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Eleven cases of enlarged cisterna magna were found in a series of 3000 computerized tomography scans. We believe mega cisterna magna by itself is not related to any specific symptoms and may not require further study or treatment.
Linear echoes are seen in the fetal cisterna magna, (CM) on obstetrical sonography. These echoes often are paired, joining as they descend toward the base of the posterior fossa. Histologic correlation suggests that these echoes are most consistent with dural folds, which likely represent the inferior attachment of the falx cerebelli. A prospective series of 322 prenatal studies was performed in which the sonographer was asked to look for the linear echoes in the cisterna magna and image them. Linear echoes were identified in 84% of all fetuses studied. Identification of these echoes was dependent on CM size, in that they were seen less commonly when the CM was less than 3 mm in diameter. However, their identification was not dependent on gestational age. In addition, 18 fetuses with Dandy Walker cyst or Dandy Walker variant were evaluated and in 16 linear echoes were not seen. We conclude that recognition of normal anatomy within the fetal brain, specifically the fetal CM, is helpful for identifying abnormalities in the size of the CM, whether large or small.
Six hundred thirty-eight gravidas at 14-21 weeks' gestation, who were at increased risk for an abnormal fetal karyotype, had sonographic measurement of the fetal cisterna magna at the level of the posterior fossa before genetic amniocentesis. The size of the fetal cisterna magna increased significantly with advancing gestational age in the normal fetus (P less than .001). Twenty-eight fetuses had abnormal karyotypes: 12 with trisomy, eight with translocation or structural rearrangements, seven with sex chromosome abnormalities, and one with triploidy. In each of these fetuses with abnormal karyotypes, the cisterna magna measurement was normal. We conclude that measurement of the fetal cisterna magna at 14-21 weeks' gestation is not useful as a screening test for abnormal fetal karyotype.
Islets were isolated from the pancreata of Sprague-Dawley rats and transplanted into streptozotocin-induced diabetic outbred Wistar rats. The effect of transplantation of islets into the cisterna magna on the diabetic state of the recipients was compared with that of the conventional transplantation of islets into liver via the portal vein. After successful intraportal (IP) transplantation, rejection took place between days 7 and 15 in all diabetic recipients. All of the eleven rats surviving after stereotaxic implantation of islets into the cisterna magna returned to normoglycemia within 7 days after transplantation. Nine of the recipients with intra-cisterna magna (IM) islet allografts were still normoglycemic at 210 days after transplantation. The glucose disappearance rate of the IM transplant rats was slower than that of the IP transplant rats, and blood glucose returned to the normal basal level within 5 hr following glucose administration. Although the insulin levels were almost undetectable in cerebrospinal fluid before IM transplantation, the insulin levels were markedly increased after IM transplantation and twice as great in CSF than blood. Thus, these findings indicate that the cisterna magna can serve as an immunologically privileged site for implantation of allogeneic pancreatic islets, and islets in CSF can regulate and maintain normal glucose homeostasis via secretion of insulin across the blood-brain barrier.
Thirty-three fetuses with an enlarged cisterna magna (10 mm or more) were evaluated to determine factors that might be associated with an underlying chromosome abnormality. Eighteen fetuses (55%) proved to have a chromosome abnormality, including trisomy 18 or trisomy 18 variant (12), trisomy 13 (three), Turner syndrome (one), or other rearrangements (two). Among various risk factors analyzed, the absence of ventricular dilatation correlated most strongly with a chromosome abnormality. Chromosome abnormalities were found in 17 of 22 fetuses (77%) lacking ventricular dilatation, compared with only one of 11 fetuses (9%) with ventricular dilatation (P less than .001). Other factors statistically associated (P less than .01) with an underlying chromosome abnormality included mild enlargement of the cisterna magna (10-14 mm), concurrent anomalies detected sonographically, and fetal growth retardation. However, stepwise logistic regression showed that only the absence of ventricular dilatation and the presence of concurrent anomalies were significant when multiple factors were evaluated. These observations support the utility of evaluating the cisterna magna as part of a routine anatomical survey.
A linear hyperechoic structure in the cisterna magna, previously described as the straight sinus, was investigated during routine obstetric ultrasound (US) examination. One hundred three fetal US examinations were performed to determine the prevalence and appearance of this finding. Also, US water-bath examination of 18 fixed postmortem specimens and fetuses was performed, and results were correlated with those of gross and microscopic examination of the fetal brain. The structure was identified in 95 (92%) prenatal examinations between 15 and 38 menstrual weeks. It was located posteriorly between the cerebellar hemispheres in the cisterna magna. In those 95 cases in which it was identified, it appeared as a single echogenic line in 31 cases (33%), as two echogenic lines in 47 (49%), or as three or more lines in 17 (18%). When two echogenic lines were identified, they appeared "cystlike" in 17 (18%) of the 95 examinations. Correlation of the gross and histologic findings demonstrated these lines to represent normal subarachnoid septa rather than the straight sinus.
The unusual appearance of the large cisterna magna on computed tomography is presented and the radiographic signs are reviewed and correlated. This entity may be confused with a variety of other lesions. Awareness of such developmental anomalies may obviate the need for angiography and pneumoencephalography in selected cases.
A case of a large cisterna magna cyst presented a problem in differential diagnosis. Characteristic changes were shown on plain skull roentgenograms and on radionuclide brain scan. The diagnosis was established on the basis of pneumoencephalography and isotope cisternography. The lesion responded well to surgical management.
This report deals with a family in which the maternal grandmother, the mother, and all three male children have port-wine nevi and mega cisterna magna. Two of the three male children have, in addition, congenital communicating hydrocephalus associated with agenesis of the posterior cerebellar vermis. This case of familial communicating hydrocephalus, posterior cerebellar vermis agenesis, port-wine nevus, and mega cisterna magna represents a new neurocutaneous syndrome, possibly transmitted as an autosomal dominant.
Microdialysis is used in vivo for measuring compounds in brain interstitial fluid. The authors describe another application of this technique to the central nervous system, namely microprobe dialysis in the cisterna magna to study the dynamics of ion transport and cerebrospinal fluid (CSF) formation in the rat. The choroid plexus is the major source of CSF, which is produced by active transport of Na from blood into the cerebral ventricles. Formation of CSF is directly proportional to the blood-to-CSF transport of Na. By injecting 22Na into the systemic circulation and quantifying its movement into CSF by microdialysis, one can reliably estimate alterations in the rate of CSF formation. The sensitivity of this system was determined by administering acetazolamide, a standard inhibitor of CSF production. Because acetazolamide is known to decrease CSF formation by 40% to 50%, the cisternal microdialysis system in animals treated with this drug should detect a corresponding decrease in the amount of 22Na dialyzed. This hypothesis is supported by the 22Na uptake curves for control versus treated animals: that is, by the acetazolamide-induced average diminution of about 45% in both the rate and extent of tracer accession to dialysate. Bumetanide, a loop diuretic, reduced by 30% the 22Na entry into dialysate. Microprobe dialysis of fluid in the cisterna magna is thus a minimally invasive and economical method for evaluating effects of drugs and hormones on the choroid plexus-CSF system.
Alterations of brain and cerebrospinal fluid amino acids have consistently been described in human and experimental fulminant liver failure. To evaluate the significance of such changes in the pathogenesis of hepatic encephalopathy in fulminant liver failure, brain and cerebrospinal fluid amino acids (glutamate, aspartate, GABA, glycine, taurine) were measured at various stages during the development of neurological dysfunction in rats after hepatic devascularization or thioacetamide treatment to induce acute liver failure. To facilitate repetitive removal of cerebrospinal fluid, a technique employing long-term implantation of cisterna magna catheters in conscious, freely moving rats was developed. Brain but not cerebrospinal fluid concentrations of the excitatory amino acids glutamate and aspartate were reduced in both animal models of fulminant liver failure in parallel with deterioration of neurological status. Brain and cerebrospinal fluid GABA levels were not significantly altered. Cerebrospinal fluid glycine levels were increased two to three times in parallel with increasing brain glycine content in the devascularized rat but were unchanged in thioacetamide-induced liver failure, suggesting distinct pathophysiological mechanisms in these two experimental situations. On the other hand, onset of coma in both animal models of fulminant liver failure was accompanied by significantly increased cerebrospinal fluid taurine levels. We suggest that such changes result from taurine release from astrocytes in brain into the extracellular fluid; this is consistent with taurine's role in the regulation of intracellular osmolarity in brain. Sequential measurements of amino acids in the cerebrospinal fluid of small rodents with indwelling cisterna magna catheters adds a useful new approach for exploring the neurobiology of hepatic encephalopathy in fulminant liver failure.
The total protein content of CSF collected from the cisterna magna (cisternal fluid) of 98 patients (58 males and 40 females) with no neurological diseases was determined by the colorimetric method devised by Lowry and co-workers. This method has been previously chosen based mainly on it's sensitivity, accuracy and low fluid consumption. The CSF samples were normal with regard to pressure, color, citology and it's content in glucose, chloride and urea. Complement fixation tests for syphilis and cisticercosis, as well as the globulin tests (Pandy, Nonne--Appelt and Takata-Ara) were negative. The average value and the normal range of cisternal fluid total protein was calculated for the mixed population (males and females). The mean protein value was 26.78 mg/100 ml, the lower and upper limits were respectively 13.20 and 40.36 mg/100 ml. These data are higher than those stated in some publications, and factors that could interfere in the different results mentioned in the literature are briefly discussed. Since the statistical analysis of the results showed that the mean total protein concentration in males (28.76 mg/100 ml) was higher than in females (23.91 mg/100 ml), normal limits for each sex were established: 16.96 to 47.13 mg/100 ml for males and 14.76 to 42.76 mg/100 ml for females.
We have designed a cannula system that can be chronically implanted to end above the dura of the cisterna magna of the dog. During experiments in the awake dog, a screw cap with stylet is removed from the cannula and a spinal needle inserted for the withdrawal of samples of cisternal cerebrospinal fluid (CSF) or for making continuous measurements of pressure. The system can be used for repeated experiments extending over several weeks.
Computed tomography was performed on 5 children with posterior fossa cystic abnormalities. On an axial tomogram, an enlarged cisterna magna could not be distinguished from a Dandy-Walker variant, nor could an encysted fourth ventricle be distinguished from a subarachnoid cyst. Supplementary air encephalography or sagittal reconstruction of tomograms is necessary to define posterior fossa cysts accurately.
A new 1.45-mm endoscope is described that can be inserted through a thin-walled No. 16 needle. The instrument was used in 10 cadavers for endoscopic exploration of the cisterna magna, the C1-2 space, Meckel's cave, and the cerebellopontine angle. Its potential clinical application is discussed.
A report is given of the results of supra-occipital tapping of the cisterna magna and dynamic encephalography by that route. In 72 patients with cranial hypertension this encephalography was well tolerated. Supra-occipital tapping is less dangerous than suboccipital puncture as regards the possibility of injury to the medulla. In 38 cases, the method led immediately to the diagnosis of herniation of the tonsils.
One family of 17 cases of general fibrosis syndrome was reported. Four out of five patients examined with CT and/or MRI revealed cavum vergae or cyst of the cavum septi pellucidi or mega cisterna magna, which were characterized by existing on the midline of the brain. The patient with cavum vergae had also platybasia. In one patient, surgical correction of vertical deviation and blepharoptosis of both eyes was performed. There was abnormal insertion of the superior and inferior rectus muscles in posterior and nasal direction, and adhesion of the superior oblique muscle to the superior rectus muscle at the point of it's insertion was found in both eyes. Histopathological findings of the extraocular muscles of two patients showed mixture of relatively normal muscle tissues and vast amounts of collagen fibers. Electron microscopically many glycogen granules were found in muscle fibers. From these findings, this syndrome may be based on failure in development and differentiation.
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