Occipital Sinus-Sparing Linear Paramedian Dural Incision: A Technical Note and Case Series for Median Suboccipital Approach.

BACKGROUND: Durotomies, traditionally used during the midline suboccipital approach, involve sacrificing the occipital sinus (OS) with consequent shrinking of the dura, risk of venous complications, difficulty performing watertight closure, and a higher rate of postoperative cerebrospinal fluid (CSF) leaks. The present technical note describes the OS-sparing linear paramedian dural incision, which leads to a decrease in the risk of complications during the median suboccipital approach in our case series. METHODS: The OS-sparing linear incision technique involves a dural incision placed 1 cm lateral to the OS. The angle of view of the microscope is frequently changed to overcome the narrowed exposure of the linear durotomy. Copious irrigation with saline prevents drying of the dura. A running watertight closure of the dura is performed. The overall results of 5 cases are reviewed. RESULTS: The cases were 3 tumors and 2 cavernomas. The OS was preserved in all 5, and no duraplasty was needed. The average dura closure time was 16.8 minutes. No CSF leak occurred, and no wound complications were observed. A gross total resection of the lesion was achieved in all the patients. The mean follow-up was 10.2 months, and there were no late complications related to the dura closure. CONCLUSIONS: In comparison to the types of durotomies conventionally used for the midline suboccipital approach, the OS-sparing linear paramedian dural incision entails lower risks of bleeding, venous complications, CSF leaks, and infections by avoiding duraplasty. Validation of this technical note on a larger patient cohort is needed.

Evaluation of Long-Term Follow-Up in Ecchordosis Physaliphora versus Chordoma.

OBJECTIVE: Ecchordosis physaliphora (EP) is a non-neoplastic notochord remnant with limited literature. We present a review on surgically resected clival EP to evaluate if available follow-up is adequate to distinguish EP from chordomas. METHODS: A systematic literature review was completed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Case reports or series of adults with histopathologic and radiographic findings of surgically resected EP were included. Articles including pediatric patients, systematic reviews, chordomas, and without microscopic or radiographic confirmation, or the surgical approach, were excluded. Corresponding authors were contacted twice to further evaluate outcomes. RESULTS: Eighteen articles were included (n = 25 patients; mean age 47.5 years ± 12.6 [standard deviation] months). All patients had symptomatic, surgically resected EP, with cerebrospinal fluid leak or rhinorrhea the most common symptom (48%). All but 3 had gross total resection, with endoscopic endonasal transsphenoidal transclival the most common approach (80%). All but 3 reported immunohistochemistry findings, with physaliphorous cells the most common. All but 5 patients had definitive follow-up (80%), with average of 19.5 ± 17.2 months. One corresponding author reported longer-term follow-up for 1 patient (57 months). No recurrence or malignant transformation was reported. Mean time to clival chordoma recurrence (53.9 ± 26.8 months) was also evaluated in a review of 8 studies. CONCLUSIONS: Mean follow-up for resected EP was almost 3 times shorter than mean time to recurrence of chordomas. Available literature is likely inadequate to confirm the suspected benign nature of EP especially in reference to chordoma, precluding treatment and follow-up recommendations.

Blood-spinal cord barrier leakage is independent of motor neuron pathology in ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving progressive degeneration of upper and lower motor neurons. The pattern of lower motor neuron loss along the spinal cord follows the pattern of deposition of phosphorylated TDP-43 aggregates. The blood-spinal cord barrier (BSCB) restricts entry into the spinal cord parenchyma of blood components that can promote motor neuron degeneration, but in ALS there is evidence for barrier breakdown. Here we sought to quantify BSCB breakdown along the spinal cord axis, to determine whether BSCB breakdown displays the same patterning as motor neuron loss and TDP-43 proteinopathy. Cerebrospinal fluid hemoglobin was measured in living ALS patients (n = 87 control, n = 236 ALS) as a potential biomarker of BSCB and blood-brain barrier leakage. Cervical, thoracic, and lumbar post-mortem spinal cord tissue (n = 5 control, n = 13 ALS) were then immunolabelled and semi-automated imaging and analysis performed to quantify hemoglobin leakage, lower motor neuron loss, and phosphorylated TDP-43 inclusion load. Hemoglobin leakage was observed along the whole ALS spinal cord axis and was most severe in the dorsal gray and white matter in the thoracic spinal cord. In contrast, motor neuron loss and TDP-43 proteinopathy were seen at all three levels of the ALS spinal cord, with most abundant TDP-43 deposition in the anterior gray matter of the cervical and lumbar cord. Our data show that leakage of the BSCB occurs during life, but at end-stage disease the regions with most severe BSCB damage are not those where TDP-43 accumulation is most abundant. This suggests BSCB leakage and TDP-43 pathology are independent pathologies in ALS.

[Definitions and MR imaging of duropathies].

Kumar defined duropathies as disorders with dural defects-related cerebrospinal fluid leaks, particularly of spinal anterior dura mater, Superficial (hemo) siderosis (SS) and multisegemental amyotrophy (MSAM) were included in duropathies. Dural defects of SS had two types; one was incomplete closure of the dura in the spinal and cranial operations, the other was a spontaneous defect in the spinal anterior dura mater. In a majority of SS patients, spontaneous dural defects were detected at the levels of C7/Th1 to Th2/Th3 on axial FIESTA (fast imaging employing steady state acquisition) images. Similarly, dural defects in our 6 cases with MSAM were showed at C7/Th1 to Th2/Th3. Axial FIESTA images were crucial on MR imaging. T2 weighted images demonstrated abnormal hyperintense lesions in both anterior horns at the level of C3 spinal cord in all of 7 patients with MSAM. A dural defect in one case was not found.

Chronic Aspiration Pneumonitis Caused by Spontaneous Cerebrospinal Fluid Fistulae of the Skull Base.

OBJECTIVES/HYPOTHESIS: Spontaneous cerebrospinal fluid (CSF) leaks of the skull base are associated with obesity, multiparity, and elevated intracranial pressure. Although spontaneous CSF leaks often present with rhinorrhea, they can be an underdiagnosed cause of chronic aspiration pneumonitis, a complication that has not been previously reported in detail. STUDY DESIGN: Retrospective case series. METHODS: The authors retrospectively reviewed all patients undergoing surgical repair of CSF fistulae at the University of Southern California between 2011 and 2018 to identify those presenting with pulmonary symptoms including dyspnea, aspiration, chronic cough, and shortness of breath caused by chronic noniatrogenic CSF pneumonitis. RESULTS: Symptomatic chronic pneumonitis was evident in six of 20 patients with spontaneous CSF rhinorrhea. Five women (mean body mass index = 36) had CSF leaks arising from the fovea ethmoidalis (n = 4) and lateral sphenoid region (n = 1). One man had a middle fossa floor dehiscence draining through the eustachian tube. All patients had bilateral ground-glass opacities in their lungs on computed tomography imaging that were attributed to spontaneous CSF fistulae arising from noniatrogenic skull base defects, and one patient underwent a biopsy of a lung lesion at another hospital showing chronic bronchiolitis and adjacent peribronchiolar metaplasia. Five patients underwent endoscopic endonasal repair using an autologous fascial graft and pedicled nasoseptal flap, and one underwent craniotomy for repair. All patients underwent successful repair with no complications or evidence of recurrence. Upon repair of the spontaneous CSF leaks, both pneumonitis symptoms and ground-glass opacities on imaging resolved in all six cases. CONCLUSIONS: Skull base CSF fistulae should be considered as a reversible cause of chronic pneumonitis that is not alleviated or worsens with standard treatment. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:462-466, 2021.

Calvarium Thinning in Patients with Spontaneous Cerebrospinal Fluid Leaks of the Anterior Skull Base.

OBJECTIVES/HYPOTHESIS: Patients with spontaneous cerebrospinal fluid leaks (sCSF-L) of the temporal bone have isolated calvarial and skull base thinning that is independent of obesity. This study determines if anterior skull base (ASB) sCSF-L patients also have calvarial thinning. STUDY DESIGN: Retrospective Cohort Study. METHODS: This was a retrospective cohort study of ASB sCSF-L patients compared to nonobese (body mass index [BMI] < 30 kg/m2 ) and obese (BMI ≥ 30) control groups. Twenty-one patients in the ASB sCSF-L group and 25 patients in each control group were included. Calvarium and extracranial zygoma thicknesses were measured bilaterally with blinded, standardized, volumetric analysis. RESULTS: ASB sCSF-L patients had a mean (SD) age of 50.43 (10.19) years, an average (SD) BMI of 38.81 (8.92) kg/m2 , and most were female (85.71%). The calvarium in patients with ASB sCSF-L was significantly thinner than the nonobese (2.55 mm [0.77] vs. 2.97 [0.67] mm; P = .006; 95% confidence intervals [CI], 0.12-0.30; Cohen d, 0.58) and obese control groups (2.55 [0.77] vs. 2.92 [0.76] mm; P = .02; 95% CI, 0.05-0.34; Cohen d, 0.66). The calvarium thickness of the nonobese patients was not significantly different from the obese patient controls (2.97 [0.67] vs. 2.92 [0.76] mm, P = .9). The extracranial zygoma was not significantly different among the groups (analysis of variance, P = .33). CONCLUSIONS: ASB sCSF-L patients have isolated calvarial thinning that is independent of obesity. Like lateral skull base sCSF-L patients, these data suggest that the additional obesity-associated intracranial process contributes to skull thinning. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:1271-1276, 2021.

Incidental spontaneous CSF fistula with pterygoid process meningoencephalocele.

Spontaneous cerebrospinal fluid (CSF) fistula is a rare entity, most commonly occurs at the ethmoid roof, cribriform plate, or the sphenoid sinus; at the perisella, inferolateral or pterygoid recesses. Imaging plays a major role in diagnosis, thereby guiding the treatment of a spontaneous CSF fistula, evolving multiple modalities. We report a case of a patient with spontaneous Meningio-encephalocele presented as an expansile lytic lesion in the left pterygoid body, this patient was successfully treated surgically.

Blood-brain barrier impairment and hypoperfusion are linked in cerebral small vessel disease.

OBJECTIVE: To investigate the link between blood-brain-barrier (BBB) permeability and cerebral blood flow (CBF) and the relation with white matter hyperintensities (WMH) in cerebral small vessel disease (cSVD). METHODS: Twenty-seven patients with cSVD received dynamic susceptibility contrast and dynamic contrast-enhanced MRI to determine CBF and BBB permeability (expressed as leakage rate and volume), respectively. Structural MRI were segmented into normal-appearing white matter (NAWM) and WMH, for which a perilesional zone was defined. In these regions, we investigated the BBB permeability, CBF, and their relation using Pearson correlation r. RESULTS: We found a decrease in CBF of 2.2 mL/min/100 g (p < 0.01) and an increase in leakage volume of 0.7% (p < 0.01) per mm closer to the WMH in the perilesional zones. Lower CBF values correlated with higher leakage measures in the NAWM and WMH (-0.53 < r < -0.40, p < 0.05). This relation was also observed in the perilesional zones, which became stronger in the proximity of WMH (p = 0.03). CONCLUSION: BBB impairment and hypoperfusion appear in the WMH and NAWM, which increase in the proximity of the WMH, and are linked. Both BBB and CBF are regulated in the neurovascular unit (NVU) and the observed link might be due to the physiologic regulation mechanism of the NVU. This link may suggest an early overall deterioration of this unit.

Ventral longitudinal intraspinal fluid collection: Rare presentation as brachial amyotrophy and intracranial hypotension.

CONTEXT: Ventral longitudinal intraspinal fluid collection (VLISFC) presenting as hand amyotrophy has been described only in a few cases and there are no reports on associated intracranial CSF hypovolemia (ICH). We describe the clinical and imaging findings of a case with combined brachial amyotrophy and ICH secondary to VLISFC. FINDINGS: A 31 year old man presented with severe positional neck discomfort, radiating pain, progressive asymmetrical wasting and weakness of distal upper limbs. Contrast Magnetic Resonance Imaging (MRI) of the spine demonstrated a ventral extradural intraspinal fluid collection extending from upper border of C6 to lower border of T3 vertebra with pockets of dorsal collection. Three-dimensional constructive interference in steady state (CISS 3D) used in spinal imaging for identification of CSF leak corroborated with the extent seen on T2 sagittal sections; however, the site of the leak was not identified. After a year he developed disturbing postural headache which was relieved in recumbent position. Follow up MRI of brain was normal while spine demonstrated significant cervical cord atrophy and bilateral cord white matter hyperintensities. Conclusion / Clinical Relevance: We report this unusual case where local compression by VLISFC located at the cervical and upper thoracic level not only caused distal bi-brachial amyotrophy mimicking Hirayama disease but also led to secondary intracranial hypotension. An early identification and intervention could possibly have prevented the onset of ICH.

Repair of Temporal Bone Defects via the Middle Cranial Fossa Approach: Treatment of 2 Pathologies With 1 Operation.

BACKGROUND: Temporal bone dehiscence (TBD) often results in leakage of cerebrospinal fluid (CSF) and/or encephalocele. TBD can also occur over the superior semicircular canal, causing debilitating vertigo. Both can be repaired surgically, but traditional treatment is focused only on one pathology, not both. OBJECTIVE: To report our experience in the treatment of TBD via the middle cranial fossa (MCF) approach. METHODS: A retrospective review was conducted for all patients who underwent MCF approach for surgical repair of any temporal fossa dehiscence. RESULTS: A total of 34 patients underwent a total of 37 surgeries. Obesity was prevalent; 21 patients (61.8%) were obese (BMI [body mass index] > 30 kg/m2), and 7 (20.6%) were overweight (BMI 25-30 kg/m2). The most common presenting symptom was hearing disturbance (70.3%), followed by otorrhea (51.4%). Empty sella was noted on computed tomography or magnetic resonance imaging in 15 patients (45.5%). Eight of the 34 patients (23.5%) were found to have superior semicircular canal dehiscence (SCD). Hearing improved with surgical intervention in 25 of 26 patients with hearing loss as a presenting symptom (96%). CSF resolved in 18 of 19 cases (95%). Seventy-three percent of patients reported at least minimal improvement in vertigo. CONCLUSION: TBD may present with symptoms of CSF leak/encephalocele, but may also present with superior SCD. We recommend consistent review of the temporal bone imaging to check for superior SCD, and repair of the SCD first to prevent complications involving the labyrinth and cochlea. MCF approach using a multilayer repair without a lumbar drain is highly effective with minimal risk of complications.

Lateral Transorbital Versus Endonasal Transpterygoid Approach to the Lateral Recess of the Sphenoid Sinus-A Comparative Anatomic Study.

BACKGROUND: The treatment of cerebrospinal fluid leaks of the lateral recess of the sphenoid sinus (LRSS) faces difficulties due to the deep location of the osseous defect. When treated with craniotomies, brain retraction is a concern. The endoscopic endonasal transpterygoid approach (EETA) is a direct and less invasive procedure; however, it may require transection of the vidian nerve (VN). OBJECTIVE: To investigate the feasibility of a lateral transorbital approach (LTOA) as an alternative pathway to the LRSS that avoids VN sacrifice. METHODS: Six embalmed heads with well-pneumatized LRSS were preselected by inspecting their computed tomography scans. One LTOA and one EETA were performed on 1 side of each specimen. The approaches were compared regarding working distance and neurovascular structures being sacrificed. The working area of the LTOA was also measured. RESULTS: The average working distances were 59.9 (±2.94) mm for the LTOA and 76.4 (±3.99) mm for the EETA (P < .001). The LTOA generated a working area with a diameter of 9 to 14 mm. The EETA demanded the sacrifice of VN and the sphenopalatine artery in all specimens to expose the LRSS. No neurovascular structures were found in the trajectory of the LTOA. CONCLUSION: The LTOA to the LRSS is feasible, with minimal risk of injuring neurovascular structures. It offers a shorter pathway when compared to the EETA. Although the LTOA provides no options for vascularized flap reconstruction, it allows immediate access to muscle grafts. The LTOA may serve as an alternative to treating cerebrospinal fluid leaks of the LRSS.

Rostral cranial fossa as a site for cerebrospinal fluid drainage - volumetric studies in dog breeds of different size and morphotype.

BACKGROUND: Hydrocephalus is a multifactorial condition, whose aetiology is not fully understood. Congenital hydrocephalus frequently occurs in small and brachycephalic dog breeds. Although it is widely accepted that the cribriform plate located in the rostral cranial fossa (RCF) is a site of cerebrospinal fluid (CSF) drainage, the RCF has not been studied extensively. Literature reports indicate that a decreased caudal cranial fossa (CCF) volume in the course of the Chiari-like malformation may obstruct CSF circulation. We hypothesised that morphological diversity among different breeds in the volume of the RCF may affect CSF circulation. The aim of the study was to carry out a volumetric analysis of the RCF and the cranial cavity and to determine the ratio between them in dog breeds of different size and morphotype. We performed computed tomography (CT) morphometric analysis of the RCF compartment by obtaining volume measurements from the transverse and reformatted sagittal and dorsal planes. RESULTS: The rostral cranial fossa percentage - volume of the rostral cranial fossa/volume of cranial cavity × 100 (volRCF/volCC × 100) was lower in small and brachycephalic dog breeds than in the other dogs. CONCLUSIONS: A reduced RCF volume was detected in small and brachycephalic dog breeds, some of which are predisposed to congenital hydrocephalus. This may lead to overcrowding of brain parenchyma in the RCF and may impede CSF circulation. Our observations may be useful for future studies focusing on the causes and new therapies to treat conditions such as hydrocephalus and syringomyelia.

Analysis of various tracts of mastoid air cells related to CSF leak after the anterior transpetrosal approach.

OBJECTIVE: The anterior transpetrosal approach (ATPA) was established in 1984 and has been particularly effective for petroclival tumors. Although some complications associated with this approach, such as venous hemorrhage in the temporal lobe and nervous disturbances, have been resolved over the years, the incidence rate of CSF leaks has not greatly improved. In this study, some varieties of air cell tracts that are strongly related to CSF leaks are demonstrated. In addition, other pre- and postoperative risk factors for CSF leakage after ATPA are discussed. METHODS: Preoperative and postoperative target imaging of the temporal bone was performed in a total of 117 patients who underwent ATPA, and various surgery-related parameters were analyzed. RESULTS: The existence of air cells at the petrous apex, as well as fluid collection in the mastoid antrum detected by a postoperative CT scan, were possible risk factors for CSF leakage. Tracts that directly connected to the antrum from the squamous part of the temporal bone and petrous apex, rather than through numerous air cells, were significantly related to CSF leak and were defined as "direct tract." All patients with a refractory CSF leak possessed "unusual tracts" that connected to the attic, tympanic cavity, or eustachian tube, rather than through the mastoid antrum. CONCLUSIONS: Preoperative assessment of petrous pneumatization types is necessary to prevent CSF leaks. Direct and unusual tracts are particularly strong risk factors for CSF leaks.

Repair of Cerebrospinal Fluid Leakage Using a Transfrontal, Radial Adipofascial Flap: An Individual Approach Supported by Three-Dimensional Printing for Surgical Planning.

BACKGROUND: Leakage of cerebrospinal fluid (CSF) because of large prolactinomas represents a complex issue. Because of limited anatomic space, multiple leakage sites, and scarce locally available tissue for repair, surgical possibilities are limited. We report an initial case of using a radial fasciocutaneous flap applied subfrontally to cover a large skull base defect, supported by preoperative three-dimensional (3D) printing for surgical planning. CASE DESCRIPTION: A 29-year-old woman developed severe nuchal pain that was caused by destruction of large parts of her skull base by a prolactinoma. After occipitocervical fusion, medical treatment showed good tumor response but led to CSF leakage after 12 months. An endoscopic approach and ventriculoperitoneal shunt implantation failed to stop the leakage. A 3D model of the skull improved the understanding of the expanded osseous destruction and multiple CSF leakage sites and supported surgical planning. For an extensive coverage of the former clivus and sella region, an intracranially applied radial flap was planned. Dopamine-agonist medication was increased before the operation. Intraoperatively, the flap was brought into position subchiasmatically and wound around the pituitary stalk. CSF leakage was not observed on follow-up (10 weeks). Long-term follow-up will determine the effectiveness of this method.

Superficial siderosis of the central nervous system associated with intraspinal hemorrhage from ventral thoracic epidural veins and a ventral spinal CSF leak: case report.

In most patients with superficial siderosis of the CNS, the exact source of bleeding remains unknown because of a lack of objective surgical data. The authors herein describe the case of a 58-year-old man with superficial siderosis of the CNS. The patient also had spinal CSF leakage due to a spinal dural defect. Repair surgery for the dural defect was performed using posterior laminoplasty with a transdural approach without spinal fixation. During repair surgery, the bleeding source was found to be the epidural vein around the defect. The intraoperative and histological results of the present case suggest that epidural veins exposed to CSF represent a chronic bleeding source in patients with superficial siderosis of the CNS complicated by CSF leakage. Dural repair surgery may result in discontinuation of the CSF leaks, resolution of the epidural CSF collection, and cessation of chronic epidural bleeding.

Nonrandom spatial clustering of spontaneous anterior fossa cerebrospinal fluid fistulas and predilection for the posterior cribriform plate.

OBJECTIVE The anterior skull base is a common site for the spontaneous development of meningoceles, encephaloceles, and meningoencephaloceles that can lead to cerebrospinal fluid (CSF) fistula formation, particularly in association with idiopathic intracranial hypertension. In some circumstances the lesions are difficult to localize. Whether all sites in the anterior skull base are equally prone to fistula formation or whether they are distributed randomly throughout the anterior skull base is unknown, although the anterior cribriform plate has been proposed as the most frequent location. The purpose of this study was to identify sites of predilection in order to provide assistance for clinicians in finding occult leaks and increase the understanding of the etiology of this pathology. METHODS The authors performed a retrospective review of a prospectively acquired surgical database of all endonasal endoscopic surgeries performed at Weill Cornell Medical College by the senior authors. Spontaneous CSF fistulas of the anterior skull base were identified. The anatomical sites of the defects were located on radiographic images and normalized to a theoretical 4 × 2 grid representing the anterior midline skull base. Data from the left and right skull base were combined to increase statistical power. This grid was then used to analyze the distribution of defects. Frequency analysis was performed by means of a chi-square test, with a subsequent Monte Carlo simulation to further strengthen the statistical support of the conclusions. RESULTS Nineteen cases of spontaneous CSF fistulas were identified. Frequency analysis using chi-square indicated a nonrandom distribution of sites (p = 0.035). Monte Carlo simulation supported this conclusion (p = 0.034). Seventy-four percent of cases occurred in the cribriform plate (p = 0.086). Moreover, 37% of all defects occurred in the posterior third of the cribriform plate. CONCLUSIONS Anterior skull base spontaneous CSF leaks are distributed in a nonrandom fashion. The most likely site of origin of the spontaneous CSF leaks of the anterior midline skull base is the cribriform plate, particularly the posterior third of the plate, likely because of the lack of significant thick bony buttressing. Clinicians searching for occult spontaneous leaks of the anterior skull base should examine the cribriform plate, especially the posterior third with particularly close scrutiny.

The Effect of l-Arginine on Dural Healing After Experimentally Induced Dural Defect in a Rat Model.

BACKGROUND: Incomplete repair of the dura mater may result in numerous complications such as cerebrospinal fluid leakage and meningitis. For this reason, accurate repair of the dura mater is essential. In this study, the effect of systemic and local supplementation of l-arginine on dural healing was evaluated. METHODS: Thirty male Wistar rats were used and divided into control, local, and systemic l-arginine groups, with 10 rats in each. In each group, a 5-mm experimental incision was made at the lumbar segment of the dura mater and cerebrospinal fluid leakage was induced. Each group was divided into 2 subgroups and at the end of the first and sixth weeks, the rats were killed and the damaged segments of the dura were separated, histologically evaluated and the dural healing indicators including cell types, granulation tissue formation, collagen deposit, and vascularization were compared between groups. RESULTS: The systematic supplementation of l-arginine showed a significant effect in dural healing compared with the control group. After the first week, granulation formation increased considerably (P < 0.031), and after 6 weeks, collagen deposition and neovascularization were significantly different compared with the control group (P < 0.030; P < 0.009). In comparison between different groups at the end of the first and sixth weeks, maximum changes in healing indicators were observed in the systemic group and the least variations were related to the control group. CONCLUSIONS: The systemic supplementation of l-arginine may accelerate dural healing by increasing the level of granulation tissue formation, collagen deposition, and vascularization.

Enlargement of Meckel's cave in patients with spontaneous cerebrospinal fluid leaks.

BACKGROUND: Spontaneous cerebrospinal fluid (CSF) leaks have imaging findings consistent with chronically elevated intracranial pressure, such as empty sella. Meckel's cave is a CSF-filled space that houses the trigeminal ganglion at the cranial base. Our objective in this study was to evaluate "dilated" Meckel's cave as a radiologic sign in patients with elevated intracranial pressure spontaneous CSF leaks and compare the dimensions with those from a control cohort. METHODS: Meckel's cave dimensions were measured in patients with spontaneous CSF leaks and documented elevated intracranial pressure. A control group of subjects who underwent magnetic resonance imagine (MRI) scans for unrelated diagnoses were also evaluated. Subjects were included only if suitable MRIs with T2-weighted sequences in the axial plane were available. RESULTS: Sixty-three patients with spontaneous CSF leaks and 91 normal control patients were included in the study. There was significant (p < 0.05) enlargement in all measured dimensions (length and width) for the spontaneous CSF leak group. When evaluating area, spontaneous CSF leak subjects again showed significant enlargement compared with controls (0.81 ± 0.35 cm2 vs 0.52 ± 0.15 cm2 ; p < 0.0001). Average intracranial pressure measurements were 25.9 ± 9.0 cmH2 O. CONCLUSION: Patients with spontaneous CSF leaks have evidence of enlarged Meckel's caves. Evaluation of Meckel's cave dimensions should be included in preoperative imaging assessment as an additional indicator of chronically elevated intracranial pressure.

Asymmetric radiotracer activity of enlarged cerebral spinal fluid space on radionuclide cisternography with SPET/CT.

OBJECTIVE: Cerebrospinal fluid (CSF) leak is a well-known complication of skull or sinus surgery. Radionuclide cisternography has high sensitivity for detection of CSF leak, commonly performed in conjunction with radioactivity assay of nasal pledgets. Our objective was to highlight the usefulness of single photon emission tomography/computed tomography (SPET/CT) in radionuclide cisternography by presenting a case of a 41 years old man with right sided rhinorrhea following craniotomies and sinus surgery, who was subjected to radioactivity assay of nasal pledgets and radionuclide cisternography for suspected CSF leak. Although no CSF leak was detected by radioactivity assay of pledgets placed in the nasal cavity, asymmetric radiotracer activity was noted on cisternographic images in the left temporal region, which was found to correspond to an enlarged CSF space in the left middle cranial fossa, not CSF leak, on SPET/CT images. CONCLUSION: SPET/CT was useful in the differentiation of asymmetric CSF radiotracer activity caused by a normal variant or post surgical changes of anatomic structures from abnormal radiotracer activity secondary to CSF leakage on radionuclide cisternography.