylvian aqueduct (n = 3), and fourth ventricle outlet obstruction (n = 3). Intraoperative magnetic resonance (iMR) ventriculography was performed before and after the ETV.

RESULTS

In each case, iMR-ventriculography was a safe procedure and determined the exact site of obstruction of cerebrospinal fluid flow. In all cases, iMR-ventriculography performed after ETV showed with the greatest accuracy the patency of the performed fenestrations, demonstrating in 9 patients good flow of the contrast from the third ventricle to the basal cisterns, restricted flow in 1 patient, and no flow in 1 patient. The results of ventriculography were consistent with the postoperative neurological status of operated-on patients. In 3 patients, the opinion of the surgeons about the patency of endoscopic fenestration, based on intraoperative observation of the third ventricle floor, was inconsistent with the results from iMR-ventriculography.

CONCLUSION

Low-field iMR-ventriculography is a safe procedure that can be successfully applied during ETV to determine the site of obstruction in hydrocephalus and the patency of performed ventricle fenestration.

Endoscopic third ventriculostomy

Endoscopic third ventriculostomy (ETV) is considered as a treatment of choice for obstructive hydrocephalus. It is indicated in hydrocephalus secondary to congenital aqueductal stenosis, posterior third ventricle tumor, cerebellar infarct, Dandy-Walker malformation, vein of Galen aneurism, syringomyelia with or without Chiari malformation type I, intraventricular hematoma, post infective, normal pressure hydrocephalus, myelomeningocele, multiloculated hydrocephalus, encephalocele, posterior fossa tumor and craniosynostosis. It is also indicated in block shunt or slit ventricle syndrome. Proper Pre-operative imaging for detailed assessment of the posterior communicating arteries distance from mid line, presence or absence of Liliequist membrane or other membranes, located in the prepontine cistern is useful. Measurement of lumbar elastance and resistance can predict patency of cranial subarachnoid space and complex hydrocephalus, which decides an ultimate outcome. Water jet dissection is an effective technique of ETV in thick floor. Ultrasonic contact probe can be useful in selected patients. Intra-operative ventriculo-stomography could help in confirming the adequacy of endoscopic procedure, thereby facilitating the need for shunt. Intraoperative observations of the patent aqueduct and prepontine cistern scarring are predictors of the risk of ETV failure. Such patients may be considered for shunt surgery. Magnetic resonance ventriculography and cine phase contrast magnetic resonance imaging are effective in assessing subarachnoid space and stoma patency after ETV. Proper case selection, post-operative care including monitoring of ICP and need for external ventricular drain, repeated lumbar puncture and CSF drainage, Ommaya reservoir in selected patients could help to increase success rate and reduce complications. Most of the complications develop in an early post-operative, but fatal complications can develop late which indicate an importance of long term follow up.

The constant flow ventricular infusion test: a simple and useful study in the diagnosis of third ventriculostomy failure

Object

The evaluation of third ventriculostomy function in hydrocephalic patients is challenging. The utility of the constant flow infusion test in predicting response to shunt insertion in normal-pressure hydrocephalus, as well as in identifying shunt malfunction, has been previously demonstrated. The object of this study was to evaluate its usefulness in determining whether a revision CSF diversion procedure was indicated in patients presenting with recurring symptoms and persisting ventriculomegaly after endoscopic third ventriculostomy (ETV).

Methods

The authors conducted a prospective study of all patients who, after undergoing ETV at their institution, presented postoperatively with recurring symptoms and persisting ventriculomegaly.

Results

Forty-six patients (mean age 40.7 years, including 11 patients younger than 18 years) underwent 56 constant flow ventricular infusion tests (VITs) at a mean of 24.7 months post-ETV. Thirty-three patients with resistance to CSF outflow (Rout) less than 13 mm Hg/ml/min underwent follow-up (median 17 months) and experienced resolution of symptoms. In 10 episodes Rout was greater than 13 mm Hg/ml/min; the patients in these cases underwent revisional CSF diversion. Two patients demonstrated high and frequent B (slow) waves despite a low Rout; these patients also underwent successful revisions. Patients who improved after surgery had increased B wave activity in the plateau phase of the VIT (p = 0.01). Thirty-four patients underwent MR imaging at the same time; 4 had high Rout despite evidence of flow across the stoma. These 4 patients underwent surgery and experienced resolution of symptoms. Of 9 patients without flow, Rout was less than 13 mm Hg/ml/min in 4; these patients were successfully treated conservatively.

Conclusions

The VIT is a useful and safe adjunct to clinical and MR imaging evaluation when ETV failure is suspected.

The pulsating brain: A review of experimental and clinical studies of intracranial pulsatility

The maintenance of adequate blood flow to the brain is critical for normal brain function; cerebral blood flow, its regulation and the effect of alteration in this flow with disease have been studied extensively and are very well understood. This flow is not steady, however; the systolic increase in blood pressure over the cardiac cycle causes regular variations in blood flow into and throughout the brain that are synchronous with the heart beat. Because the brain is contained within the fixed skull, these pulsations in flow and pressure are in turn transferred into brain tissue and all of the fluids contained therein including cerebrospinal fluid. While intracranial pulsatility has not been a primary focus of the clinical community, considerable data have accrued over the last sixty years and new applications are emerging to this day. Investigators have found it a useful marker in certain diseases, particularly in hydrocephalus and traumatic brain injury where large changes in intracranial pressure and in the biomechanical properties of the brain can lead to significant changes in pressure and flow pulsatility. In this work, we review the history of intracranial pulsatility beginning with its discovery and early characterization, consider the specific technologies such as transcranial Doppler and phase contrast MRI used to assess various aspects of brain pulsations, and examine the experimental and clinical studies which have used pulsatility to better understand brain function in health and with disease.

Endoscopic minimally invasive neurosurgery: emerging techniques and expanding role through an extensive review of the literature and our own experience - part I: intraendoscopic neurosurgery

BACKGROUND/AIMS

Minimally invasive neurosurgery is a growing field, more so in recent decades. The modernization of tools, especially the endoscope, has allowed for critical improvements and crucial advancements in minimally invasive neurosurgery. The current classification scheme for endoscopic procedures needs to be updated to reflect these advancements.

METHODS

Although the field of neuroendoscopy is continually evolving, the terminologies utilized to describe endoscopic procedures reflect and favor its use as mostly an assisting device complementing the microscope. Even though the classification was adequate for its time, it has become inexact and therefore confusing. We therefore propose a new classification scheme that encompasses the growing independence of endoscopic minimally invasive neurosurgery (EMIN) as well as the changing landscape within EMIN procedures.

RESULTS

We have classified our EMIN procedures, since 2002, as either 'intraendoscopic' (IEN) or 'extraendoscopic' (XEN) in relation to the endoscope's axis. Exemplary cases of IEN and a review of the literature are presented as well.

CONCLUSION

Our proposed classification scheme for solely endoscopic procedures is presented. The role of the endoscope as an independent tool is clarified.

Role of interpeduncular and prepontine cistern cerebrospinal fluid flow measurements in prediction of endoscopic third ventriculostomy success in pediatric triventricular hydrocephalus

AIM

The aim of the present study was to evaluate the correlation of the clinical success of the endoscopic third ventriculostomy (ETV) procedure with the measurements of cerebrospinal fluid (CSF) flow through the interpeduncular and prepontine cisterns in pediatric triventricular hydrocephalus.

METHODS

51 children (age range: 25-201 months; mean: 55.3 months) with primary aqueductal stenosis who have been treated with ETV were included in the study. All patients were analyzed by conventional and cine magnetic resonance imaging (MRI) before and after endoscopic treatment. Both the stroke volume and the flow velocity of CSF in the interpeduncular and prepontine cisterns were evaluated. The MRI findings were correlated with clinical outcome. Simple descriptive and independent t tests were used for statistical analyses, and receiver operating characteristic curve analysis was used for the cutoff value of the 'flow index' (FI).

RESULTS

Among the 51 patients, 37 patients (72.5%) responded to ETV clinically during long-term follow-up. A further analysis was made for the prediction of who would respond to ETV, using the formula (stroke volume of prepontine cistern/stroke volume of interpeduncular cistern) ×100, which was defined as the FI. Early postoperative FI values of over 40% were significantly correlated with ETV success.

CONCLUSION

Our results suggest that ETV success can be predicted by the ratio of early CSF stroke volume values of the interpeduncular and prepontine cisterns.