Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?. These include digital subtraction myelography and dynamic or ultrafast CTM techniques. Transependymal edema, also known as interstitial cerebral edema or periventricular lucency (PVL), is a type of cerebral edema that occurs with increased pressure within the cerebral ventricles. Welcome to the Radiology Assistant Educational site of the Radiological Society of the Netherlands by Robin Smithuis MD Image acquisition is stopped once a leak is seen. Fig. Leakage of CSF into the epidural space through a defect in the thecal sac has been found to be the underlying cause of almost all cases of SIH [8, 9]. Depending on the leak site and whether the patient is imaged in the prone or supine position, the collection may preferentially be located ventrally or dorsally in the spinal canal. Because these degenerative lesions erode through the dura and may become interposed into the resultant dural defect, treatment with epidural patching can be ineffective in some cases, and surgical resection of the offending lesion may be required. AJNR Am J Neuroradiol. Dural sac is seen as thin black line separating intrathecal CSF from epidural collection. FLAIR is the most sensitive MRI sequence for detection. Although some have suggested that lumbar puncture should be avoided in patients with low CSF pressure because of the theoretic risk of exacerbating CSF hypovolemia [33], in the authors' experience, this concern is overstated and is almost never an issue in actual practice. First, because contrast-enhanced brain MRI is critical to establishing the diagnosis of SIH, this should be part of the routine imaging assessment. Agenesis of corpus callosum and frontal encephalocele. Evidence of typical changes associated with SIH, including dural enhancement, brain sagging, the venous distention sign, and other signs associated with low pressure, should be sought, recognizing that they may not be present in all patients [7, 55–57]. For patients for whom nontargeted patching fails, targeted epidural patching or surgical intervention may be required; both require precise knowledge of the site of the leak [6, 7]. A, Axial CT myelography (CTM) image shows focal diverticulum (arrow) located anterior to nerve root sleeve. B, Sequential lateral images from myelogram performed with patient in prone position show progressive leakage of CSF (arrowheads) originating at disk space seen in (A). CSF leaks: Correlation of High-Resolution CT and Multiplanar reformations with Intraoperative Endoscopic findings. This technique seeks to combine the benefits of CSF-specific contrast obtained with CTM with the excellent contrast resolution inherent to MRI. 7. net pics. ... 6.Associatd whitemater lesions could be explained by defective CSF absorption and transependymal seepage of CSF . CSF opening pressure can also be measured during the procedure, a criterion used in all currently accepted diagnostic schema for SIH [1, 2]. Fig. In CTM, the introduction of iodinated contrast material into the thecal sac provides a means for the specific visualization of CSF, including CSF that has leaked into the epidural space (Fig. Extensive leakage of CSF into epidural space is also seen. Several cases of overdosage resulting in acute neurotoxicity have been reported, however, and the long-term safety profile of intrathecal gadolinium is largely unknown [49–51]. (2016) Journal of Neurosurgery. Spontaneous intracranial hypotension (SIH) is an increasingly recognized disease caused in nearly all cases by spontaneous spinal CSF leaks. Extrathecal contrast material may be more conspicuous when digital subtraction is used. CT myelography (CTM) is probably the most commonly used modality in investigating CSF leaks. Early activity within the kidneys and bladder must be interpreted with caution because leakage of tracer at the lumbar puncture site can result in renal uptake due to systemic reabsorption [52]. Cerebrospinal fluid, clear colorless bodily fluid found in the brain and spine; Colony-stimulating factor, secreted glycoproteins; Cancer slope factor, estimate the risk of cancer; Classical swine fever, contagious disease of pigs; Contrast sensitivity function, relationship of contrast threshold vs angular frequency for an observer CSF is of lower density than the grey or white matter of the brain, and therefore appears darker on CT images. W M Nizamani, Department of Radiology, Aga Khan University Hospital Karachi Pakistan. In cases where fat suppression has not be used, decreased T1 signal caused by fluid in the epidural space may be seen, a sign that can easily be overlooked if not actively sought. In most cases of SIH, CSF leakage originates from a single spinal level. Intracranial Hypotension: Improved MRI Detection With Diagnostic Intracranial Angles, Original Research. Fig. This is usually seen surrounding the lateral ventricles in the setting of an acute obstructive hydrocephalus. In conclusion: CSF pseudocyst formation is a rare cause of a gradually enlarging breast lump, and should be borne in mind in patients with an 4D —30-year-old woman with high-flow CSF leak. Fig. When CSF leakage is slower, a focal leak may be detected without a large associated pool of epidural contrast material. Semiquantitative graphical analysis of tracer activity over multiple craniospinal segments may aid in the detection of the indirect signs of reduced intracranial activity and rapid loss of spinal activity and may improve the modest sensitivity and specificity of this technique [53]. FIRST PART INTRODUCTION AND METHODOLOGY. Nuclear medicine imaging findings can be divided into direct and indirect evidence of leak (Fig. If symptoms persist despite nontargeted treatment, alternative imaging strategies that offer greater sensitivity for subtle low-flow leaks may be pursued. Next, selection of any myelographic imaging test should be based on the information desired and its intended effect on the management of the individual patient. In some cases, slow-flow leaks may be depicted best with delayed imaging, allowing time for contrast material accumulation at the leak site, whereas in other cases, immediate imaging might best depict the leaked contrast material before it is reabsorbed into the soft tissues. Radiology 1985;154:795–799. UCSF Department of Radiology & Biomedical Imaging. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. 6C —22-year-old woman with CT myelography (CTM) findings of high-flow CSF leak. No neutrophils present, primarily lymphocytes 2. Because they are more easily localized than fast leaks, represent slower rates of CSF leakage, and are more anatomically accessible than ventrally located leaks, these leaks are often easier to treat percutaneously than their high-flow counterparts. Because fat also shows T2 hyperintensity on fast spin-echo T2-weighted images, homogeneous fat suppression is helpful [39]. Fig. A, Sagittal STIR MR image shows extensive collection of fluid in epidural space (arrowheads). B, Coronal CTM image shows CSF leak (arrowhead) in neural foramen at same level, without significant epidural pooling of fluid in spinal canal. OBJECTIVE. Indirect signs include early uptake of activity within the kidneys and bladder within 4 hours, absence of activity over the cerebral convexities at 24 hours, and rapid loss of spinal activity [8, 54]. On the other hand, MRI has the advantage of being noninvasive and does not use ionizing radiation. In addition to cross-sectional images, maximum-intensity-projection images can be used to create a 3D representation of the thecal sac [40]. Total CSF volume is 90–150 ml in adults and 10–60 ml in neonates. Empirical patching targeted at nerve root diverticula, even if leakage from these sites is not directly visualized, may be efficacious in some patients, although it becomes more technically challenging if numerous diverticula are present [27]. These techniques, termed “MR myelography” by several authors (not to be confused with myelography using intrathecal gadolinium, as discussed later in this article), have shown promise in detecting CSF leaks, with several reports of similar sensitivity for CSF leak detection compared with other modalities such as CTM or radionuclide cisternography [36, 40, 41]. SIH occurs with increased frequency in patients with disorders such as Marfan and Ehlers-Danlos syndromes, suggesting that underlying weakness of the connective tissues may contribute in some patients [13, 14]. B, Axial T2-weighted image again shows extradural fluid (arrowhead). AJR Am J Roentgenol. Cerebrospinal fluid (CSF) leak may occur from the nose (rhinorrhea), from the external auditory canal (otorrhea), or from a traumatic or operative defect in the skull or spine. Hakseung Kim, Eun-Jin Jeong, Dae-Hyeon Park, Zofia Czosnyka, Byung C. Yoon, Keewon Kim, Marek Czosnyka, Dong-Joo Kim. One series of surgically confirmed cases described a variety of configurations of these dural defects, including defects located at the axilla of the nerve root, others along the length of the nerve root sleeve, and circumferential absence of the dura surrounding the base of the nerve root [10]. A, Sagittal CT myelography (CTM) image shows dorsal collection of CSF (arrowheads), with gradient of myelographic contrast indicating CSF leak at inferior aspect of collection. In a significant proportion of cases of SIH, no leak will be seen on myelography despite exhaustive investigation. 3B —27-year-old woman with Marfan syndrome and intraperitoneal CSF leak. Fig. This requires breath-holding while the contrast material column passes through the area of interest. Fig. Focal dural thinning and dehiscence are common causes of spontaneous CSF leak. Fig. Digital subtraction myelography is a technique that is used to monitor the passage of intrathecal contrast material along the spine in real time to pinpoint the source of a high-flow CSF leak, taking advantage of the high temporal resolution of conventional fluoroscopy [34]. B, Coronal CTM image again shows diverticulum (arrow). Occasionally, 48-hour delayed images are also obtained [52]. No evidence of periventricular CSF seepage. Keywords: CSF, CSF leak, myelography, spontaneous intracranial hypotension. 4A —30-year-old woman with high-flow CSF leak. Fig. LaFata V, et al. With dynamic CTM, the entire spinal canal can be examined, and spatial resolution is outstanding. Third ventricular lesions can … 8. Figure 1182.1: Cranial meninges If imaging is rapid enough, the exact site of the leak can be pinpointed, potentially opening the door for targeted therapy. It is quite useful in the evaluation of high-flow leaks, but because digital subtraction myelography is not generally used to evaluate the entire spine, it is not generally used as the initial myelographic test for SIH. Comparative anatomy of the meninges helps to elucidate the functional anatomy and ontogenesis of the CSF system in man [1]. Cerebral edema. 6A —22-year-old woman with CT myelography (CTM) findings of high-flow CSF leak. 7). Leakage of CSF into spaces other than the epidural space, such as the pleural space or peritoneum, can also cause SIH and usually is found in patients with connective tissue disorders [26] (Fig. Of note, a retrospinal fluid collection may be seen at the C1–C2 level in patients with CSF leak and is best seen on T2-weighted images. Conventional MRI is most helpful in identifying high-flow CSF leaks with conspicuous epidural pooling of fluid, although it typically will not localize the exact leak site. Estimates from previous series suggest that this may occur in 46–55% of cases [5, 29]. AJNR Am J Neuroradiol 1987;8:155–156. Thecal sac is partially collapsed because of loss of CSF. More delayed imaging produces a gradient of contrast material that is often greatest close to the leak site and decreases further away [18] (Fig. Fluid may stream out of the spinal canal through the neural foramina at multiple levels and may track into the paraspinal soft tissues. For example, if the diagnosis of SIH is not in doubt and a nontargeted epidural blood patch is planned as first-line therapy, myelography of any sort may be unnecessary. A, Normal scans in 54-year-old man without CSF leak. 4C —30-year-old woman with high-flow CSF leak. 2. In addition, leak localization can be important for treatment. 2012;199 (3): W258-73. A tiny arachnoid bleb was present extending into this dural rent. Typically, the leak is caused by one of two main categories of pathologic process: spontaneous dural dehiscence and dural tears caused by degenerative causes. A, Axial CTM image shows epidural pooling of contrast material (arrowhead) due to high-flow CSF leak. Even faster dynamic or ultrafast CTM techniques, in which imaging begins while contrast material is still being actively injected, have also been described elsewhere [17, 32]. CNS MOCKS 2016 2. 3). 1C —40-year-old woman with CSF leak caused by meningeal diverticulum. 6B —22-year-old woman with CT myelography (CTM) findings of high-flow CSF leak. As a result, multiple different imaging studies may be needed before the leak is localized. 1986;147 (2): 331-7. Multiple sclerosis 10. The appearance of cerebrospinal fluid inside the neuraxis precedes circulation of cerebrospinal fluid in subarachnoid spaces during phylogenesis [2] Abnormally narrow ventricles, described as slit ventricles, are observed in complex disorders of CSF circulation associated with cerebral oedema in patients with a CSF shunt. Ventriculoperitoneal shunt is commonly used to treat hydrocephalus whereby the peritoneal cavity is used for cerebrospinal fluid (CSF) absorption. Midline shift measures 20mm. A, Axial myelography image shows small spiculated osteophyte (arrow) associated with small thoracic disk protrusion. Transependymal edema, also known as interstitial cerebral edema or periventricular lucency (PVL), is a type of cerebral edema that occurs with increased pressure within the cerebral ventricles. Advantages of CTM include wide availability, familiarity among radiologists, good spatial resolution, good detail of degenerative changes that may contribute to CSF leaks, and infrequent technical artifacts. Spinal leakage of CSF causes almost all cases of spontaneous intracranial hypotension. ADVERTISEMENT: Supporters see fewer/no ads, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 9B —27-year-old woman who underwent MR myelography with intrathecal gadolinium. Most of the lesions are asymptomatic and incidentally found. Schizencephaly..pics from net 6. The right lateral ventricle is effaced and the left lateral ventricle entrapped and dilated, with posterior periventricular CSF seepage causing hypodensity. Furthermore, single or multiple nerve root sleeve diverticula of various sizes and configurations are seen commonly as an incidental finding in healthy patients and, therefore, should not be assumed to be pathologic when observed in isolation [10, 15]. MS..pics from net 11. Fig. The investigation should be targeted toward the lower cervical and thoracic spine in most cases because most high-flow CSF leaks occur in these areas [17]. Spinal MRI has also been used to evaluate for CSF leaks [36–38]. In appropriate dilution, it has been found by multiple investigators to be well tolerated [30, 44, 45, 47, 48]. In retrospect, there may be very subtle extradural contrast material seen in right neural foramen. There is also indirect evidence of CSF leak indicated by activity in bladder (arrowheads) and kidneys at 1, 2, and 4 hours, as well as rapid loss of spinal activity and absence of activity over cerebral convexities at 24 hours. Fig. Close attention should be paid to the presence of thoracic disk protrusions or osteophytes in patients with this leak type, because degenerative lesions often cause fast CSF leaks [18]. 1Department of Radiology, Gulhane Military Medical School, Etlik, Ankara, Turkey, and 2Department of Radiology, Edremit Military Hospital, Edremit, Balikesir, Turkey ABSTRACT. 2 Department of Radiology, Mayo Clinic, Rochester, MN. 8A —39-year-old woman with findings of high-flow CSF leak on conventional MRI. Although there is no universal consensus as to how to optimally and most efficiently image CSF leaks, some general principles can be advanced. Head-hanging CT: an alternative method for evaluating traumatic CSF rhinorrhea. J Neurol Neursurg B, Coronal CTM image shows focal diverticulum of lower thoracic nerve root sleeve (arrow) on right, thought to be likely site of leak. Although nontargeted epidural blood patching is often used to treat SIH, it may not provide durable relief in a substantial number of patients [3–5]. CSF comprises all intracerebral ventricles, spinal and brain subarachnoid spaces, such as cisterns and sulci, and the central canal of the spinal cord. Artikel Terkait. Fig. Cerebrospinal fluid is contained within the cerebral ventricles, the spinal canal and the subarachnoid space (space between arachnoid externally and pia mater internally) surrounding the brain and spinal cord (Figure 1182.1).Cerebrospinal fluid (CSF) is reabsorbed into the blood through the arachnoid villi of dural venous sinuses. B, Image from digital subtraction myelography with patient in prone position shows leakage of contrast material (arrowhead) originating at level of disk space seen in A. 16–18 csf seepage radiology or White matter of the utility of each modality in various leak types is presented in Table.. 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