Compression Syndromes of the Vertebral Artery at the Craniocervical Junction.

Compression syndromes of the vertebral artery that occur at the craniocervical junction are extremely rare causes of haemodynamic insufficiency of the posterior cerebral circulation. The aetiology of the compression syndrome may be a malformation, trauma, tumour, infection or degenerative pathology. This may lead to dynamic vertebral artery occlusion where the vessel courses around the atlas and the axis-the so-called V3 segment. This in turn may result in insufficient collateral flow to the posterior fossa. The clinical picture is a vertebrobasilar insufficiency syndrome of variable expression ranging from vertigo to posterior fossa stroke. The typical clinical presentation is syncope occurring during rotation of the head, also known as 'bow hunter's syndrome'. The workup is based on dynamic angiography and computed tomography angiography. The treatment of choice is surgical vascular decompression, resulting in a good clinical outcome. However, in some instances, atlantoaxial fusion may be indicated. Alternatively, conservative and endovascular options have to be considered in inoperable patients.

Cystic meningioma: radiological, histological, and surgical particularities in 43 patients.

BACKGROUND: The presence of cysts is a rare occurrence for intracranial meningiomas in adults. We report our experience in a large consecutive series of cystic meningiomas. METHOD: We prospectively collected data for a dedicated database of cystic meningioma cases between January 2004 and December 2011 in two tertiary neurosurgical centers. Studied data included preoperative imaging, surgical records, and pathology reports. RESULTS: Among 1214 surgeries for intracranial meningioma, we identified 43 cases of cystic meningioma, corresponding to an incidence of 3.5 %. The most common localization was the hemispheric convexity (17/43 cases). Twenty-eight patients had intratumoral cysts, nine peritumoral, and five mixed intra and extratumoral. In 29 patients with available diffusion imaging, ADC coefficients were significantly lower in grade II-III tumors compared to grade I (p = 0.01). Complete resection of the cystic components was possible in 27/43 patients (63 %); partial resection in 4/43 (9 %); in 6/43 (14 %) cyst resection was not possible but multiple biopsies were performed from the cystic walls; in another 6/43 (14 %) the cystic wall was not identified during surgery. Cells with neoplastic features were identified within the cyst walls at pathology in 26/43 cases (60 %). All patients were followed-up for 24 months; long-term follow-up was available only in 32 patients for an average period of 49 months (range, 36-96 months). No recurrence requiring surgery was observed. CONCLUSIONS: Cystic meningiomas are rare. Cells with neoplastic features are often identified within the cyst walls. Complete cyst resection is recommendable when considered technically feasible and safe.

Growth stabilization and regression of meningiomas after discontinuation of cyproterone acetate: a case series of 12 patients.

BACKGROUND: The relationship between meningiomas and exogenous sex hormones is well known, but cyproterone acetate (CA), a progesterone agonist, seems to have a stronger influence on tumor growth. OBJECTIVE: To show the close relationship between CA treatment and meningioma growth. METHODS: Since 2010, all patients referred to our clinic for a suspicion of meningioma were questioned specifically about exogenous sex hormone intake and more specifically about CA intake. Twelve patients harboring one or multiple meningiomas and treated with CA were identified. CA was stopped in all cases. Tumor volumes and diameters were measured on serial MRIs and compared to the last MRI before CA withdrawal. RESULTS: Ten patients with multiple tumors had been taking the drug for a longer period of time (mean of 20.4 years) than the two patients with one tumor (10 years). Two patients with multiple tumors underwent surgery because of rapidly decreased visual acuity at the time of diagnosis. Discontinuation of CA led to tumor shrinkage in 11 patients and a stop in tumor growth in one [mean tumor volume reduction was around 10 cm(3)/year; range (0.00; 76)]. There was no regrowth during a mean follow-up period of 12 months (range: 5-35). CONCLUSION: For patients diagnosed with a meningioma and treated with CA, medication withdrawal followed by observation should be the first line of treatment. Care should be taken with long-term use of high doses of CA, and serial brain MRIs should be considered after several years of CA.

Sporadically second localization of cerebellar hemangioblastoma in sella turcica mimicking a meningioma with no associated von Hippel-Lindau disease.

A 72-year-old man presented with a gradual bilateral decrease in visual acuity. Imaging showed lesion in the sella turcica diagnosed as meningioma but proving secondarily to be a hemangioblastoma. His neurosurgical history included a resection of a cerebellar hemangioblastoma 30 years ago. To our knowledge, such a hemangioblastoma second localization from the infratentorial to supratentorial has not been reported in the literature for patients not presenting with von Hippel-Lindau disease.

Endoscopic endonasal approach in the management of skull base chordomas--clinical experience on a large series, technique, outcome, and pitfalls.

Skull base chordomas represent very interesting neoplasms, due to their rarity, biological behavior, and resistance to treatment. Their management is very challenging. Recently, the use of a natural corridor, through the nose and the sphenoid sinus, improved morbidity and mortality allowing also for excellent removal rates. Prospective analysis of 54 patients harboring a skull base chordoma that were managed by extended endonasal endoscopic approach (EEA). Among the 54 patients treated (during a 72 months period), 21 were women and 33 men, undergoing 58 procedures. Twenty-two cases (40%) were recurrent and 32 (60%) newly diagnosed chordomas. Among the 32 newly diagnosed chordomas, a gross total resection was achieved in 28 cases (88%), a near total (>95% of tumor) in 2 cases (6%), a partial (>50% of tumor) in 2 cases (6%). Among the 22 recurrent chordomas, resection was complete in 7 cases (30%), near total in 7 (30%), and partial in 8 (40%). The global gross total resection rate was 65% (35/54 cases). Four patients (11%) recurred and 4 (11%) progressed within a mean follow-up of 34 months (range 12-84 months). Four patients (11%) were re-operated; one patient (1.8%) died due to disease progression, one patient (1.8%) died 2 weeks after surgery due to a massive bleeding from an ICA pseudo aneurysm. CSF leakage occurred in four patients (8%), and meningitis in eight cases (14%). No new permanent neurological deficit occurred. The EEA management of skull base chordomas requires a long and gradual learning curve that once acquired offers the possibility of either similar or better resection rates as compared to traditional approaches while morbidity is improved.

Causative role of infection in chronic non-thromboembolic pulmonary hypertension following ventriculo-atrial shunt.

A severe complication of ventriculo-atrial (VA) shunt placement for treatment of hydrocephalus is chronic thromboembolic pulmonary hypertension (CTEPH). We report here a patient with a VA shunt for treatment of hydrocephalus who presented two consecutive episodes of VA shunt-induced infection by Staphylococcus epidermidis and who rapidly developed chronic PH. Extensive radiological investigations and normal ventilation/perfusion lung scan allowed us to rule out CTEPH. To our knowledge, no other case of chronic pulmonary hypertension (PH) related to VA shunt insertion has been reported so far. PH in this patient with VA shunt is clinically distinct from CTEPH and has been caused by VA shunt-induced S. epidermidis infection per se.

Impact of extensive surgery in multidisciplinary approach of pterygopalatine/infratemporal fossa soft tissue sarcoma.

BACKGROUND: To evaluate a strategy whereby extensive surgery ± external radiotherapy (RT) could improve local control in pterygopalatine/infratemporal fossa (PIF) sarcoma. PROCEDURE: Forty-one patients with a diagnosis of sarcoma involving the PIF and referred to our Institute from 1984 to 2009 were included in the analysis. Patients received multidrug chemotherapy and radiotherapy ± surgery, depending on the period of treatment. RESULTS: The median age at diagnosis was 7.6 years (range: 0.1-22 years). There were 36 RMS, 3 undifferentiated sarcoma and 2 other soft-tissue sarcomas. Sixty-eight percent of patients had meningeal risk factors at diagnosis. Local treatment consisted of RT alone in 19 patients, surgery in combination to RT in 19 patients and surgery alone in 3 patients. The local progression rate (LPR) at 5 years was 45% for the entire population, 59% for the 19 patients treated with RT alone and 34% for the 22 patients who had surgery as part of their treatment. All locoregional failures after extensive surgery occurred at the skull base and/or in leptomeningeal spaces. CONCLUSIONS: Multidisciplinary approach including extensive surgery for PIF sarcoma is feasible and yields good local control with 15/22 patients in local complete remission. Future studies are warranted to confirm these promising results, to evaluate the possibility of avoiding RT or limiting the RT field, and to extend the indication for extensive surgery to other "worse" sites of PM sarcoma such as the paranasal sinuses.

Malignant potential of skull base versus non-skull base meningiomas: clinical series of 1,663 cases.

BACKGROUND: About 90 % of meningiomas are benign (WHO grade I), atypical and anaplastic variants exist (WHO grade II/III, 10 %). Tumour grade has important implications for management. Non-invasive diagnosis of tumour grade is still not feasible. The purpose of this survey was to analyse epidemiological risk factors such as sex, age and location for a higher grade (WHO grade II/III) meningioma in a large surgical series. METHODS: A retrospective study comprising 1,663 patients operated on for an intracranial meningioma in a single tertiary-care centre. The population was analysed for correlations including WHO grade, histological subtype, tumour localisation, patient age and gender. Additionally correlations between Ki67 index/WHO grade and localisation were analysed. RESULTS: A binary logistic regression analysis revealed non-skull base localisation (OR 1.779 [CI 1.069-2.960, p = 0.0027]) and age ≥65 years (OR 1.549 [CI 1.214-2.624, p = 0.012]) as significant risk factors for a higher WHO grade. Male gender showed a trend for a higher risk in χ(2) analysis. An analysis of the Ki67 index revealed an increased index for non-skull base localisation compared with skull base (p < 0.001). Correlation analysis of Ki67 distribution in WHO grade I meningiomas revealed higher Ki67 indices for non skull base localisation (p = 0.0024). CONCLUSIONS: Non-skull base localisation and age ≥65 years are independent risk factors for higher grade meningiomas. In other terms, the malignant potential of skull base meningiomas is low. This information is important when advising a patient about individual treatment options (observation, surgery or radio-surgery) and prognosis.

Comics as a Physical Education Tool for Health Promotion in Brazilian Primary Education, Based on Paulo Freire's Principles of Empowerment.

Incorrect postural habits developed already at an early age are predictors of low back pain and functional limitations in adult life. Postural education programs (PEPs) are activities developed in Physical Education classes with the aim of promoting healthy habits. One tool used by PEPs is comics. The objective of this study was to develop comics and apply them as a teaching tool in PEPs for students aged seven to ten years. The procedures were based on individual empowerment principles, including creation activities, reading, painting, crosswords, and discussion of comics. The activities strengthened the students' interactions, gaining new knowledge that required cognitive and expressive resources to interpret, associate, and conceptualize themes of correct body posture. During six weeks of intervention, knowledge about body posture, anatomy, and health promotion exercises increased significantly in relation to the beginning of activities. The comic book proved to be an effective, attractive, and low-cost didactic resource.

Bow-hunter's syndrome caused by dynamic vertebral artery stenosis at the cranio-cervical junction--a management algorithm based on a systematic review and a clinical series.

Bow hunter's syndrome (BHS) is defined as symptomatic, vertebro-basilar insufficiency caused by mechanical occlusion of the vertebral artery (VA) at the atlanto-axial level during head rotation. In the literature, about 40 cases have been reported. However, due to the rarity of this pathology, there are no guidelines for diagnosis and treatment. Conservative, surgical, and endovascular concepts have been proposed. In order to work out an algorithm, we performed a systematic review of the literature and a retrospective analysis of patients, which have been treated in our institutions over the last decade. The clinical series was comprised of five patients. The symptoms ranged from transient vertigo to posterior circulation stroke. Diagnosis was established by dynamic angiography. In all patients, the VA was decompressed; one patient required additional fusion. The clinical and radiological results were good, and the treatment-related morbidity was low. The literature review demonstrated that Bow hunter's syndrome is a rare pathology but associated with a pathognomonic and serious clinical presentation. The gold standard of diagnosis is dynamic angiography, and patients were well managed with tailored vertebral artery decompression. By this management, clinical and radiological results were excellent and the treatment-related morbidity was low.

Chordomas of the skull base and cervical spine: clinical outcomes associated with a multimodal surgical resection combined with proton-beam radiation in 40 patients.

Previous studies of chordoma have focused on either surgery, radiotherapy, or particular tumor locations. This paper reviewed the outcomes of surgery and proton radiotherapy with various tumor locations. Between 2001 and 2008, 40 patients with chordomas of the skull base and cervical spine had surgery at our hospital. Most patients received proton therapy. Their clinical course was reviewed. Age, sex, tumor location, timing of surgery, extent of resection, and chondroid appearance were evaluated in regard to the progression-free survival (PFS) and overall survival (OS). The primary surgery (PS) group was analyzed independently. The extensive resection rate was 42.5%. Permanent neurological morbidity was seen in 3.8%. Radiotherapy was performed in 75% and the mean dose was 68.9 cobalt gray equivalents. The median follow-up was 56.5 months. The 5-year PFS and OS rates were 70% and 83.4%, respectively. Metastasis was seen in 12.5%. The tumor location at the cranio-cervical junction (CCJ) was associated with a lower PFS (P = 0.007). In the PS group, a younger age and the CCJ location were related to a lower PFS (P = 0.008 and P < 0.001, respectively). The CCJ location was also related to a lower OS (P = 0.043) and it was more common in young patients (P = 0.002). Among the survivors, the median of the last Karnofsky Performance Scale score was 80 with 25.7% of patients experiencing an increase and 11.4% experiencing a decrease. Multimodal surgery and proton therapy thus improved the chordoma treatment. The CCJ location and a younger age are risks for disease progression.

Management strategies in clival and craniovertebral junction chordomas: a 29-year experience.

OBJECTIVE: Chordomas represent one of the most challenging subsets of skull base and craniovertebral junction (CVJ) tumors to treat. Despite extensive resection followed by proton-beam radiation therapy, the recurrence rate remains high, highlighting the importance of developing efficient treatment strategies. In this study, the authors present their experience in treating clival and CVJ chordomas over a 29-year period. METHODS: The authors conducted a retrospective study of clival and CVJ chordomas that were surgically treated at their institution from 1991 to 2020. This study focuses on three aspects of the management of these tumors: the factors influencing the extent of resection (EOR), the predictors of survival, and the outcomes of the endoscopic endonasal approaches (EEAs) compared with open approaches (OAs). RESULTS: A total of 265 surgical procedures were performed in 210 patients, including 123 OAs (46.4%) and 142 EEAs (53.6%). Tumors that had an intradural extension (p = 0.03), brainstem contact (p = 0.005), cavernous sinus extension (p = 0.004), major artery encasement (p = 0.01), petrous apex extension (p = 0.003), or high volume (p = 0.0003) were significantly associated with a lower EOR. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 52.1% and 75.1%, respectively. Gross-total resection and Ki-67 labeling index < 6% were considered to be independent prognostic factors of longer PFS (p = 0.0005 and p = 0.003, respectively) and OS (p = 0.02 and p = 0.03, respectively). Postoperative radiation therapy correlated independently with a longer PFS (p = 0.006). Previous surgical treatment was associated with a lower EOR (p = 0.01) and a higher rate of CSF leakage after EEAs (p = 0.02) but did not have significantly lower PFS and OS compared with primary surgery. Previously radiation therapy correlated with a worse outcome, with lower PFS and OS (p = 0.001 and p = 0.007, respectively). EEAs were more frequently used in patients with upper and middle clival tumors (p = 0.002 and p < 0.0001, respectively), had a better rate of EOR (p = 0.003), and had a lower risk of de novo neurological deficit (p < 0.0001) compared with OAs. The overall rate of postoperative CSF leakage after EEAs was 14.8%. CONCLUSIONS: This large study showed that gross-total resection should be attempted in a multidisciplinary skull base center before providing radiation therapy. EEAs should be considered as the gold-standard approach for upper/middle clival lesions based on the satisfactory surgical outcome, but OAs remain important tools for large complex chordomas.

Laser thermal therapy: real-time MRI-guided and computer-controlled procedures for metastatic brain tumors.

BACKGROUND AND OBJECTIVE: We report the final results of a pilot clinical trial exploring the safety and feasibility of real-time magnetic resonance-guided laser-induced thermal therapy (MRgLITT) for treatment of resistant focal metastatic intracranial tumors. STUDY DESIGN: In patients with chemotherapy, whole-brain radiation, and radiosurgery resistant metastatic intracranial tumors, minimally invasive stereotaxic placement of a saline-cooled interstitial fiberoptic laser applicator under local anesthesia was followed by laser irradiation during continuous magnetic resonance imaging (MRI) scanning. A computer workstation extracted real-time temperature-sensitive information for feedback control over laser delivery. A total of 15 metastatic tumors were treated in 7 patients. Patients were followed with physical exam and imaging for 30 months. RESULTS: In all cases, the procedure was well tolerated, and patients were discharged home within 24 hours. Follow-up imaging at up to 30 months showed an acute increase in apparent lesion volume followed by a gradual and steady decrease. No tumor recurrence within thermal ablation zones was noted. Kaplan-Meier analysis indicated that the median survival was 19.8 months. CONCLUSION: Real-time magnetic resonance (MR) guidance of laser-induced thermal therapy (LITT) offers a high level of control. This tool therefore enables a minimally invasive option for destruction and treatment of resistant focal metastatic intracranial tumors. MR-guided LITT appears to provide a safe and potentially effective treatment for recurrent focal metastatic brain disease. A larger phase II and III series would be of interest to quantify potential median survival advantage.

Transnasal endoscopic odontoidectomy after occipito-cervical fusion during the same operative setting--technical note.

Recently, a purely transnasal endoscopic approach (TNEA) for decompression of the anterior cranio-cervical junction has been described. At present, there is only a limited number of patients having been operated on in a few specialized centers. The possibilities, safety, and limits of this approach are still under investigation. The relationship between TNEA and occipito-cervical fusion, especially, which may typically be considered in this kind of pathologies, should be further elucidated. So far, the feasibility of TNEA after previous occipito-cervical fusion has only been reported for a single case. In that case, there was a posterior atlanto-axial subluxation and basilar invagination. In the present paper, another example of a surgical procedure of TNEA after previous posterior fusion during the same operative setting is given. It differs from the other case concerning the pathophysiology. In fact, here, there was anterior atlanto-axial subluxation and no basilar invagination. The possibilities and limits of this novel approach are thoroughly discussed. Special interest is given to the problem of CCJ instability and previous occipito-cervical fusion. Technical hints and pitfalls are described in detail.

Study of dural suture watertightness: an in vitro comparison of different sealants.

BACKGROUND: CSF leakages constitute a major complication of intradural procedures, especially for posterior fossa and skull base surgery. Dural suture watertightness is a decisive issue, and neurosurgeons routinely use different products to reinforce their dural closure. We have designed an experimental system capable of testing CSF leak pressure levels in order to compare two types of sutures in vitro and particularly four different sealants. METHODS: Twenty-five fresh human cadaveric dural samples were removed and prepared for testing in a pressure chamber system connected to a hydraulic pressure motor. CSF leak levels were objectively registered. First, simple interrupted stitches were compared to running simple closure on 50-mm linear suture. Secondly, four sealants (two sealants/glues, Bioglue®, Duraseal®; two haemostatics, Tachosil®, Tissucol®) were tested. Statistical analysis was performed with paired Student's t-test. RESULTS: No significant difference between interrupted closure and running suture was observed (p = 0.079). All sealants increased the watertightness of the suture significatively. However, comparison of the means of the differences for each product revealed large variations. In the conditions of our experiment, one sealant (Duraseal®) and one haemostatic (Tachosil®) seemed to show better results. We observed two different types of leakage: at the dura-sealant interface and through the sealant itself. CONCLUSIONS: We have developed an experimental device capable of testing dural closure watertightness. Interrupted stitch suturing seemed no different from running simple closure. On the contrary, the sealants tested show different watertightness capacities.

Endoscopy skull-base resection for ethmoid adenocarcinoma and olfactory neuroblastoma.

STATEMENT OF PROBLEM: Olfactory neuroblastoma (ON) and ethmoid adenocarcinoma (AC) are rare sinonasal malignancies that often involve the skull base. Standard surgical treatment is craniofacial resection (CFR), which allows for efficient removal but entails significant morbidity and mortality. Because expanded endoscopy nasal approaches are newly developed, we aimed to describe the procedure in patients with ON and AC and compare it with CFR in terms of efficiency and morbidity. METHODS: This work reports on a retrospective series of 16 patients with AC and ON treated endoscopically with anterior skull-base resection in a single institution over 9 years. Invasion of the frontal sinus, massive extension to the cerebral parenchyma, spread of the tumour above the orbits or lysis of anterior facial skeleton were contraindications for endoscopy resection. RESULTS: Of the 16 patients, 11 had AC and 5 ON. In total, 37.5% (6) exhibited skull-base invasion. All patients had postoperative radiotherapy. In the early postoperative period, one patient experienced delayed seizure due to a minor subdural hematoma. Two delayed complications were observed: one encephalocele related to inappropriate postoperative care, which required revision surgery, and one extended radionecrosis. Five-year disease-free survival was 83% and 5-year recurrence-free survival 58%. Local control rate was 91% for AC and 100% for ON. CONCLUSIONS: With low perioperative morbidity and efficient local control, ethmoidectomy combined with anterior skull-base resection is a promising approach for managing selected cases of AC and ON. These findings need further investigation with prolonged follow-up.

Tumor Growth Rate as a New Predictor of Progression-Free Survival After Chordoma Surgery.

BACKGROUND: Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor's volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types. OBJECTIVE: To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence. METHODS: A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo. RESULTS: A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P < .0001). TGR ≥ 10.12%/m (odds ratio = 26, P = .001) was observed more frequently in recurrent chordoma. In a subgroup analysis, we found that the association of Ki-67 labeling index ≥ 6% and TGR ≥ 10.12%/m was correlated with recurrence (P = .0008). CONCLUSION: TGR may be considered as a preoperative radiological indicator of tumor proliferation and seems to preoperatively identify more aggressive tumors with a higher tendency to recur. Our findings suggest that the therapeutic strategy and clinical-radiological follow-up of patients with chordoma can be adapted also according to this new parameter.

Sinking skin flap syndrome and paradoxical herniation after hemicraniectomy for malignant hemispheric infarction.

BACKGROUND AND PURPOSE: "Sinking skin flap" (SSF) syndrome is a rare complication after large craniectomy that may progress to "paradoxical" herniation as a consequence of atmospheric pressure exceeding intracranial pressure. The prevalence and characteristics of SSF syndrome after hemicraniectomy for malignant infarction of the middle cerebral artery are not well known. METHODS: We analyzed a prospective cohort of 27 patients who underwent hemicraniectomy for malignant middle cerebral artery infarction. All had a clinical and brain imaging follow-up at 3 months and were followed until cranioplasty. RESULTS: Three of 27 patients (11%) had, at 3 to 5 months posthemicraniectomy, SSF syndrome with severe orthostatic headache as the main symptom. In addition, 4 patients (15%) had radiological SSF syndrome but no clinical symptoms except partial seizures in one. Patients with SSF syndrome had a smaller surface of craniectomy (76.2 cm(2) versus 88.7 cm(2), P=0.05) and a tendency toward larger infarct volume, an older age, and a longer delay to cranioplasty than those without this syndrome. CONCLUSIONS: SSF syndrome either clinically symptomatic or asymptomatic affects one fourth of patients 3 to 5 months after hemicraniectomy for malignant middle cerebral artery infarction. It should be diagnosed as early as possible to avoid progression to a paradoxical herniation.

Histological and biomechanical study of dura mater applied to the technique of dura splitting decompression in Chiari type I malformation.

Many techniques are described to treat Chiari type I malformation. One of them is a splitting of the dura, removing its outer layer only to reduce the risks of cerebrospinal fluid (CSF) leak. We try to show the effectiveness of this technique from histological and biomechanical observations of dura mater. Study was performed on 25 posterior fossa dura mater specimens from fresh human cadavers. Dural composition and architecture was assessed on 47 transversal and sagittal sections. Uniaxial mechanical tests were performed on 22 dural samples (15 entire, 7 split) to focus on the dural macroscopic mechanical behavior comparing entire and split samples and also to understand deformation mechanisms. We finally created a model of volume expansion after splitting. Dura mater was composed of predominant collagen fibers with a few elastin fibers, cranio-caudally orientated. The classical description of two distinct layers remained inconstant. Biomechanical tests showed a significant difference between entire dura, which presents an elastic fragile behavior, with a small domain where deformation is reversible with stress, and split dura, which presents an elasto-plastic behavior with a large domain of permanent strain and a lower stress level. From these experimental results, the model showed a volume increase of approximately 50% below the split area. We demonstrated the capability of the split dura mater to enlarge for suitable stress conditions and we quantified it by biomechanical tests and experimental model. Thus, dural splitting decompression seems to have a real biomechanical substrate to envision the efficacy of this Chiari type I malformation surgical technique.

Supratentorial craniotomy complicated by an homolateral remote cerebellar hemorrhage and a controlateral perisylvian infarction: case report.

The authors present the case of a 49-year-old male patient with a right remote cerebellar hemorrhage and left perisylvian venous infarction complicating a right supratentorial craniotomy for temporal meningomia resection. These two events may result from a functional stenosis (due to perioperative brainstem sag) of the junction between the vein of Galen and the straight sinus. Remote cerebellar hemorrhage could then be explained by infarction in the territory of cerebellar veins emptying in the vein of Galen, and the left perisylvian infarction could be caused by venous infarction in the territory of a dominant superficial sylvian vein emptying in the basal vein. This hypothesis could shed light on the pathophysiology of remote cerebellar hemorrhage.