Subarachnoid Cerebrospinal Fluid Space Research Articles

Physiological alterations of pineal recess crowding in symptomatic non-hydrocephalic pineal cysts.

Pineal cysts are prevalent in the population. Due to more widespread use of magnetic resonance imaging, an increasing number of symptomatic patients with non-hydrocephalic pineal cysts are referred to neurologists and neurosurgeons. Currently, there is no generally accepted theoretical framework for linking symptoms to a pineal cyst. We have previously suggested that cyst-induced crowding of the pineal recess may affect venous runoff from the deep cerebral veins crossing the cyst. However, evidence underpinning this hypothesis is sparse. In the present study, we asked whether crowding of the pineal recess without imaging signs of hydrocephalus may be accompanied with alterations in blood flow of the internal cerebral veins, cerebrospinal fluid flow in the Sylvian aqueduct and cerebrospinal fluid-mediated tracer clearance from the brain along extravascular pathways (referred to as glymphatic function). This prospective, observational study included symptomatic individuals with non-hydrocephalic pineal cysts who underwent a standardized magnetic resonance imaging protocol (n = 25): Eleven patients were treated surgically with craniotomy and cyst extirpation and 14 individuals were managed conservatively without surgery. Our findings suggest that cyst-induced crowding of the pineal recess may have brain-wide effects: (i) There was a significant negative correlation between degree of crowding within the pineal recess and change in maximum venous flow velocity at the cyst, and a significant positive correlation between maximum venous flow velocity change at the cyst and net cerebrospinal fluid flow in the Sylvian aqueduct; (ii) increased degree of crowding in the pineal recess was accompanied by significantly impaired glymphatic enrichment in the cerebral cortex and subcortical white matter, indicative of a brain-wide effect in this cohort who also reported markedly impaired subjective sleep quality; (iii) there was a significant negative correlation between the apparent diffusion coefficient (suggestive of interstitial water content) within the thalamus and glymphatic enrichment of tracer and (iv) pineal recess crowding associated with symptoms. Comparison of the surgical cases [in whom 10/11 (91%) reported marked clinical improvement at follow-up] and the conservatively managed cases [in whom 1/14 (7%) reported marked clinical improvement at follow-up] showed differences in pre-treatment glymphatic tracer enrichment as well as differences in tracer enrichment in subarachnoid cerebrospinal fluid spaces. Taken together, we interpret these observations to support the hypothesis that cyst-induced crowding of the pineal recess without hydrocephalus may alter blood flow of the internal cerebral veins and cerebrospinal fluid flow and even cause brain-wide impairment of glymphatic transport with possible implications for cerebrospinal fluid transport of trophic factors such as melatonin.

Intrathecal Contrast-Enhanced Magnetic Resonance Imaging of Cerebrospinal Fluid Dynamics and Glymphatic Enhancement in Idiopathic Normal Pressure Hydrocephalus.

Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease, characterized by cerebrospinal fluid (CSF) flow disturbance. Today, the only available treatment is CSF diversion surgery (shunt surgery). While traditional imaging biomarkers typically assess CSF space anatomy, recently introduced imaging biomarkers of CSF dynamics and glymphatic enhancement, provide imaging of CSF dynamics and thereby more specifically reveal elements of the underlying pathophysiology. The biomarkers address CSF ventricular reflux grade as well as glymphatic enhancement and derive from intrathecal contrast-enhanced MRI. However, the contrast agent serving as CSF tracer is administered off-label. In medicine, the introduction of new diagnostic or therapeutic methods must consider the balance between risk and benefit. To this end, we performed a prospective observational study of 95 patients with iNPH, comparing different intrathecal doses of the MRI contrast agent gadobutrol (0.10, 0.25, and 0.50 mmol, respectively), aiming at the lowest reasonable dose needed to retrieve diagnostic information about the novel MRI biomarkers. The present observations disclosed a dose-dependent enrichment of subarachnoid CSF spaces (cisterna magna, vertex, and velum interpositum) with dose-dependent ventricular reflux of tracer in iNPH, as well as dose-dependent glymphatic tracer enrichment. The association between tracer enrichment in CSF and parenchymal compartments were as well dose-related. Intrathecal gadobutrol in a dose of 0.25 mmol, but not 0.10 mmol, was at 1.5T MRI considered sufficient for imaging altered CSF dynamics and glymphatic enhancement in iNPH, even though 3T MRI provided better sensitivity. Tracer enrichment in CSF at the vertex and within the cerebral cortex and subcortical white matter was deemed too low for maintaining diagnostic information from a dose of 0.10 mmol. We conclude that reducing the intrathecal dose of gadobutrol from 0.50 to 0.25 mmol gadobutrol improves the safety margin while maintaining the necessary diagnostic information about disturbed CSF homeostasis and glymphatic failure in iNPH.

CSF shunting in myelomeningocele-related hydrocephalus and the role of prenatal imaging.

Hydrocephalus is commonly associated with myelomeningocele (MMC). Indication and timing of cerebrospinal fluid (CSF) shunting are still a topic of discussion. The aim of this study was to investigate whether the analysis of prenatal cerebral imaging studies could provide information that is predictive of the necessity of CSF shunting in the postnatal period. Among 73 infants operated on because of MMC between January 2003 and June 2020, 50 had undergone prenatal and postnatal MRI studies and were considered for analysis. For each patient, frontal horn width, atrial ventricle diameter, third ventricle diameter, and subarachnoid spaces (sinocortical width, craniocortical width, and the interhemispheric width) have been measured on prenatal, postnatal, and a follow-up MRI study. The need of CSF shunting device placement in relation to prenatal and early postnatal MRI data was investigated. Of the 50 infants, 31 (62%) developed a progressive hydrocephalus. Of these, 30 needed a CSF shunt and the majority of them (n=29) was operated on within 28 days after birth. One patient needed CSF shunt implantation at 45 days after birth and one child developed a late progressive hydrocephalus, successfully treated by ETV alone, at 14.2 months of age. All patients with an atrial ventricle diameter greater than 1.9 cm and a 3rd ventricle diameter larger than 0.3 cm on antenatal third trimester imaging have undergone CSF shunting within 1 month after birth. Conversely, all the children that did not undergo a CSF shunt placement showed an atrial cerebral ventricle diameter inferior to 1.2 cm and a 3rd ventricle width < 0.3 cm on antenatal imaging. Frontal horn width and subarachnoid CSF spaces' evolution did not seem to play a role. The prenatal MRI assessment of the associated prenatal ventriculomegaly in MMC provides parameters that have a predictive value heralding the probability of a CSF diversion procedure after birth. In the same way, the analysis of intrauterine MRI studies may identify those subjects that are less at risk of developing a progressive hydrocephalus after birth, therefore encouraging a more cautious attitude towards the early implantation of CSF shunting devices in the current clinical practice.

Hyperintense Acute Reperfusion Marker on FLAIR in Patient with Possible Contrast-Induced Encephalopathy Following Cerebral Angiography

Contrast-induced encephalopathy (CIE) is a rare complication of angiography and endovascular intervention following administration of iodinated intravenous contrast agents. Neuroimaging findings of CIE usually show cerebral edema, leptomeningeal enhancement, and parenchymal signal abnormality on fluid-attenuated inverse recovery (FLAIR). Hyperintense acute reperfusion marker (HARM) generally implies an enhancement of the subarachnoid cerebrospinal fluid space on brain FLAIR imaging in cases of acute ischemic stroke or hyperperfusion syndrome. We report a case of possible CIE following cerebral angiography, accompanied by HARM sign.

Epidemiology of Benign External Hydrocephalus in Norway—A Population-Based Study

BackgroundBenign external hydrocephalus is defined as a rapidly increasing head circumference (occipitofrontal circumference) with characteristic radiological findings of increased subarachnoid cerebrospinal fluid spaces on neuroimaging. The incidence of benign external hydrocephalus has not been previously reported, and there is no available information on the ratio of benign external hydrocephalus in the population of hydrocephalic children. MethodsThis study is retrospective and population-based study, geographically covering two health regions in the southern half of Norway with a total mean population of 3.34 million in the ten-year study period, constituting approximately 75% of the Norwegian population. Children with a head circumference crossing two percentiles, or greater than the 97.5th percentile, and with typical imaging findings of enlarged frontal subarachnoid spaces with or without enlarged ventricles were included. Children were excluded if they had a history of head trauma, intracranial hemorrhage, central nervous system infection, other known causes of hydrocephalus, or were born preterm defined as birth before 37 weeks of gestation. ResultsA total of 176 children fitting the criteria were identified, giving an incidence of 0.4 per 1000 live births. One hundred fifty-two (86.4%) of the patients were male, and mean age at referral was 7.3 months. Increasing head circumference was the main reason for referral in 158 (89.8%) patients and the only finding in 60 (34.1%) patients. Thirty-seven (21%) children had normal ventricles on imaging; the remainder had increased ventricular size. The incidence of pediatric hydrocephalus in Norway is reported to be 0.75 per 1000 live births, thus benign external hydrocephalus accounts for approximately 50% of hydrocephalic conditions in this population. ConclusionsThe incidence of benign external hydrocephalus was found to be 0.4 per 1000 live births in this population.

Superficial subarachnoid cerebrospinal fluid space expansion after surgical drainage of chronic subdural hematoma.

The present study examined the computed tomography (CT) findings after surgery and overnight drainage for chronic subdural hematoma (CSDH) to clear the significance of inner superficial subarachnoid CSF space and outer subdural hematoma cavity between the brain surface and the inner skull. A total of 73 sides in 60 patients were evaluated. Head CT was performed on the day after surgery and overnight drainage (1st CT), within 3 weeks of surgery (2nd CT), and more than 3 weeks after surgery (3rd CT). Subdural and subarachnoid spaces were identified to focus on density of fluid, shape of air collection, and location of silicone drainage tube, etc. Cases with subdural space larger than the subarachnoid CSF space were classified as Group SD between the brain and the skull. Cases with subarachnoid CSF space larger than the subdural space were classified as Group SA. Cases with extremely thin (<3 mm) spaces between the brain and the skull were classified as Group NS. Group SA, SD, and NS accounted for 31.9, 55.6 and 12.5% of cases on the 1st CT. No statistical differences were found between Groups SA, SD, and NS in any clinical factors, including recurrence. Group SA were found significantly more on 1st CT than on 2nd and 3rd CT. Subarachnoid CSF space sometimes expands between the brain and skull on CT after surgical overnight drainage. Expansion of the arachnoid space may be a passive phenomenon induced by overnight drainage and delayed re-expansion of the brain parenchyma.

Intracranial cerebrospinal fluid spaces imaging using a pulse-triggered three-dimensional turbo spin echo MR sequence with variable flip-angle distribution

To assess the three-dimensional turbo spin echo with variable flip-angle distribution magnetic resonance sequence (SPACE: Sampling Perfection with Application optimised Contrast using different flip-angle Evolution) for the imaging of intracranial cerebrospinal fluid (CSF) spaces. We prospectively investigated 18 healthy volunteers and 25 patients, 20 with communicating hydrocephalus (CH), five with non-communicating hydrocephalus (NCH), using the SPACE sequence at 1.5T. Volume rendering views of both intracranial and ventricular CSF were obtained for all patients and volunteers. The subarachnoid CSF distribution was qualitatively evaluated on volume rendering views using a four-point scale. The CSF volumes within total, ventricular and subarachnoid spaces were calculated as well as the ratio between ventricular and subarachnoid CSF volumes. Three different patterns of subarachnoid CSF distribution were observed. In healthy volunteers we found narrowed CSF spaces within the occipital aera. A diffuse narrowing of the subarachnoid CSF spaces was observed in patients with NCH whereas patients with CH exhibited narrowed CSF spaces within the high midline convexity. The ratios between ventricular and subarachnoid CSF volumes were significantly different among the volunteers, patients with CH and patients with NCH. The assessment of CSF spaces volume and distribution may help to characterise hydrocephalus.

Changes in the volumes of the brain and cerebrospinal fluid spaces after shunt surgery in idiopathic normal-pressure hydrocephalus

ObjectivesTo investigate volumetric changes of the brain and cerebrospinal fluid (CSF) spaces after shunt surgery in shunt-responsive idiopathic normal-pressure hydrocephalus (iNPH), and correlations between the changes and postoperative clinical improvements. MethodsTwenty-one patients with shunt-responsive iNPH were studied. Magnetic resonance imaging (MRI) of the brain was performed before and 1year after surgery, and clinical symptoms were assessed by the iNPH Grading Scale, a validated assessment tool of the triad of iNPH, the Modified Rankin Scale, the Timed Up and Go Test, and neuropsychological tests including the Mini-Mental State Examination. The volumes of the left cerebral hemisphere, infratentorial brain, ventricles, and suprasylvian and infrasylvian subarachnoid CSF spaces were measured using an MRI-based volumetric technique. ResultsThe volumes of the cerebral hemisphere and infratentorial brain did not change significantly after shunt surgery (p=0.231, 0.109, respectively). The volumes of the ventricles and infrasylvian subarachnoid CSF spaces were significantly decreased (p<0.0001, <0.05, respectively), with a mean change rate of −26.1% and −4.5%, respectively. The volumes of the suprasylvian subarachnoid CSF spaces increased significantly (p<0.0001), with a mean change rate of 43.5%. The decrease in ventricular volumes was significantly correlated with clinical improvement.

Decompressive Surgery in a Patient with Posttraumatic Syringomyelia

Posttraumatic syringomyelia may result from a variety of inherent conditions and traumatic events, or from some combination of these. Many hypotheses have arisen to explain this complex disorder, but no consensus has emerged. A 28-year-old man presented with progressive lower extremity weakness, spasticity, and decreased sensation below the T4 dermatome five years after an initial trauma. Magnetic resonance imaging (MRI) revealed a large, multi-septate syrinx cavity extending from C5 to L1, with a retropulsed bony fragment of L2. We performed an L2 corpectomy, L1-L3 interbody fusion using a mesh cage and screw fixation, and a wide decompression and release of the ventral portion of the spinal cord with an operating microscope. The patient showed complete resolution of his neurological symptoms, including the bilateral leg weakness and dysesthesia. Postoperative MRI confirmed the collapse of the syrinx and restoration of subarachnoid cerebrospinal fluid (CSF) flow. These findings indicate a good correlation between syrinx collapse and symptomatic improvement. This case showed that syringomyelia may develop through obstruction of the subarachnoid CSF space by a bony fracture and kyphotic deformity. Ventral decompression of the obstructed subarachnoid space, with restoration of spinal alignment, effectively treated the spinal canal encroachment and post-traumatic syringomyelia.

Prenatal Diagnostic Challenges and Pitfalls for Schizencephaly

Schizencephaly is a developmental anomaly that causes unilateral or bilateral clefts of the cerebral hemisphere as a result of disordered neuronal migration. The clefts are lined by gray matter that can extend medially from the subarachnoid cerebrospinal fluid space into the lateral ventricle as part of a disease spectrum that includes porencephaly. Closed-lip schizencephaly (Type 1) occurs when the gray-matter lined walls are in contact with each other (1). By contrast, the open lip variety (Type 2) has separated lips with a cleft of cerebrospinal fluid that extends to the ventricles (2). Barkovich and co-workers (3) have reported that the clinical manifestations of affected infants are related to the size and location of the cleft defect. Late prenatal schizencephaly has been well documented. We now report well-documented case that demonstrates diagnostic challenges and pitfalls associated with its early diagnosis by 2D/3D ultrasonography and magnetic resonance imaging (MR).

Positional skull deformities in children: skull deformation without synostosis

Patients with craniosynostosis are readily diagnosed by clinical and neuroimaging findings. Surgical treatment is indicated for preventing neurological deficits and for correcting esthetically unacceptable head deformities. In recent years, we have witnessed a progressive number of neurosurgical consultations for abnormal head shapes unrelated to premature fusion of the cranial sutures, especially of positional plagiocephaly. There have been descriptions of abnormalities in the cerebrospinal fluid (CSF) spaces in children with craniosynostosis. The aim of the present study was to investigate the role of the changes of the CSF spaces in the development of positional skull deformities in children. The authors reviewed demographic, clinical, and neuroimaging data of 23 patients assessed for some form of nonsynostotic skull deformity (group A). The results were compared with those of a simultaneous group of nine infants diagnosed with benign extracerebral collections of fluid (group B). The study group was composed of 11 boys and 12 girls, aged 3 years or younger. Seventeen children had plagiocephaly, four scaphocephaly, and two brachycephaly. Sixteen children (15 with plagiocephaly and 1 with brachycephaly) exhibited enlarged subarachnoid CSF spaces. In group B, the boy/girl ratio was of 7:2. Infants in group A presented at an older age (mean 12.7 months) than group B (mean age at presentation of 7.17 months). Children with benign extracerebral fluid collections were born with a head circumference (HC) greater than infants with positional skull deformities (p=0.005). The percentile of the children's HC at consultation was also larger for children of group B (p=0.03). The form of clinical presentation differed between the two groups. Most infants of group A were seen because of a type of head deformity, and children in group B were studied for macrocephaly. Long-term follow-up assessment showed better outcomes for patients in group B than for children of group A in regard to regression of initial symptoms (p=0.03). Most positional head deformities appear to be related with the children's positioning for sleeping. We have not confirmed macrocephaly as a contributing factor for positional deformities. The distribution of extracerebral CSF and the presence of abnormal collections of fluid in children with positional head deformities do not seem to be related with the findings of pericerebral CSF encountered in children with benign extracerebral collections of fluid. In our view, brain pulsations, transmitted to these accumulations of CSF, play an important part in the development of the infants' skull deformities (p=0.02). The findings of enlarged CSF spaces in children with nonsynostotic skull deformation constituted an age-related event, as these collections tended to disappear as the children grew older (p=0.04).

Dissemination of fat in CSF: a common finding following translabyrinthine acoustic neuroma surgery*

Following translabyrinthine craniotomy the temporal bone defect is commonly obliterated using a free autologous fat graft. In this series the dura was put back in place but not closed primarily. As the fat graft remains in direct contact with the cerebro spinal fluid (CSF) there is potential for dispersal of fat within the CSF space. This paper aims to determine the frequency of such CSF fat dissemination and its clinical significance. A retrospective review of translabyrinthine acoustic neuroma removal with free fat autograft obliteration of the temporal bone defect between the years 1997 and 2000. Tertiary referral oto-neurosurgical centre. Postoperative magnetic resonance (MR) imaging. All translabyrinthine patients who had postoperative MR imaging were included. Twenty-six cases were identified. Age range was 13-70 years. Fourteen were male patients. Evidence of CSF fat dissemination on MR and patients' clinical findings. Twenty-two of the 26 scans (85%) demonstrated evidence of fat dissemination into the subarachnoid CSF spaces in the form of microemboli. The cerebellopontine angle was the most common site involved. No evidence of ventricular dilation or any other abnormality was noted. There was no relationship between the presence or extent of fat microembolization and the patients' clinical course. This study suggests that free fat placed in temporal bone defects commonly migrate into the subarachnoid space and subsequently move around in these spaces. This is not associated with any complications such as hydrocephalus, meningitis or prolonged postoperative headache.

Intracranial compartment volumes in patients with enlarged ventricles assessed by magnetic resonance-based image processing.

Magnetic resonance image-based computerized segmentation was used to measure the volumes of the brain, gray and white matter components, and to identify regions with prolonged enhancement on T2-weighted imaging, such as periventricular or deep white matter hyperintensities. The authors also determined the volumes of the ventricles and subarachnoid space in control subjects and in patients with: 1) aqueductal stenosis (AS); 2) other causes of obstructive hydrocephalus (OH); 3) Alzheimer's disease (AD); and 4) normal-pressure hydrocephalus (NPH). In AS the volume of the brain was smaller, whereas that of ventricles and subarachnoid cerebrospinal fluid space was larger than that of controls. The decrease in brain volume was due primarily to white matter loss. Although in OH the ventricles were larger, the subarachnoid space was smaller than in controls, presumably due to encroachment by the brain, in which the volume remained unchanged. In AD, loss of both gray and white matter resulted in a smaller brain volume, whereas that of ventricles and subarachnoid space was larger than in controls. In NPH patients, only ventricular volume was greater, whereas all other compartments were similar to controls. The brain normally occupies 87% to 92% of the intracranial volume and consequently, as observed in our patients, relatively small decrements in brain size lead to large increments in ventricular and/or extraventricular volumes. The magnitude of such changes differed markedly among our patient groups, and whether such changes prove useful in clinical assessment and differentiation needs to be determined.

Ventricular cerebrospinal fluid dynamics examined radiographically in the cat

Intracranial cannulas were inserted chronically into various ventricular and subarachnoid cerebrospinal fluid spaces of cats. The animals were anesthetized with pentobarbital sodium to ascertain spatial distribution and dissipation of microliter amounts of x-ray contrast media injected into the different sites. Radiographic observations were made at intervals from 0 (< 5 sec) to 60 min and in repeated sessions up to several weeks later. The water soluble radiopaque substance meglumine iothalamate (Conray) essentially disappeared within 60 min without apparent movement from all sites of injection, whether ventricular, subarachnoid or in the brain tissue per se. However, ventricular fields presented a nonuniform pattern of persistence showing early “mainstream” fading in areas between the interventricular foramen and the lateral apertures of the fourth ventricle which cleared within the first few minutes. Conversely, regions of greatest persistence included the anterior and inferior portions of the lateral ventricle, the ventral portion of the third ventricle and that portion of the fourth ventricle caudal to the lateral apertures. The same nonuniform pattern of clearing from the ventricular system was observed after injection of the oily contrast medium iophendylate (Pantopaque), but this substance was not absorbed locally and progressed by mass movement through the ventricular channels. The results provide evidence for remarkable regional differences in turn-over of the ventricular cerebrospinal fluid.