Temporal sylvian fissure arachnoid cyst in children: treatment outcome following microsurgical cyst fenestration with special emphasis on cyst reduction and subdural collection.

OBJECTIVES: Controversy remains regarding surgical managements of sylvian fissure arachnoid cyst (SFAC). This review presents our experience in the microsurgical fenestration of pediatric patients with SFAC to define surgical indication, and risks and benefits with special emphasis on postoperative subdural fluid collection (SDFC) and cyst size reduction. METHODS: Thirty-four children with SFAC who underwent microsurgical cyst fenestration at a single institution over a 10-year period were retrospectively reviewed for their clinical presentation, neuroimaging findings, and postsurgical course. The SFACs were classified by a novel grading system based on the degree of arachnoid cyst extension from the sylvian fissure to the insular cistern shown on MR images: grade 0 - little or no prominence of sylvian fissure, grade I - SFAC confined to the sylvian fissure, grade II - SFAC partially extending to the insular cistern, grade III - SFAC extending to the entire insular cistern. RESULTS: There were 26 males and 8 females. SFAC was present in the left side in 24. Twelve patients presented with cyst rupturing to the subdural space. Cyst grading did not show significant difference compared with rupture status (p > 0.9). All patients underwent microsurgical cyst fenestration. Postoperative SDFC is common but often resolved overtime in two-thirds of the cases with the mean average of 6 months. However, 3 patients had symptomatic postoperative SDFC and needed reoperation shortly after the first operation. Microsurgical cyst fenestrations for SFAC effectively resolved the presenting symptoms and often showed restorations of intracranial structures on follow-up imaging. Cyst resolution or reduction greater than 75% was noted in 61.8% of the patients postoperatively which was noted in a half of the SFAC of children even with age of 11 years or older. During the follow-up, no cyst recurrence or SDFC was noted. Patients with greater surgical reduction of cyst size tended to occur in younger children, and those with lower MR grade. CONCLUSION: Our results showed a high reduction rate of SFAC and brain re-expansion after microsurgical fenestration together with symptomatic improvements regardless the patient's age. Considering the developing CNS during childhood, reductions of a large space-occupying lesion followed by restorations of the structural integrity of the developing brain are very desirable. However, a multi-center cooperative prospective longitudinal study on long-term comparative data of those treated and untreated of neuro-psychological outcome and cyst rupture incidence is needed.

Trigeminal Schwannomas in Middle Fossa Could Breach into Subdural Space: Report of 4 Cases and Review of Literature.

OBJECTIVE: The objectives of this study were to report 4 cases diagnosed with trigeminal schwannomas (TS), among whom tumor in epidural space of middle fossa broke through dura mater into subdural space, and to analyze the potential reason for recurrence of TS in middle fossa after surgical removal by endoscopic endonasal approach (EEA) or interdural approach. METHODS: The information of 4 patients diagnosed with TS who were surgically treated was retrospectively analyzed and the selection of approaches, surgical strategies, and potential reason for recurrence after middle fossa TS removal by EEA and interdural approach were discussed. RESULTS: During last 10 years, 43 patients with TS received surgical treatment at Xuan Wu Hospital of Capital Medical University, among whom 1 patient with TS extending from middle fossa to infratemporal fossa was first treated by EEA, then the tumor recurred and the patient underwent a second operation via a frontotemporal subdural approach. During the second operation, we found part of tumor had broken through the dura mater into subdural space. Moreover, this phenomenon was detected in another 3 patients with middle-posterior fossa TS. CONCLUSIONS: TS in middle fossa has been widely believed to be totally located at epidural space, whereas we found that it could occasionally breach into subdural space and accept blood supply from the pial artery. We believe this could be the potential reason for recurrence after tumor resection by EEA and interdural approach.

Investigation of subdural electrode displacement in invasive epilepsy surgery workup using neuronavigation and intraoperative MRI.

OBJECTIVES: One of the main obstacles of electrode implantation in epilepsy surgery is the electrode shift between implantation and the day of explantation. We evaluated this possible electrode displacement using intraoperative MRI (iopMRI) data and CT/MRI reconstruction. METHODS: Thirteen patients (nine female, four male, median age 26 ± 9.4 years) suffering from drug-resistant epilepsy were examined. After implantation, the position of subdural electrodes was evaluated by 3.0 T-MRI and thin-slice CCT for 3D reconstruction. Localization of electrodes was performed with the volume-rendering technique. Post-implantation and pre-explantation 1.5 T-iopMRI scans were coregistered with the 3D reconstructions to determine the extent of electrode dislocation. RESULTS: Intraoperative MRI at the time of explantation revealed a relevant electrode shift in one patient (8%) of 10 mm. Median electrode displacement was 1.7 ± 2.6 mm with a coregistration error of 1.9 ± 0.7 mm. The median accuracy of the neuronavigation system was 2.2 ± 0.9 mm. Six of twelve patients undergoing resective surgery were seizure free (Engel class 1A, median follow-up 37.5 ± 11.8 months). CONCLUSION: Comparison of pre-explantation and post-implantation iopMRI scans with CT/MRI data using the volume-rendering technique resulted in an accurate placement of electrodes. In one patient with a considerable electrode dislocation, the surgical approach and extent was changed due to the detected electrode shift. ABBREVIATIONS: ECoG: electrocorticography; EZ: epileptogenic zone; iEEG: invasive EEG; iopMRI: intraoperative MRI; MEG: magnetoencephalography; PET: positron emission tomography; SPECT: single photon emission computed tomography; 3D: three-dimensional.

The Pathogenesis of Subacute Subdural Hematoma: A Report of 3 Cases and Literature Review.

OBJECTIVE: To discuss the pathologic mechanism of subacute subdural hematoma (sASDH). METHODS: Three typical cases of sASDH were reported, and related literature in Chinese published in the past 15 years was reviewed. RESULTS: Intervals from onset of acute subdural hematoma to surgery or symptom deterioration resulting in sASDH were 12.5-15.5 days (mean 14.1 days). Delayed liquefaction of hematoma clots occurred in all 3 reported cases. One patient achieved good curative effect after administration of dexamethasone, and another patient relapsed owing to poor drainage after evacuation of hematoma. CONCLUSIONS: The conversion of acute subdural hematoma to sASDH is an inflammatory reaction process with very regular in time, and it is speculated that the pathologic mechanism may be a delayed hypersensitivity reaction. Antigen released during the liquefaction process of blood clot, with subdural neomembrane cells as antigen-presenting cells, is presented to the T lymphocytes released from the capillaries in the neomembrane and forms sensitized T lymphocytes. When the subsequent antigen is released from the blood clots with a delayed liquefaction and is exposed to sensitized T lymphocytes, the delayed hypersensitivity process occurs.

Reorganized neural activation in motor cortex following subdural fluid collection: an fMRI and DTI study.

We report a patient with a cavernous malformation involving the right lentiform nucleus. Pre-surgical planning included fMRI localization of language, motor, and sensory processing, and DTI of white matter tracts. fMRI results revealed no activation near the planned resection zone. However, post-surgery the patient developed a subdural fluid collection, which applied pressure to the primary motor cortex (M1). Follow-up scans revealed that motor activation had shifted due to pressure, and then shifted to a new location after the fluid collection subsided. This case report suggests that long-term neural reorganization can occur in response to short term compression in the cortex.

Rosai-Dorfman disease of the subdural spine with a long segment lesion: A case report and literature review.

Rosai-Dorfman disease (RDD) or sinus histiocytosis with massive lymphadenopathy is a rare benign disorder usually characterized by massive painless cervical lymphadenopathy and systemic manifestations. Extranodal involvement, especially spinal involvement, is extremely rare. We report a 41-year-old man who presented with only intermittent dorsodynia. His condition was diagnosed as non-specific inflammatory disease on the basis of preoperative puncture biopsy results. We performed total surgical resection. Histopathological findings showed distinctive emperipolesis and immunohistochemistry results were positive for cluster of differentiation CD68 and S100 and negative for CD1a. A good prognosis was confirmed at the 3-month follow-up visit. This is the first case of RDD of the subdural spine with such a long segment lesion. There is still no consensus regarding appropriate therapy for this type of RDD and the preoperative diagnosis remains challenging. The unusual presentation of our case serves as a reference when diagnosing and treating RDD.

Primary Melanotic Schwannoma with Typical Histology.

We present a case of a 17-year male with a soft tissue density spreading from the neural foramina (T3) of the spinal cord and involving the right upper thoracic cavity. We managed the patient through surgical intervention and resected the complete tumor. Gross definition and microscopic findings of the resected tissue revealed the definitive diagnosis of melanotic schwannoma. The histological characteristics in this case were very specific and harbour an important diagnostic clue for this rare disease. Malignant melanoma was ruled out on the basis of histological findings. The patient recovered completely and was healthy on one-year follow-up.

The effectiveness of microsurgical fenestration for middle fossa arachnoid cysts in children.

OBJECTIVE: Although middle fossa arachnoid cysts (MFACs) are common, the optimal surgical treatment for these lesions remains controversial. In this study, we present our experiences of treating MFACs by microsurgical fenestration and evaluate its effectiveness. METHODS: We performed retrospective review of 28 patients who underwent microsurgical fenestration for MFACs between May 2003 and December 2014. We reviewed patient characteristics and treatment outcomes including age, sex, symptoms, complicating hydrocephalus, Gallasi classification, change in cyst size after surgery, complicating subdural hygroma, symptom resolution, regrowth of the cyst, and reoperation (including additional CSF diversion). RESULTS: Twenty-eight MFACs in 28 patients were investigated. The average age at the time of surgery was 61.6 months. The average follow-up duration was 53.5 months. After surgery, 19 (90.5 %) of 21 patients with symptomatic MFACs experienced improvements. The cysts decreased in size in all cases (100 %, 28/28) and disappeared in three cases (11 %, 3/28). None of the cases experienced regrowth of the cyst. Subdural hygroma was identified in 23 cases (82.1 %) at the immediate postoperative period. Hygroma was asymptomatic in all cases but one. Hygroma disappeared in 19 cases (83 %) and decreased in size in three cases (13 %) in the long term. Only one case (4 %) required an additional subdural-peritoneal shunt. The rate of CSF diversion after the fenestration was significantly higher in patients with preoperative ventricular dilation (p = 0.0002). CONCLUSION: Microsurgical fenestration for pediatric MFACs was considered to be safe and effective. Although subdural hygroma developed in significant number of patients at the immediate postoperative period, it was mostly asymptomatic and disappeared or decreased in size in the long term.

Use of Spongostan™ for Prevention of Cranial Subdural Adhesions Following Craniotomy in an Experimental Rabbit Model.

AIM: Spongostan™ is a sterile, water-insoluble, porcine gelatin absorbable sponge, which is widely used as a hemostatic material. The aim of this study is to test the anti-fibrotic capacity of Spongostan™, using a craniotomy model in an experimental rabbit model. MATERIAL AND METHODS: Eighteen rabbits were divided into two groups: Each group consisted of 9 rabbits, duratomy plus Spongostan™ (group 1), and duratomy without Spongostan™ (group 2). Right parietal bone was removed via trephine and low speed drill and dura was opened. On the group 1 rabbits, an appropriate piece of Spongostan™ was meticulously placed under dural layer. On group 2 rabbits, same procedures were repeated without Spongostan™. Histological sections were taken from each group and evaluated for degree of fibrosis and collagen fibers. RESULTS: There was marked increase in number of fibroblasts and collagen fibers in group 2 rabbits, however most of the rabbits in Spongostan™ group demonstrate scarce histopathological findings for fibrosis. CONCLUSION: We conclude that an appropriately placed subdural Spongostan™ over cerebral tissue may prevent postoperative surgical adhesions after neurosurgical operations.

[Dural cavernous angioma:a case report and review of the literature].

Here, we report a case of dural cavernous angioma. A 54-year-old man presented with headache in his right frontal area for the previous few weeks. Computed tomography (CT) and magnetic resonance imaging revealed a well-demarcated extramedullary mass, 3 x 2.5cm in size, within the subdural space at the right frontal region. The mass was not enhanced on a contrast-enhanced CT scan, and heterogeneously enhanced after administration of Gd-DTPA on magnetic resonance images. Cerebral angiography revealed an avascular mass. Right frontal craniotomy was performed. On surgery, the mass was found to be mainly extramedullar, and partially intramedullar. No adhesion between the mass and the overlying dura was observed. It was removed in an en bloc fashion. The pathological diagnosis was cavernous angioma. The patient's headache was resolved soon after surgery. Cavernous angiomas are usually intramedullar in the subcortical white matter of the cerebral hemispheres;extramedullary cavernous angiomas are rare. Extramedullary dural cavernous angiomas located in the subdural space at the cerebral convexity are extremely rare. They usually present with headache or mass signs, and resemble meningioma radiologically. During surgery they are easily resected with minimal blood loss. Dural cavernous angiomas should be considered in the differential diagnosis of intradural extramedullary mass at the cerebral convexity.

Subdural extramedullary melanotic schwannoma of the thoracic spinal cord: a case report.

Melanotic schwannoma is a rare "Schwann" cell tumor characterized by the deposition of melanin in the cell cytoplasm. Melanotic schwannoma varies greatly in terms of morphology and clinical manifestations. Here, we describe a patient with subdural extramedullary melanotic schwannoma of the thoracic spinal cord. The 47-year-old man presented with pain in his chest and back that had lasted a year, numbness and weakness in both his lower extremities for 20 days, and urinary retention for 4 days. Magnetic resonance imaging (MRI) revealed a subdural extramedullary lesion at the level of the T2-T4 thoracic spinal cord. A total resection of the mass was performed. A diagnosis of melanotic schwannoma was made based on the histopathological examination. During the six-month follow-up period, no recurrence of the tumor was observed. A long-term follow-up will be necessary to fully evaluate this case.

Transoral vs. endoscopic endonasal approach for clival/upper cervical chordoma.

The surgical results of 18 cases of clival/upper cervical chordoma treated in the last decade via the endoscopic endonasal approach (EEA, 9 cases) and the transoral-transpalatal approach (TO-TPA, 9 cases) were compared. Each group showed the same incidence of subdural invasion, with 5 cases each. The superior (frontal base) and lateral surgical fields were wider by EEA, but the inferior view lower than the cranio-vertebral junction (CVJ) was wider by TO-TPA. Gross total removal was achieved in 3 cases in the EEA group, but in only 1 case in the TO-TPA group. Differences in radicality might be due to the extent of the lateral and subdural overview. However for large tumors extending below the CVJ, TO-TPA was the only viable approach for surgical removal. Surgical complications were higher in the EEA (4 cases) than the TO-TPA group (1 case), and were mainly caused by aggressive management of subdural invasion in the EEA group. Post-operative oral intake was earlier and the operative time was shorter in the EEA group. The surgical results were more radical and less invasive in the EEA group than the TO-TPA group. However in tumors extending below the CVJ, the surgical field in EEA was limited, indicating the need to use the transoral route or a combination of routes. A higher complication rate following subdural management was a negative factor that requires improvement in the EEA group and two-staged EEA followed by a transcranial approach may be considered for the cases with subdural invasion.

An open-source automated platform for three-dimensional visualization of subdural electrodes using CT-MRI coregistration.

OBJECTIVE: Visualizing implanted subdural electrodes in three-dimensional (3D) space can greatly aid in planning, executing, and validating resection in epilepsy surgery. Coregistration software is available, but cost, complexity, insufficient accuracy, or validation limit adoption. We present a fully automated open-source application, based on a novel method using postimplant computerized tomography (CT) and postimplant magnetic resonance (MR) images, for accurately visualizing intracranial electrodes in 3D space. METHODS: CT-MR rigid brain coregistration, MR nonrigid registration, and prior-based segmentation were carried out on seven patients. Postimplant CT, postimplant MR, and an external labeled atlas were then aligned in the same space. The coregistration algorithm was validated by manually marking identical anatomic landmarks on the postimplant CT and postimplant MR images. Following coregistration, distances between the center of the landmark masks on the postimplant MR and the coregistered CT images were calculated for all subjects. Algorithms were implemented in open-source software and translated into a "drag and drop" desktop application for Apple Mac OS X. RESULTS: Despite postoperative brain deformation, the method was able to automatically align intrasubject multimodal images and segment cortical subregions, so that all electrodes could be visualized on the parcellated brain. Manual marking of anatomic landmarks validated the coregistration algorithm with a mean misalignment distance of 2.87 mm (standard deviation 0.58 mm)between the landmarks. Software was easily used by operators without prior image processing experience. SIGNIFICANCE: We demonstrate an easy to use, novel platform for accurately visualizing subdural electrodes in 3D space on a parcellated brain. We rigorously validated this method using quantitative measures. The method is unique because it involves no preprocessing, is fully automated, and freely available worldwide. A desktop application, as well as the source code, are both available for download on the International Epilepsy Electrophysiology Portal (https://www.ieeg.org) for use and interactive refinement.

Spectrum of imaging appearances in Australian children with central nervous system hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare multisystem disorder characterised by the proliferation and infiltration of lymphocytes and histiocytes. Central nervous system (CNS) infiltration is particularly devastating. Neuroradiological findings have been reported predominantly as individual case reports due to the rarity of the condition. To our knowledge there have been no published studies of imaging in Australian patients. This study aimed to retrospectively describe and illustrate the MRI appearances of CNS involvement by HLH in a cohort of seven Australian children from two paediatric centres between 2000 and 2011. MRI appearances demonstrate intersubject and intrasubject variability over time, likely reflecting the severity of CNS infiltration and associated demyelination. Familiarity with MRI patterns is important for assessing and monitoring disease activity.

Analysis of a bleeding mechanism in patients with the sylvian arachnoid cyst using a finite element model.

OBJECTIVE: The sylvian arachnoid cyst (AC) is a common benign disease; however, it sometimes leads to subdural or intracystic hemorrhage without major trauma. The reason of easy bleeding of the AC is not fully understood. The purpose of this study was to investigate the bleeding mechanism of the sylvian AC in biomechanical aspect and suggest treatment guidelines. METHODS: A finite element (FE) model of normal male adult head/brain was developed and validated by comparison with cadaveric experimental studies. Based on the normal FE model, two sylvian AC models with different sizes (mean size, 55.5 cm(3); large size, 75.2 cm(3)) were developed. To simulate the interface between the dura mater and the arachnoid membrane, spot-weld constraints were assigned. The vulnerability of vein rupture was forecasted with calculated shear force at the spot-weld elements (SFSW). Simulation was performed for four different loading directions. RESULTS: The newly developed normal FE models showed reliable biomechanical responses comparable with the cadaveric experiments. The sylvian AC model showed significantly increased SFSW compared with normal model. As AC size increased, higher shear force was generated at the spot-weld element of outer wall of sylvian AC regardless of impact directions. CONCLUSION: Outer wall of sylvian AC receives higher shear force comparing with normal brain, which is a possible cause of vulnerability to bleeding. Although the size-reducing surgery may decrease bleeding risk of sylvian AC, clinicians need to consider the rare incidence of AC bleeding and unsatisfactory volume reduction in many cases of fenestration.

Depths and grids in brain tumors: implantation strategies, techniques, and complications.

Patients with intracranial mass lesions are at increased risk of intractable epilepsy even after tumor resection due to the potential epileptogenicity of lesional and perilesional tissue. Risk factors for tumoral epilepsy include tumor location, histology, and extent of tumor resection. In epilepsy that occurs after tumor resection, the epileptogenic zone often does not correspond precisely with the area of abnormality on imaging, and seizures often arise from a relatively restricted area despite widespread changes on imaging. Invasive monitoring via subdural grids and/or depth electrodes can therefore be helpful to delineate areas of eloquence and localize the epileptogenic zone for subsequent resection. Subdural grids offer excellent contiguous coverage of superficial cortex and allow resection using the same craniotomy, facilitating understanding of anatomic relationships. Depth electrodes offer superior coverage of deep structures, are easier to use in cases where a previous craniotomy is present, are not associated with anatomic distortion due to brain shift, and may be associated with a lower complication rate. We review the biology of focal postoperative epilepsy and invasive diagnostic strategies for the surgical evaluation of medically refractory epilepsy in patients who have undergone resection of intracranial mass lesions.

High-grade intracranial chondrosarcoma presenting with haemorrhage.

Chondrosarcomas are rare sarcomas that produce malignant cartilage, infrequently arising as a primary intracranial tumour. We present a patient with intracranial chondrosarcoma with intratumoural haemorrhage arising in an unusual location and with unusual imaging findings. A 46-year-old man presented with headache, nausea, and vomiting over the previous 24 hours. Physical and neurological examinations were normal. Cranial CT scans and MRI revealed a large right pre-frontal (subdural) and interhemispheric heterogeneous density associated with a frontal, partially calcified mass and midline shift. An awake craniotomy was performed. With the intra-operative quick section favouring subdural hematoma, the lesion was subtotally resected. Follow-up imaging confirmed residual mass. Pathology examination revealed a high-grade malignant neoplasm with chondroid differentiation, diagnosed as conventional Grade III chondrosarcoma. The patient was referred to oncology for follow-up and radiation therapy. Intracranial chondrosarcoma was first reported in 1899, and since then continues to be an extremely rare malignancy of the brain. These tumours commonly present as extra-axial masses, originating from the skull base, and produce symptoms due to progressive enlargement and compression of local structures. Unusual presentations of these tumours, such as vascularity, intratumoural haemorrhage, and intra-axial location, may complicate pre-surgical decision making by altering the provisional diagnosis prior to intervention. This patient emphasises the importance of careful analysis and incorporation of imaging findings into surgical decision making. Specific imaging characteristics that, in such unusual situations, are suggestive of chondrosarcoma should motivate an aggressive surgical approach to optimise adjuvant interventions.

Chronic spinal subdural abscess mimicking an intradural-extramedullary tumor.

Spinal subdural abscesses (SSA) are very rare disease. The etiologies of SSA are hematogenous spread, iatrogenic contamination, and local extension. Elevated WBC counts, ESR, and C-reactive protein are usually found in laboratory tests. But they are not sensitive indicators of SSA, especially chronic abscesses patient tend to have a less specific characteristic. We report the case of a healthy man with chronic subdural abscess referred to our hospital as an intradural-extramedullary (IDEM) tumor. The patient presented with voiding difficulty and pain in the back and left leg. In a contrast MRI scan, a rim-enhanced mass-like lesion was seen at the L5/S1 level. But adjacent ill-defined epidural fat enhancement that are unusual imaging manifestation for IDEM tumors was seen. He had no fever and normal WBC, ESR, and CRP. In addition, the patient had no previous infection history or other disease, but he did have an epidural block for back pain at another hospital 2 years previously. So, we repeated the MRI with a high-resolution 3-T scanner. The newly taken MR images in our hospital revealed a clear enlargement of lesion size compared to the previous MRI taken 1 week before in other hospital. We suspected a chronic spinal subdural abscess with recent aggravation and immediately performed surgical evacuation. In the surgical field, tensed dura was observed and pus was identified after opening the abscess capsule. Because chronic spinal subdural abscesses are difficult to diagnose, we could differentiate with IDEM tumor exactly and an exact history taking, contrast MRI are required.