Dimensions of Arachnoid Bulk Ratio: A Superior Optic Nerve Sheath Index for Intracranial Pressure.

Background Discrepancies in the literature regarding optimal optic nerve sheath diameter (ONSD) cutoffs for intracranial pressure (ICP) necessitate alternative neuroimaging parameters to improve clinical management. Purpose To evaluate the diagnostic accuracy of the dimensions of the perineural subarachnoid space to the optic nerve sheath ratio, measured using US, in predicting increased ICP. Materials and Methods In a prospective cohort study from April 2022 to December 2023, patients with suspected increased ICP underwent optic nerve US to determine the dimensions of arachnoid bulk (DAB) ratio and ONSD before invasive ICP measurement. Correlation between the parameters and ICP, as well as diagnostic accuracy, was assessed using area under the receiver operating characteristic curve (AUC) analysis. Results A total of 30 participants were included (mean age, 39 years ± 14 [SD]; 24 female). The DAB ratio and ONSD were significantly larger in participants with increased ICP (38% [0.16 of 0.42] and 14% [0.82 of 6.04 mm], respectively; P < .001). The DAB ratio showed a stronger correlation with ICP than ONSD (rs = 0.87 [P < .001] vs rs = 0.61 [P < .001]). The DAB ratio and ONSD optimal cutoffs for increased ICP were 0.5 and 6.5 mm, respectively, and the ratio had higher sensitivity (100% vs 92%) and specificity (94% vs 83%) compared with ONSD. Moreover, the DAB ratio better predicted increased ICP than ONSD, with a higher AUC (0.98 [95% CI: 0.95, 1.00] vs 0.86 [95% CI: 0.71, 0.95], P = .047). Conclusion An imaging ratio was proposed to predict ICP based on the relative anatomy of the cerebrospinal fluid space, demonstrating more accurate diagnosis of increased ICP and a strong correlation with ICP values, suggesting its potential utility as a neuroimaging marker in clinical settings. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Shepherd in this issue.

Arachnoid granulations in idiopathic intracranial hypertension: Do they have an influence?

OBJECTIVE: The aim of this study was to investigate whether the relative narrowing of the dural venous sinuses by arachnoid granulations (AGs) is more pronounced in patients with idiopathic intracranial hypertension (IIH) compared to healthy controls. BACKGROUND: IIH is characterized by increased intracranial pressure, which is associated with symptoms such as headache and visual disturbances. The role of cerebral venous drainage obstruction in IIH is the subject of ongoing research. MATERIALS AND METHODS: In this retrospective case-control study, 3D contrast-enhanced magnetic resonance images of a cohort of 43 patients with IIH were evaluated for (1) the number of AGs per venous sinus and (2) the diameters of the dural venous sinuses at the site of an AG and at standardized measurement points. In addition, the minimum width of the transverse/sigmoid sinus was measured. All data were compared to the same data from a cohort of 43 control participants. RESULTS: Patients with IIH showed less relative sinus narrowing by AG compared to controls (median: 7%, interquartile range [IQR] 10% vs. 11%, IQR 9% in controls; p = 0.009). In patients with IIH, sinus diameter was larger at the site of an AG (70 ± 25 mm2) compared to its diameter at the standardized measurement point (48 ± 23 mm2; p = 0.010). In the superior sagittal sinus (SSS), patients with IIH had smaller AGs (median: 3 mm2, IQR 2 mm2 vs. 5 mm2, IQR 3 mm2 in controls; p = 0.023) while the respective sinus segment was larger (median: 69 mm2; IQR 21 mm2 vs. 52 mm2, IQR 26 mm2 in controls; p = 0.002). The right transverse sinus was narrower in patients with IIH (41 ± 21 mm vs. 57 ± 20 mm in controls; p < 0.001). CONCLUSIONS: In contrast to our hypothesis, patients with IIH showed less pronounced relative sinus narrowing by AG compared to controls, especially within the SSS, where AGs were smaller and the corresponding sinus segment wider. Smaller AGs could result in lower cerebrospinal fluid resorption, favoring the development of IIH. Conversely, the smaller AGs could also be a consequence of IIH due to backpressure in the SSS because of the narrower transverse/sigmoid sinus, which widens the SSS and compresses the AG.

Predicting the presence of 4th ventricular outlet obstruction in Chiari I Malformation.

INTRODUCTION: A subset of children with Chiari 1 malformation (CM-1) have a 4th ventricle arachnoid veil-a thin membrane covering the outlet of the 4th ventricle. Studies suggest that failure to disrupt this veil during posterior fossa decompression can reduce the likelihood of syringomyelia resolution. However, there is no reliable method for predicting the presence of the veil without direct surgical exploration. This study aims to evaluate the association between pre-operative symptoms, radiographic measurements, and the arachnoid veil. METHODS: A retrospective review of an institutional database of children evaluated for CM-I was conducted. For patients treated with surgery, operative notes were reviewed to determine if an arachnoid veil was present. Logistic regression was used to test for relationship of clinical variables and radiographic measurements with the presence of an arachnoid veil. RESULTS: Out of 997 children with CM-1, 226 surgical patients were included in the analysis after excluding those with inadequate documentation. An arachnoid veil was found in 23 patients (10.2%). Larger syrinx, spinal canal, and thecal sac diameters were significantly associated with the presence of a veil, with odds ratios of 1.23 (95% CI 1.2-1.48; p = 0.03), 1.27 (95% CI 1.02-1.59; p = 0.03), and 1.35 (95% CI 1.03-1.77; p = 0.03), respectively. No significant associations were found with any signs or symptoms. CONCLUSIONS: Arachnoid veil was present in 10% of cases. Radiographic measurements indicating larger syrinx size were the only variables found to be significantly associated with an arachnoid veil. Exploration of the 4th ventricular outlet is recommended for CM-I decompression in the setting of expansile syringomyelia.

Description and clinical relevance of the variable conformation of canine spinal arachnoid diverticula.

The conformation of spinal arachnoid diverticula (SAD) and their clinical implications are poorly characterized in dogs. This retrospective cross-sectional study describes different SAD conformations in dogs and aims to identify if there is an association between SAD conformation and clinical features, localization, syringomyelia (SM) presence, concurrent vertebral condition, treatment option, and short as well as long-term outcome. Sixty-two dogs were included (12 cervical and 50 thoracolumbar SAD). All dogs with a cervical SAD had a cranial tethered conformation and were not included in the statistical analysis. Half of the dogs with a thoracolumbar SAD were cranial tethered, and the other half were caudal tethered. SM associated with SAD had a moderate prevalence in the cervical region (58.3%) and a high prevalence in the thoracolumbar region (82%). All dogs with the presence of SM and caudal tethered SAD had a cranial positioned SM, and all dogs with SM and a cranial tethered SAD had a caudal positioned SM. The SM absolute length and SM length/L2 ratio were significantly higher (P = .018, respectively) in the caudal tethered SAD compared with the cranial tethered SAD. The short-term outcome was statistically different (P = .045) between caudal and cranial tethered thoracolumbar SAD, but not the long-term outcome (P = .062). Multivariable logistic regression identified thoracolumbar caudal tethered SAD conformation had a better short-term outcome (P = 0.017, OR: 0.043, CI: 0.003-0.563), independently of SM length measurements. SAD conformation in dogs can influence SM formation. A possible link between short-term outcome and SAD conformation was found, but further research is warranted.

Brain herniation (encephalocele) into arachnoid granulations: prevalence and association with pulsatile tinnitus and idiopathic intracranial hypertension.

PURPOSE: Brain herniation into arachnoid granulations (BHAG) of the dural venous sinuses is a recently described finding of uncertain etiology. The purpose of this study was to investigate the prevalence of BHAG in a cohort of patients with pulsatile tinnitus (PT) and to clarify the physiologic and clinical implications of these lesions. METHODS: The imaging and charts of consecutive PT patients were retrospectively reviewed. All patients were examined with MRI including pre- and post-contrast T1- and T2-weighted sequences. Images were reviewed separately by three blinded neuroradiologists to identify the presence of BHAG. Their location, signal intensity, size, presence of arachnoid granulation, and associated dural venous sinus stenosis were documented. Clinical records were further reviewed for idiopathic intracranial hypertension, history of prior lumbar puncture, and opening pressure. RESULTS: Two hundred sixty-two consecutive PT patients over a 4-year period met inclusion criteria. PT patients with BHAG were significantly more likely to have idiopathic intracranial hypertension than PT patients without BHAG (OR 4.2, CI 1.5-12, p = 0.006). Sixteen out of 262 (6%) patients were found to have 18 BHAG. Eleven out of 16 (69%) patients had unilateral temporal or occipital lobe herniations located in the transverse sinus or the transverse-sigmoid junction. Three out of 16 (19%) patients had unilateral cerebellar herniations and 2/16 (13%) patients had bilateral BHAG. CONCLUSION: In patients with PT, BHAG is a prevalent MRI finding that is strongly associated with the clinical diagnosis of IIH. The pathogenesis of BHAG remains uncertain, but recognition should prompt comprehensive evaluation for IIH.

Tissue damage in herniated brain parenchyma into giant arachnoid granulations: demonstration with high resolution MRI.

BACKGROUND: Brain herniation (BH) into arachnoid granulation has been remarkable in recent years. PURPOSE: To evaluate the damage in herniated parenchyma into the giant arachnoid granulation (GAG) and to investigate the clinical-demographic importance of this damage. MATERIAL AND METHODS: Patients with BH into GAG were retrospectively included in the study. Each of the patients had at least one high-resolution 3D magnetic resonance imaging (MRI) sequence. The arachnoid granulation dimensions, locations, and origin of herniated parenchyma were evaluated by two experienced radiologists. The demographic and symptomatic features of the patients were recorded from the hospital database. RESULTS: A total of 27 patients (21 females, 6 males; age range 6-71 years; mean age 41.3 years) were found to contain BH into GAG. It was most commonly seen in the transverse sinus (67%); the origin was most common in the cerebellar parenchyma (56%). Abnormal signal and morphology were detected in herniated parenchyma in 11 (47%) patients, atrophy in six, and atrophy and gliosis in five. The most common complaints were headache (47%), while other frequent symptoms were vertigo (15%) and blurred vision (11%). There was a statistically significant positive correlation between frequency of damage in herniated brain parenchyma and the maximal size of GAG (P<0.05). CONCLUSION: In patients with BH into GAG, parenchymal damage may be associated with various symptoms, such as headache and vertigo, although they have not been statistically proven. It is important to carefully evaluate hernia tissue, as the risk of tissue damage may increase in larger GAGs.

Changes of arachnoid granulations after subarachnoid hemorrhage in cynomolgus monkeys.

This research explores ultrastructural changes of arachnoid granulations associated with hydrocephalus after subarachnoid hemorrhage in cynomolgus monkeys. It provides a theoretical basis for further study of the etiology and prevention of hydrocephalus. Female cynomolgus monkeys about one-year-old were selected. The position range of arachnoid granulations in superior sagittal sinus and transverse sinus was determined in a randomly selected control monkey. The morphology of normal arachnoid granulations in cynomolgus monkeys was observed under a transmission electron microscope. A primate model of subarachnoid hemorrhage was established by injecting autologous blood into cisterna magna. Vomiting, movement disorder, and reduced level of consciousness were gradually observed in monkeys. Computed tomography and magnetic resonance imaging scan results confirmed subarachnoid hemorrhage and hydrocephalus, and the morphology of arachnoid granulations in hydrocephalus was observed under a transmission electron microscope. Extensive fibrosis of arachnoid granulations was observed under a transmission electron microscope in cynomolgus monkeys with hydrocephalus after subarachnoid hemorrhage.

Utility of True Fast Imaging with Steady-State Precession in Detecting Arachnoid Veils of the Posterior Fossa.

INTRODUCTION: Arachnoid membranes are well recognized as a cause of cerebrospinal fluid (CSF) flow impairment in disorders such as obstructive hydrocephalus and syringohydromyelia, but can be difficult to detect with standard noninvasive imaging techniques. True fast imaging with steady-state precession (TrueFISP) can exhibit brain pulsations and CSF dynamics with high spatiotemporal resolution. Here, we demonstrate the utility of this technique in the diagnosis and management of arachnoid membranes in the posterior fossa. CASE PRESENTATIONS: Three symptomatic children underwent cine TrueFISP imaging for suspicion of CSF membranous obstruction. Whereas standard imaging failed to or did not clearly visualize the site of an obstructive lesion, preoperative TrueFISP identified a membrane in all 3 cases. The membranes were confirmed intraoperatively, and postoperative TrueFISP helped verify adequate marsupialization and recommunication of CSF flow. Two out of the 3 cases showed a decrease in cerebellar tonsillar pulsatility following surgery. All children showed symptomatic improvement. CONCLUSION: TrueFISP is able to detect pulsatile arachnoid membranes responsible for CSF outflow obstruction that are otherwise difficult to visualize using standard imaging techniques. We advocate use of this technology in pre- and postsurgical decision-making as it provides a more representative image of posterior fossa pathology and contributes to our understanding of CSF flow dynamics. There is potential to use this technology to establish prognostic biomarkers for disorders of CSF hydrodynamics.

Arachnoid granulations bulging into the transverse sinus, sigmoid sinus, straight sinus, and confluens sinuum: a magnetic resonance imaging study.

PURPOSE: Few studies have explored arachnoid granulations (AGs) bulging into the cranial dural sinuses using contrast-enhanced magnetic resonance imaging (MRI). This study aimed to explore such AGs in the transverse (TS), sigmoid (SigS), and straight (StS) sinuses, and confluens sinuum (ConfS) using thin-sliced, contrast MRI. METHODS: A total of 102 patients with intact dural sinuses underwent thin-sliced, contrast MRI in the axial, coronal, and sagittal planes. RESULTS: In 88.2%, more than one AG was identified in the TS and SigS, StS, and ConfS. In the TS, AGs were identified in 40.2% on the right side and 37.3% on the left and were frequently located in the middle and lateral thirds. In the SigS, AGs were identified on the right in 17.6% and on the left in 18.6% in the distal region. In the StS, AGs were identified in 35.3% of cases, most frequently located in the proximal third, followed by the distal third. In the ConfS, AGs were identified in 20.6% of cases. Furthermore, in 23.5%, a collection of multiple AGs of varying sizes was found in the TS. A statistical difference was not shown between the mean age of 90 patients with AGs and that of 12 patients without identifiable AGs. CONCLUSIONS: Bulging AGs may more frequently found in the TS. Thin-sliced, contrast MRI is useful for delineating AGs.

Spatial distribution of human arachnoid trabeculae.

Traumatic brain injury (TBI) is a common injury modality affecting a diverse patient population. Axonal injury occurs when the brain experiences excessive deformation as a result of head impact. Previous studies have shown that the arachnoid trabeculae (AT) in the subarachnoid space significantly influence the magnitude and distribution of brain deformation during impact. However, the quantity and spatial distribution of cranial AT in humans is unknown. Quantification of these microstructural features will improve understanding of force transfer during TBI, and may be a valuable dataset for microneurosurgical procedures. In this study, we quantify the spatial distribution of cranial AT in seven post-mortem human subjects. Optical coherence tomography (OCT) was used to conduct in situ imaging of AT microstructure across the surface of the human brain. OCT images were segmented to quantify the relative amounts of trabecular structures through a volume fraction (VF) measurement. The average VF for each brain ranged from 22.0% to 29.2%. Across all brains, there was a positive spatial correlation, with VF significantly greater by 12% near the superior aspect of the brain (p < .005), and significantly greater by 5%-10% in the frontal lobes (p < .005). These findings suggest that the distribution of AT between the brain and skull is heterogeneous, region-dependent, and likely contributes to brain deformation patterns. This study is the first to image and quantify human AT across the cerebrum and identify region-dependencies. Incorporation of this spatial heterogeneity may improve the accuracy of computational models of human TBI and enhance understanding of brain dynamics.

The Role of Arachnoid Granulations and the Glymphatic System in the Pathophysiology of Idiopathic Intracranial Hypertension.

PURPOSE OF REVIEW: Idiopathic intracranial hypertension (IIH) is a disorder characterized by long-standing elevated intracranial pressure (ICP). As the name applies, no uniform cause has been identified. IIH is typically characterized by headaches, pulsatile tinnitus, and visual deterioration. RECENT FINDINGS: Anomalies in cerebrospinal fluid (CSF) absorption are implicated in the pathophysiology of IIH. Non-invasive imaging of the brain parenchyma and the cerebral venous sinus has improved, and research has gained a better understanding of the role of cerebral venous sinus stenosis. Both have led to a better delineation of the role of arachnoid granulations (AG) and the glymphatic system in the development of IIH. IIH may occur as a result of restrictions of CSF absorption from the venous system, and or the congestion and overflow of the glymphatic system. Elucidating these mechanisms will lead to greater understanding of its underlying pathophysiologic mechanisms.

Syringomyelia caused by an arachnoid web in a patient with shunted Dandy-Walker malformation.

INTRODUCTION: Dandy-Walker malformation (DWM) is a congenital brain anomaly characterized by dysgenesis of the cerebellar vermis and the presence of a posterior fossa cyst. The association of syringomyelia with DWM is extremely rare. CASE REPORT: A 10-year-old patient who was diagnosed with DWM in infancy presented with progressive scoliosis and fecal incontinence. He had been treated with cystoventriculoperitoneal shunting with a Y-connection during infancy, which was followed by a revision 6 years later. During the revision surgery, intraventricular bleeding occurred and was managed conservatively. Imaging studies for the current visit revealed syringomyelia along the cervicothoracic spinal cord and a membranous structure around the cervicomedullary junction. Phase-contrast cine magnetic resonance imaging (MRI) revealed disturbed cerebrospinal fluid (CSF) flow across the membrane. We excised the arachnoid web that was tethering the brainstem and blocking CSF flow. Postoperatively, the patient experienced symptom relief, and the follow-up imaging study demonstrated a dramatic decrease in the size of the syringomyelia. DISCUSSION: We suggest that syrinx formation in this patient was possibly caused by disturbed CSF flow and tethering of the brainstem. CONCLUSION: We experienced an unusual case of DWM with syringomyelia which was caused by an arachnoid web blocking CSF flow and tethering the brainstem. The arachnoid web seems to be formed by previous bleeding which occurred at the time of shunt revision. After excision of the arachnoid web, the patient showed good outcome.

Altered cerebrospinal fluid dynamics in neurofibromatosis type l: severe arachnoid thickening in patients with neurofibromatosis type 1 may cause abnormal CSF dynamic.

INTRODUCTION: The object of this study is to understand abnormal dynamic of cerebrospinal fluid (CSF) in patients with neurofibromatosis type 1 (NF1), which may cause temporal lobe herniation and bulging of temporal fossa. METHODS: Four patients, three females and one male, with NF1 were studied retrospectively. They presented with a similar craniofacial deformity, which consisted of pulsatile exophthalmos, an enlarged bony orbit, dysplasia of the sphenoid wing with the presence of a herniation of the temporal lobe into the orbit, and a bulging temporal fossa. RESULTS AND DISCUSSION: Surgical exploration demonstrated abnormally thickened arachnoid membrane in one case. Protruding temporal lobe, which was one of the main symptoms in NF1 patients, could be stopped by control of intracranial pressure (ICP) via programmable ventriculoperitoneal shunt (VPS) or extra ventricle drainage implantation. The dense fibrosis of the arachnoid membrane and consequent altered hemispheric CSF dynamics may cause symptoms including pulsatile exophthalmos and consequent worsening of vision, prolapse of the temporal lobe, and enlargement of the temporal fossa. This finding may not present with general features of hydrocephalus, so that delays in diagnosis often result. CONCLUSION: For the NF1 patients with cranio-orbito-temporal deformities, prior to any surgical reconstruction, control of increased ICP (IICP) should be primarily considered.

Pile driving into the skull and suspending the bridging veins? An undescribed role of arachnoid granulations.

PURPOSE: Arachnoid granulations (AGs) occasionally appear to protrude into the calvarial convexity, lying close to the bridging veins (BVs). This study aims to characterize such AGs and BVs using magnetic resonance imaging (MRI). METHODS: Ninety-five patients were enrolled in this study. Initially, stepwise frontal craniotomy was performed in an injected cadaver head. Next, examinations with contrast MRI were performed involving the whole cranial vault. RESULTS: In cadaveric dissection, the AGs located in the parasagittal regions appeared as outward protrusions through the dura mater and in contact with the diploic veins. Forming tent-shaped sleeves, these AGs and the continuous arachnoid membranes suspended the BVs coursing just below. A total of 237 AGs were identified on contrast MRI that protruded into the skull, lying close to the BVs. Among them, 78 % were located in parasagittal regions as AG-BV pairs. These pairs were most frequently found in the middle third of the calvarial hemisphere, followed by the anterior and posterior thirds. In 34 %, the BV segments were lodged in the AGs. CONCLUSIONS: Some AGs located in the parasagittal regions and cerebral convexity pass through the dura mater and pile drive into the skull, which contribute to forming hanging-type arachnoid sleeves suspending the BVs. These structures may underpin the predisposition of BVs to injury following mechanical impacts.

Brain herniations into arachnoid granulations: about 68 cases in 38 patients and review of the literature.

INTRODUCTION: Brain herniations (BH) into arachnoid granulations (AG) in dural venous sinuses and calvarium have rarely been reported in the literature. METHODS: MRIs of 38 patients with BH into AG (BHAG) were retrospectively analyzed. Locations of BHAG, gyrus/lobe of the herniated brain, parenchymal abnormalities of the BH, and clinical and radiological conditions with raised intracranial pressure were recorded. RESULTS: Sixty-eight BHAG were found, by order of frequency, in the occipital squama (OS), transverse sinus (TS), lateral lacuna of the superior sagittal sinus (LLSSS), and straight sinus (SS), with cerebellar tissue being the most frequently involved in BHAG (94.5 % of OS, 55 % of TS, 100 % SS BHAG). Multiple BHAG were found in 58 % of the patients (up to five per patient). Parenchymal signal and structural changes (SSCG) were observed in 46 % of BHAG (100 % were cerebellar). Three patients had pseudotumor cerebri (PTCS); one patient had only MRI signs of PTCS. Twenty-one percent of patients had intracranial conditions susceptible of increasing cerebrospinal fluid (CSF) pressure other than PTCS. CONCLUSIONS: BHAG occurred in the OS, TS, LLSSS, and the SS. SSCG of the herniated cerebellum were frequent and possibly result from tethering/strangulation in the AG. No symptoms could be clearly attributed to BHAG, though in three cases of PTCS, TS BHAG could have contributed to sustaining the raised CSF pressure. Various factors are probably involved in the development of BHAG including normal pia-arachnoid bridges between the brain surface and the AG, hydrodynamic constrains on the brain and AG, and, in some cases, increased intracranial pressure.

Assessment of Liliequist membrane by 3D-SPACE technique at 3 T.

INTRODUCTION: Liliequist membrane (LM) is the most important anatomic structure for the success of endoscopic third ventriculostomy (ETV). Identification of this membrane is difficult with conventional MRI techniques. The purpose of this retrospective study is to determine the impact of three-dimensional sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) sequence with variant flip-angle mode (VFAM) in the assessment of LM at 3-T MRI devices. METHODS: 3D-SPACE with VFAM images were obtained in 445 patients. LM visibility and integrity were scored as 0 (good), 1 (moderate), and 2 (poor) on these images for each parts (sellar, diencephalic, and mesencephalic) and overall of the membrane. RESULTS: According to the LM overall integrity scores, 11 % (48 cases) of the patients had perforated membrane. According to subsegmental integrity scores, sellar part was completely intact in 63 % of patients, diencephalic segment was completely intact in 60 % of the patients, and mesencephalic segment was completely intact in 95 % of the patients. Visibility scores of the third ventricle inferior wall were significantly higher in the patients with intact LM (p = 0.001). There was not any statistically significant relationship between LM pattern and overall integrity (p = 0.352). LM attachment sites could be detected easier in the patients who had better visibility of third ventricle inferior wall or intact LM (p < 0.001 for both). CONCLUSION: 3D-SPACE technique is a useful alternative for the evaluation of morphology, integrity, individual variations, topographic relationships, and visibility of LM since it has some advantages including lower SAR values, fewer artifacts, and high-resolution images.

Imaging characteristics of cervical spine extra-arachnoid fluid collections managed conservatively.

OBJECTIVE: Determine the MRI characteristics of large post-traumatic cervical spine extra-arachnoid collections managed conservatively in clinically stable patients and whether evidence of clinical or imaging deterioration materialized. MATERIALS AND METHODS: Following IRB approval, we conducted a retrospective search for all patients (>16 years old) over a 17-months period who had an extra-arachnoid fluid collection reported on a post-traumatic cervical spine MRI. Patients were excluded if they had surgery for an unstable fracture (n = 21), emergent decompression (n = 1) or lacked a follow-up MRI within 15 days (n = 1). Two MSK radiologists recorded the size, morphology and MRI signal characteristics of the collections. RESULTS: Eight patients (5 male, 3 female) met the inclusion criteria (mean age 40 years; range 19-78 years). Seven of the eight patients had fluid collections that demonstrated thin, tapered margins, extended >7 vertebral bodies and involved >180 degrees of the spinal canal. The signal characteristics of these collections varied: hyper-T1/iso-T2 (n = 1), iso-T1/T2 (n = 3), hyper-T1/hypo-T2 (n = 3) and mixed-T1/T2 (n = 1). Six of seven collections were ventral. Follow-up MRI demonstrated resolution/significant decrease in size (n = 4 between 1 and 12 days) or no change/slight decrease in size (n = 3; between 2 and 11 days). None of the seven fluid collections enlarged, no patient had abnormal cord signal, and no patient's neurologic symptoms worsened. One of eight patients had a dorsal "mass-like" collection that was slightly smaller 9 days later. CONCLUSION: In stable patients with large, tapered post-traumatic cervical spine extra-arachnoid collections managed non-surgically, none developed (1) clinical worsening, (2) abnormal cord signal or (3) collection enlargement, regardless of the collection's signal characteristics.

Value of systematic analysis of the olfactory cleft in case of cerebrospinal rhinorrhea: incidence of olfactory arachnoid dilatation.

To report on the presence of olfactory arachnoid dilatations (OAD), a previously undescribed radiologic feature of spontaneous cerebrospinal fluid (CSF) rhinorrhea originating from the cribriform plate of the ethmoid bone. The medical records of all patients treated between 2001 and 2011 at a tertiary care center for a spontaneous CSF rhinorrhea originating from the cribriform plate were retrospectively reviewed. The radiological work-up included high-resolution computed tomography and magnetic resonance imaging with at least the following sequences: T1, T2, and T2 with fast imaging employing steady state acquisition (FIESTA). Thirty cases were identified. The mean age at diagnosis was 49. Fourteen patients (47 %) had a body mass index (BMI) of 30 or more and 3 patients (10 %) had a BMI between 25 and 29.9. Five patients had a history of meningitis. The imaging work-up revealed a bone defect of the cribriform plate in 6 cases (20 %), associated to a typical meningocele in 14 cases (47 %). In ten patients (33 %), there was no defect of the cribriform plate, but ultrathin coronal T2-FIESTA sequences revealed an OAD, i.e. a dilatation of the arachnoid sheath of the olfactory fibers, in nine cases (30 %), or a "pseudo-polyp" outlined by a thin layer of arachnoid (1 patient, 3 %). Preoperative imaging should be carefully analyzed for the presence of OAD or "pseudo-polyp" in patients presenting with a CSF rhinorrhea without bony defect of the cribriform plate.

Leptomeningeal collaterals are associated with modifiable metabolic risk factors.

OBJECTIVE: We sought to identify potentially modifiable determinants associated with variability in leptomeningeal collateral status in patients with acute ischemic stroke. METHODS: Data are from the Keimyung Stroke Registry. Consecutive patients with M1 segment middle cerebral artery ± intracranial internal carotid artery occlusions on baseline computed tomographic angiography (CTA) from May 2004 to July 2009 were included. Baseline and follow-up imaging was analyzed blinded to all clinical information. Two raters assessed leptomeningeal collaterals on baseline CTA by consensus, using a previously validated regional leptomeningeal score (rLMC). RESULTS: Baseline characteristics (N = 206) were: mean age = 66.9 ± 11.6 years, median baseline National Institutes of Health Stroke Scale = 14 (interquartile range [IQR] = 11-20), and median time from stroke symptom onset to CTA = 166 minutes (IQR = 96-262). Poor collateral status at baseline (rLMC score = 0-10) was seen in 73 of 206 patients (35.4%). On univariate analyses, patients with poor collateral status at baseline were older; were hypertensive; had higher white blood cell count, blood glucose, D-dimer, and serum uric acid levels; and were more likely to have metabolic syndrome. Multivariate modeling identified metabolic syndrome (odds ratio [OR] = 3.22, 95% confidence interval [CI] = 1.69-6.15, p < 0.001), hyperuricemia (per 1mg/dl serum uric acid; OR = 1.35, 95% CI = 1.12-1.62, p < 0.01), and older age (per 10 years; OR = 1.34, 95% CI = 1.02-1.77, p = 0.03) as independent predictors of poor leptomeningeal collateral status at baseline. INTERPRETATION: Metabolic syndrome, hyperuricemia, and age are associated with poor leptomeningeal collateral status in patients with acute ischemic stroke.