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At least 19 recordsLinked to original sources
PubMed1978

Anterior cervical arachnoid cyst simulating syringomyelia: a case with preceding posterior arachnoid cysts.

An arachnoid cyst lying anterior to the cervical cord at level C6-7 was found in a 28-year-old woman believed to have syringomyelia. This diagnosis was based both on previous findings at laminectomy and on computerized tomography. The diagnosis of arachnoid cyst was suspected because of clinical features atypical for classical syringomyelia and a history of arachnoid cysts found during childhood. Air myelography demonstrated an extramedullary intradural mass anteriorly that proved to be an arachnoid cyst. Drainage and subtotal resection resulted in marked clinical improvement. This case illustrates the need for reevaluation when a patient with "known" syringomyelia presents an atypical clinical picture. Anterior cervical arachnoid cyst, which may accompany or succeed posterior arachnoid cysts, should be considered.

Adolescent↗
PubMed1986

Fluid secretion in arachnoid cysts as a clue to cerebrospinal fluid absorption at the arachnoid granulation.

The morphological similarity of the lining of arachnoid cysts to subdural neurothelium and the mesothelium of arachnoid granulations suggested that the latter tissues might be the origin of arachnoid cysts. Transport Na+-K+-adenosine triphosphatase was shown by enzyme ultracytochemistry to be an indication of secretory activity in the lining of arachnoid cysts and in the endothelial lining of arachnoid granulations. This secretory activity suggests the existence of a biochemical mechanism for cerebrospinal fluid absorption at these granulations separate from the mechanisms already demonstrated.

Absorption↗
PubMedDate not supplied

Spinal arachnoiditis. What is the clinical spectrum? II. Arachnoiditis induced by Pantopaque/autologous blood in dogs, a possible model for human disease.

Experimentally induced chronic arachnoiditis was studied over a one-year period in beagle dogs. All animals demonstrated severe extensive changes at postmortem which were strikingly similar to those reported in man. Arachnoid inflammation, fibrosis, and adhesions were often associated with nerve roots embedded in collagen. These changes were present in all four experimental dogs, and were absent in four controls. In spite of having pathologically severe changes of arachnoiditis, two of four dogs appeared clinically normal. We suggest that the clinical appearance of chronic arachnoiditis in this animal model may reflect the human experience, wherein presentations may vary from merely complaints of back pain to severe sensory-motor impairment.

Animals↗
PubMed1990

Arachnoiditis ossificans with arachnoid cyst after cranial tuberculous meningitis.

A 34-year-old woman developed symptomatic arachnoiditis ossificans and an arachnoid cyst as a consequence of tuberculous meningitis adequately treated 20 years before. Surgical decompression of the cyst stopped the progression of her spastic paraparesis. Pathologic examination confirmed the presence of ossification of the arachnoid.

Adult↗
PubMedDate not supplied

[Ultrastructure of the cellular patches of the arachnoid membrane of the human brain (concerning the origin of the arachnoid-endothelial cleavages of the cerebral dura mater). Electron microscopic study].

The ultrastructure of cellular spots was studied--growths of the external arachnoidendothelial layer of the arachnoid membrane of the human cerebral hemispheres. The peculiarities of their ultrastructure depending on the stage of their development were revealed. "Young", cellular spots were formed by accumulations of osmiophobic round-shaped cells that are lined from the outside by osmiophilic cells like the whole of the arachnoid membrane surface. "Mature" cellular spots contain great number of oxmiophobic (viable) cells located in a immediate proximity of the subdural space, and they form the main source of viable arachnoidenodthelial cells found in the subdural fluid. The author believes that these cells penetrate together with the subdural fluid flow into the dura mater where, under specific conditions, they may become a source of arachnoidendothelial chippings.

Adult↗
PubMed1991

Meningiomas differentiating to arachnoid trabecular cells: a proposal for histological subtype "arachnoid trabecular cell meningioma".

Three cases of meningiomas which had abundant small vacuoles in the tumor tissue are reported. By electron microscopy, the tumor cells exhibited long and thin processes, the tips of which were united by desmosomes. The tumor tissue was revealed to have wide extracellular spaces which corresponded to the vacuoles observed by light microscopy. In previous literature, various terms have been used when referring to this meningioma, such as microcystic meningioma or vacuolated meningioma. Since the ultrastructure of the tumor showed similarity to that of normal arachnoid trabecular cells, we propose to call the tumor "arachnoid trabecular cell meningioma" denoting its morphological nature clearly.

Cell Differentiation↗
PubMed1981

Ultrastructure and pathogenesis of intracranial arachnoid cysts.

A detailed light, transmission, and scanning electron microscopic study of the arachnoid cyst wall was made in four cases and compared with that of the normal arachnoid mater in the human. Two hundred and eight reported cases of arachnoid cysts were analyzed to evaluate the anatomical distribution of these lesions and to get r an insight into their pathogenesis. The structural features of the arachnoid cyst wall that distinguish it from the normal arachnoid membrane are as follows: (1) splitting of the arachnoid membrane at the margin of the cyst, (2) a very thick layer of collagen in the cyst wall, (3) the absence of traversing trabecular processes within the cyst, and (4) the presence of hyperplastic arachnoid cells in the cyst wall, which presumably participate in collagen synthesis. The distribution of arachnoid cysts in two hundred and eight reported cases was as follows: Sylvian fissure, 49%; cerebellopontine angle, 11%; supracollicular area, 10%; the vermis, 9%; sellar and suprasellar area, 9%; interhemispheric fissure, 5%; cerebral convexity, 4%; and the clival and interpeduncular area, 3%. At each site, except possibly on the cerebral convexity, the cyst was associated with a normal subarachnoid cistern. This striking and nearly invariable association of arachnoid cysts with normal subarachnoid cisterns prompts the authors to hypothesize that arachnoid cysts represent a congenital anomaly of the developing subarachnoid cisterns in early intrauterine life. It is postulated that, during the process of the complex folding of the primitive neural tube and the formation of normal subarachnoid cisterns, an anomalous splitting of the arachnoid membrane occurs.

Arachnoid↗
PubMed1988

A light and electron microscopic and immunohistochemical study of human arachnoid villi.

The structure of human arachnoid villi was investigated by light and electron microscopy with the aid of immunohistochemical techniques. The human arachnoid villi examined were basically composed of four portions: a fibrous capsule, an arachnoid cell layer, a cap cell cluster, and a central core. The arachnoid cell layer encompassing the central core was mostly covered by the thin fibrous capsule with an endothelial investment. However, the fibrous capsule was often absent at the apical portion of the villus and a factor VIII-related antigen stain failed to confirm the investment of endothelial cells. Instead, the arachnoid cell layer abutted directly upon the lumen of a lateral lacuna or the sinus. The arachnoid cell layer was thickened in places, forming cap cell clusters; it usually consisted of outer and inner zones. On vimentin staining, the former was slightly positive while the latter was strongly positive. The central core contained a network of arachnoid cells intermingled with connective tissue fibers and was in continuity with the cranial subarachnoid space. Electron microscopy showed that the arachnoid cells contained a larger number of intermediate filaments in the inner zone than the outer zone. Ultrastructural immunohistochemical localization showed that vimentin was localized at the intermediate filaments and desmosomal plaques of the arachnoid cells. The arachnoid cells showed a marked variety in both the cell forms and the number of intermediate filaments or desmosomes, depending on their location.

Adolescent↗
PubMed1983

[Chronic subdural hematoma associated with arachnoid cyst--study of the mechanism of its development].

A significant number of cases of chronic subdural hematoma associated with middle fossa arachnoid cyst has been reported in literature, but sufficiently tenable explanation for co-occurrence of both lesions has not yet proposed. In this study, authors try to elucidate mechanisms involved in development of chronic subdural hematoma and arachnoid cyst in the same patient. Eighteen cases with arachnoid cyst in the middle fossa were diagnosed by CT scan during last 5 years in our institute. Among these, five patients had chronic subdural hematoma additionally to their middle fossa arachnoid cyst. Analysis of clinical, roentgenological data and operative findings in our five cases and reviewing of cases reported so far in the literature makes clear the following characteristics in this pathological condition. 1) Patients of chronic subdural hematoma associated with arachnoid cyst were obviously younger than patients with usual chronic subdural hematoma. 2) Chronic subdural hematoma developed in the same side to the associated arachnoid cyst. 3) Characteristic changes in the skull on x-ray films indicated the long lasting existence of middle fossa arachnoid cyst. On the other hand, history of cases suggested that chronic subdural hematomas had developed within recent 1-3 months. 4) Intracranial pressure tended to remain normal or slightly elevate. 5) Abnormal, small veins which run on the surface of the membranous capsule of arachnoid cyst and bridge the Sylvian fissure were not infrequently found at operation. These veins were not able to visualized on routine angiography. On the basis of these clinical and pathological characteristics, authors infer a mechanism for development of subdural hematoma associated with arachnoid cyst. The presence of middle fossa arachnoid cyst must increase a compressibility of the intracranial content, especially of the ipsilateral cerebral hemisphere and it predisposes for development of chronic subdural hematoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Ultrastructural findings of arachnoid cysts and epithelial cysts].

There may be several kinds of pathological conditions in the cystic lesion which are clinically diagnosed as benign intracranial cysts on CT scan. Light and electron microscopic studies on cyst walls were important in the differential diagnosis of benign intracranial cysts. We have studied 5 cases of intracranial arachnoid cysts and two epithelial cysts using the light and electron microscopy. Five cases of intracranial arachnoid cysts included two children and three adults (three females and two males). Three cases of them were localized in the middle cranial fossa, one case in the anterior and middle cranial fossa and one case in the lateral ventricle, giving headache and convulsion as the initial complaints. As for the epithelial cysts, one was localized at the para-collicular area complaining enlarged head and swollen anterior fontanelle and the other of four years was located in the fourth ventricle with headache and ataxic gait. On CT all of them demonstrated diffuse low density areas in both the arachnoid and the epithelial cysts without communicating findings between the cystic cavities and subarachnoid space on metrizamide CT cisternography. The arachnoid cyst walls were basically similar in structure to the normal arachnoid membrane and composed of elongated epithelial cells like the arachnoid cell and the connective tissues with lamellar collagen fiber bundles. However, 3 of the 5 cases had only fibrous tissues without epithelial cells. The inner sheath of the arachnoid cyst walls was composed of one or several layers of the arachnoid cells with flattened and relatively electron-dense cytoplasm on electron micrograph. They had a lot of elongated process and were tangled with each other, making large extracellular spaces between them. Below the electron dense arachnoid cells, compact packed cells with interdigitation partly demonstrated intercellular contacts such as numerous desmosomes and tight junctions. In those intercellular spaces collagen fibers and microfibrils were observed. The cells contained abundant cytoplasmic microfibrils and numerous organelles. They were separated from numerous collagen fibers and fibroblasts by non continuous basal lamina under the epithelial cells. Epithelial cyst wall had a layer of cuboidal or columnal epithelium in the inner layer of cyst wall. Those epithelial cells demonstrated granules having positive in PAS and mucicarmine stain in their cytoplasm. On electron microscopical study epithelial cells revealed a lot of microvilli and coating materials on the surface of them without cilia. The basement membranes were well developed under the epithelial cells separated from the connective tissues. In the intercellular clefts of the epithelial cells tight junctions and interdigitations were recognized.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1983

Cytokeratin provides a specific marker for human arachnoid cells grown in vitro.

Cells from cranial and spinal arachnoid membranes of humans were grown in culture. Their growth characteristics, morphology and details of their cytoskeletal composition are described. Arachnoid membranes, obtained at autopsy, were finely minced and incubated in tissue culture medium. Monolayers of cells of homogeneous morphology grew from these tissue fragments. The cells were flat and polygonal. They divided slowly to form nonoverlapping monolayers of low cell density. Electron microscopic examination of cultured arachnoid cells revealed numerous desmosome-like tight junctions and abundant intermediate filaments (tonofilaments). Both morphological features are characteristic of arachnoid cells in situ, but not of cells in the fibroblast-rich dura mater. Immunofluorescence microscopy with monoclonal antibodies demonstrated cytokeratin in the cytoplasm of primary cultures of arachnoid cells. Thus we demonstrated that these cultured cells retained certain of the specific differentiated properties of arachnoid cells in situ and that they are not fibroblasts (which lack tight junctions and cytokeratins). To our knowledge, there have been no previous reports of in vitro growth of arachnoid cells. This in vitro model should be useful in studying the response of arachnoid cells to a variety of substances thought to be involved in the chronic inflammatory condition of the meninges known as arachnoiditis.

Arachnoid↗
PubMed1988

Ultrastructural comparison of arachnoid villi and meningiomas in man.

An ultrastructural comparison of arachnoid villi and meningiomas was made in man. Human arachnoid villi basically consisted of four portions: fibrous capsule; arachnoid cell layer; cap cell cluster; and central core. Arachnoid cells had many characteristic structures in common with meningioma cells: plasmalemmal interdigitations; desmosomes; hemidesmosome-like junctions; and cytoplasmic filaments. Both arachnoid villi and meningiomas were characterized by the numerous extracellular cisterns which appeared to form outflow channels of cerebrospinal or serum fluid. Differences between arachnoid villi and meningiomas pertained to cytoplasmic components reflecting the states of permeability of endothelial cells, junctional complexes, and matrix substances of psammoma bodies. Endothelial cells investing the fibrous capsule contained a number of micropinocytotic vesicles and intracytoplasmic vacuoles, but showed no fenestrations. In contrast, meningiomas not only contained numerous micropinocytotic vesicles and intracytoplasmic vacuoles but also exhibited numerous fenestrations. Furthermore, there were a larger number of junctional complexes between arachnoid cells than meningioma cells. Arachnoid villi contained abundant matrix granules while meningiomas contained only a few matrix granules but a larger number of matrix minerals and vesicles, as the presumptive precursors of psammoma bodies.

Adolescent↗
PubMedDate not supplied

Pathogenesis of postmyelographic arachnoiditis.

The causal relationship between a myelogram with an aqueous contrast medium and postmyelographic arachnoiditis has not been clarified. Primates after myelography with metrizamide or meglumine iocarmate were studied with fluorescent microscopy, energy dispersion analysis and with scanning and transmission electron and light microscopy. All controls and, up to the eighth day after myelography, all treated animals had normal-appearing arachnoid membranes by microscopy. After eight days the treated animals had progressively more severe arachnoid fibrosis. Energy dispersive analysis revealed iodine in the arachnoid only up to 24 hours after myelography. Fluorescent microscopy revealed no evidence of immune complexes in the arachnoid. The chronic effects of water-soluble media on the arachnoid are not apparently mediated by contrast medium persisting in the arachnoid or by immune complexes.

Animals↗
PubMed1990

[Intraventricular arachnoid cyst appearing with attacks of orbital pain: case report and review of the literature].

While there have been 5 cases of intraventricular arachnoid cyst published in the literature, the occurrence in the anterior horn of the lateral ventricle has not been reported. We report a case of intraventricular arachnoid cyst of the anterior horn causing attacks of orbital pain. A 30-year-old man was admitted with frequent attacks of orbital pain on his right side. Neurological examination revealed no abnormality. Plain CT showed a cystic dilatation of the anterior horn of the right lateral ventricle, and enhanced CT showed a deviation of the septal veins to the left side. T1-weighted MRI demonstrated a low-intensity mass in the anterior horn of the right lateral ventricle, and T2-weighted image demonstrated the mass as having high intensity. PEG in the sitting position showed no filling of air into the right lateral ventricle due to obstruction of the right foramen of Monro. The patient underwent an operation under a diagnosis of intraventricular benign cyst. The cyst wall was subtotally removed and the right foramen of Monro was opened. Histological examination of the specimen showed an arachnoid membrane with prolific collagen fibers. From an embryological point of view, the arachnoid membrane is derived from the arachnoid cell. We think intraventricular arachnoid cysts to originate from the remnants of the arachnoid cell on the tela choroidea or on the choroid plexus like intraventricular meningiomas.

Adult↗
PubMed1989

Pineal corpora arenacea produced by arachnoid cells in the bat Myotis blythi oxygnathus.

There are corpora arenacea among the cell layers of the arachnoid on the dorsal surface of the pineal organ of the bat (Myotis blythi oxygnathus). The pineal arachnoid consists of electron lucent cells connected by cell injunctions to flat sheets and sandwiched on both sides by electron-dense cell rows. Among the superficial cell layers, collagen fibrils form loose bundles. In the electron-lucent cells, pinocytotic vesicles, rough surfaced endoplasmic reticulum, active Golgi areas and granular vesicles of various sizes can be found. Electron dense cells display fewer cytoplasmic organelles than the light ones. Lying between and below the hemispheres and cerebellum the pineal arachnoid does not contact the dura mater directly, therefore it continues on its both sides into arachnoid trabeculae. Corpora arenacea occur in lacunar enlargements of the arachnoid, first of all in the thickened dorsal portion of the pineal leptomeninx. The acervuli are insulated by collagen fibrils and exhibit concentric layers of various density. Needle-shaped structures resembling hydroxyapatite crystals were found in these concentric layers. There was no sign of formation of acervuli in the pinealocytes or elsewhere in the pineal nervous tissue proper. These findings confirm that view that corpora arenacea can be produced by the pineal arachnoid. The formation of acervuli is accompanied by secretory and resorptive phenomena of arachnoid cells.

Animals↗