Search

Idiopathic syringomyelia (IS) and refractory syringomyelia (RS) are types of syringomyelia that often pose a management challenge and are associated with long-term clinical sequela. They are usually an epiphenomenon reflecting an underlying pathology where the treatment of the primary cause should be the aim for any surgical intervention. In the case of IS, the initial step is agreeing on the definition of the terms idiopathic and syringomyelia. After a rigorous exhaustive clinic-radiological workup, only IS patients with progressive neurology are treated, usually unblocking subarachnoid cerebrospinal fluid (CSF) pathway obstruction somewhere in the thoracic spinal canal and reserving shunting techniques to nonresponsive cases. Similar to IS, also RS is multifactorial, and its management varies based on the initial pathology, strongly supported by radiological and clinical features. We aim to address this topic focusing on the etiopathology, investigation paradigm, and surgical pathway, formulating algorithms of management with available evidence in literature. Surgical techniques are discussed in detail., (© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Neurofluids, a recently developed term that refers to interstitial fluids in the parenchyma and cerebrospinal fluid (CSF) in the ventricle and subarachnoid space, play a role in draining waste products from the brain. Neurofluids have been implicated in pathological conditions such as Alzheimer's disease and normal pressure hydrocephalus. Given that CSF moves faster in the CSF cavity than in the brain parenchyma, CSF motion can be detected by magnetic resonance imaging. CSF motion is synchronized to the heartbeat and respiratory cycle, but respiratory cycle-induced CSF motion has yet to be investigated in detail. Therefore, we analyzed CSF motion using dynamic improved motion-sensitized driven-equilibrium steady-state free precession-based analysis. We analyzed CSF motion linked to the respiratory cycle in four women and six men volunteers aged 23 to 38 years. We identified differences between free respiration and tasked respiratory cycle-associated CSF motion in the ventricles and subarachnoid space. Our results indicate that semi-quantitative analysis can be performed using the cranial site at which CSF motion is most prominent as a standard. Our findings may serve as a reference for elucidating the pathophysiology of diseases caused by abnormalities in neurofluids.

The study of brain clearance mechanisms is an active area of research. While we know that the cerebrospinal fluid (CSF) plays a central role in one of the main existing clearance pathways, the exact processes for the secretion of CSF and the removal of waste products from tissue are under debate. CSF is thought to be created by the exchange of water and ions from the blood, which is believed to mainly occur in the choroid plexus. This exchange has not been thoroughly studied in vivo. We propose a modified arterial spin labeling (ASL) MRI sequence and image analysis to track blood water as it is transported to the CSF, and to characterize its exchange from blood to CSF. We acquired six pseudo-continuous ASL sequences with varying labeling duration (LD) and post-labeling delay (PLD) and a segmented 3D-GRASE readout with a long echo train (8 echo times (TE)) which allowed separation of the very long-T 2 CSF signal. ASL signal was observed at long TEs (793 ms and higher), indicating presence of labeled water transported from blood to CSF. This signal appeared both in the CSF proximal to the choroid plexus and in the subarachnoid space surrounding the cortex. ASL signal was separated into its blood, gray matter and CSF components by fitting a triexponential function with T 2 s taken from literature. A two-compartment dynamic model was introduced to describe the exchange of water through time and TE. From this, a water exchange time from the blood to the CSF (T bl->CSF ) was mapped, with an order of magnitude of approximately 60 s., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the association between signal changes over time in perivenous cystic structures near the superior sagittal sinus and leakage of a gadolinium-based contrast agent (GBCA) into the subarachnoid space in patients with suspected endolymphatic hydrops., Methods: Fifty-one cystic structures in 27 cases were evaluated. The signal intensity of the cystic structures was measured on 3D real inversion recovery (3D-real IR) images obtained at pre-, and at 10 min, 4 hrs and 24 hrs post-intravenous administration (IV) of GBCA. Signal enhancement of the cystic structures from the pre-contrast images at each time point was compared in subjects with leakage (positive) versus those without leakage (negative) using an ANOVA. Fisher's exact probability test was used to compare the maximum contrast-enhanced time point between positive and negative groups. We used 5% as a threshold to determine statistical significance., Results: In leakage positive subjects, mean signal enhancement of the cysts was significantly greater at 4 and 24 hrs compared to 10 min. However, although there was a trend of an increase from 4 to 24 hrs, the difference was not significant. In the leakage negative group, mean signal enhancement of the cysts was significantly higher at 4 hrs compared to 10 min and 24 hrs. There was no significant difference between 10 min and 24 hrs. In the positive group, the maximum signal increase was found in 10/38 and 28/38 cysts at 4 and 24 hrs after IV-GBCA, respectively. In the leakage negative group, the maximum signal increase was found in 10/13 and 3/13 cysts at 4 and 24 hrs, respectively (P = 0.0019)., Conclusion: There was an association between signal changes over time after IV-GBCA in perivenous cystic structures and leakage of GBCA. Further research to clarify the impact of cystic structures on the function of the waste clearance system of the brain is warranted.

Subarachnoid-pleural fistula (SPF) is a rare complication of spine surgery with a transthoracic approach. The outcome of such an injury is affected by not only the pulmonary status due to the pleural effusion but also the neurological one, secondary to the intracranial hypotension. After reviewing the few published cases of SPF, the journey to diagnosis seams heterogenous and the management plan non-uniform. We report the case of a 48-year old women who underwent a right transthoracic discectomy that was complicated by an SPF. The diagnosis, although suspected perioperatively, was established with the gathering of an abundant post-operative pleural effusion, a subdural hematoma on head Computerized Tomography after drainage and Cerebro-Spinal Fluid markers present in the pleural fluid. The defect was effectively corrected with a radiological procedure. We compare our clinical and paraclinical findings and management plans to those reported in the few other published cases of SPF., (Copyright © 2020. Published by Elsevier Masson SAS.)

Cerebrospinal fluid (CSF) leak is a common phenomenon encountered by the neurosurgeon. It is most commonly come across after a neurosurgical procedure, but it can be seen idiopathically. Treatment usually ranges from conservative management through cerebrospinal fluid diversion to direct surgical repair. Continuous CSF drainage provides a path for diversion and allowing the site of the dural injury to heal effectively.1 Cervical subarachnoid drain is a safe and effective alternative when lumbar access is contraindicated or not achievable.2 Here we present a case of a 22-yr-old female with progressive symptomatic positional headaches due to a CSF leak from a prior deformity surgery treated with a cervical subarachnoid drain after a failed attempt at a direct repair. This 2-dimensional video illustrates the technique used for the placement of a cervical subarachnoid drain for the treatment of symptomatic CSF leak.  Patient consented to the procedure and for the publication of their image., (© Congress of Neurological Surgeons 2021.)

Aim: To evaluate the reliability of synthetic magnetic resonance imaging (SyMRI) for detecting complications associated with subarachnoid haemorrhage (SAH), such as ischaemic lesions, hydrocephalus, or bleeding complications., Materials and Methods: Twenty patients with SAH, who underwent a conventional brain MRI and a SyMRI on a 3 T MRI machine. Comparable conventional and synthetic T2-weighted fluid attenuated inversion recovery (FLAIR) images were acquired. The presence of ischaemic lesions, hydrocephalus, extra-axial blood collections as well as the volumes of grey matter (GMv), white matter (WMv), and cerebrospinal (CSFv) were compared. The acquisition times of both sequences was also analysed., Results: The concordance between the two techniques was excellent for the detection of ischaemic lesions and extra-axial collections (kappa = 0.80 and 0.88 respectively) and good for the detection of hydrocephalus (kappa = 0.69). No significant differences were detected in the number of ischaemic lesions (p=0.31) or in the Evans index (p=0.11). The WMv and CSFv measures were also similar (p=0.18 and p=0.94, respectively), as well as the volume of ischaemic lesions (p=0.79). Compared to conventional MRI, the SyMRI acquisition time was shorter regardless of the number of sections (32% and 6% time reduction for 4 or 3 mm section thickness, respectively)., Conclusions: SyMRI allows the detection of potential complications of SAH in a similar way to conventional MRI with a shorter acquisition time., (Copyright © 2021 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: To identify magnetic resonance cisternography (MRC) imaging findings related to Gadolinium-based contrast agent (GBCA) leakage into the subarachnoid space., Materials and Methods: The number of voxels of GBCA leakage (V-leak) on 3D-real inversion recovery images was measured in 56 patients scanned 4 h post-intravenous GBCA injection. Bridging veins (BVs) were identified on MRC. The numbers of BVs with surrounding cystic structures (BV-cyst), with arachnoid granulations protruding into the superior sagittal sinus (BV-AG-SSS) and the skull (BV-AG-skull), and including any of these factors (BV-incl) were recorded. Correlations between these variables and V-leak were examined based on the Spearman's rank correlation coefficient. Receiver-operating characteristic (ROC) curves were generated to investigate the predictive performance of GBCA leakage., Results: V-leak and the number of BV-incl were strongly correlated (r = 0.609, p < 0.0001). The numbers of BV-cyst and BV-AG-skull had weaker correlations with V-leak (r = 0.364, p = 0.006; r = 0.311, p = 0.020, respectively). The number of BV-AG-SSS was not correlated with V-leak. The ROC curve for contrast leakage exceeding 1000 voxels and the number of BV-incl had moderate accuracy, with an area under the curve of 0.871., Conclusion: The number of BV-incl may be a predictor of GBCA leakage and a biomarker for waste drainage function without using GBCA., (© 2021. The Author(s).)

Syrinx resolution has been associated with an increase in the size of the posterior subarachnoid space (pSAS) after foramen magnum decompression (FMD) for type I Chiari malformation (CM1). The present study investigated the influence of pSAS increase on syrinx resolution and symptom improvement after FMD. 32 patients with CM1 with syrinx were analyzed retrospectively. FMD was performed for the 24 patients with CM1 with syrinx. pSAS areas were measured on sagittal magnetic resonance images. Neurological symptoms were grouped into three clinical categories and scored. The rates of symptom improvement in the CM1 patients with syrinx after FMD was 19.7% ± 12.9%. The mean times to the improvement of neurological symptoms in CM1 patients with syrinx after FMD was 23.4 ± 50.2 months. There were no significant differences between the patients with and without improvement of syrinx after FMD with regard to the age, length of tonsillar herniation, BMI, and preoperative pSAS areas. The rate of increase in the pSAS areas was significantly higher in the group with syrinx improvement within 1 year (p < 0.0001). All patients with a > 50% rate of increase in the pSAS area showed syrinx improvement. Our results suggested that the increasing postoperative pSAS area accelerated the timing of syrinx resolution., (© 2021. The Author(s).)

Disproportionately enlarged subarachnoid space hydrocephalus (DESH) is the characteristic feature of idiopathic normal pressure hydrocephalus. We aimed to characterize the prevalence, development, and association of DESH to cognitive deficit in a large population. We reviewed the data of 1384 subjects eligible for the present study among 1590 participants who underwent magnetic resonance imaging (MRI) in the Ohasama Study, a population-based study in Ohasama, Japan. The participants with Mini-Mental State Examination (MMSE) score <  = 25 were assumed to have cognitive deficit and DESH was evaluated by reviewing the MRIs. We assessed the association between DESH, Evans index (EI), and cognitive deficit using multivariate logistic regression models adjusted for relevant confounders. Furthermore, we evaluated the new development of DESH and the deterioration of cognitive function in the participants with DESH. There were nine participants with DESH (0.65%), seven of whom showed cognitive deficit. DESH was significantly associated with cognitive deficit in multivariate regression analyses (odds ratio; 8.50 [95% confidence interval: 1.61-44.88]). In the 669 participants who underwent follow-up MRI, we found four participants newly presenting with DESH; the development of DESH was observed before/after the presence of EI > 0.3. We also found two participants with existing DESH showing no remarkable worsening in MMSE and EI. The present study demonstrated a positive association between the presence of DESH and cognitive deficit. DESH can develop independently of EI > 0.3, and ventricular enlargement in combination with DESH may be an important factor in the worsening of cognitive deficit., (© 2021. The Author(s).)

Background: Disproportionately enlarged subarachnoid space hydrocephalus is a specific radiologic marker for idiopathic normal pressure hydrocephalus. However, controversy exists regarding the prognostic utility of disproportionately enlarged subarachnoid space hydrocephalus., Purpose: Our aim was to evaluate the prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus and its predictive utility regarding prognosis in patients treated with ventriculoperitoneal shunt surgery., Data Sources: We used MEDLINE and EMBASE databases., Study Selection: We searched for studies that reported the prevalence or the diagnostic performance of disproportionately enlarged subarachnoid space hydrocephalus in predicting treatment response., Data Analysis: The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus was obtained. Pooled sensitivity, specificity, and area under the curve of disproportionately enlarged subarachnoid space hydrocephalus to predict treatment response were obtained. Subgroup and sensitivity analyses were performed to explain heterogeneity among the studies., Data Synthesis: Ten articles with 812 patients were included. The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus was 44% (95% CI, 34%-54%). The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus was higher in the studies using the second edition of the Japanese Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus compared with the studies using the international guidelines without statistical significance (52% versus 43%, P = .38). The pooled sensitivity and specificity of disproportionately enlarged subarachnoid space hydrocephalus for prediction of treatment response were 59% (95% CI, 38%-77%) and 66% (95% CI, 57%-74%), respectively, with an area under the curve of 0.67 (95% CI, 0.63-0.71)., Limitations: The lack of an established method for assessing disproportionately enlarged subarachnoid space hydrocephalus using brain MR imaging served as an important cause of the heterogeneity., Conclusions: Our meta-analysis demonstrated a relatively low prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus and a poor diagnostic performance for treatment response., (© 2021 by American Journal of Neuroradiology.)

Enhancement of the subarachnoid space after intravenous administration of gadolinium contrast agent is not common. Enhancement usually occurs in pathological conditions that increase the permeability of the blood-cerebrospinal fluid barrier, most notably in meningitis. We herein describe possible subarachnoid enhancement in patients with no apparent effect on the meninges. These patients had clinical signs of Meniere's disease and underwent specific magnetic resonance imaging of the inner ear to possibly visualize endolymphatic hydrops. The endolymphatic space can be noninvasively imaged by intravenous administration of contrast agent, usually at a double dose, 4 hours before the scanning process. During this time, the contrast agent penetrates not only the perilymph but also the subarachnoid space, where the highest concentration occurs after 4 hours according to some studies.

The presence of intracranial adipose tissue is often overlooked, although it may be detected in different physiological (dural sinuses or falx deposition of fat) and pathological (lipoma, dermoid cyst, subarachnoid fat dissemination) conditions. In this review, we illustrate various scenarios in which radiologists and neuroradiologists may encounter intracranial fat, providing a list of differential diagnosis.

Background: It is important to distinguish foramen magnum arachnoiditis (FMA) from Chiari malformation (CM) before surgery because the operative strategies for these diseases differ. In the current study, we compared pretreatment magnetic resonance imaging (MRI) of FMA with CM and investigated the MRI findings useful to differentiate between these diseases., Methods: We retrospectively reviewed patients with FMA or CM aged ≥ 18 years who underwent surgeries at our institution between 2007 and 2019. The morphologies of the syrinx, neural elements, and posterior cranial fossa were preoperatively evaluated with MRI. We used the receiver operating characteristic (ROC) curve for the fourth ventricle-to-syrinx distance (FVSD)., Results: Ten patients with FMAs and 179 with CMs were included. FVSD in the FMA group was significantly shorter than that in the CM group (7.5 mm [IQR, 2.8-10 mm] in FMA vs. 29.9 mm [IQR, 16.3-52.9 mm] in CM, p < 0.0001). The other MRI findings that showed the height, size, and length of the syrinx; size of the foramen magnum; degree of cerebellar tonsillar descent; shape of the cerebellar tonsil; and dorsal subarachnoid space at the foramen magnum differed significantly between the two groups. The ROC curve analysis showed that patients whose FVSD was less than 11 mm could be diagnosed with FMA with a specificity of 90% and sensitivity of 96%., Conclusions: A more cranial syrinx development (FVSD < 11 mm) appears to be the characteristic MRI finding in FMA.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH), characterized by tight high convexity CSF spaces, ventriculomegaly, and enlarged Sylvian fissures, is thought to be an indirect marker of a CSF dynamics disorder. The clinical significance of DESH with regard to cognitive decline in a community setting is not yet well defined. The goal of this work is to determine if DESH is associated with cognitive decline. Participants in the population-based Mayo Clinic Study of Aging (MCSA) who met the following criteria were included: age ≥ 65 years, 3T MRI, and diagnosis of cognitively unimpaired or mild cognitive impairment at enrollment as well as at least one follow-up visit with cognitive testing. A support vector machine based method to detect the DESH imaging features on T1-weighted MRI was used to calculate a "DESH score", with positive scores indicating a more DESH-like imaging pattern. For the participants who were cognitively unimpaired at enrollment, a Cox proportional hazards model was fit with time defined as years from enrollment to first diagnosis of mild cognitive impairment or dementia, or as years to last known cognitively unimpaired diagnosis for those who did not progress. Linear mixed effects models were fit among all participants to estimate annual change in cognitive z scores for each domain (memory, attention, language, and visuospatial) and a global z score. For all models, covariates included age, sex, education, APOE genotype, cortical thickness, white matter hyperintensity volume, and total intracranial volume. The hazard of progression to cognitive impairment was an estimated 12% greater for a DESH score of +1 versus -1 (HR 1.12, 95% CI 0.97-1.31, p = 0.11). Global and attention cognition declined 0.015 (95% CI 0.005-0.025) and 0.016 (95% CI 0.005-0.028) z/year more, respectively, for a DESH score of +1 vs -1 (p = 0.01 and p = 0.02), with similar, though not statistically significant DESH effects in the other cognitive domains. Imaging features of disordered CSF dynamics are an independent predictor of subsequent cognitive decline in the MCSA, among other well-known factors including age, cortical thickness, and APOE status. Therefore, since DESH contributes to cognitive decline and is present in the general population, identifying individuals with DESH features may be important clinically as well as for selection in clinical trials., Competing Interests: Declaration of Competing Interest C.R.J. serves on an independent data monitoring board for Roche and has consulted for Eisai, but he receives no personal compensation from any commercial entity. He receives research support from NIH and the Alexander Family Alzheimer's Disease Research Professorship of the Mayo Clinic. D.T.J. receives funding from the NIH and the Minnesota Partnership for Biotechnology and Medical Genomics. D.S.K. served on a Data Safety Monitoring Board for the DIAN study. He serves on a Data Safety Monitoring Board for a tau therapeutic for Biogen, but receives no personal compensation. He is an investigator in clinical trials sponsored by Biogen, Lilly Pharmaceuticals, and the University of Southern California. He serves as a consultant for Samus Therapeutics, Third Rock, and Alzeca Biosciences but receives no personal compensation. He receives research support from the NIH. R.C.P. has consulted for Roche, Inc.; Merck, Inc.; Biogen, Inc.; Eisai, Inc. and is on a Data and Safety Monitoring Committee for Genentech, Inc. He receives research support from the National Institute on Aging, the GHR Foundation, and the Alzheimer's Association. J.G-R. receives research support from the NIH. C.G.S. receives research support from the NIH. M.L.S. has owned shares of the following medical related stocks, unrelated to the current work: Align Technology, Inc., LHC Group, Inc., Mesa Laboratories, Inc., Natus Medical Incorporated, Varex Imaging Corporation, CRISPR Therapeutics, Gilead Sciences, Inc., Globus Medical Inc., Inovio Biomedical Corp., Ionis Pharmaceuticals, Johnson & Johnson, Medtronic, Inc., Parexel International Corporation. P.M.C., J.L.G., H.J.W., and S.D.W. report no competing interests., (Copyright © 2021. Published by Elsevier Inc.)

A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal computed tomography-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M = 25:15, with a mean age of 44.9 years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7 mm. Using two-way analysis of variance, there were significant sex differences for needle distances (p = .001), and full and limited sacral curvatures (p = .02, and p = .046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle., (© 2020 Wiley Periodicals LLC.)

Purpose: We hypothesize that a collapse of the optic nerve subarachnoid space (ONSAS) in the upright posture may protect the eyes from large translamina cribrosa pressure differences (TLCPD) believed to play a role in various optic nerve diseases (e.g., glaucoma). In this study, we combined magnetic resonance imaging (MRI) and mathematical modeling to investigate this potential ONSAS collapse and its effects on the TLCPD., Methods: First, we performed MRI on six healthy volunteers in 6° head-down tilt (HDT) and 13° head-up tilt (HUT) to assess changes in ONSAS volume (measured from the eye to the optic canal) with changes in posture. The volume change reflects optic nerve sheath (ONS) distensibility. Second, we used the MRI data and mathematical modeling to simulate ONSAS pressure and the potential ONSAS collapse in a 90° upright posture., Results: The MRI showed a 33% decrease in ONSAS volume from the HDT to HUT (P < 0.001). In the upright posture, the simulations predicted an ONSAS collapse 25 mm behind lamina cribrosa, disrupting the pressure communication between the ONSAS and the intracranial subarachnoid space. The collapse reduced the simulated postural increase in TLCPD by roughly 1 mm Hg, although this reduction was highly sensitive to ONS distensibility, varying between 0 and 4.8 mm Hg when varying the distensibility by ± 1 SD., Conclusions: The ONSAS volume along the optic nerve is posture dependent. The simulations supported the hypothesized ONSAS collapse in the upright posture and showed that even small changes in ONS stiffness/distensibility may affect the TLCPD.

Competing Interests: The authors report no conflicts of interest.

Among the various disorders that manifest with gait disturbance, cognitive impairment, and urinary incontinence in the elderly population, idiopathic normal pressure hydrocephalus (iNPH) is becoming of great importance. The first edition of these guidelines for management of iNPH was published in 2004, and the second edition in 2012, to provide a series of timely, evidence-based recommendations related to iNPH. Since the last edition, clinical awareness of iNPH has risen dramatically, and clinical and basic research efforts on iNPH have increased significantly. This third edition of the guidelines was made to share these ideas with the international community and to promote international research on iNPH. The revision of the guidelines was undertaken by a multidisciplinary expert working group of the Japanese Society of Normal Pressure Hydrocephalus in conjunction with the Japanese Ministry of Health, Labour and Welfare research project. This revision proposes a new classification for NPH. The category of iNPH is clearly distinguished from NPH with congenital/developmental and acquired etiologies. Additionally, the essential role of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in the imaging diagnosis and decision for further management of iNPH is discussed in this edition. We created an algorithm for diagnosis and decision for shunt management. Diagnosis by biomarkers that distinguish prognosis has been also initiated. Therefore, diagnosis and treatment of iNPH have entered a new phase. We hope that this third edition of the guidelines will help patients, their families, and healthcare professionals involved in treating iNPH.

Purpose: We aimed to image the optic nerve, subarachnoid space and optic nerve sheath in emmetropes and myopes ultra-high field (7-Tesla) magnetic resonance imaging (MRI). We targeted the retrobulbar distance of approximately 3 mm behind the eyeball, an area of clinical interest because of optic nerve sheath distensibility and pressure-related enlargement., Methods: Eleven emmetropes (+0.75 to -0.50D, aged 20-41 years) and 10 myopes (-4.5 to -12D, aged 21-37 years) participated. Cross-sectional area of the optic nerve, subarachnoid space and optic nerve sheath at approximately 3 mm behind the eye were measured from two-dimensional T2-weighted coronal oblique MRI images obtained through the left optic nerve. Axial length of the left eye was measured from T2-weighted axial MRI images. In nine emmetropes and seven myopes, the optic nerve head was imaged with optical coherence tomography to compare retrobulbar and intraocular measures., Results: Retrobulbar optic nerve, subarachnoid space and optic nerve sheath dimensions differed between myopes and emmetropes. Myopes tended to have smaller optic nerve and subarachnoid space. Longer MRI-derived axial length was associated with smaller optic nerve area (P = 0.03). Bruch's membrane opening area did not predict retrobulbar optic nerve area (P = 0.48)., Conclusions: This study demonstrates the feasibility of using 7-Tesla MRI to measure optic nerve, subarachnoid space, and optic nerve sheath dimensions behind the eye. In healthy adults, the retrobulbar optic nerve and subarachnoid space size are influenced by the degree of myopia., Translational Relevance: ultra-high field MRI is a practical tool for assessing the morphometry of the optic nerve and surrounding anatomy behind the eye.

Spinal extradural cysts are uncommon and may cause cord and nerve root compression. The cysts usually appear in thoracic spine. We report a 29-year-old man with an extradural arachnoid cyst from T4 to T6. The cyst was communicated to the subarachnoid space through a fistula at the left T6 nerve root. To access the fistula, we had to unroof the foramen of left T6 nerve root which could lead to spinal instability. We decided to save the bony and soft tissue elements of the foramen at the mentioned thoracic spine level. Therefore, the cyst walls were excised and then the ostia of the cyst at the cystic side of the fistula was tightly closed.

Purpose of Review: To provide an update on recent developments in the understanding, diagnosis, and treatment of CSF-venous fistula (CVF)., Recent Finding: CVF is a recently recognized cause of spontaneous intracranial hypotension (SIH), an important secondary headache, in which an aberrant connection is formed between the spinal subarachnoid space and an adjacent spinal epidural vein permitting unregulated loss of CSF into the circulatory system. CVFs often occur without a concurrent epidural fluid collection; therefore, CVF should be considered as a potential etiology for patients with SIH symptomatology but without an identifiable CSF leak. Imaging plays a critical role in the detection and localization of CVFs, with a number of imaging techniques and provocative maneuvers described in the literature to facilitate their localization for targeted and definitive treatment. Increasing awareness and improving the localization of CVFs can allow for improved outcomes in the SIH patient population. Future prospective studies are needed to determine the diagnostic performance of currently available imaging techniques as well as their ability to inform workup and guide treatment decisions.

Almost 150 papers about brain lymphatics have been published in the last 150 years. Recently, the information in these papers has been synthesized into a picture of central nervous system (CNS) "glymphatics," but the fine structure of lymphatic elements in the human brain based on imaging specific markers of lymphatic endothelium has not been described. We used LYVE1 and PDPN antibodies to visualize lymphatic marker-positive cells (LMPCs) in postmortem human brain samples, meninges, cavernous sinus (cavum trigeminale), and cranial nerves and bolstered our findings with a VEGFR3 antibody. LMPCs were present in the perivascular space, the walls of small and large arteries and veins, the media of large vessels along smooth muscle cell membranes, and the vascular adventitia. Lymphatic marker staining was detected in the pia mater, in the arachnoid, in venous sinuses, and among the layers of the dura mater. There were many LMPCs in the perineurium and endoneurium of cranial nerves. Soluble waste may move from the brain parenchyma via perivascular and paravascular routes to the closest subarachnoid space and then travel along the dura mater and/or cranial nerves. Particulate waste products travel along the laminae of the dura mater toward the jugular fossa, lamina cribrosa, and perineurium of the cranial nerves to enter the cervical lymphatics. CD3-positive T cells appear to be in close proximity to LMPCs in perivascular/perineural spaces throughout the brain. Both immunostaining and qPCR confirmed the presence of adhesion molecules in the CNS known to be involved in T cell migration., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

Purpose: The study explores microscope integrated optical coherence tomography (OCT) as a intraoperative imaging technique to delineate the microstructural composition of human dura mater cranialis and underlying leptomeninges for surgical guidance., Methods: OCT volume scans, light microscopic pictures and light microscopic videos of the dura mater were acquired in patients (n = 20) with indication for craniotomy. OCT volume scans and corresponding light microscopic data were analyzed post procedural. Thickness of anatomical structures was measured during this phase., Results: OCT scanning of the human cranial dura mater was feasible during microsurgical dissection. A discrimination of the endosteal and inner meningeal layer of the cranial dura mater was possible in 70 % (n = 14) of the patients. Transdural OCT scans could further demonstrate subdural anatomical structures: subdural space 10 % (n = 2), subarachnoid space in 35 % (n = 7), arachnoid vessels in 80 % (n = 16) and brain cortex in 90 % (n = 16) of the patients. Orthogonal distance measurement was possible. The cranial dura mater showed a mean depth of 216 μm, the endosteal layer of 120 μm and the inner meningeal layer of 132 μm. Imaging quality of the dural segment was high - approaching spatial resolution of histopathology. Imaging quality of subdural segments was lower and demonstrated A-line artifacts in 45 % (n = 7)., Conclusion: These results illustrate - for the first time - strengths and weaknesses of three dimensional microscope integrated OCT as an in vivo imaging method of the human cranial dura mater, underlying leptomeninges and human brain cortex as a surgical guidance tool. OCT imaging of the cranial dura mater showed extensive details. Transdural imaging of subdural micro anatomical structures was possible, but showed lower image quality with intermittent A-line artifacts. OCT stated the first intraoperative imaging tool to measure the depth of micro anatomical structures with a high spatial resolution of 7,5 μm., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Cerebrospinal Fluid (CSF) is produced mainly by the choroid plexus but with a substantial influence by the ependymal lining of the ventricles in the brain. Hydrocephalus occurs as a result of discrepancy in the production as well as circulation of CSF as a result of congenital and acquired conditions. Nevertheless, studies on the differences between CSF dynamics according to age and gender are still insufficient. Thus, this study evaluated the volume of intracranial CSF in healthy people and hydrocephalus patients taking into account the differences between CSF dynamics according to age and gender using Sampling Perfection with Application optimised Contrast using different flip-angle Evolution (SPACE) sequence., Methods: 120 healthy volunteers and 60 patients with hydrocephalus were included in this study. SPACE sequence was used to evaluate intracranial CSF with a 3.0T magnetic resonance machine. The total volume of intracranial CSF and the amount of CSF in the ventricle were obtained using a software, and the volume ratio of CSF in the subarachnoid space, the ventricle and the subarachnoid space were calculated., Results: The mean volume of intracranial CSF, ventricular CSF, and subarachnoid CSF of male volunteers were (206.9±47.7) cm3, (33.0±10.7) cm3, (173.9±37.9) cm3 respectively. The average volume of intracranial CSF, ventricular CSF, and subarachnoid CSF of female volunteers were (199.7±44.9) cm3, (30.8±9.4) cm3, and (168.9±37.0) cm3, respectively. Thus, no significant statistically (P>0.05) difference between males and females was found. (3) The mean values of intracranial CSF, ventricle CSF and subarachnoid CSF, ventricle and subarachnoid CSF volume ratio in patients with hydrocephalus were significantly greater than health volunteers. Thus, the difference between the two groups was statistically significant (P<0.05)., Conclusion: SPACE sequence can quantitatively determine the content of CSF. The change of CSF volume has nothing to do with gender but with age. It is feasible to use SPACE sequence to evaluate the spatial distribution and volume of intracranial CSF., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: The differentiation of idiopathic normal pressure hydrocephalus (iNPH) from neurodegenerative diseases such as Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) is often challenging because of their non-specific symptoms. Therefore, various neuroradiological markers other than ventriculomegaly have been proposed. Despite the utility of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) for the appropriate selection of shunt surgery candidates, the specificity and neuropathology of this finding have not been sufficiently evaluated., Objective: Investigation of the clinicopathological features and comparison of the neuroradiological findings between DESH with postmortem neuropathological diagnoses (pDESH) and clinically-diagnosed iNPH (ciNPH) patients are the main purposes of this study., Method: In addition to the retrospective evaluation of clinicopathological information, quantitative, semiquantitative, and qualitative magnetic resonance imaging (MRI) indices were compared between pathologically-investigated 10 patients with pDESH and 10 patients with ciNPHResults:Excluding one patient with multiple cerebral infarctions, the postmortem neuropathological diagnoses of the pathologically-investigated patients were mainly neurodegenerative diseases (five AD, one DLB with AD pathologies, one DLB, one argyrophilic grain disease, and one Huntington's disease). In addition to the common neuroradiological featuresConclusion:Hippocampal atrophy and deformation with temporal horn enlargement seem to be characteristic neuroradiological findings of long-standing severely demented patients with DESH and neurodegenerative diseases, mainly advanced-stage AD.

Background and Purpose: The spinal subarachnoid space (SSAS) is vital for neurologic function. Although SSAS alterations are known to occur after spinal cord injury (SCI), there is a lack of high-resolution imaging studies of the SSAS after SCI in rodents. Therefore, the aim here was to assess changes in the SSAS of rats subjected to graded SCI, using high-resolution micro-CT myelography., Methods: Long-Evans adult rats were subjected to mild or severe spinal cord contusion at T9. Imaging studies of SSAS features were carried out in injured rats at acute (day 1) and subacute (day 15) stages postinjury, as well as in control rats, using high-resolution micro-CT myelography with a contrast-enhanced digital subtraction protocol. We studied a total of 33 rats randomly allocated into five experimental groups. Micro-CT myelograms were assessed by expert observers using both qualitative and quantitative criteria., Results: Qualitative and quantitative analyses showed that SCI induces changes in the SSAS that vary as a function of both injury severity and time elapsed after injury. SSAS blockage was the main alteration detected. Moreover, the method used here allowed fine details to be observed in small animals, such as variations in the preferential pathways for contrast medium flow, neuroimaging nerve root enhancement, and leakage of contrast medium due to tearing of the dural sac., Conclusion: Micro-CT myelography provides high-resolution images of changes in the SSAS after SCI in rats and is a useful tool for further experimental studies involving rat SCI in vivo., (© 2020 American Society of Neuroimaging.)

Introduction: The motion of the brain relative to the skull is influenced by the architecture of the subarachnoid space (SAS), and in particular, by the arachnoid trabeculae. In previous studies of these structures, specific shapes were identified. However, the work presented here shows much finer detail of the SAS geometries using SEM and TEM., Materials and Methods: These images were acquired by maintaining the SAS structure of a rat using glutaraldehyde formaldehyde to strengthen the tissues via crosslinking with the biological proteins., Results: The results showed the detailed shape of five dominant arachnoid trabeculae structures: single strands, branched strands, tree like shapes, sheets, and trabecular networks. Each of these architectures would provide a different response when exposed to a tensile load and would provide different levels of resistance to the flow of the cerebrospinal fluid (CSF) within the SAS., Conclusion: This very detailed level of geometric information will therefore allow more accurate finite element models of the SAS to be developed., (© 2020 Wiley Periodicals LLC.)

Background: The techniques described for the identification of the lumbosacral (LS) epidural space in dogs do not guarantee the needle position or an accidental subarachnoid puncture, especially in small size dogs., Aim: To determine the relationship between body weight and the location of the dural sac (DS) using myelography in dogs, and to determine the possibility of subarachnoid puncture during LS epidural based on the position of the DS., Methods: Four masked observers evaluated 70 myelographic studies of dogs, annotating the vertebrae where the DS ended, if it was localized before or after the LS space, and if accidental subarachnoid puncture during LS epidural injection was possible (yes/no). Body weight (kg) was categorized into: less than 10 kg, between 10 and 20 kg, and more than 20 kg and was also converted to body surface area (BSA) as a continuous variable., Results: The DS ended at the LS space or caudally in 50% of dogs. There was a statistically significant difference between the position of the DS and the dog's BSA ( p = 0.001). The DS ended caudal to the LS space in 72.7% of dogs weighing <10 kg, in 25% of dogs between 10 and 20 kg and in 15% of dogs in the >20 kg category. The observers considered a possible subarachnoid puncture during LS epidural in 69.7% of patients <10 kg, 16.6% on those between 10 and 20 kg, and in 11.7% of the dogs >20 kg., Conclusion: The DS ended caudal to the LS space in almost 3/4 dogs in the <10 kg category, so accidental subarachnoid puncture during LS epidural is highly possible in this weight range., Competing Interests: The authors declare that there is no conflict of interest.

Abstract: Ultrasound (US) imaging of the spinal canal is applied in early infants before formation of posterior spine bony elements. Here, we demonstrate for the first time in adult healthy subjects that excellent visualization of intrathecal structures at the level of C1-C2 is possible by transcutaneous US in flexion, extension, and neutral head positions through the soft tissue US window between C1-C2. We show with US that the posterior subarachnoid space increases significantly in head extension. Accordingly, C1-C2 US guidance can facilitate cervical myelography. In addition, we suggest that US of the C1-C2 spine level may offer an adjunct tool to diagnosing structural abnormalities in the setting of traumatic, congenital, or degenerative pathologies of the craniocervical junction., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: Our study aimed to determine the possible differences in linear measurements and linear indices values of intracranial fluid spaces (IFS) between right- and left-handed adults. Methods: This work has been carried out on 148 subjects (72 men and 76 women). In the study, 88 right-handers and 60 left-handers were included. Forty of the right-handers were male, 48 were female, and 32 of the left-handers were male, and 28 were female. The ages were between 20 and 50 years. Linear measurements were obtained based on magnetic resonance imaging (MRI) studies. A 1.5-T MRI scanner was used to obtain axial images. The ten parameters were estimated from MRI scans. Results: There was no correlation between parameters and age. In our study, interestingly, as can be seen from the tables, most of the parameters with statistically significant differences were higher in favour of left-handed subjects. In most of the linear measurement results, IFS values of the right hemisphere in right-handers, and the left hemisphere in left-handers were higher. Similar results were found in favour of the left-handed in most of the linear ventricular indices. Conclusion: Linear measurements and linear indices values of IFS were mostly higher in left-handers than in right-handed individuals.

Objective: To examine the occurrence and outcomes of fetuses with wide subarachnoid space (WSS) without ventriculomegaly in pregnant women with fetal macrocephaly as a sole diagnosis. Study design: A retrospective study was performed, analyzing patients with fetal macrocephaly between the years 2008 and 2018. All these patients underwent MRI, in order to detect brain anomalies. In the absence of any other brain abnormality, they were evaluated for WSS and their offspring's database was followed for at least two years after birth. Results: Ten patients were found to be carrying fetuses with macrocephaly, nine of them were diagnosed with WSS without ventriculomegaly prior to delivery. Following at least two years of follow up, all patients did not present significant neurodevelopmental abnormalities, apart from one child that had a genetic mutation of 15q21.2-22.31 deletion with other anomalies that were not diagnosed prenatally. Conclusions: We present herein for the first time in the literature a cohort of patients with a prenatal diagnosis of WSS without ventriculomegaly in fetuses with macrocephaly. Our data show that, in the presence of normal anomaly scan and normal chromosomal study, there is a low chance for significant neurodevelopmental abnormalities in fetuses with WSS without ventriculomegaly.

Background: Areas of contrast accumulation (CA) are commonly found on routine computed tomography (CT) performed immediately after thrombectomy. In the present study, we investigated the types of CA associated with the different outcomes, including symptomatic intracranial hemorrhage (sICH)., Methods: The present study analyzed the data from 145 patients with anterior circulation stroke who had undergone non-contrast-enhanced conventional CT immediately after thrombectomy. The following variables were investigated: collateral status, failure of recanalization, Alberta stroke program early CT score (ASPECTS) applied to CA lesions and diffusion-weighted imaging infarct lesions, and sICH., Results: Of the 145 patients, 102 (70.3%) had CA lesions. All types of CA (any CA, cortical CA, subarachnoid CA, and CA ASPECTS) were significantly associated with poor outcomes (modified Rankin scale score >2). In particular, subarachnoid CA (odds ratio, 23.994; 95% confidence interval, 4.696-122.589) and CA ASPECTS (odds ratio, 0.550; 95% confidence interval, 0.404-0.750) were independently associated with sICH. Patients with subarachnoid CA had poorer collateral status and a larger final infarct size than those without subarachnoid CA, although the initial National Institutes of Health stroke scale score and recanalization rate were comparable between the 2 groups. A CA ASPECTS of ≤5 predicted sICH with a sensitivity of 66.7% and a specificity of 92.6% (area under the curve, 0.854)., Conclusions: Our data suggest that a subarachnoid CA location and CA ASPECTS are predictors of sICH. In particular, a subarachnoid location of CA might signify damage of the subarachnoid collateral arteries, leading to a larger infarct., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Percutaneous transforaminal lumbar punctures (TFLPs) offer alternative access routes to the lumbar subarachnoid cistern. Safe fluoroscopic insertion of a needle through a lumbar intervertebral foramen (IVF) should ideally avoid the exiting spinal nerve and surrounding vascular pedicles. A crescentic region in the posterior aspect of IVF is the conventional position for needle placement during TFLP, but the underlying anatomic basis for this has not been evaluated fully. To enhance TFLP safety, we defined the morphometry of normal lumbar IVFs and precise locations of neurovascular structures in the IVF posterior crescent. We retrospectively reviewed high-resolution T2-weighted lumbar spine magnetic resonance images of 40 normal adults to establish normative dimensions of each IVF from L1 to L5 bilaterally. We segmented the IVF posterior crescent into three parts, and within each, measured the areas occupied by neurovascular structures. We statistically correlated the presence or absence of neurovascular structures in each crescent segment using a chi-square test. The mean morphometrics for all 304 IVFs in 10 males and 30 females of similar ages were: area 115.3 ± 29.5 mm 2 ; height 18.0 ± 2.4 mm; and width at mid-disc level 5.6 ± 2.1 mm. We found a significant association between crescent segment and presence or absence of neurovascular structures (χ 2 = 95.9, p < .001). A post-hoc calculation of adjusted standardized residuals identified a significant association between the middle crescent segment and absence of neurovascular structures. Thus, the middle segment of the IVF posterior crescent is significantly most devoid of neurovascular structures, and more often would be the safest target for needle placement during TFLP., (© 2019 Wiley Periodicals, Inc.)

We report an unusual case of a young male patient who presented with severe pain and swelling of his left eyelid following an air compressor tip accident. He suffered extensive facial edema accompanied by deep tissue emphysema and an elevated intraocular pressure. On noncontrast CT scan, air was detected in the intraconal and extraconal orbital compartments, and intracranially within the subarachnoid spaces as well as in the suprasellar and perimesencephalic cisterns. There were no detectable fractures. We presume that by perforating the orbital septum, Tenon's capsule, and the optic nerve sheath, air had managed to penetrate the cranium through the optic nerve subarachnoid space and into the intracranial subarachnoid space.

Objective: Syringogenesis in Chiari malformation type I (CM-I) is thought to occur secondary to impaction of the cerebellar tonsils within the foramen magnum (FM). However, the correlation between the CSF area and syringogenesis has yet to be elucidated. The authors sought to determine whether the diminution in subarachnoid space is associated with syringogenesis. Further, the authors sought to determine if syrinx resolution was associated with the degree of expansion of subarachnoid spaces after surgery., Methods: The authors performed a retrospective review of all patients undergoing posterior fossa decompression for CM-I from 2004 to 2016 at the University of Virginia Health System. The subarachnoid spaces at the FM and at the level of the most severe stenosis were measured before and after surgery by manual delineation of the canal and neural tissue area on MRI and verified through automated CSF intensity measurements. Imaging and clinical outcomes were then compared., Results: Of 68 patients, 26 had a syrinx at presentation. Syrinx patients had significantly less subarachnoid space at the FM (13% vs 19%, p = 0.0070) compared to those without syrinx. Following matching based on degree of tonsillar herniation and age, the subarachnoid space was significantly smaller in patients with a syrinx (12% vs 19%, p = 0.0015). Syrinx resolution was associated with an increase in patients' subarachnoid space after surgery compared with those patients without resolution (23% vs 10%, p = 0.0323)., Conclusions: Syrinx development in CM-I patients is correlated with the degree to which the subarachnoid CSF spaces are diminished at the cranial outlet. Successful syrinx reduction is associated with the degree to which the subarachnoid spaces are increased following surgery.