Is all "communicating" hydrocephalus really communicating? Prospective study on the value of 3D-constructive interference in steady state sequence at 3T

The presence of a foramen of Luschka in the American alligator (Alligator mississippiensis) and the continuity of the intraventricular and subdural spaces

In humans and most mammals, there is a notch-like portal, the foramen of Luschka (or lateral foramen), which connects the lumen of the fourth ventricle with the subdural space. Gross dissection, light and scanning electron microscopy, and μCT analysis revealed the presence of a foramen of Luschka in the American alligator (Alligator mississippiensis). In this species, the foramen of Luschka is a notch in the dorsolateral wall of the pons immediately caudal to the peduncular base of the cerebellum, near the rostral end of the telovelar membrane over the fourth ventricle. At the foramen of Luschka there was a transition from a superficial pia mater lining to a deep ependymal lining. There was continuity between the lumen of the fourth ventricle and the subdural space, via the foramen of Luschka. This anatomical continuity was further demonstrated by injecting Evans blue into the lateral ventricle which led to extravasation through the foramen of Luschka and pooling of the dye on the lateral surface of the brain. Simultaneous subdural and intraventricular recordings of cerebrospinal fluid (CSF) pressures revealed a stable agreement between the two pressures at rest. Perturbation of the system allowed for static and dynamic differences to develop, which could indicate varying flow patterns of CSF through the foramen of Luschka.

The endoscopic treatment of fourth ventricle outlet obstruction: Report of two children and systematic review

Fourth ventricle outlet obstruction (FVOO) is a rare cause of hydrocephalus. In the last century, the standard treatment was the suboccipital craniotomy with magendieplasty or ventriculoperitoneal shunt (VP shunt). Since the beginning of the 21st century, the endoscopic third ventriculostomy (ETV) has been considered a less invasive alternative. The medical literature lacks sufficient reports of FVOO cases and strong evidence about ETV's efficacy in treating this condition. We report two cases of FVOO treated with ETV and review published similar cases. Clinical and radiological findings of two FVOO cases with outcomes after ETV were presented. Moreover, we conducted a systematic review after protocol registration in PROSPERO (CRD42021281474). MEDLINE, Embase, Scopus, and Web of Science were searched from inception till December 31, 2022. Studies were included if they reported cases of FVOO treated initially with ETV. Cases with Chiari malformation, Dandy-Walker malformation, tuberous sclerosis, trapped fourth ventricle, or space-occupying lesions were excluded. Two reviewers independently examined title/abstract records in the first stage and full-text publications in the second for eligibility. The primary outcome was the recurrence rate, defined by the need for re-ETV or other invasive treatments (e.g., VP shunt or magendieplasty). Other outcomes included clinical state at follow-up and mortality. Two cases, a 3-year-old male and 3.5-year-old female, with FVOO, were treated with ETV in our department by the same neurosurgeon (SH) in 2013 and 2021. Both cases improved significantly after ETV, and there was no recurrence through the follow-up. Besides the present cases, we found 57 other cases of FVOO treated with ETV reported in 17 studies between 2001 and 2021. The median age was 26 years, with an IQR from 2.4 to 59 years, and 56% of cases were females. The recurrence rate was 32% in the sample (19 out of 59), with a 95% CI from 21% to 46%. The median time to recure was 2 months with IQR from 1.25 to 26. A VP shunt was the treatment for recurrence in 68% and a re-ETV in 32%. At the follow-up (41 ± 29 months), only one case died, and one deteriorated clinically. FVOO is a rare cause of hydrocephalus encountered mainly in the first or sixth decades of life. ETV provides the first reasonable treatment. Despite the moderate recurrence rate, the outcomes are favorable.

16p11.2 Microduplication Syndrome with Increased Fluid in the Cisterna: Coincidence or Phenotype Extension?

We report the first case of a child with 16p11.2 microduplication syndrome with increased fluid in the cisterna magna seen on magnetic resonance imaging (MRI). This finding may correspond to a Blake's Pouch Cyst (BPC) or a Mega Cisterna Magna (MCM), being impossible to differentiate through image examination. The molecular duplication was diagnosed using chromosomal microarray analysis with single nucleotide polymorphism (SNP). We review the clinical and neuroimaging features in published case reports in order to observe the findings described in the literature so far and present a skull three-dimensional model to contribute to a better understanding. Despite the variable expressivity of the syndrome being well known, there is no case described in the available literature that mentions the association of 16p11.2 microduplication and the presence of BPC or MCM seen in neuroimaging exams. This finding may represent an extension of the phenotype not yet reported or may present itself as a coincidence in a child with various malformations.

MR Protocols for Paediatric Neurosurgical Common Conditions: An Update Guide for Neurosurgeons

The biggest challenge for clinicians and surgeons when it comes to radiological examinations is the ability to request the right modalities and to understand the strengths and limitations of each modality. This is particularly important in paediatric neurosciences where despite magnetic resonance imaging (MRI) being the main imaging modality, there are several protocols, technical limitations of specific scanners and issues related to sedation that need to be taken into account. In this chapter, we describe a simple approach for six common neurosurgical conditions to guide the paediatric neurosurgeons in requesting the right MR protocol and understanding the rationale of it.Paediatric neuro-oncology, epilepsy and neck/skull base protocols are discussed elsewhere in this book and therefore will not be a focus in this chapter (Bernasconi et al., Epilepsia 60:1054-68, 2019; D'Arco et al., Neuroradiology 64:1081-100; 2022; Avula et al., Childs Nerv Syst 37:2497-508; 2021).

Imaging of Headaches due to Intracranial Pressure Disorders

Changes in intracranial pressure are a potentially serious etiology of headache. Headache secondary to changes in intracranial pressure frequently present with characteristic clinical features. Imaging plays a key role in the diagnosis and management of this category of headache. In this article, we will review the physiology, clinical presentation, and key imaging findings of major etiologies of changes in intracranial pressure resulting in headache including obstructive and nonobstructive hydrocephalous, idiopathic intracranial hypertension (IIH), and cerebrospinal fluid (CSF) leak.

Arachnoid Membranes: Crawling Back into Radiologic Consciousness

The arachnoid membranes are projections of connective tissue in the subarachnoid space that connect the arachnoid mater to the pia mater. These are underappreciated and largely unrecognized by most neuroradiologists despite being found to be increasingly important in the pathogenesis, imaging, and treatment of communicating hydrocephalus. This review aims to provide neuroradiologists with an overview of the history, embryology, histology, anatomy, and normal imaging appearance of these membranes, as well as some examples of their clinical importance.

Arachnoid and dural reflections

The dura mater is the major gateway for accessing most extra-axial lesions and all intra-axial lesions of the central nervous system. It provides a protective barrier against external trauma, infections, and the spread of malignant cells. Knowledge of the anatomical details of dural reflections around various corners of the skull bases provides the neurosurgeon with confidence during transdural approaches. Such knowledge is indispensable for protection of neurovascular structures in the vicinity of these dural reflections. The same concept is applicable to arachnoid folds and reflections during intradural excursions to expose intra- and extra-axial lesions of the brain. Without a detailed understanding of arachnoid membranes and cisterns, the neurosurgeon cannot confidently navigate the deep corridors of the skull base while safely protecting neurovascular structures. This chapter covers the surgical anatomy of dural and arachnoid reflections applicable to microneurosurgical approaches to various regions of the skull base.

Long-standing Overt Ventriculomegaly in Adults and Endoscopic Third Ventriculostomy, the Perfect Treatment for the Proper Diagnosis

OBJECTIVE

Long-standing overt ventriculomegaly in adults (LOVA) is form of hydrocephalus that develops during childhood, manifesting its symptoms during adulthood. Only a small number of LOVA case series have been published, and controversies regarding optimal management still exist. The authors collected a series of symptomatic LOVA patients treated successfully using endoscopic third ventriculostomy (ETV), aiming to strengthen what has been reported in the literature on ETV's role in both neurologic and neurocognitive outcomes.

METHODS

Between 2002 and 2020, we collected 40 case studies of patients treated using an ETV. Associated pathologies were documented in 14 cases. All patients underwent magnetic resonance scans preoperatively and postoperatively while only 29 patients were submitted during follow-up to neurocognitive assessment.

RESULT

At a mean follow-up of 6 years, 36 patients (90%) reported either an improvement or a stabilization of their presenting symptoms. Headache improved subjectively in 11 patients (27.5%), balance and gait disturbances improved in all patients, urinary incontinence improved in 24 patients (60%), memory disturbances subjectively improved in 21 patients (52.5%), and visual deficits improved in 5 patients (12.5%). Four patients (10%) had symptom progression, which occurred 6 to 24 months after surgery with radiologic evidence of ETV failure.

CONCLUSIONS

LOVA is a form of hydrocephalus that must be correctly identified. A correct magnetic resonance study and comprehensive neuropsychologic assessment are crucial to identify it in order to define proper management. From our analysis, ETV represents the gold standard treatment granting rewarding results that are maintained in a long-term follow-up.

Idiopathic fourth ventricular outlet obstruction misdiagnosed as normal pressure hydrocephalus: A cautionary case

Background:

Fourth ventricular outlet obstruction is an infrequent but well-established cause of tetraventricular hydrocephalus characterized by marked dilatation of the ventricular system with ballooning of the foramina of Monro, Magendie, and Luschka. Multiple processes including inflammation, infection, hemorrhage, neoplasms, or congenital malformations are known to cause this pathological obstruction. However, true idiopathic fourth ventricular outlet obstruction is a rare phenomenon with only a limited number of cases reported in the literature.

Case Description:

A 61-year-old female presented with several months of unsteady gait, intermittent headaches, confusion, and episodes of urinary incontinence. Conventional magnetic resonance imaging demonstrated tetraventricular hydrocephalus without transependymal flow, but with ventral displacement of the brainstem and dorsal displacement of the cerebellum without an obvious obstructive lesion on pre- or post-contrast imaging prompting a diagnosis of normal pressure hydrocephalus. However, constructive interference in steady state (CISS) and half-Fourier acquisition single-shot turbo spin echo (HASTE) sequences followed by fluoroscopic dynamic cisternography suggested encystment of the fourth ventricle with thin margins of arachnoid membrane extending through the foramina of Luschka bilaterally into the pontocerebellar cistern. Operative intervention was pursued with resection of an identified arachnoid web. Postoperative imaging demonstrated marked reduction in the size of ventricular system, especially of the fourth ventricle. The patient’s symptomatology resolved a few days after the procedure.

Conclusion:

Here, we describe an idiopathic case initially misdiagnosed as normal pressure hydrocephalus. The present case emphasizes the necessity of CISS sequences and fluoroscopic dynamic cisternography for suspected cases of fourth ventricular outlet obstruction as these diagnostic tests may guide surgical management and lead to superior patient outcomes.

Postoperative patency assessment of Cystocisternostomy and Cystoventriculostomy stomas in cases with Arachnoidal cyst

PURPOSE

The goal of this study was to determine stoma and flow patency with 3D SPACE T2 and 3D CISS sequences in cases with cystocisternostomy or cystoventriculostomy.

METHODS

A total of sixty three patients (total 106 MRI examinations) with endoscopic cystocisternostomy or cystoventriculostomy of arachnoid cyst underwent 1.5-3 T MRI to determine flow patency between June 2007 and April 2018. Postoperative results, the patients' clinic and arachnoid cyst volume were used to confirm stoma and flow patency in MRI.

RESULTS

The stoma was open and functional in forty three patients. Minimal flow was detected in five patients. Fifteen patients with closed stoma (total 17 MR images) were evaluated with the clinician. Patients' clinic, physical examination, and growth (for pediatric patients) were evaluated. Three of fifteen patients were re-operated. Operative findings and postoperative follow-up MR imaging findings were correlated with our preoperative MRI results. The findings were in compliance in both groups (operated-non-operated groups).

CONCLUSION

3D SPACE T2 and 3D CISS are effective sequences in addition to other routine conventional sequences to evaluate stoma and flow patency.

Intraventricular neurocysticercosis presenting as Bruns’ syndrome: An uncommon presentation

Background

Though parenchymal neurocysticercosis is common and a major contributor to burden of seizures in most parts of the world, intraventricular neurocysticercosis (IVNCC) comprises 10–20% of cases and poses a diagnostic challenge to the clinician.

Case presentation

We report an adult female presenting with intermittent occipital headache, used to be worse in lying down position, and aggravated with head movements, and there was mild relief in the sitting position. Her physical examination was unremarkable, and laboratory tests were within normal limits. Her multimodal neuroimaging showed cystic lesion in the fourth ventricle suggestive of neurocysticercosis. Patient underwent neuroendoscopic removal of the cyst, and the final diagnosis was confirmed on histopathology. Post removal of cyst patient had complete resolution of her symptoms.

Discussion

Intraventricular neurocysticercosis can present as acute hydrocephalus which may clinically manifest as Bruns’ syndrome in which sudden attacks of headache vertigo and nausea or vomiting are precipitated by abrupt head movements which was observed in our patient. Multimodal neuroimaging supported by histopathology helped in confirmation of the diagnosis, thus averting an inadvertent use of unnecessary medications in such patients. Furthermore, neuroendoscopy has evolved as minimally invasive technique for extirpation of fourth ventricular cysts.

Fourth Ventricular Outflow Obstruction in an Infant with Ileal Atresia and Laryngomalacia: Endoscopic Management

Fourth ventricle outflow obstruction (FVOO) is a rare cause of obstructive hydrocephalus. In this study, we described a case of idiopathic FVOO with ileal atresia and laryngomalacia which was managed with endoscopic third ventriculostomy (ETV) and re-endoscopy. We also described the techniques of fenestration of Liliequist membrane and partial removal of arachnoid membrane over dorsum sella (DS) to prevent closure of fenestration and recurrence of hydrocephalus. The patient was a 4-month-old infant presented with progressively increasing head size, feeding difficulty, respiratory distress, and tense fontanel. The infant had a history of laparotomy for ileal atresia. CT scan showed panventriculomegaly due to FVOO. ETV with fenestration of Liliequist membrane was done on emergency basis. After operation, the patient improved clinically and radiologically. Four weeks later, the patient returned with recurrent hydrocephalus. Endoscopic reoperation showed closure of fenestration in arachnoid membrane (Lilieqiest membrane). Endoscopic refenestration with partial excision of arachnoid on DS was done. The patient again recovered radiologically and clinically till last follow-up. In idiopathic FVOO, ETV with wide fenestration of Liliequist membrane, preferably with partial removal of arachnoid on DS, may be very useful in treating hydrocephalus (HCP) and preventing recurrent HCP even in infants.

The value of CSF flow studies in the management of CSF disorders in children: a pictorial review

CSF flow disorders are frequently encountered in children. The advent of MR technology with the emergence of new pulse sequences allowed better understanding of CSF flow dynamics. In this pictorial review, we aim to conduct a comprehensive review of the MR protocol used to study CSF flow disorders and to discuss the utility of each pulse sequence in the adopted protocol. We will focus on the key anatomical structures that should be examined to differentiate hydrocephalus form ventricular dilatation ex-vacuo. The MR features of obstructive and communicating hydrocephalus will be discussed, in addition to the manifestations of CSF disorders associated with posterior fossa malformations (Dandy-Walker malformation, Chiari, and Blake’s pouch cyst). Moreover, the value of MRI in the assessment of patients following interventional procedures (ventriculoperitoneal shunt and third ventriculostomy) will be addressed.

Phase-contrast and three-dimensional driven equilibrium (3D-DRIVE) sequences in the assessment of paediatric obstructive hydrocephalus

BACKGROUND

Recently, most cases of hydrocephalus are related to obstruction. Accurate localization of the site of obstruction is crucial in determination of the treatment strategy.

PURPOSE

To describe the phase-contrast and 3D-DRIVE findings in cases of obstructive hydrocephalus in paediatric patients and to determine their functional and anatomical correlates.

MATERIAL AND METHODS

Brain MRIs of 25 patients (2 months to 11 years) with obstructive hydrocephalus were retrospectively reviewed. Phase-contrast and 3D-DRIVE were performed to assess cerebrospinal (CSF) pathways through the aqueduct of Sylvius and subarachnoid spaces. In addition to flow velocity measurement at the aqueduct of Sylvius, functional and anatomical correlation was analysed at the level of aqueduct of Sylvius, infracerebellar CSF space and at the third ventriculostomy using Spearman's rank test.

RESULTS

Aqueduct of Sylvius was the most common site of obstruction (19 patients) either secondary to focal, multifocal or tubular stenosis, adhesions, or secondary to extrinsic compression. Functional and anatomical correlation was analysed in 58 regions revealing strong correlation (ro = 0.8, p < .001). Functional anatomical mismatch was found in nine regions. Flow velocity measurements revealed diminished flow in most of the cases with obstruction at the aqueduct and normal velocity in cases with obstruction proximal to aqueductal level, while accelerated flow was seen in cases with infra-aqeuductal obstruction.

CONCLUSION

Phase-contrast and 3D-DRIVE sequences are essential sequences in the diagnosis of hydrocephalus enabling perfect localization of the site of obstruction. Both sequences should be interpreted in conjunction to avoid false results. Velocity measurements through the aqueduct can help understand CSF hydrodynamics.

Role of 3D SPACE sequence and susceptibility weighted imaging in the evaluation of hydrocephalus and treatment-oriented refined classification of hydrocephalus

OBJECTIVE

The aim of our study was to evaluate the diagnostic utility of three-dimensional sampling perfection with application optimized contrast using different flip angle evolution (3D SPACE) sequence and Susceptibility Weighted Imaging (SWI) in hydrocephalus and to propose a refined definition and classification of hydrocephalus with relevance to the selection of treatment option.

MATERIALS AND METHODS

A prospective study of 109 patients with hydrocephalus was performed with magnetic resonance imaging (MRI) brain using standardized institutional sequences along with additional sequences 3D SPACE and SWI. The images were independently read by two senior neuroradiologists and the etiopathogenesis of hydrocephalus was arrived by consensus.

RESULTS

With conventional sequences, 46 out of 109 patients of hydrocephalus were diagnosed as obstructive of which 21 patients showed direct signs of obstruction and 25 showed indirect signs. In the remaining 63 patients of communicating hydrocephalus, cause could not be found out in 41 patients. Whereas with 3D SPACE sequence, 88 patients were diagnosed as obstructive hydrocephalus in which all of them showed direct signs of obstruction and 21 patients were diagnosed as communicating hydrocephalus. By including SWI, we found out hemorrhage causing intraventricular obstruction in three patients and hemorrhage at various sites in 24 other patients. With these findings, we have classified the hydrocephalus into communicating and noncommunicating, with latter divided into intraventricular and extraventricular obstruction, which is very well pertaining to the selection of surgical option.

CONCLUSION

We strongly suggest to include 3D SPACE and SWI sequences in the set of routine MRI sequences, as they are powerful diagnostic tools and offer complementary information regarding the precise evaluation of the etiopathogenesis of hydrocephalus and have an effective impact in selecting the mode of management.

Evaluation of hydrocephalus patients with 3D-SPACE technique using variant FA mode at 3T

The major advantages of three-dimensional sampling perfection with application optimized contrasts using different flip-angle evolution (3D-SPACE) technique are its high resistance to artifacts that occurs as a result of radiofrequency or static field, the ability of providing images with sub-millimeter voxel size which allows obtaining reformatted images in any plane due to isotropic three-dimensional data with lower specific absorption rate values. That is crucial during examination of cerebrospinal-fluid containing complex structures, and the acquisition time, which is approximately 5 min for scanning of entire cranium. Recent data revealed that T2-weighted (T2W) 3D-SPACE with variant flip-angle mode (VFAM) imaging allows fast and accurate evaluation of the hydrocephalus patients during both pre- and post-operative period for monitoring the treatment. For a better assessment of these patients; radiologists and neurosurgeons should be aware of the details and implications regarding to the 3D-SPACE technique, and they should follow the updates in this field. There could be a misconception about the difference between T2W-VFAM and routine heavily T2W 3D-SPACE images. T2W 3D-SPACE with VFAM imaging is only a subtype of 3D-SPACE technique. In this review, we described the details of T2W 3D-SPACE with VFAM imaging and comprehensively reviewed its recent applications.

Cerebrospinal fluid circulation and hydrocephalus

Hydrocephalus (HC) is classically defined as dynamic imbalance between the production and absorption of cerebrospinal fluid (CSF) leading to enlarged ventricles. Potential causative factors include various brain disorders like tumors causing obstruction of CSF flow within the ventricular system or the subarachnoid space. Classification of HC is based on the site of CSF flow obstruction guiding optimal treatment, with endoscopic third ventriculostomy in intraventricular obstruction and CSF shunt in communicating HC. Another clinically relevant classification is acute and chronic; the most frequent chronic form is idiopathic normal-pressure hydrocephalus (iNPH). The reported incidence of HC varies according to the study population and classification used. The incidence of congenital HC is approximately 0.4-0.6/1,000 newborns and the annual incidence of iNPH varies from 0.5/100,000 to 5.5/100,000. Radiologically, ventricular dilatation may be nonspecific, and differentiation of iNPH from other neurodegenerative diseases may be ambiguous. There are no known specific microscopic findings of HC but a systematic neuropathologic examination is needed to detect comorbid diseases and possible etiologic factors of HC. Depending on the etiology of HC, there are several nonspecific signs potentially to be seen.

Fourth Ventricle Outlet Obstruction with Expanding Space on the Surface of Cerebellum

BACKGROUND

Hydrocephalus is classified as noncommunicating and communicating based on whether all ventricular and subarachnoid spaces are communicating. Although the diagnosis between the two different states is crucial, it is difficult in certain conditions. In particular, communicating hydrocephalus and noncommunicating hydrocephalus owing to fourth ventricle outlet obstruction are highly misdiagnosed. We describe a case of fourth ventricle outlet obstruction of unknown origin that was initially misdiagnosed as communicating hydrocephalus.

CASE DESCRIPTION

A 66-year-old woman with gait disturbance and incontinence caused by hydrocephalus underwent ventriculoperitoneal shunt surgery. After 9 months, her fourth ventricle became enlarged and could not be controlled by lowering the shunt pressure. Magnetic resonance imaging (MRI) demonstrated obstruction at the foramen of Magendie, foramina of Luschka, and the cerebral aqueduct. Endoscopic surgery for aqueduct plasty with third ventriculostomy was planned. Because the aqueduct was observed to open spontaneously, only the standard third ventriculostomy was performed. When MRI findings were reviewed retrospectively, an unnatural space was observed between the lower cranial nerves and cerebellar hemisphere that grew along with the fourth ventricular enlargement. This space was determined by MRI cisternography to be the cystic membrane ballooning out from the foramen of Luschka. The primary hydrocephalus likely resulted from fourth ventricle outlet obstruction.

CONCLUSIONS

Enlargement of the whole ventricular system with an expanded space between the lower cranial nerves and cerebellar hemisphere can be caused by fourth ventricle outlet obstruction. In such cases, preoperative evaluation of anatomic architecture and cerebrospinal fluid obstruction using MRI cisternography is essential and leads to a successful endoscopic strategy.

Endoscopic transventricular exploration with biopsy of the basal cisterns and the role of endoscopic third ventriculostomy in patients suffering with basal cistern meningitis and consecutive hydrocephalus

OBJECTIVES

The purpose of this work is to elucidate the efficacy of endoscopic basal cisterns exploration, biopsy, and third ventriculostomy (ETV) in patients with basal cistern meningitis and arachnoiditis.

MATERIALS AND METHODS

The cases and videos of all patients in whom flexible neuroendoscopy was performed during the period of January 2005-June 2012 at the University Hospital 'Dr. Ignacio Morones Prieto' in San Luis Potosí, México. A group of 47 patients with radiological diagnosis of basal meningitis, arachnoiditis, and negative cerebrospinal fluid analysis were included.

RESULTS

From the 28 (60%) patients with histological diagnosis, 22 (47%) were made from biopsy from the arachnoid membranes of the basal cisterns only, 4 (9%) only from the cerebral cortex, and 2 (4%) from both sites. There were no complications related to the endoscopic procedure. In 23 patients from the 42 with hydrocephalus, ETV was successful. The grade of diagnostic accuracy of both biopsies in detect etiology was 68% (28 of 47 patients), the diagnostic accuracy of arachnoid biopsy was 60%, and diagnostic accuracy of convexity brain biopsy was 21% with 24 and 6 patients, respectively.

DISCUSSION

Endoscopic transventricular biopsy of the basal cisterns seems to be a safe and a relatively accurate procedure. As longs as frozen subarachnoid space was not seen, the possibilities of performing ETV in hydrocephalus condition are elevated depending on the causal micro-organism.

A prospective study of magnetic resonance imaging patterns of central nervous system infections in pediatric age group and young adults and their clinico-biochemical correlation

Background:

Infections of the central nervous system (CNS) are common and routinely encountered. Our aim was to evaluate the neuroimaging features of the various infections of the CNS so as to differentiate them from tumoral, vascular, and other entities that warrant a different line of therapy.

Aims:

Our aim was to analyze the biochemical and magnetic resonance imaging (MRI) features in CNS infections.

Settings and Design:

This was a longitudinal, prospective study over a period of 1½ years.

Subjects and Methods:

We studied cerebrospinal fluid (CSF) findings and MRI patterns in 27 patients of 0–20 years age group with clinical features of CNS infections. MRI was performed on MAGNETOM Avanto 18 Channel 1.5 Tesla MR machine by Siemens India Ltd. The MRI protocol consisted of diffusion-weighted and apparent diffusion coefficient imaging, turbo spin echo T2-weighted, spin echo T1-weighted, fluid-attenuated inversion recovery (FLAIR), and gradient-echo in axial, FLAIR in coronal, and T2-weighted in sagittal plane. Contrast-enhanced T1-weighted sequence and MR spectroscopy were done whenever indicated.

Results and Conclusions:

We found that most of the children belong to 1–10 years age group. Fungal infections were uncommon, mean CSF adenosine deaminase values specific for tuberculosis and mean CSF glucose-lowered in pyogenic. Hemorrhagic involvement of thalamus with/without basal ganglia and brainstem involvement may indicate Japanese encephalitis or dengue encephalitis. Diffusion restriction or hemorrhage in not expected in the brainstem afflicted lesions of rabies. Congenital cytomegalovirus can cause cortical malformations. T1 hyperintensities with diffusion restriction may represent viral encephalitis. Lesions of acute disseminated encephalomyelitis (ADEM) may mimic viral encephalitis. Leptomeningeal enhancement is predominant in pyogenic meningitis. Basilar meningitis in the presence of tuberculomas is highly sensitive and specific for tuberculosis.

Lower rates of symptom recurrence and surgical revision after primary compared with secondary endoscopic third ventriculostomy for obstructive hydrocephalus secondary to aqueductal stenosis in adults

OBJECT

Endoscopic third ventriculostomy (ETV) is the treatment of choice for obstructive hydrocephalus; however, the success of ETV in patients who have previously undergone shunt placement remains unclear. The present study analyzed 103 adult patients with aqueductal stenosis who underwent ETV for obstructive hydrocephalus and evaluated the effect of previous shunt placement on post-ETV outcomes.

METHODS

This study was a retrospective review of 151 consecutive patients who were treated between 2007 and 2013 with ETV for hydrocephalus. One hundred three (68.2%) patients with aqueductal stenosis causing obstructive hydrocephalus were included in the analysis. Postoperative ETV patency and aqueductal and cisternal flow were assessed by high-resolution, gradient-echo MRI. Post-ETV Mini-Mental State Examination, Timed Up and Go, and Tinetti scores were compared with preoperative values. Univariate and multivariate analyses were performed comparing the post-ETV outcomes in patients who underwent a primary (no previous shunt) ETV (n = 64) versus secondary (previous shunt) ETV (n = 39).

RESULTS

The majority of patients showed significant improvement in symptoms after ETV; however, no significant differences were seen in any of the quantitative tests performed during follow-up. Symptom recurrence occurred in 29 (28.2%) patients after ETV, after a median of 3.0 (interquartile range 0.8–8.0) months post-ETV failure. Twenty-seven (26.2%) patients required surgical revision after their initial ETV. Patients who received a secondary ETV had higher rates of symptom recurrence (p = 0.003) and surgical revision (p = 0.003), particularly in regard to additional shunt placement/revision post-ETV (p = 0.005). These differences remained significant after multivariate analysis for both symptom recurrence (p = 0.030) and surgical revision (p = 0.043).

CONCLUSIONS

Patients with obstructive hydrocephalus due to aqueductal stenosis exhibit symptomatic improvement after ETV, with a relatively low failure rate. Patients with a primary history of shunt placement who undergo ETV as a secondary intervention are at increased risk of symptom recurrence and need for surgical revision post-ETV.

MR assessment of pediatric hydrocephalus: a road map

PURPOSE

This study was conducted to design a rational approach to the MR diagnosis of hydrocephalus based on a pathophysiologic reevaluation of its possible mechanisms and to apply it to the different etiological contexts.

METHOD

A review of the literature reports describing new physiologic models of production and absorption and of the hydrodynamics of the CSF was made.

RESULTS

Besides the secretion of CSF by the choroid plexuses, and its passive, pressure-dependent transdural absorption (arachnoid villi, dural clefts, cranial, and spinal nerve sheaths), water transporters, aquaporins, allow water (if not ions and organic molecules) to exchange freely between the brain parenchyma and the CSF spaces across the ependymal and the pial interfaces (including the Virchow-Robin spaces). Consequently, the CSF bulk flow is not necessarily global, and situations of balanced absorption-secretion may occur separately in different CSF compartments such as the ventricular, intracranial, or intraspinal CSF spaces. This means that rather than from a hypothetical pressure gradient from the plexuses to the dural sinuses, the dynamics of the CSF depend on the force provided in those different compartments by the arterial systolic pulsation of the pericerebral (mostly), intracerebral, and intraventricular (choroid plexuses) vascular beds.

CONCLUSION

Using MR imaging, diverse varieties of hydrocephalus may tentatively be explained by applying those concepts to the correspondingly diverse causal diseases. Hopefully, this may have an impact on the choice of the treatment strategies also.

Noncommunicating Hydrocephalus

Noncommunicating hydrocephalus is often referred to as obstructive hydrocephalus and is by definition an intraventricular obstruction of cerebrospinal fluid flow. Patient symptoms depend on the rapidity of onset. Acute obstructive hydrocephalus causes sudden rise in the intracranial pressure, which may lead to death, whereas in chronic hydrocephalus there may not be any symptoms. Computed tomography and magnetic resonance imaging play important roles in the diagnosis and management of hydrocephalus. Advances in magnetic resonance imaging such as the 3D sequences and phase-contrast imaging have revolutionized the preoperative and postoperative assessment of noncommunicating hydrocephalus. We would be discussing the various causes of noncommunicating hydrocephalus and their imaging.

Idiopathic fourth ventricle outlet obstruction successfully treated by endoscopic third ventriculostomy: a case report

Introduction

Fourth ventricle outlet obstruction (FVOO) is a rare cause of obstructive hydrocephalus. We describe a case of idiopathic FVOO that was successfully treated with endoscopic third ventriculostomy (ETV).

Case report

A 3-year old boy without any remarkable medical history presented with a headache and vomiting. Computed tomography (CT) images, which had incidentally been taken 2 years previously due to a minor head injury, showed no abnormality. Magnetic resonance imaging on admission showed tetra-ventricular hydrocephalus associated with the dilatation of the fourth ventricle outlets, without any obstructive lesions. However, CT ventriculography, involving contrast medium injection through a ventricular catheter, suggested mechanical obstruction of the cerebrospinal fluid (CSF) at the fourth ventricle outlets. Thus, the patient was diagnosed with FVOO and ETV was performed; the hydrocephalus was subsequently resolved. Although hydrocephalus recurred 1 year postoperatively, re-ETV for the highly stenosed fenestration successfully resolved this condition.

Conclusions

ETV should be considered for FVOO treatment, particularly in idiopathic cases without CSF malabsorption.

Feasibility of 3-dimensional sampling perfection with application optimized contrast sequence in the evaluation of patients with hydrocephalus

PURPOSE

This study aimed to investigate the effectiveness and additive value of T2W 3-dimensional sampling perfection with application optimized contrast (3D-SPACE) with variant flip-angle mode in imaging of all types of hydrocephalus. Our secondary objective was to assess the reliability of 3D-SPACE sequence and correspondence of the results with phase-contrast magnetic resonance imaging (PC-MRI)-based data.

MATERIALS AND METHODS

Forty-one patients with hydrocephalus have undergone 3-T MRI. T2W 3D-SPACE sequence has been obtained in addition to routine hydrocephalus protocol. Cerebrospinal fluid circulation, presence/type/etiology of hydrocephalus, obstruction level scores, and diagnostic levels of confidence were evaluated separately by 2 radiologists. In the first session, routine sequences with PC-MRI were evaluated, and in another session, only 3D-SPACE and 3-dimensional magnetization prepared rapid acquisition gradient echo sequences were evaluated. Results obtained in these sessions were compared with each other and those obtained in consensus session.

RESULTS

Agreement values were very good for both 3D-SPACE and PC-MRI sequences (P < 0.001 for all). Also, the correlation of more experienced reader's 3D-SPACE-based scores and consensus-based scores was perfect (κ = 1, P < 0.001).The mean value of PC-MRI-based confidence scores were lower than those obtained in 3D-SPACE and consensus sessions.

CONCLUSIONS

T2W 3D-SPACE sequence provides morphologic cerebrospinal fluid flow data. It is a noninvasive technique providing extensive multiplanar reformatted images with a lower specific absorption rate. These advantages over PC-MRI make 3D-SPACE sequence a promising tool in management of patients with hydrocephalus.

Assessment of sedated pediatric brain with 3D-FLAIR sequence at 3T MRI

BACKGROUND AND PURPOSE

In sedated pediatric brains, 2D-FLAIR causes increased signal intensity of the cerebrospinal fluid (CSF) leading to false-positive diagnoses. Our aim is to determine whether increased CSF signal intensity is observed on 3D-FLAIR images.

METHODS

In this institutional review board-approved study, a 2-year retrospective analysis of our MRI database was conducted which revealed 48 sedated pediatric patients with normal cranial MRI findings and 3D-FLAIR sequence. One adult volunteer was imaged before and after O2 inhalation with 2D and 3D-FLAIR sequences. The hyperintensity in the subarachnoid spaces and basal cisterns were quantified as follows: 0: artifact free; 1: homogeneous minimal CSF signal; 2: abnormal CSF signal. Inter-observer agreement was assessed with kappa agreement analysis.

RESULTS

Grade 0 and grade 1 signals were observed at inferior to Liliequist membrane (LLQ) in 48/48 and 0/48 cases; prepontine cistern 47/48 and 1/48; superior to LLQ 26/48 and 22/48; 4th ventricle 16/48 and 32/48; 3rd ventricle 34/48 and 14/48; lateral ventricle 3/48 and 45/48; subarachnoid space 36/48 and 12/48, respectively. No patients showed grade 2 signal. Inter-observer agreement was 0.81-1. In the volunteer, after O2 inhalation, grade 2 signal intensity was evident on 2D-FLAIR however; 3D-FLAIR did not show any signal increase.

CONCLUSIONS

In sedated pediatric brains, 3D-FLAIR suppresses CSF signal, and enables reliable assessment free from CSF artifacts.

Diagnostic performance of heavily T2-weighted techniques in obstructive hydrocephalus: comparison study of two different 3D heavily T2-weighted and conventional T2-weighted sequences

PURPOSE

To evaluate efficacy of three-dimensional (3D) heavily T2-weighted (W) MRI sequences in assessment of cerebrospinal fluid (CSF) pathways and to compare two different types of 3D heavily T2W MRI sequences (CISS and SPACE) with two-dimensional (2D) T2W turbo spin echo (TSE) sequences for hydrocephalus with intraventricular obstruction.

MATERIALS AND METHODS

Sixty-two patients who were diagnosed with intraventricular obstructive hydrocephalus, according to clinical and radiological findings, were included in this retrospective study. 2D-TSE-T2, 3D-CISS, and 3D-SPACE, which are part of the protocol, were analyzed quantitatively by measuring ventricle-to-parenchyma contrast-to-noise ratio (CNR), and qualitatively by evaluating the capabilities of visualization of the obstructive pathology, overall image quality, severity of artifacts, and delineation of the CSF pathways. One-way ANOVA and Friedman's test were used for statistical analysis.

RESULTS

CNR between CSF and brain parenchyma was significantly higher using 3D-SPACE sequences compared with 3D-CISS and 2D-TSE-T2 sequences. The qualitative findings showed that 3D heavily T2W sequences were superior to 2D-TSE-T2 sequences. 3D-SPACE sequences showed fewer artifacts than 3D-CISS or 2D-TSE-T2 sequences.

CONCLUSION

3D heavily T2W sequences are necessary tools for assessment of CSF pathways in patients with intraventricular obstructive hydrocephalus. 3D-SPACE sequences allowed heavy T2W, which is necessary for CSF flow imaging and provided significantly fewer image artifacts and improved CNR in comparison with 3D-CISS sequences.

Evaluation of aqueductal patency in patients with hydrocephalus: three-dimensional high-sampling-efficiency technique (SPACE) versus two-dimensional turbo spin echo at 3 Tesla

Objective

To compare the accuracy of diagnosing aqueductal patency and image quality between high spatial resolution three-dimensional (3D) high-sampling-efficiency technique (sampling perfection with application optimized contrast using different flip angle evolutions [SPACE]) and T2-weighted (T2W) two-dimensional (2D) turbo spin echo (TSE) at 3-T in patients with hydrocephalus.

Materials and Methods

This retrospective study included 99 patients diagnosed with hydrocephalus. T2W 3D-SPACE was added to the routine sequences which consisted of T2W 2D-TSE, 3D-constructive interference steady state (CISS), and cine phase-contrast MRI (PC-MRI). Two radiologists evaluated independently the patency of cerebral aqueduct and image quality on the T2W 2D-TSE and T2W 3D-SPACE. PC-MRI and 3D-CISS were used as the reference for aqueductal patency and image quality, respectively. Inter-observer agreement was calculated using kappa statistics.

Results

The evaluation of the aqueductal patency by T2W 3D-SPACE and T2W 2D-TSE were in agreement with PC-MRI in 100% (99/99; sensitivity, 100% [83/83]; specificity, 100% [16/16]) and 83.8% (83/99; sensitivity, 100% [67/83]; specificity, 100% [16/16]), respectively (p < 0.001). No significant difference in image quality between T2W 2D-TSE and T2W 3D-SPACE (p = 0.056) occurred. The kappa values for inter-observer agreement were 0.714 for T2W 2D-TSE and 0.899 for T2W 3D-SPACE.

Conclusion

Three-dimensional-SPACE is superior to 2D-TSE for the evaluation of aqueductal patency in hydrocephalus. T2W 3D-SPACE may hold promise as a highly accurate alternative treatment to PC-MRI for the physiological and morphological evaluation of aqueductal patency.

Evaluation of hydrocephalus and other cerebrospinal fluid disorders with MRI: An update

MRI is not only beneficial in the diagnosis of cerebrospinal fluid (CSF)-related diseases, but also aids in planning the management and post-surgery follow-up of the patients. With recent advances in MRI systems, there are many newly developed sequences and techniques that rapidly enable evaluation of CSF-related disorders with greater accuracy. For a better assessment of this group of disorders, radiologists should follow the developments closely and should be able to apply them when necessary. In this pictorial review, the role of MRI in the evaluation of hydrocephalus, CSF diversion techniques, and other CSF disorders is illustrated.

Teaching Points

• The 3D-SPACE seems to be most efficient technique for evaluation of hydrocephalus and ventriculostomy.

• In complex cases, PC-MRI, 3D-heavily T2W, and/or CE-MRC images may prevent false results of 3D-SPACE.

• MRI is beneficial in the diagnosis and management of hydrocephalus and other CSF-related diseases.

Role of magnetic resonance ventriculography in multiloculated hydrocephalus

OBJECT

In this paper the authors' goal was to investigate the clinical usefulness of Gd-enhanced MR ventriculography (MRV) in pediatric patients affected by multiloculated hydrocephalus.

METHODS

Eighteen patients (11 boys and 7 girls, age range 2-14 months) with a diagnosis of multiloculated hydrocephalus were included in the study. After injection of gadodiamide (0.02-0.04 mmol) into the lateral ventricle by tapping the anterior fontanel, sagittal, coronal, and axial T1-weighted MR images were acquired. The location of the septations and the sites of obstruction of CSF flow were assessed. Postoperative MRV was obtained to confirm the results of endoscopic treatment in most complex cases.

RESULTS

No adverse events were observed after injection of contrast medium into the ventricular system. Preoperative MRV accurately defined the exact morphology of septae and ventricular walls in all cases. In 1 case the diagnosis of multiloculated hydrocephalus was ruled out. Sites of obstruction of CSF flow within the ventricular system were also well established. In 4 cases the multiple compartments were proven to intercommunicate. Postoperative MRV was useful in assessing the functional status of third ventriculostomy, aqueductoplasty, and other endoscopic fenestrations.

CONCLUSIONS

Magnetic resonance ventriculography is a safe, effective, and reliable technique. The accurate definition of the anatomy of the ventricles and the site of obstruction in multiloculated hydrocephalus can help to plan the most appropriate treatment and minimize the number of procedures. Although MRV is also useful during postoperative follow-up to determine the results of endoscopic treatment, it should be limited to particularly complex cases, due to its invasiveness.

Aqueductal flow of cerebrospinal fluid (CSF) and anatomical configuration of the cerebral aqueduct (AC) in patients with communicating hydrocephalus--the trumpet sign

PURPOSE

We explore the relationship of aqueductal flow of cerebrospinal fluid (CSF) and the changes of the anatomical configuration of the cerebral aqueduct (AC) in patients with communicating hydrocephalus (CH) in a routine MRI setting.

METHODS/PATIENTS

We performed a retrospective evaluation of different anatomical configurations of the AC on midsaggital MRI images in 43 patients (medial age 67 years, median 68 years, range from 14 to 85, 25 women) with suspected communicating hydrocephalus and compared the anatomical form of the AC on the sagittal sequences with MRI CSF flow data. The measured acqueductal cross sectional area was correlated (Pearson's correlation coefficient, which is a measure of the linear dependence between two variables, is 0.747. From 0.7 to 1 correlation is strong, from 0.7 to 0.5 moderate correlation, from 0.5 to 0.3 weak correlation, and 0.3 to 0 means no correlation) with MRI CSF flow data based on phase contrast measurements.

RESULTS

Two independent neuroradiologists were blinded to the patients' diagnosis. In 53% (Rater I) and 67% (Rater II) the anatomical appearance of the AC on sagittal MRI was tubular shaped and in 47% (Rater I) and 33% (Rater II) trumpet shaped. Highly elevated CSF flow correlated with a dilated and trumpet shaped AC lumen area.

CONCLUSION

The anatomical morphology of the AC in midsagittal MRI sequences may be a significant diagnostic sign for suspected communicating hydrocephalus, already discernible on routine MRI scans; consequently, this may also be a sensitive method of supporting the clinical diagnosis of communicating hydrocephalus and moreover supports patients' selection for further CSF flow measurements.

Neonatal post-hemorrhagic hydrocephalus resulting in foraminal septae-radiological technique and surgical implications

BACKGROUND

Intraventricular haemorrhage is the most common cause of hydrocephalus in a pre-term baby and may require surgical intervention depending on severity.

CLINICAL CASE

This case illustrates foraminal septae as a subtle cause of progressive quadriventricular hydrocephalus in a child born pre-term with a history of grade III intraventricular haemorrhage. The septae within the fourth ventricular exits were clearly demonstrated with 3D-FIESTA (fast imaging employing steady-state acquisition) MRI acquisitions and assisted in differentiation from communicating hydrocephalus. This finding guided the decision to a successful endoscopic third ventriculostomy.

CONCLUSION

3D-FIESTA sequence is recommended for investigating children with hydrocephalus secondary to intraventricular haemorrhage due to its diagnostic potential and implications on surgical technique.

Magnetic resonance imaging of noncommunicating hydrocephalus

INTRODUCTION

The purpose of this review is to describe the magnetic resonance imaging (MRI) findings in patients with noncommunicating hydrocephalus (NCH).

METHODS

We describe the technical aspects of MR sequences that are of use for the imaging of cerebrospinal fluid (CSF). Both the diagnosis of NCH and the follow-up after endoscopic third ventriculostomy (ETV) are discussed through clinical cases.

RESULTS

NCH is related to an obstacle hindering the CSF pathways. The combined use of anatomical and flow-sensitive MR sequences may help to characterize hydrocephalus. An imaging protocol is described at 1.5-T.

CONCLUSIONS

The first step of the diagnostic work-up consists of the detection of an obstacle hindering CSF flow pathways using both constructive interference in steady state and flow-sensitive MR sequences. CSF volumetry and quantification of ventricular wall movement may also improve the diagnosis and follow-up of patients with NCH.

Intrathecal gadolinium-enhanced MR cisternography: a comprehensive review

CE-MRC has been in use for the past 15 years and was reported to be a useful method in the evaluation of CSF disorders and hydrocephalus. The use of CE-MRC in conjunction with other MR imaging techniques has been shown to be effective in selected cases for the evaluation of several disorders of cerebrospinal system. CE-MRC has certain advantages over other cisternographic studies with fewer side effects if performed properly. Although intrathecal Gd administration is not widely accepted yet, several recent studies have reported the safety of small-dose intrathecal gadolinium injection. In this review, we describe CE-MRC and review recent applications in several clinical conditions.

Applications of 3D CISS sequence for problem solving in neuroimaging

Three-dimensional (3D) constructive interference in steady state (CISS) is a gradient-echo MRI sequence that is used to investigate a wide range of pathologies when routine MRI sequences do not provide the desired anatomic information. The increased sensitivity of the 3D CISS sequence is an outcome of the accentuation of the T2 values between cerebrospinal fluid (CSF) and pathological structures. Apart from its well-recognized applications in the evaluation of the cranial nerves, CSF rhinorrhea and aqueduct stenosis, we have found the CISS sequence to be useful for the cisternal spaces, cavernous sinuses and the ventricular system, where it is useful for detecting subtle CSF-intensity lesions that may be missed on routine spin-echo sequences. This information helps in the management of these conditions. After a brief overview of the physics behind this sequence, we illustrate its clinical applications with representative cases and discuss its potential role in imaging protocols.

Radiologic evaluation of pediatric hydrocephalus

INTRODUCTION

The aim of this review is to present the contemporary role of radiology in evaluating pediatric hydrocephalus. Although conventional brain imaging with ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) reveal the degree of ventricular enlargement and often the etiology of the hydrocephalus, the diagnosis and management of hydrocephalus present common problems in pediatric populations.

DISCUSSION

US, usually sufficient to assess and monitor ventricular size, is used most commonly in preterm infants who have germinal matrix hemorrhages and not able to tolerate transport to the radiology department. Although CT can demonstrate gross dilatation of ventricles, in most cases, it will be necessary to more closely define the nature of the obstruction, either functionally or anatomically. MRI is the best imaging modality to provide such functional and anatomic information. However, since identification of obstructive pathologic processes at any level through the cerebrospinal fluid (CSF) pathway in patients with hydrocephalus is of significant importance because it can change the treatment options, avoiding shunt insertion, a more sophisticated MRI approach is needed instead of obtaining a routine cranial MRI. Furthermore, the outcome after neuroendoscopic procedures is clearly related to patient selection under guidance of neuroimaging.

CONCLUSION

Therefore, the article focuses mainly on the effective usage of various MRI sequences in both diagnosis and follow-up of pediatric hydrocephalus, such as 3D CISS, cine PC, TSE, and GRE T2* sequences, to be able to investigate all possible obstructive pathology through the CSF pathway and to assess the efficiency of treatment in a standardized way.

Microsurgical and endoscopic anatomy of Liliequist's membrane and the prepontine membranes: cadaveric study and clinical implications

BACKGROUND

Liliequist's membrane is mostly described as having a diencephalic leaf, mesencephalic leaf, and diencephalic-mesencephalic leaves in the literature. Also different descriptions of the prepontine membranes were reported. In this study, we visualized the regular structural forms of membranes without disturbing any attachments and defined infrachiasmatic and prepontine safety zones. We discussed the clinical significance of these structures.

MATERIALS AND METHODS

The study was carried out on 24 adult human cadavers at the Morgue Specialization Department of the Forensic Medicine Institution following the initial autopsy examination. Liliequist's membrane and the prepontine membranes were explored after retraction of the frontal lobes. Dissections were performed under the operative microscope. A 0- and 30-degree, 2.7-mm angled rigid endoscope (Aesculap, Tuttlingen, Germany) was advanced through the prepontine cistern from the natural holes of membranes, or small holes were opened without damaging the surrounding structures.

RESULTS

The basal arachnoid membrane (BAM) continued as Liliequist's membrane (LM) without any distinct separation in all specimens. The LM coursed over the posterior clinoids and split into two leaves as the diencephalic leaf (DL) and mesencephalic leaf (ML) in 18 specimens; the medial pontomesencephalic membrane (MPMM) coursed anterolaterally as a continuation of the ML and attached to the medial surfaces of the fifth and sixth nerves, joining with the lateral pontomesencephalic membrane (LPMM), which was also a posterolateral continuation of the ML in all specimens. The medial pontomedullar membrane (MPMdM) and lateral pontomedullar membrane (LPMdM) were observed in 21 specimens. The MPMdM membrane was a continuation of the MPMM, and the LPMdM was a continuation of the LPMM in all 21 specimens.

CONCLUSION

We observed that the LM is a borderless continuation of the BAM. The MPMM and LPMM split from the ML without any interruptions. The MPMdM and LPMdM were a single membrane continuing from the MPMM and LPMM. We determined infrachiasmatic and prepontine areas that can be important for inferior surgical approaches.

Hydrocephalus in patients with neurofibromatosis type 1: MR imaging findings and the outcome of endoscopic third ventriculostomy

Although hydrocephalus associated with NF-1 is not rare, up to now the MR imaging findings in these patients and the role of ETV in the treatment of hydrocephalus associated with NF-1 have not been investigated thoroughly. We present the MR imaging findings of hydrocephalus associated with NF-1 in 7 of 54 patients with NF-1. Although the types of obstruction were various, including aqueductal web, superior velum medullary synechia, periaqueductal/tectal hamartomas, cerebellar and pontine tegmentum hamartomas, brain stem glioma, or a combination, the presence of hamartomas was a consistent finding in patients with NF-1 with hydrocephalus. In 5 cases, 8 ETV procedures were performed and followed for up to 53 months. All children treated with ETV were shunt-free at their most recent examinations. ETV may be the primary procedure for the treatment of hydrocephalus associated with NF-1, regardless of the cause and the level of the obstruction.

Analysis of endoscopic third ventriculostomy patency by MRI: value of different pulse sequences, the sequence parameters, and the imaging planes for investigation of flow void

PURPOSE

The aim of the study is to evaluate the efficiency of turbo spin-echo (TSE), three-dimensional constructive interference in the steady state (3D CISS) and cine phase contrast (Cine PC) sequences in determining flow through the endoscopic third ventriculostomy (ETV) fenestration, and to determine the effect of various TSE sequence parameters.

MATERIALS AND METHODS

The study was approved by our institutional review board and informed consent from all patients was obtained. Two groups of patients were included: group I (24 patients with good clinical outcome after ETV) and group II (22 patients with hydrocephalus evaluated preoperatively). The imaging protocol for both groups was identical. TSE T2 with various sequence parameters and imaging planes, and 3D CISS, followed by cine PC were obtained. Flow void was graded as four-point scales. The sensitivity, specificity, accuracy, positive and negative predictive values of sequences were calculated.

RESULTS

Bidirectional flow through the fenestration was detected in all group I patients by cine PC. Stroke volumes through the fenestration in group I ranged 10-160.8 ml/min. There was no correlation between the presence of reversed flow and flow void grading. Also, there was no correlation between the stroke volumes and flow void grading. The sensitivity of 3D CISS was low, and 2 mm sagittal TSE T2, nearly equal to cine PC, provided best result.

CONCLUSION

Cine PC and TSE T2 both have high confidence in the assessment of the flow through the fenestration. But, sequence parameters significantly affect the efficiency of TSE T2.

Phase-contrast MRI and 3D-CISS versus contrast-enhanced MR cisternography for the detection of spontaneous third ventriculostomy

PURPOSE

To compare the diagnostic efficacies of phase-contrast MRI (PC-MRI) and three-dimensional constructive interference in steady-state (3D-CISS) sequence for the detection of spontaneous third ventriculostomy (STV) on the basis of contrast-enhanced MR cisternography (MRC).

PATIENTS AND METHODS

Eleven obstructive hydrocephalus patients with clinically-radiologically suspected STV and ten controls were examined by PC-MRI, 3D-CISS and MRC. PC-MRI and 3D-CISS sequence were applied to view the third ventricle and basal cisterns. Following injection of 0.5-1ml intrathecal Gd-DTPA injection, postcontrast MRC images were obtained in three planes. Presence of STV was scored as follows: grade 0, no existence of STV; grade 1, STV present. Results of PC-MRI and 3D-CISS were compared with the MRC findings.

RESULTS

In PC-MRI, five patients were assessed as grade 0 and six cases grade 1. As a result of 3D-CISS sequence, eight cases were evaluated as grade 0 and three cases grade 1. Based on MRC, nine cases were assessed as grade 0 and two cases grade 1. False positivity was found in four cases by PC-MRI and in one case by 3D-CISS. The sensitivity, specificity and accuracy of PC-MRI and 3D-CISS sequence regarding demonstration of STV, were 100, 100, 56, 89, 64, and 91% respectively.

DISCUSSION

PC-MRI and 3D-CISS are helpful in confirming the STV. PC-MRI and 3D-CISS should be the first preference. If PC-MRI and 3D-CISS give negative results, then MRC is not required. MRC should be performed on patients who demonstrate suspected STV findings on PC-MRI and 3D-CISS sequences. MRC may prevent false positive results.

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.