Cerebral Aqueduct Research Articles

Validating the accuracy of real-time phase-contrast MRI and quantifying the effects of free breathing on cerebrospinal fluid dynamics

BackgroundUnderstanding of the cerebrospinal fluid (CSF) circulation is essential for physiological studies and clinical diagnosis. Real-time phase contrast sequences (RT-PC) can quantify beat-to-beat CSF flow signals. However, the detailed effects of free-breathing on CSF parameters are not fully understood. This study aims to validate RT-PC’s accuracy by comparing it with the conventional phase-contrast sequence (CINE-PC) and quantify the effect of free-breathing on CSF parameters at the intracranial and extracranial levels using a time-domain multiparametric analysis method.MethodsThirty-six healthy participants underwent MRI in a 3T scanner for CSF oscillations quantification at the cervical spine (C2-C3) and Sylvian aqueduct, using CINE-PC and RT-PC. CINE-PC uses 32 velocity maps to represent dynamic CSF flow over an average cardiac cycle, while RT-PC continuously quantifies CSF flow over 45-seconds. Free-breathing signals were recorded from 25 participants. RT-PC signal was segmented into independent cardiac cycle flow curves (Qt) and reconstructed into an averaged Qt. To assess RT-PC’s accuracy, parameters such as segmented area, flow amplitude, and stroke volume (SV) of the reconstructed Qt from RT-PC were compared with those derived from the averaged Qt generated by CINE-PC. The breathing signal was used to categorize the Qt into expiratory or inspiratory phases, enabling the reconstruction of two Qt for inspiration and expiration. The breathing effects on various CSF parameters can be quantified by comparing these two reconstructed Qt.ResultsRT-PC overestimated CSF area (82.7% at aqueduct, 11.5% at C2-C3) compared to CINE-PC. Stroke volumes for CINE-PC were 615 mm³ (aqueduct) and 43 mm³ (spinal), and 581 mm³ (aqueduct) and 46 mm³ (spinal) for RT-PC. During thoracic pressure increase, spinal CSF net flow, flow amplitude, SV, and cardiac period increased by 6.3%, 6.8%, 14%, and 6%, respectively. Breathing effects on net flow showed a significant phase difference compared to the other parameters. Aqueduct-CSF flows were more affected by breathing than spinal-CSF.ConclusionsRT-PC accurately quantifies CSF oscillations in real-time and eliminates the need for cardiac synchronization, enabling the quantification of the cardiac and breathing components of CSF flow. This study quantifies the impact of free-breathing on CSF parameters, offering valuable physiological references for understanding the effects of breathing on CSF dynamics.

Diagnosis and Treatment of Sylvian Aqueduct Syndrome.

Sylvian aqueduct syndrome is a rare complication after ventriculoperitoneal (V-P) shunt surgery and is not easily diagnosed. A 26-year-old male with obstructive hydrocephalus due to tectal glioma was treated with a V-P shunt surgery in another hospital. After the surgery, the patient developed an intractable disturbance of consciousness. When the V-P shunt pressure was raised or lowered, the patient's consciousness disorder still could not be improved. The patient was diagnosed with Sylvian aqueduct syndrome, a rare complication after V-P shunt operation. The paper clarifies the treatment experience with simultaneous endoscopic third ventriculostomy (ETV) and tectum gliomas biopsy, postoperative pathology suggestive of fibrillary astrocytoma; after surgery, the Sylvian aqueduct syndrome was cured and the patient recovered well. The preferred treatment for obstructive hydrocephalus caused by tumors in the Pineal region is the ETV operation. If an ETV operation and biopsy operation are performed simultaneously, more details need to be noted.

The Child with a Large Head: Cranial Computed Tomography Findings in 123 Nigerian Children with Macrocephaly

Objectives: Differentiation of benign macrocephaly from other etiologies that may require prompt evaluation and intervention is very necessary to prevent long term neurological deficits. Cross-sectional imaging of the brain with Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) is recommended in evaluation of such patients. In resource poor-settings, CT is more readily available, hence the objective in this study is to evaluate the spectrum of CT findings in children with macrocephaly in our locality and document the possible etiologic factors that are amenable to surgical intervention.
 Materials and Methods: This is a retrospective study of pediatric patients with clinical diagnosis of large head/macrocephaly who were evaluated with cranial CT in a tertiary hospital in Abuja from January 2018- June 2022. SAS software (SAS Institute, Cary, North Carolina, USA) version 9.4 was used for database management and analysis with P≤ 0.05 level of significance.
 Results: One hundred and twenty three children were included in the study with ages ranging from 2 days to 4 years. Majority of the children were males, 74 (60.2%). The predominant age group at presentation was between 0 to 6 months,78 (63.4%). Hydrocephalus was the main cause of macrocephaly in 110 patients (89.4%). Congenital hydrocephalus was predominant in 81 children (73.6%). Communicating hydrocephalus was noted in 44 children (40%) while 62 (56.4%) were non-communicating. The commonest level of obstruction was at the aqueduct of Sylvius and exit foramina in 22 (35.5%) patients each. There was no significant statistical difference between the genders(P=0.920).
 Conclusion: CT is a veritable tool in the evaluation of the child with a large head with an appreciable number of surgically amenable pathologies noted. Hydrocephalus is the commonest etiology of macrocephaly in our environment with the majority of the cases due to congenital abnormalities.

An in vitro experimental investigation of oscillatory flow in the cerebral aqueduct

This in vitro study aims at clarifying the relation between the oscillatory flow of cerebrospinal fluid (CSF) in the cerebral aqueduct, a narrow conduit connecting the third and fourth ventricles, and the corresponding interventricular pressure difference. Dimensional analysis is used in designing an anatomically correct scaled model of the aqueduct flow, with physical similarity maintained by adjusting the flow frequency and the properties of the working fluid. The time-varying pressure difference across the aqueduct corresponding to a given oscillatory flow rate is measured in parametric ranges covering the range of flow conditions commonly encountered in healthy subjects. Parametric dependences are delineated for the time-averaged pressure fluctuations and for the phase lag between the transaqueductal pressure difference and the flow rate, both having clinical relevance. The results are validated through comparisons with predictions obtained with a previously derived computational model. The parametric quantification in this study enables the derivation of a simple formula for the relation between the transaqueductal pressure and the stroke volume. This relationship can be useful in the quantification of transmantle pressure differences based on non-invasive magnetic-resonance-velocimetry measurements of aqueduct flow for investigation of CSF-related disorders.

Neurocognitive outcome post cranioplasty: The role of cerebral hemodynamics and cerebrospinal fluid dynamics.

Cranioplasty has been useful in treating the symptoms associated with the "Sunken skin flap syndrome" post decompressive craniectomy, for which various mechanisms have been proposed. In this study, we aim to assess the changes in the cerebral blood flow and intracranial cerebrospinal fluid (CSF) dynamics post cranioplasty and correlate with the improvement in the neurocognitive status. Computed tomography perfusion and cine magnetic resonance imaging studies were done to study the changes in cerebral perfusion and CSF flow dynamics postcranioplasty. The cognitive status was assessed using Montreal cognitive assessment, mini-mental state examination, and frontal assessment battery scores in the preoperative period and at 1 and 6 months follow-up. There was a significant change in cognitive status postcranioplasty, both at 1 and 6 months follow-up, which was associated with a significant improvement in cerebral blood flow, decreased mean transit time, and improvement in the mean and peak CSF flow velocities at the foramen of Magendie and aqueduct of Sylvius. Cranioplasty leads to a marked improvement in cerebral hemodynamics, which is more significant on the ipsilateral side. It also leads to increased CSF turnover and improved CSF circulation. Improved cerebral perfusion and, more importantly, CSF dynamics may be responsible for the demonstrable improvement in the neurocognition in the postcranioplasty period.

Changes of cerebrospinal fluid pressure gradient in different body positions under experimental impairment of cerebrospinal fluid pathway: new insight into hydrocephalus development.

It is generally accepted that hydrocephalus is a consequence of the disbalance between cerebrospinal fluid (CSF) secretion and absorption which should in turn lead to CSF pressure gradient development and ventricular enlargement. To test CSF pressure gradient role in hydrocephalus development, we experimentally caused CSF system impairment at two sites in cats. In the first group of animals, we caused Sylvian aqueduct obstruction and recorded CSF pressure changes pre and post obstruction at three measuring sites (lateral ventricle -LV, cortical-CSS and lumbar subarachnoid space -LSS) during 15 min periods and in different body positions over 360 degrees. In the second group of experiments, we caused cervical stenosis by epidural plastic semiring implantation and monitored CSF pressure changes pre and post stenosis implantation at two measuring sites (lateral ventricle and lumbar subarachnoid space) during 15 min periods in different body positions over 360 degrees. Both groups of experimental animals had similar CSF pressures before stenosis or obstruction at all measuring points in the horizontal position. During head-up verticalization, CSF pressures inside the cranium gradually became more subatmospheric with no significant difference between LV and CSS, as they are measured at the same hydrostatic level, while CSF pressure inside LSS became more positive, causing the development of a large hydrostatic gradient between the cranial and the spinal space. With cervical stenosis, CSF pressure inside the cranium is positive during head-up verticalization, while in cats with aqueductal obstruction CSF pressure inside the CSS remains negative, as it was during control period. Concomitantly, CSF pressure inside LV becomes less negative, thus creating a small hydrostatic gradient between LV and CSS. Since CSF pressure and gradient changes occur only by shifting body position from the horizontal plane, our results indicate that cervical stenosis in a head-up vertical position reduces blood perfusion of the whole brain, while aqueductal obstruction impairs only the perfusion of the local periventricular brain tissue. It seems that, for evolutionary important bipedal activity, free craniospinal communication and good spinal space compliance represent crucial biophysical parameters for adequate cerebral blood perfusion and prevention of pathophysiological changes leading to the development of hydrocephalus.

Individualized Functional Decompression Options for Adult Chiari Malformation With Syringomyelia and A Novel Scale for Syringomyelia Resolution: A Single-Center Experience.

To compare outcomes of posterior fossa bony decompression alone (PFD) versus PFD with duraplasty (PFDD) versus PFDD with additional obex exploration (PFDDO) in patients with Chiari malformation type I (CMI) combining syringomyelia. Clinical records of adult patients who underwent decompressions from 2014 to 2022 were retrospectively analyzed. The decompression procedure was individualized based on the cerebrospinal fluid pulse in the surgical field. The Chicago Chiari Outcome Scale (CCOS) was used to assess the prognosis of the patients and a novel syringomyelia resolution scale, based on 3-dimensional volume, was introduced. The percentage change in the cervical syrinx volume was classified as follows by resolution: ≥ 70%, 30%-70%, and < 30%. Seventy-eight individuals were enrolled, of which 22, 20, and 36 underwent PFD, PFDD, and PFDDO, respectively. The three decompression groups had no significant difference in the preoperative characteristics and postoperative prognosis. Multivariate analyses revealed that better CCOS was significantly correlated with younger age at surgery (p = 0.018), syrinx originated from lower cervical levels (p = 0.037), narrower preoperative cerebral aqueduct (p = 0.005), and better syrinx volume resolution (p = 0.004). Additionally, a better cervical syrinx volume resolution was significantly correlated with higher CCOS (p = 0.017), narrower cerebral aqueduct (p = 0.035), and better tonsillar descent resolution (p = 0.007). Individualized functional decompression induced an equal effect on CCOS and syrinx volume resolution for all CMI patients with syringomyelia. Our syringomyelia resolution scale facilitates communication and prediction of CMI prognosis.

Endoscopic anatomy of the ventricles

The cerebral ventricles are structures known since antiquity. At the beginning of its description there was a belief that human thoughts and intellect were generated inside the ventricular cavity, and this idea persisted even after the Renaissance. In this period after the Dark Ages, the anatomical description of the ventricles evolved a lot, but it took a long time to conclude the true liquid nature of the ventricular content. The ventricles are divided into lateral, third and fourth ventricles, and each of these regions presents communications between themselves and very precise limits. For endoscopic procedures, a thorough knowledge of the anatomy of the lateral and third ventricles is extremely important. The cerebrospinal fluid circulates inside the ventricles according to a complex mechanism, and there are still controversies nowadays, especially regarding its resorption. Each lateral ventricle is a “C”-shaped cavity that surrounds the thalamus and is deeply located in the brain, following the contour of the choroid fissure. These structures represent, from an embryological point of view, the light of the telencephalic vesicles. Each lateral ventricle has five parts: frontal horn, body, atrium, occipital horn, and temporal horn. The frontal horn is the part of the lateral ventricle located anteriorly to the foramen of Monro. The lateral ventricle body extends from the posterior margin of the foramen of Monro to the point where the fornix and the corpus callosum converge, thus disappearing the septum pellucidum. The atrium of the lateral ventricle and its occipital extension form a triangle with an anterior base in the pulvinar and a posterior apex in the occipital lobe. The occipital horn is triangular, with a posterior vertex and a base in the atrium. The temporal horn is the inferior extension of the ventricle, being the continuation of the atrium, directing itself anteriorly and laterally. Each of these divisions has a medial, lateral, ceiling, and floor wall. In addition, the frontal, temporal, and atrial horns have anterior walls. These walls are formed by the thalamus, septum pellucidum, white matter, corpus callosum, caudate nucleus, and fornix. The third ventricle is a funnel-shaped, unilocular, narrow midline cavity. It communicates at the anterosuperior margin with each lateral ventricle through the foramen of Monro and, subsequently, with the fourth ventricle through the cerebral aqueduct. In adult individuals, the lateral distance of the third ventricle is 5.5 mm on average. In a study using MRI images, the hydrocephalic configuration of the third ventricle disappeared after the endoscopic third ventriculostomy (ETV), with a decrease in diameter, elevation, and horizontal direction of the floor and reduction of the infundibular angle . The floor of the third ventricle extends from the optic chiasm anteriorly to the opening of the cerebral aqueduct posteriorly. It descends ventral and is formed by at least 12 cellular clusters or nuclei within the hypothalamic region. Anatomically, three portions can be described on the floor of the third ventricle: (1) premammillary portion, which extends from the infundibulum to the premammillary sulcus, constituting a very thin layer of gray substance of the hypothalamus; (2) interpeduncular portion, which extends from the postmammillary recess to the posterior margin of the interpeduncular space, being formed of gray substance and firmer than the first; and (3) peduncular portion, which corresponds to the portion of the cerebral peduncles, being the most solid portion, being formed by the medial aspect of the peduncles covered by the peduncular ependyma. The knowledge of the endoscopic anatomy of the ventricles is of the key importance for endoscopic neuroendoscopy

Impact of Shunt Placement on CSF Dynamics.

CSF dynamics are disturbed in chronic hydrocephalus (NPH). We hypothesise that these alterations reflect a disturbance of intracranial compliance. The aim of our study is to investigate the variations in intracranial hydrodynamics in NPH after ventricular shunt surgery. We included 14 patients with definite NPH. All patients improved after ventriculoperitoneal shunting. The patients underwent an analysis of intracranial haemodynamics by phase-contrast MRI (pcMRI) preoperatively, at 6 months postoperatively, and at 1 year postoperatively. We analysed the dynamics of intraventricular CSF at the level of the aqueduct of Sylvius (SVAQU) and CSF at the level of the high cervical subarachnoid spaces (SVCERV). We calculated the ratio between SVAQU and SVCERV, called CSFRATIO, which reflects the participation of intraventricular pulsatility in overall intracranial CSF pulsatility. SVAQU significantly (p = 0.003) decreased from 240 ± 114 μL/cc to 214 ± 157 μL/cc 6 months after shunt placement. Six months after shunt placement, SVCERV significantly (p = 0.007) decreased from 627 ± 229 μL/cc to 557 ± 234 μL/cc. Twelve months after shunt placement, SVCERV continued to significantly (p = 0.001) decrease to 496 ± 234 μL/cc. CSFRATIO was not changed by surgery. CSF dynamics are altered by shunt placement and might be a useful marker of the shunt's effectiveness-especially if pressure values start to rise again. The detection of changes in CSF dynamics would require a reference postoperative pcMRI measurement for each patient.

Neuroradiological characteristics of hydrocephalus due to idiopathic extraventricular CSF pathways obstruction

The development of research on CSF flow disorders made it possible initially to divide hydrocephalus into «communicating» and «non-communicating», and subsequently to distinguish the concepts of «intraventricular» and «extraventricular» obstruction. Improvement of radiological imaging technologies has allowed determining the exact level of CSF obstruction. In some cases, CSF flow disorders combine signs of different forms of hydrocephalus. Their correct classification allows selecting the type of surgical treatment, which reduces the rate of complications and patient»s dependence on the doctor. Purpose of the research: To study the radiological signs of hydrocephalus in idiopathic obstruction at the level of the posterior cranial fossa cisterns. Materials and methods. This study included adult patients (18 years old and over) whose disease was idiopathic in nature. From 2007 to 2020, 289 patients diagnosed with idiopathic hydrocephalus were treated at the N. N. Burdenko National Medical Research Center of Neurosurgery. Of these, 65 patients (18.7 %) had clinical and radiological signs of extraventricular obstruction. The male to female ratio was 25 and 40 (38.5 % and 61.5 %), respectively. A variety of radiological signs were assessed and their origin and occurrence in various forms of idiopathic hydrocephalus were determined. Results. FOHR was the highest (compared with other forms of idiopathic hydrocephalus (mean 0.52)). Other ventricular indices were also high. None of them correlated with the patient»s condition. Ventral dislocation of the premamillary membrane was detected in 89.2 %. Turkish saddle was of normal size in 51 (78.4 %) patients, while its enlargement was found in 13 (20 %) patients. A change in the periventricular signal was noted in 18.4 %. Aqueduct and IV ventricle outlets were patent in all cases as evidenced by CSF pulsation artifacts in T2 3D CUBE. The cerebral aqueduct was dilated in 63 (96.9 %) patients. Enlargement of the cisterna magna associated with hypotrophy of the caudal cerebellum was noted in 90.7 %, and this sign was significant for extraventricular cisternal obstruction (p &lt;0.001). In addition to the T2 mode, the presence of sagittal sections in cisternography modes (FIESTA or CISS) was a prerequisite. By means of these modes, the ventral dislocation of the premamillary membrane was more clearly visualized, the presence of obstacles to the CSF flow in the cerebral aqueduct was excluded, and, most importantly, it was possible to determine the presence of additional membranes in the subarachnoid spaces between the ventral surface of the brain stem and the clivus. These were found in 100 % of the patients, which was also a significant pathognomonic sign (p &lt; 0.001). Conclusion. The MRI picture of hydrocephalus with obstruction at the level of the posterior cranial fossa cisterns has specific signs. It combines the signs of other forms of hydrocephalus, chronic disease in combination with symptoms of the CSF pathways obstruction. It can be classified into a separate form and both endoscopic and shunt surgery can be used for treatment.

The Role of Cerebrospinal Fluid Flow in the Subarachnoid Space in Beta‐Amyloid Clearance

AbstractBackgroundRecent studies identified the lymphatic drainage system in the brain. Here, cerebrospinal fluid (CSF) carries waste from brain tissue. However, it is still not well understood how CSF flow in the brain affects waste removal. In this study, we hypothesize that CSF flow patterns in the subarachnoid space will be correlated with beta‐amyloid deposition in the brain.MethodThirteen participants (7 Cognitively Normal and 2 Mild Cognitive Impairment, Age = 68±7.7 yrs. M/F = 5/4) who had prior amyloid PET imaging were recruited for CSF flow MRI from the Wake Forest Alzheimer’s Disease Research Center. The CSF flow patterns during the cardiac cycle were measured using the phase‐contrast MRI at the cerebral aqueduct, pontine cistern and cerebellomedullary cistern (Fig. 1). Images were acquired for 40 cardiac cycles with a pulse oximeter and CSF flow profiles were estimated using the retrospective cardiac gating method. PET Amyloid burden in the whole gray matter (GM) was measured as the standardized update value ratio (SUVR, cerebellar gray matter as a reference region) from the prior PET imaging and corresponding MRI.ResultCSF flow amplitude normalized by the brain tissue volume demonstrated moderate to strong correlations with beta‐Amyloid SUVR in GM (Fig. 2); Pearson’s correlation coefficient (rho) was ‐0.59 (p = 0.036) and ‐0.84 (p = 0.004) at pontine cistern and cerebellomedullary cistern, respectively. The lateral ventricle volume normalized by brain volume was also moderately correlated with GM SUVR (rho = 0.495).ConclusionAt an early stage of AD, the CSF circulation in the subarachnoid space could be correlated with beta‐Amyloid deposition. Therefore, CSF flow in the subarachnoid space could be a useful imaging marker to predict the clearance of beta‐amyloid in the brain.

Advanced cerebrospinal fluid flow MRI findings of aqueductal stenosis caused by web.

The aqueductal web (AW) is one of the causes of aqueductus stenosis (AS). Recent advances in Magnetic resonance (MR) imaging have enabled us to better reveal the cerebrospinal fluid (CSF) flow dynamics and aqueductal anatomy. The aim of this study is to evaluate the CSF flow dynamics of patients with AW with phase contrast Magnetic resonance imaging (MRI) and compare them with the imaging findings. We evaluated 23 patients under 65-year-old age. On constructive interference in steady-state (T2 CISS) images, the width of prepontine cistern (PPC) and the width of Sylvian aqueduct (SA) were measured. Localization and number of webs were evaluated. The existence of flow at the aqueduct and the presence of spontaneous third ventriculostomy (STV) were evaluated on sagittal Sampling Perfection with Application optimized Contrast (SPACE) sequences. Of the 23 patients included in the study, 11 were male and 12 were female. The mean age was 34.02 (0.5-64). A total of 31 AWs were detected in 23 patients. Six of 23 patients (26.1%) had STV and 17 of those not. Four of 23 patients (17.4%) had aqueductal flow on SPACE sequences. The PPC distance was significantly wider in patients with STV (median: 6.7-4.5, interquartile range (IQR): 1.35, p = 0.004). In the cases where artifact secondary to flow is observed in SPACE sequences in aqueduct, the Evan index (EI) was significantly lower (median: 0.2955-0.3900, IQR: 0.03-0.14, p < 0.001). In patients with a low EI, there may be flow in the SA even if there is a web. In patients with a wide PPC distance, it is necessary to consider the presence of STV and evaluate the presence of flow with the SPACE sequences.

Cerebrospinal Fluid Flow Parameters in Normal Subjects above 40 Years of Age

Abstract Background Cerebrospinal fluid (CSF) flow is altered in many conditions like normal pressure hydrocephalus (NPH), aqueduct stenosis, or Chiari malformation. It is very important to know the normal CSF flow parameters for properly diagnosing these conditions. No data on CSF flow parameters of the Indian population are available. Hence, this study was undertaken to generate normative CSF flow parameters in the Indian population. Aim Our aim was to estimate normal CSF flow parameters across the cerebral aqueduct in Indian subjects over 40 years of age. Settings and Design This observational study was done in the tertiary care institute on subjects undergoing magnetic resonance imaging (MRI) for indications like headache and having normal MRI. Methods Phase-contrast quantitative flow sequence was done in 100 subjects perpendicular to the cerebral aqueduct on 3.0T MRI (Discovery 750w with GEM suit, GE, Milwaukee, WI, United States) using a dedicated 32-channel head coil with 10 cm/s velocity encoding. The region of interest was kept at the cerebral aqueduct in cross-section. The inbuilt software calculated flow-time and velocity-time graphs and calculated peak systolic velocity (PSV), peak diastolic velocity (PDV), systolic flow (SF), and diastolic flow (DF). Stroke volume (SV) was calculated by averaging systolic and DFs. p-Value &lt; 0.05 was considered significant. Results Mean age was 53.72 ± 10.53 (40–78) years with 41 males and 59 females. PSV, PDV, SF, DF, and SV all showed a significant linear correlation with age with p-values of 0.001, 0.004, 0.009, &lt;0.001, and &lt;0.001, respectively. Only PDV (p = 0.035) and DF (p = 0.045) varied significantly with sex, values being higher in males. Conclusion All five CSF flow parameters studied vary positively with age, and this variation is linear. Normal decadal median values calculated for these parameters can act as baseline values for the local population and help in defining conditions like NPH.

Symptomatic postoperative compressive pneumocephalus after cholecystectomy

A 75-year-old woman with a history of chronic hydrocephalus due to stenosis of the aqueduct of Sylvius was examined at the emergency department for altered mental status. There was placement of a ventriculoperitoneal shunt in 1970 complicated by meningitis, leading to removal of the material and ventriculociternostomy as definitive treatment in 2004. About one month previously, she had undergone a laparoscopic cholecystectomy complicated by an intra-abdominal collection. Clinical examination at the emergency department revealed a Glasgow score of 8 (E3 V1 M4). In the emergency department the patient presented a tonic-clonic seizure before a cerebral CT scan was performed showing a massive compressive pneumocephalus, then a second seizure. The patient was finally admitted to the neurosurgery department and underwent surgery.

Endoscopic placement of a triventricular stent for complex hydrocephalus and isolated fourth ventricle: illustrative case

BACKGROUND Hydrocephalus is commonly encountered in pediatric neurosurgery. The etiology is diverse, and complexity in management increases in patients with loculated or trapped ventricles. The authors sought to examine a treatment option of endoscopic placement of a triventricular stent in a pediatric patient with complex hydrocephalus and a trapped fourth ventricle. OBSERVATIONS In this case, the authors present the treatment of complex hydrocephalus with a trapped fourth ventricle in a pediatric patient using endoscopic placement of a triventricular aqueductal stent. The patient had a complex neurosurgical history, which included over 15 surgeries for shunted hydrocephalus. This case highlights the unique approach used, and the authors discuss surgical nuances of the technique, as well as learning points. LESSONS Complex hydrocephalus can be difficult to manage because patients often have multiple catheters, loculated or trapped ventricles, and extensive surgical histories. Endoscopic placement of a triventricular stent can decrease shunt system complexity, restore normal cerebrospinal fluid pathway circulation across the cerebral aqueduct, and promote communication between the ventricles. The authors’ treatment modality resulted in the successful resolution of the trapped fourth ventricle and symptomatic improvement in hydrocephalus.

A Pineal Parenchymal Tumor of Intermediate Differentiation in an Octogenarian Contains a Rare KBTBD4 Insertion.

Pineal parenchymal tumors are rare central nervous system tumors that pose diagnostic challenges for surgical pathologists. Due to their paucity, their clinicopathologic features are still being defined. We report an 86-year-old woman with a remote history of breast lobular carcinoma who presented with a 2-month neurologic history that included gait instability, blurry vision, and headaches. Magnetic resonance imaging revealed a lobular, heterogeneously enhancing pineal region mass compressing the aqueduct of Sylvius. A biopsy performed concomitant with endoscopic third ventriculostomy consisted of small sheets of cells with eosinophilic to clear cytoplasm, multipolar processes, and ovoid nuclei with stippled chromatin. Whole exome sequencing revealed a small in-frame insertion (duplication) in exon 4 of KBTBD4 (c.931_939dup, p.P311_R313dup/ p.R313_M314insPRR), which has very recently been reported in 2 pineal parenchymal tumors of intermediate differentiation (PPTID). Additionally, variants of uncertain significance in CEBPA (c.863G > C, p.R288P) and MYC (c.655T > C, p.S219P) were identified. Although PPTID is considered a disease of young adulthood, review of 2 institutional cohorts of patients with pineal region tumors revealed that 25% of individuals with PPTID were over 65 years of age. In conclusion, PPTID should be considered in the differential diagnosis of pineal region tumors in older adults.

Surgical aspects of classification and neuroimaging characteristics of idiopathic hydrocephalus in adults

Background. Hydrocephalus can be developing by a traumatic brain injury, intracranial hemorrhage, tumor, meningitis of congenital malformation of the central nervous system. When the cause of the hydrocephalus is unclear it is supposed as idiopathic hydrocephalus. The most important classification features are the etiology and level of CSF obstruction. The classification was improved and developed with diagnostic and surgical methods simultaneously. Currently, the neurosurgeons have the possibility for usage of various methods and techniques of surgical treatment with their advantages and disadvantages. Systematization of radiological parameters is necessary to make a decision about the type of the surgery.Aim. To analyze and systematize the neuroimaging characteristics of various forms of idiopathic hydrocephalus in adults, to assess the possible classification of idiopathic hydrocephalus.Materials and methods. Between October 2011 and March 2021 290 patients with idiopathic adult hydrocephalus were operated at the N.N. Burdenko National Medical Research Center of Neurosurgery of the Ministry of Health of Russia: onset of symptoms in adulthood; no indications of the etiology of hydrocephalus and congenital hydrocephalus. The age of the patients was 50 ± 18.2 (18–85) years. The magnetic resonance images of patients were evaluated for the size of the ventricles, condition of convexital and basal subarachnoid spaces, obstruction of the CSF pathways, and changes in the position of the premamillary membrane, septum pellucidum, the roof of the 3rd ventricle and the tonsils of the cerebellum, the size of the sella turcica, the angle of the corpus callosum. The frequency of each of these parameters is statistically estimated for each form of idiopathic hydrocephalus.Results. Aqueduct stenosis has become the most frequent form of idiopathic hydrocephalus. Hydrocephalus in obstruction of the foramen of Monroe, aqueduct, foramen of Magendie, and cisterns of the posterior cranial fossa was significantly more characteristic of young people (p &lt;0.05). Hydrocephalus with obstruction of convexital CSF spaces can be called hydrocephalus of the elderly (p &lt;0.001). Hydrocephalus without verified signs of occlusion CSF pathways occurs equally in all age groups. The FOHR index was significantly more important, and only in case of cisternal obstruction. Enlargement one or both lateral ventricles and flattening of the roof of the 3rd ventricle is characterized for Monro’s foramen obstruction (p &lt;0.001). The membrane at the outlet of the 4th ventricle and the absence of the “flow void” was typically only for patients with obstruction of the foramen of Magendie (p &lt;0.001). Ventral dislocation of the premamillary membrane was characteristic of obstruction of the cerebral aqueduct, the foramen of Magendie, and cisterns of the posterior cranial fossa. Compression of the convexital CSF spaces occurred in case of obstruction of the aqueduct, the foramen of Magendie, but CSF spaces of the posterior cranial fossa – only with obstruction of the foramen of Magendie. Dilation of the 4th ventricle was significantly associated with obstruction of the foramen of Magendie and cisterns of the posterior cranial fossa (p &lt;0.05). DESH symptom was significantly associated with obstruction of convexital CSF spaces (p &lt;0.001). Additional membranes in the cisterns of the posterior fossa were found only in cases of cisternal obstruction (p &lt;0.001). Cerebellar tonsils herniation was observed with obstruction of the foramen of Monroe, cerebral aqueduct, and foramina of Magendie.Conclusion. Because of statistical analysis, general signs found in all types of hydrocephalus, and private ones, characterizing only specific signs of the type of the disease, both were found. The classification is logical and justified, it is well applicable in neurosurgical and radiological practice. It allows rational planning of diagnostic evaluation and treatment of patients. A modern magnetic resonance imaging protocol should include T2 scans (with “flow void”) and FIESTA/CISS scans in the required planes, axial FLAIR scans.

Distribution of corpora amylacea in the human midbrain: using synchrotron radiation phase-contrast microtomography, high-field magnetic resonance imaging, and histology.

Corpora amylacea (CA) are polyglucosan aggregated granules that accumulate in the human body throughout aging. In the cerebrum, CA have been found in proximity to ventricular walls, pial surfaces, and blood vessels. However, studies showing their three-dimensional spatial distribution are sparse. In this study, volumetric images of four human brain stems were obtained with MRI and phase-contrast X-ray microtomography, followed up by Periodic acid Schiff stain for validation. CA appeared as hyperintense spheroid structures with diameters up to 30 μm. An automatic pipeline was developed to segment the CA, and the spatial distribution of over 200,000 individual corpora amylacea could be investigated. A threefold-or higher-density of CA was detected in the dorsomedial column of the periaqueductal gray (860-4,200 CA count/mm3) than in the superior colliculus (150-340 CA count/mm3). We estimated that about 2% of the CA were located in the immediate vicinity of the vessels or in the peri-vascular space. While CA in the ependymal lining of the cerebral aqueduct was rare, the sub-pial tissue of the anterior and posterior midbrain contained several CA. In the sample with the highest CA density, quantitative maps obtained with MRI revealed high R2* values and a diamagnetic shift in a region which spatially coincided with the CA dense region.

Symptomatic obstructive hydrocephalus caused by choroid plexus hyperplasia in a pediatric patient: illustrative case.

Choroid plexus hyperplasia has been described as a rare cause of communicating hydrocephalus due to cerebrospinal fluid (CSF) overproduction. However, this is the first report of symptomatic obstructive hydrocephalus caused by mechanical obstruction of the aqueduct by a hyperplastic choroid plexus. A 4-year-old male presented with headaches and intermittent emesis. Magnetic resonance imaging (MRI) of the brain showed abnormal enlargement of the choroid plexus in the lateral ventricles with extension into the third ventricle, resulting in obstruction of the aqueduct of Sylvius, leading to obstructive hydrocephalus. Endoscopic third ventriculostomy (ETV) was chosen as the surgical treatment. During the procedure, high pressure flow of clear CSF was noted. Normal intraventricular anatomy was identified, and no cyst or tumor was found. The postoperative MRI showed a patent third ventriculostomy, without complication, and a significant decrease in supratentorial ventricular size. The patient was discharged 3 days after surgery with a complete resolution of symptoms. Choroid plexus hyperplasia has the potential to cause obstructive hydrocephalus, and it can be effectively treated with ETV. Our hypothesis is that the change in pressure caused by the procedure may have led to an uncorking of the aqueduct by the hyperplastic choroid plexus, contributing to the observed improvement.

Theoretical and numerical analysis of the flow through a diffuser/nozzle element in pulsatile laminar conditions

Diffuser/nozzle pipes produce a directional flow resistance that is often exploited in microcirculation to generate a pumping action. This work presents an approximate time-dependent theoretical solution based on the mechanical energy conservation equation to predict the laminar flow rate through an ideal diffuser/nozzle pump. The theoretical solution is then used to characterize the dimensionless parameters that control the dynamics of the valveless pump in the pulsatile flow regime. A suitable numerical model is also implemented to solve the flow in a parametrized two-dimensional axial-symmetric domain subjected to an oscillating pressure, and its results are used to assess the theoretical solution. The pump dynamics and the main model parameters, such as the energy-loss coefficients, result in the following dependence on the ratios between the viscous force, the advective inertia, and the temporal inertia, i.e., the Reynolds (Red), Womersley (Wod), and Strouhal (St) numbers referred to throat diameter. In particular, The Womersley number plays an essential role in controlling the global energy loss when Red &amp;lt; 100. The flow transition is also investigated and found when Red exceeds a critical value, which increases with Wod. Finally, the pump efficiency is found to reach its maximum when the convective and temporal inertia become comparable, i.e., St=O(1), consistent with the observed range of St in real-world diffuser/nozzle pumps. This optimum range of functioning of the pump is also observed for cerebrospinal pulsatile flow in the Sylvius aqueduct, suggesting that the modeled mechanism is used to promote or enhance cerebrospinal fluid circulation.