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At least 19 recordsLinked to original sources
PubMedDate not supplied

A histological study of cerebral aqueduct.

Cerebral (sylvian) aqueduct is a narrow channel in the mesencephalon. It lies between the tectum and the tegmentum of the mesencephalon and is surrounded by the periaqueductal gray matter. The aim of this study was to determine the shape of the aqueduct of sylvius and the structure of its walls in a series of transverse histological sections. Serial transverse sections of the mesencephalon were examined in twenty adult brains of both sexes. Six sections were stained by the hematoxylin-eosin method. The rostral part of the the aqueduct has a triangular shape with dorsal concavity caused by retrocommissural fossae. In the middle, its shape is oval to irregular, the rostral part has a T shape due to isthmic recess on the floor. Walls of the aqueduct are coated with a layer of prismatic cells. Determination of the morphological and histological features of the mesencephalic aqueduct is important for differentiation between physiological and pathological processes in this region.

Cerebral Aqueduct↗
PubMed1993

A scanning and transmission electron microscopic analysis of the cerebral aqueduct in the rabbit.

An examination of the surface of the cerebral aqueduct with the scanning electron microscope revealed that the walls of the cerebral aqueduct were so heavily ciliated that most of the ependymal surface was obscured, yet certain specialized supraependymal structures could be discerned lying on (or embedded within) this matt of cilia. These structures were determined by transmission electron microscopy and Golgi analysis to be either macrophages, supraependymal neurons, dendrites from medial periaqueductal gray neurons, or axons of unknown origin. Some axons, which were found to contain vesicles, appeared to make synaptic contacts with ependymal cells. Using the transmission electron microscope, the ependymal lining was found to consist of two different cell types: normal ependymal cells and tanycytes which have a long tapering basal process that was observed to contact blood vessels or, more rarely, seemed to terminate in relation to neuronal elements. While there have been previous reports on the structure of the third and lateral ventricles in other species, there are limited reports in the rabbit. The present report is not only the first description for the rabbit, but it is the first complete scanning and transmission electron microscopic analysis of the cerebral aqueduct in any species.

Animals↗
PubMedDate not supplied

CSF flow quantification of the cerebral aqueduct in normal volunteers using phase contrast cine MR imaging.

OBJECTIVE: To evaluate whether the results of cerebrospinal fluid (CSF) flow quantification differ according to the anatomical location of the cerebral aqueduct that is used and the background baseline region that is selected. MATERIALS AND METHODS: The CSF hydrodynamics of eleven healthy volunteers (mean age = 29.6 years) were investigated on a 1.5 T MRI system. Velocity maps were acquired perpendicular to the cerebral aqueduct at three different anatomical levels: the inlet, ampulla and pars posterior. The pulse sequence was a prospectively triggered cardiac-gated flow compensated gradient-echo technique. Region-of-interest (ROI) analysis was performed for the CSF hydrodynamics, including the peak systolic velocity and mean flow on the phase images. The selection of the background baseline regions was done based on measurements made in two different areas, namely the anterior midbrain and temporal lobe, for 10 subjects. RESULTS: The mean peak systolic velocities showed a tendency to increase from the superior to the inferior aqueduct, irrespective of the background baseline region, with the range being from 3.30 cm/sec to 4.08 cm/sec. However, these differences were not statistically significant. In the case of the mean flow, the highest mean value was observed at the mid-portion of the ampulla (0.03 cm(3)/sec) in conjunction with the baseline ROI at the anterior midbrain. However, no other differences were observed among the mean flows according to the location of the cerebral aqueduct or the baseline ROI. CONCLUSION: We obtained a set of reference data of the CSF peak velocity and mean flow through the cerebral aqueduct in young healthy volunteers. Although the peak systolic velocity and mean flow of the CSF differed somewhat according to the level of the cerebral aqueduct at which the measurement was made, this difference was not statistically significant.

Adult↗
PubMed1987

Ependymal foldings and other related ependymal structures in the cerebral aqueduct and fourth ventricle of man.

The ependymal lining of the cerebral aqueduct and fourth ventricle of 100 normal humans was studied with the light microscope. Ependymal foldings with normal morphology and a constant distribution pattern were detected in all. The most common sites were the median sulcus and sulcus limitans in the fourth ventricle, and the ventral and lateral walls in the cerebral aqueduct. Rows, islands and rosettes of ependymal cells embedded in normal subependyma were present in 25/82 adults (30%) and in 3/18 children (16%) in a similar distribution pattern as that of the ependymal foldings. We illustrate these normal structures which probably result from fusion between the walls of the ependymal foldings and distinguish them from granular ependymitis and postmortem artifact.

Adult↗
PubMed1982

Tumors of the cerebral aqueduct.

Two cases of tumor of the cerebral aqueduct are described. Case 1 is a pilocytic astrocytoma in a 16-year-old girl with a two-year history of intermittent increase of intracranial pressure. The tumor was completely confined within the lumen of the aqueduct. Case 2 is a subependymoma of a 68-year-old man. The tumor extended beyond the aqueduct to the periaqueductal gray matter and produced signs and symptoms suggesting normal pressure hydrocephalus. The literature contains 18 other cases of tumor of the aqueduct: 13 gliomas and five vascular malformations. All, except one, produced clinical manifestations of generalized hydrocephalus lasting from 20 days to six years. The result generally did not correspond to the histologic type of the tumor. Like gliomas of the brainstem in general, those in the aqueduct tend to occur in childhood and adolescence and affect male more than female patients.

Adolescent↗
PubMed1975

Feeding and temperature changes in sheep following injections of barbiturates, Ca-++, or Mg-++ into the lateral, third, or fourth ventricle or cerebral aqueduct.

Eleven sheep were prepared with cannula guides directed toward four areas within the ventricular system to determine effective sites of action of chemicals which when injected into the cerebrospinal fluid produce changes in feeding behavior and temperature regulation. Pentobarbital, barbital, calcium chloride, and magnesium chloride elicited feeding in sheep when injected into the third ventricle or into the cerebral aqueduct; however, feeding response was less after injections into the latter. Pentobarbital and magnesium chloride elicited an increase in body temperature when injected into the third ventricle but not when injected into the cerebral aqueduct. Perfusions (push-pull) of the lateral and third ventricles with calcium chloride and magnesium chloride solutions (50 mM) resulted in feeding while similar perfusions of the fourth ventricle resulted in no response. Responses to lateral and third ventricular injections presumably involved effects on both anterior and posterior hypothalamic areas while injections into the cerebral aqueduct, due to the caudal flux of the cerebrospinal fluid, may have affected primarily only the posterior hypothalamus and more caudal structures. The feeding response probably resulted from depression of neural fibers which inhibit feeding.

Animals↗
PubMed2006

Endoscopically-assisted resection of a choroid plexus vascular malformation traversing the cerebral aqueduct: technical case report.

OBJECTIVE: We report a case of a choroid plexus vascular malformation of the cerebral aqueduct, third, and fourth ventricles of an adolescent female that was resected with endoscopic assistance. CLINICAL PRESENTATION: A 14-year-old girl presented with a 1-week history of headaches and emesis. A noncontrasted computed tomographic scan of the head demonstrated enlarged lateral and third ventricles. Subsequent magnetic resonance imaging scans with and without contrast revealed an enhancing mass originating in the third ventricle, traversing the cerebral aqueduct, and terminating in the fourth ventricle. RESULTS: We used a suboccipital approach to remove the vascular malformation after endoscopically disconnecting it from its feeding and draining vessels in the third ventricle. Total excision was performed. Postoperative magnetic resonance imaging scans and arteriograms confirmed complete resection of the vascular malformation. CONCLUSION: Choroid plexus vascular malformations can exist intraventricularly and can be confused with a neoplasm. Resection of these intraventricular lesions can be performed with endoscopic assistance.

Adolescent↗
PubMed1981

Specialized ependymal ridges in the cerebral aqueduct of the rat.

Novel paired ependymal ridges (EPRS) have been identified in the ventrolateral wall of the cerebral aqueduct of the rat. Scanning electron microscopic techniques revealed that the dorsolateral and ventromedial ridges differ from each other in surface morphology. Using the PAP immunohistochemical technique, the EPRS demonstrate a dense innervation of both serotonin and LH-RH fibers when compared to the surrounding midbrain periaqueductal gray and the "non-ridge" ependyma of the aqueduct. Each ridge is composed of a single layer of ependymal cells with a central core of subependymal cells and numerous blood vessels. Ependymal cells resembling tanycytes extend between the lumen of the aqueduct and the subependymal capillaries. It is suggested that the EPRS may serve as sites for the release of neurochemicals into the cerebrospinal fluid.

Animals↗
PubMed2006

Endoscopic aqueductoplasty and placement of a stent in the cerebral aqueduct in the management of isolated fourth ventricle in children.

OBJECT: In this study the authors conducted a retrospective evaluation of the effectiveness of endoscopic aqueductoplasty, performed alone or accompanied by placement of a stent, in the treatment of an isolated fourth ventricle (IFV) in seven patients afflicted with loculated hydrocephalus after a hemorrhage or infection. METHODS: Seven children with symptomatic IFV and membranous aqueductal stenosis underwent endoscopic aqueductoplasty alone or combined with placement of a stent in the cerebral aqueduct. The mean age of the patients at the time of surgery was 10 months. The mean duration of follow up was 26 months. In all patients a supratentorial shunt had already been implanted, and in five patients neuroendoscopy had already been performed because other isolated compartments had been present inside the ventricular system. Aqueductoplasty alone was performed in three patients and aqueductoplasty and aqueductal stent placement in four. A precoronal approach was performed in five patients and a suboccipital approach in two. Signs and symptoms of intracranial hypertension resolved in all cases. Stent placement was successful in all five cases, resulting in clinical and neuroimaging-confirmed improvements in the IFV. Restenosis of the aqueduct occurred in two patients in whom stents had not been placed. In one of these patients restenosis was managed by an endoscopic procedure, during which the aqueduct was reopened and a stent implanted; in the other patient a shunt was placed in the fourth ventricle. Hydrocephalus was controlled by a single shunt in six cases (86%) and by a double shunt in one case. CONCLUSIONS: Endoscopic placement of a stent in the aqueduct is more effective in preventing the repeated occlusion of the aqueduct than aqueductoplasty alone and should be indicated as the initial treatment in each case of compatible anatomy.

Adolescent↗
PubMed1989

Magnetic resonance imaging of the cerebral aqueduct. Signal intensity time curves demonstrated by fast acquisition with multiple excitation (FAME).

Using cardiac-gated fast acquisition with multiple excitation (FAME), time curves of the cerebral aqueduct signals were derived in 19 healthy volunteers and 14 patients. A mean curve of the normal subjects was determined during systole. A relatively stable point of time was found at 270 msec after the R-wave supposed to be the reversal of the flow of cerebral-spinal fluid in the aqueduct. Different curves were noticed in complete aqueductal obstruction (n = 2); in other pathologic states, such as cerebral tumor (n = 3), normal pressure hydrocephalus (n = 3), and brain atrophy (n = 1), no different signal time curves were observed. Parameters such as aqueduct diameter, cerebro-spinal fluid volume and brain compliance are probably other important factors in aqueduct liquor flow.

Adolescent↗
PubMed2000

[Quantification of fluid flow in magnetic resonance tomography: an experimental study of a flow model and liquid flow measurements in the cerebral aqueduct in volunteers].

PURPOSE: To study the feasibility o MRI for quantification of fluid flow in a tube model and the cerebral aqueduct (CA) in volunteers. VOLUNTEERS AND METHODS: All studies were performed on a 1.5 T MR scanner using a head coil and a FLASH 2D phase contrast sequence with a velocity encoding at 20 cm/s. Flow (real value, ml/sec) of a saline fluid was measured in a flexible tube model with different inside diameters: 0.75-3 mm. Three flow velocities were given (normal value). To test the reproducibility, three studies were done using a flow of 0.12 or 0.14 ml/sec and a tube diameter of 0.75 and 2.0 mm. The ratio of normal to real flow value was calculated (ideal ratio = 1). MRI of CA and flow quantification was done in 24 volunteers (28 +/- 4 years). RESULTS: Using tubes with a diameter of 0.75 and 1.5 mm the real flow was sometimes higher than the velocity encoding of the phase contrast sequences. Because of this measurements of the fluid flow and the flow velocities were impossible. There was agreement for fluid flow quantification in the tube of 3.0 mm and high agreement in the tube of 2.0 mm in diameter with reproducible results. The mean diameter of the CA in normal subjects was 2.0 +/- 0.3 mm, the mean cerebral flow was 0.04 +/- 0.02 ml/sec and the peak velocity 3.06 +/- 1.59 cm/sec. CONCLUSIONS: Reliable flow quantification with MRI is feasible if the diameter of the lumen is greater than 1.5 mm, and if the flow velocity is lower than the velocity encoding. In cases of smaller diameters and higher flow velocities the velocity encoding has to be changed. Because of this the quantification seems to be inaccurate in cases of aqueductal stenosis with the method we used.

Adult↗
PubMed1984

Hydrocephalus with cerebral aqueductal dysgenesis and craniofacial anomalies.

A pre-term infant was born with multiple limb and craniofacial anomalies, including craniosynostosis and a nasopharyngeal adenohypophysis. Severe hydrocephalus of the lateral and third ventricles was attributed to cerebral aqueductal dysgenesis. Scattered aqueductules and ependymal rosettes were found throughout the midbrain and pontine tegmentum. An hypothesis to explain the unique constellation of craniocerebral findings is discussed.

Abnormalities, Multiple↗
PubMed2002

Measurement of cerebrospinal fluid flow at the cerebral aqueduct by use of phase-contrast magnetic resonance imaging: technique validation and utility in diagnosing idiopathic normal pressure hydrocephalus.

OBJECTIVE: We analyzed the reliability of a protocol for measuring quantitative cerebrospinal fluid (CSF) flow at the cerebral aqueduct and established the range of CSF flows in normal elderly patients, patients with Alzheimer's and other forms of dementia, and patients with idiopathic normal pressure hydrocephalus (NPH). METHODS: A constant flow phantom was used to establish the accuracy of the CSF flow measurement. The clinical variability of the measurement was estimated by calculating the standard deviations and coefficients of variation of intra- and interobserver and intertrial data sets derived from three normal volunteers. A total of 236 patients were studied, including 47 normal elderly patients, 115 patients with cognitive impairment (9 with mild cognitive impairment, 46 with Alzheimer's disease, and 60 with other cognitive impairment), 31 patients in whom NPH was suspected but ultimately excluded, and 43 patients with a final clinical diagnosis of NPH. RESULTS: The intraobserver, interobserver, and intertrial measurement variations of 6.4, 5.4, and 8.8%, respectively, were substantially smaller than the wide variation observed among subjects. There was no statistically significant difference in flow between normal elderly patients and patients with cognitive impairment (P = 0.91). When these populations were pooled, the average flow was 8.47 ml/min (standard deviation, 4.23; range, 0.9-18.5 ml/min). The average flow rate in patients with a final clinical diagnosis of NPH was 27.4 ml/min (standard deviation, 15.3; range, 3.13-62.2 ml/min). This was significantly higher than the flow rate in each of the other three groups (all, P < 0.001). CONCLUSION: CSF flow measurements of less than 18 ml/min with a sinusoidal flow pattern are normal. CSF flow of greater than 18 ml/min suggests idiopathic NPH.

Adult↗
PubMedDate not supplied

[Serotoninergic nerve fibers in the area of the substantia grisea and the ependyma of the cerebral aqueduct].

An electron microscopic study of the midbrain gravy with the help of degeneration caused by serotonin-like neurotoxin 5,7-dihydroxytryptamine has shown that serotonergic terminals are responsible for the innervation of dendrites, neuron bodies and ependyma cells of the cerebral aqueduct. The detection of light, dark with prevailing fine transparent or large granular synaptic vesicles as well as vacuole degeneration evidences of the existence of several sources of serotonergic innervation of the central gray substance. Continuous damage of perivascular astrocytes of the central gray by neurotoxin allows a suggestion to be made that they are also the object of serotonergic innervation. Immunomorphological data on the presence of serotoninergic neurons in the cerebral gray are confirmed.

5,7-Dihydroxytryptamine↗
PubMed2003

Cellular mechanisms involved in the stenosis and obliteration of the cerebral aqueduct of hyh mutant mice developing congenital hydrocephalus.

Two phases may be recognized in the development of congenital hydrocephalus in the hyh mutant mouse. During embryonic life the detachment of the ventral ependyma is followed by a moderate hydrocephalus. During the first postnatal week the cerebral aqueduct becomes obliterated and a severe hydrocephalus develops. The aim of the present investigation was to elucidate the cellular phenomena occurring at the site of aqueduct obliteration and the probable participation of the subcommissural organ in this process. Electron microscopy, immunocytochemistry, and lectin histochemistry were used to investigate the aqueduct of normal and hydrocephalic hyh mice from embryonic day 14 (E-14) to postnatal day 7 (PN-7). In the normal hyh mouse, the aqueduct is an irregularly shaped cavity with 3 distinct regions (rostral, middle, and caudal) lined by various types of ependyma. In the hydrocephalic mouse, these 3 regions behave differently; the rostral end becomes stenosed, the middle third dilates, and the caudal end obliterates. The findings indicate that the following sequence of events lead to hydrocephalus: 1) denudation of the ventral ependyma (embryonic life); 2) denudation of dorsal ependyma and failure of the subcommissural organ to form Reissner fiber (first postnatal week); 3) obliteration of distal end of aqueduct; and 4) severe hydrocephalus. No evidence was obtained that NCAM is involved in the detachment of ependymal cells. The process of ependymal denudation would involve alterations of the surface sialoglycoproteins of the ependymal cells and the interaction of the latter with macrophages.

Aging↗