Pressure Cooker Technique for Endovascular Treatment of Spinal Arteriovenous Fistulas: Experience in 15 Cases.

BACKGROUND AND PURPOSE: Spinal arteriovenous fistulas are challenging to cure by endovascular means, with a risk of incomplete occlusion or delayed recurrence. The authors report herein their preliminary experience using the pressure cooker technique for the embolization of spinal arteriovenous fistulas. MATERIALS AND METHODS: Fifteen patients (8 men; mean age, 60.3 years) underwent an endovascular treatment of a spinal arteriovenous fistula (12 dural spinal arteriovenous fistulas and 3 epidural spinal arteriovenous fistulas) in 2 different institutions using the pressure cooker technique. Two microcatheters could be navigated in the segmental artery in all patients using 2 guiding catheters. A proximal plug was achieved with highly concentrated cyanoacrylate ± coils. The liquid embolic agent injected to cure the fistula was diluted cyanoacrylate (n = 11) or ethylene-vinyl alcohol (n = 4). Technical and clinical complications were systematically recorded. Clinical and angiographic outcomes were systematically evaluated at follow-up. RESULTS: One (6.7%) procedure-related complication was recorded, which consisted of a transient radicular deficit, related to nerve root ischemia. Clinical improvement was observed in 10/14 (71%) patients for whom clinical follow-up was available. Complete spinal arteriovenous fistula occlusion on a follow-up angiography was observed in 11/12 patients (91.7%) for whom angiographic follow-up was available. One patient (8.3%) presented with a delayed recurrence at 29 months. CONCLUSIONS: The pressure cooker technique is feasible, with either glue or ethylene-vinyl alcohol, for the embolization of spinal arteriovenous fistulas. Our results suggest the safety and effectiveness of this technique.

[Acute visual loss related to sphenoid meningioma]. / Troubles visuels aigus associés aux méningiomes sphénoïdaux.

Meningiomas represent about 20% of intracranial tumors. Involvement of the medial sphenoid wing includes anterior clinoid, cavernous sinus and superior orbital fissure meningiomas. Due to the proximity of these tumors to the optic nerve, typically progressive unilateral vision loss, over several months to years, is the classic clinical presentation. We report three cases of acute monocular vision loss, two transient and one permanent, ipsilateral to a sphenoid meningioma. Ophthalmological involvement with sphenoid meningiomas is most often chronic, due to interruption of axoplasmic flow and demyelination of the optic nerve by local compression. However, vascular involvement with ischemia of the optic nerve or transient low blood flow secondary to compression of the carotid branches vascularizing these structures is another possible mechanism. In our series, two patients had amaurosis fugax, and one patient had sudden, persistent visual loss in relation to acute anterior ischemic optic neuropathy on the side of the meningioma. The mean age of patients with acute visual manifestations was 62 years. These ischemic and non-compressive visual symptoms, ipsilateral to sphenoid meningiomas, are difficult to interpret. Whether these temporary visual disturbances of vascular origin should be considered an early sign of future severe or permanent visual impairment when no optic nerve compression is observed is not certain. The place of these acute visual disturbances in the therapeutic decision, particularly surgical, remains to be defined. Larger multicentric prospective studies are needed to better understand the role of local circulatory factors attributable to meningioma in the occurrence of these acute visual signs.

Progestin-associated shift of meningioma mutational landscape.

Background: Meningiomas are the most common primary tumor of the central nervous system. The relationship between meningioma and progestins is frequently mentioned but has not been elucidated. Patients and methods: We identified 40 female patients operated for a meningioma after long-term progestin therapy and performed targeted next generation sequencing to decipher the mutational landscape of hormone-related meningiomas. A published cohort of 530 meningiomas in women was used as a reference population. Results: Compared with the control population of meningiomas in women, progestin-associated meningiomas were more frequently multiple meningiomas [19/40 (48%) versus 25/530 (5%), P < 10-12] and located at the skull base [46/72 (64%) versus 241/481 (50%), P = 0.03]. We found a higher frequency of PIK3CA mutations [14/40 (35%) versus 18/530 (3%), P < 10-8] and TRAF7 mutations [16/40 (40%) versus 140/530 (26%), P < 0.001] and a lower frequency of NF2-related tumors compared with the control population of meningiomas [3/40 (7.5%) versus 169/530 (32%), P < 0.001]. Conclusion: This shift in mutational landscape indicates the vulnerability of certain meningeal cells and mutations to hormone-induced tumorigenesis. While the relationship between PIK3CA mutation frequency and hormone-related cancers such as breast and endometrial cancer is well-known, this hormonally induced mutational shift is a unique feature in molecular oncology.

Ex vivo optimisation of a heterogeneous speed of sound model of the human skull for non-invasive transcranial focused ultrasound at 1 MHz.

Transcranial brain therapy has recently emerged as a non-invasive strategy for the treatment of various neurological diseases, such as essential tremor or neurogenic pain. However, treatments require millimetre-scale accuracy. The use of high frequencies (typically ≥1 MHz) decreases the ultrasonic wavelength to the millimetre scale, thereby increasing the clinical accuracy and lowering the probability of cavitation, which improves the safety of the technique compared with the use of low-frequency devices that operate at 220 kHz. Nevertheless, the skull produces greater distortions of high-frequency waves relative to low-frequency waves. High-frequency waves require high-performance adaptive focusing techniques, based on modelling the wave propagation through the skull. This study sought to optimise the acoustical modelling of the skull based on computed tomography (CT) for a 1 MHz clinical brain therapy system. The best model tested in this article corresponded to a maximum speed of sound of 4000 m.s-1 in the skull bone, and it restored 86% of the optimal pressure amplitude on average in a collection of six human skulls. Compared with uncorrected focusing, the optimised non-invasive correction led to an average increase of 99% in the maximum pressure amplitude around the target and an average decrease of 48% in the distance between the peak pressure and the selected target. The attenuation through the skulls was also assessed within the bandwidth of the transducers, and it was found to vary in the range of 10 ± 3 dB at 800 kHz and 16 ± 3 dB at 1.3 MHz.

In Vivo Measurement of Brain Tumor Elasticity Using Intraoperative Shear Wave Elastography.

Purpose: Objective Shear wave elastography (SWE) enabled living tissue assessment of stiffness. This is routinely used for breast, thyroid and liver diseases, but there is currently no data for the brain. We aim to characterize elasticity of normal brain parenchyma and brain tumors using SWE. Materials and Methods: Patients with scheduled brain tumor removal were included in this study. In addition to standard ultrasonography, intraoperative SWE using an ultrafast ultrasonic device was used to measure the elasticity of each tumor and its surrounding normal brain. Data were collected by an investigator blinded to the diagnosis. Descriptive statistics, box plot analysis as well as intraoperator and interoperator reproducibility analysis were also performed. Results: 63 patients were included and classified into four main types of tumor: meningiomas, low-grade gliomas, high-grade gliomas and metastasis. Young's Modulus measured by SWE has given new insight to differentiate brain tumors: 33.1 ±â€Š5.9 kPa, 23.7 ±â€Š4.9 kPa, 11.4 ±â€Š3.6 kPa and 16.7 ±â€Š2.5 kPa, respectively, for the four subgroups. Normal brain tissue has been characterized by a reproducible mean stiffness of 7.3 ±â€Š2.1 kPa. Moreover, low-grade glioma stiffness is different from high-grade glioma stiffness (p = 0.01) and normal brain stiffness is very different from low-grade gliomas stiffness (p < 0.01). Conclusion: This study demonstrates that there are significant differences in elasticity among the most common types of brain tumors. With intraoperative SWE, neurosurgeons may have innovative information to predict diagnosis and guide their resection.

[Focused ultrasound therapy: current status and potential applications in neurosurgery]. / La thérapie par ultrasons focalisés : état actuel et applications potentielles en neurochirurgie.

High Intensity Focused Ultrasound (HIFU) therapy is an innovative approach for tissue ablation, based on high intensity focused ultrasound beams. At the focus, HIFU induces a temperature elevation and the tissue can be thermally destroyed. In fact, this approach has been tested in a number of clinical studies for the treatment of several tumors, primarily the prostate, uterine, breast, bone, liver, kidney and pancreas. For transcranial brain therapy, the skull bone is a major limitation, however, new adaptive techniques of phase correction for focusing ultrasound through the skull have recently been implemented by research systems, paving the way for HIFU therapy to become an interesting alternative to brain surgery and radiotherapy.

[An unusual cause of compressive optic neuropathy]. / Une cause inhabituelle de neuropathie optique compressive.

Clinical manifestations of hydrocephalus vary according to the level of intracranial pressure, the speed of onset, and the etiological mechanism involved. We report the case of a 32-year-old patient with isolated compressive optic neuropathy associated with a dilated third ventricle, revealing congenital hydrocephalus.

[Paraganglioma of the cauda equina region: Report of six cases and review of the literature]. / Paragangliomes de la queue de cheval : à propos de six cas et revue de la littérature.

BACKGROUND AND PURPOSE: Paragangliomas of the cauda equina are rare tumors. The standard treatment is surgical resection. Our study aims to compare our clinical, radiological, prognostic data to the literature and to offer management and follow-up recommendations. METHODS: In this retrospective study, six patients with paraganglioma of the cauda equina region were treated. Symptoms included radicular nerve pain and low back pain with occasional sphincter dysfunction and motor deficit. MRI showed well-circumscribed lesions with homogeneous enhancement following gadolinium injection. Treatment involved complete surgical resection of the tumor under electrophysiological control. In addition to the characteristics of the tumor, we assessed operating results as well as postoperative morbidity and follow-up. RESULTS: All patients had complete removal of the tumor, which required in most cases the resection of the carrying root. The intervention allowed a regression of the initial symptoms, with possible postoperative regressive sphincter disorders. Clinical and radiological follow-up (19 months on average), showed no tumor recurrence. CONCLUSIONS: The reference treatment of these tumors is complete surgical resection, usually requiring the sacrifice of the carrying nerve root. Intra-operative nerve roots stimulation is recommended to reduce the risk of motor deficit linked to this radical treatment. A long-term clinical and radiological follow-up is recommended.

Effect of continuous cerebrospinal fluid drainage on therapeutic intensity in severe traumatic brain injury.

BACKGROUND: The aim of this study in patients with traumatic brain injury (TBI) was to assess the effectiveness of continuous cerebrospinal fluid (CSF) drainage in controlling intracranial pressure (ICP) and minimizing the use of other ICP-lowering interventions potentially associated with serious adverse events. METHODS: We studied 20 TBI patients. In each patient, we compared four consecutive 12-hour periods covering the 24 hours before CSF drainage (NoDr1 and NoDr2) and the 24 first hours of drainage (Dr1 and Dr2). During each period, we recorded ICP, cerebral perfusion pressure (CPP), sedation, propofol infusion rate, and number of hypertonic saline boluses. RESULTS: With continuous CSF drainage, ICP decreased significantly from 18 ± 6 mmHg (NoDr1) and 19 ± 7 mmHg (NoDr2) to 11 ± 5 mmHg (Dr1) and 12 ± 7 mmHg (Dr2). CPP increased significantly with drainage. Drainage led to a significant decrease in the number of hypertonic saline boluses required for ICP elevation, from 35 in 16 patients (80%) (NoDr1/2) to eight in five patients (25%) (Dr3/4). Drainage was not associated with changes in the midazolam or sufentanil infusion rates. The propofol infusion rate was non-significantly lower with drainage. No significant differences in serum sodium, body temperature, or PaCO(2) occurred across the four 12-hour periods. CONCLUSION: CSF drainage may not only lower ICP levels, but also decreases treatment intensity during the 24 hours following EVD placement in TBI patients. Because EVD placement may be associated with adverse event, the exact role for each of the available ICP-lowering interventions remains open to discussion.

MR-guided adaptive focusing of therapeutic ultrasound beams in the human head.

PURPOSE: This study aims to demonstrate, using human cadavers the feasibility of energy-based adaptive focusing of ultrasonic waves using magnetic resonance acoustic radiation force imaging (MR-ARFI) in the framework of non-invasive transcranial high intensity focused ultrasound (HIFU) therapy. METHODS: Energy-based adaptive focusing techniques were recently proposed in order to achieve aberration correction. The authors evaluate this method on a clinical brain HIFU system composed of 512 ultrasonic elements positioned inside a full body 1.5 T clinical magnetic resonance (MR) imaging system. Cadaver heads were mounted onto a clinical Leksell stereotactic frame. The ultrasonic wave intensity at the chosen location was indirectly estimated by the MR system measuring the local tissue displacement induced by the acoustic radiation force of the ultrasound (US) beams. For aberration correction, a set of spatially encoded ultrasonic waves was transmitted from the ultrasonic array and the resulting local displacements were estimated with the MR-ARFI sequence for each emitted beam. A noniterative inversion process was then performed in order to estimate the spatial phase aberrations induced by the cadaver skull. The procedure was first evaluated and optimized in a calf brain using a numerical aberrator mimicking human skull aberrations. The full method was then demonstrated using a fresh human cadaver head. RESULTS: The corrected beam resulting from the direct inversion process was found to focus at the targeted location with an acoustic intensity 2.2 times higher than the conventional non corrected beam. In addition, this corrected beam was found to give an acoustic intensity 1.5 times higher than the focusing pattern obtained with an aberration correction using transcranial acoustic simulation-based on X-ray computed tomography (CT) scans. CONCLUSIONS: The proposed technique achieved near optimal focusing in an intact human head for the first time. These findings confirm the strong potential of energy-based adaptive focusing of transcranial ultrasonic beams for clinical applications.

In vivo bubble nucleation probability in sheep brain tissue.

Gas nuclei exist naturally in living bodies. Their activation initiates cavitation activity, and is possible using short ultrasonic excitations of high amplitude. However, little is known about the nuclei population in vivo, and therefore about the rarefaction pressure required to form bubbles in tissue. A novel method dedicated to in vivo investigations was used here that combines passive and active cavitation detection with a multi-element linear ultrasound probe (4-7 MHz). Experiments were performed in vivo on the brain of trepanated sheep. Bubble nucleation was induced using a focused single-element transducer (central frequency 660 kHz, f-number = 1) driven by a high power (up to 5 kW) electric burst of two cycles. Successive passive recording and ultrafast active imaging were shown to allow detection of a single nucleation event in brain tissue in vivo. Experiments carried out on eight sheep allowed statistical studies of the bubble nucleation process. The nucleation probability was evaluated as a function of the peak negative pressure. No nucleation event could be detected with a peak negative pressure weaker than -12.7 MPa, i.e. one order of magnitude higher than the recommendations based on the mechanical index. Below this threshold, bubble nucleation in vivo in brain tissues is a random phenomenon.

[The mystery of prehistoric trepanations: Is neurosurgery the world eldest profession?]. / Le mystère des trépanations préhistoriques : la neurochirurgie serait-elle le plus vieux métier du monde ?

Trepanation is known to be the first surgical procedure ever performed. Its origins date from the Neolithic Age in Europe and the operation was particularly performed in South America at the Pre-Colombian era, a few thousand years later. Based on many archeological studies on trepanned skulls, we compare the differences and similarities of these two periods through epidemiological, topographical, and technical approaches. Signs of bony regeneration are assessed in an attempt to understand the postoperative survival of trepanned patients. The literature in surgery and archeology does not mention the possible relation between trepanations and growing skull fractures. However, it is reasonable to think that these cranial holes, occurring after a pediatric skull fracture, could mimic real trepanation orifices. The possible connections between these two entities are discussed. The etiological hypotheses on prehistoric trepanation are reviewed.

MR-guided transcranial brain HIFU in small animal models.

Recent studies have demonstrated the feasibility of transcranial high-intensity focused ultrasound (HIFU) therapy in the brain using adaptive focusing techniques. However, the complexity of the procedures imposes provision of accurate targeting, monitoring and control of this emerging therapeutic modality in order to ensure the safety of the treatment and avoid potential damaging effects of ultrasound on healthy tissues. For these purposes, a complete workflow and setup for HIFU treatment under magnetic resonance (MR) guidance is proposed and implemented in rats. For the first time, tissue displacements induced by the acoustic radiation force are detected in vivo in brain tissues and measured quantitatively using motion-sensitive MR sequences. Such a valuable target control prior to treatment assesses the quality of the focusing pattern in situ and enables us to estimate the acoustic intensity at focus. This MR-acoustic radiation force imaging is then correlated with conventional MR-thermometry sequences which are used to follow the temperature changes during the HIFU therapeutic session. Last, pre- and post-treatment magnetic resonance elastography (MRE) datasets are acquired and evaluated as a new potential way to non-invasively control the stiffness changes due to the presence of thermal necrosis. As a proof of concept, MR-guided HIFU is performed in vitro in turkey breast samples and in vivo in transcranial rat brain experiments. The experiments are conducted using a dedicated MR-compatible HIFU setup in a high-field MRI scanner (7 T). Results obtained on rats confirmed that both the MR localization of the US focal point and the pre- and post-HIFU measurement of the tissue stiffness, together with temperature control during HIFU are feasible and valuable techniques for efficient monitoring of HIFU in the brain. Brain elasticity appears to be more sensitive to the presence of oedema than to tissue necrosis.

Primary pineal melanoma with leptomeningeal spreading: case report and review of the literature.

OBJECTIVE: Primary melanomas of the pineal region are exceedingly rare and may be difficult to diagnose. Clinical, radiological and pathological features as well as diagnostic procedures are discussed. CASE HISTORY We report herein on a 44-year-old man who presented with uncontrolled epileptic seizures. Magnetic resonance imaging revealed a pineal mass hyperintense on T1-weighted and isointense on T2-weighted sequences with diffuse leptomeningeal involvement and intense homogeneous contrast enhancement after gadolinium administration. A frontal leptomeningeal and cortical biopsy was performed. Histological examination showed a malignant melanocytic tumor cell proliferation expressing Melan-A, but not HMB-45 or S100 protein. Even if we have no proof that the tumor actually arose in the pineal gland, based on the radiological and histological findings, and on the unremarkable dermatologic and ophthalmologic examinations, a primary pineal melanoma with leptomeningeal dissemination was diagnosed. The patient received temozolomide-based chemotherapy followed by whole brain irradiation. The patient died 52 weeks after disease onset and 13 weeks after treatment initiation. CONCLUSION: A diagnosis of pineal melanoma should be considered in the presence of a pineal mass that appears hyperintense on T1-weighted images and hypo- to isointense on T2-weighted images. The diagnosis is provided by pathological examination of tumor specimens obtained at surgical resection or at leptomeningeal biopsy. However, immunochemistry using anti-Melan-A, -S100 protein and/or -HMB45 antibodies on cerebrospinal fluid and leptomeningeal samples may be helpful in diagnosing such a disease. The prognosis of primary pineal melanoma is variable but meningeal spreading carries a dismal prognosis. The best therapeutic management is yet to be defined.

[Early epidural hematoma after CSF shunt for obstructive hydrocephalus]. / Hématome extradural précoce après dérivation interne du liquide céphalorachidien pour hydrocéphalie non communicante.

We present the first case of early epidural hematoma after CSF shunt probably caused by defective material. A 26-year-old man was treated for obstructive hydrocephalus associated with a tonsillar herniation, revealed by headaches and papillary edema. Ventriculoperitoneal shunt was preferred to endoscopic ventriculostomy. Three hours after the operation, the patient fell into a coma, developing a voluminous bifrontal epidural hematoma that was evacuated immediately. The patient completely recovered neurologically. One month later, to treat persistent hydrocephalus, endoscopic ventriculostomy was performed without incident. Then the shunt was removed and an opening threshold close to zero was discovered. Distant MRI showed a reduction in ventricular size, normalization of the tonsils' position and a tumor of the tectal plate. To our knowledge, this is the only case of early epidural hematoma after ventriculoperitoneal shunt. We discuss the choice of treatments for obstructive hydrocephalus and its risks and complications.

High power phased array prototype for clinical high intensity focused ultrasound : applications to transcostal and transcranial therapy.

Bursts of focused ultrasound energy three orders of magnitude more intense than diagnostic ultrasound became during the last decade a noninvasive option for treating cancer from breast to prostate or uterine fibroid. However, many challenges remain to be addressed. First, the corrections of distortions induced on the ultrasonic therapy beam during its propagation through defocusing obstacles like skull bone or ribs remain today a technological performance that still need to be validated clinically. Secondly, the problem of motion artifacts particularly important for the treatment of abdominal parts becomes today an important research topic. Finally, the problem of the treatment monitoring is a wide subject of interest in the growing HIFU community. For all these issues, the potential of new ultrasonic therapy devices able to work both in Transmit and Receive modes will be emphasized. A review of the work under achievement at L.O.A. using this new generation of HIFU prototypes on the monitoring, motion correction and aberrations corrections will be presented.

[Endovascular treatment of vasospasm following subarachnoid aneurysmal haemorrhage]. / Traitements endovasculaires du vasospasme de l'hémorragie méningée anévrysmale.

An endovascular treatment of vasospasm following a subarachnoid aneurysmal haemorrhage is to be implemented if the patient presents clinical or biological symptoms arguing for brain ischemia in conjunction with increased Doppler velocities despite well controlled systemic haemodynamic. Treatment might be either pharmacological or haemodynamic. Calcium and phosphodiesterase inhibitors can be administered. The former could also provide a neuroprotective effect as compared to the latter. In Europe, nimodipine is widely used whereas nicardipine and verapamil are the major molecules administered in North America where iv nimodipine is not FDA approved. Papaverine is less used nowadays because of its short duration of action and of the risk of aggravation of raised intracranial pressure. Balloon angioplasty has a long lasting effect but can be applied only to proximal spasm. Complications of its use are rare but life threatening. In some cases, both the pharmacological approach and the mechanical approach are used in combination.

[Craniopharyngiomas]. / Les craniopharyngiomes.

Craniopharyngiomas are rare benign epithelial tumors, arising from the pituitary stalk or gland and developing in the sellar and suprasellar region, affecting both adults and children. Incidence is 0.5 to 2 new cases per million inhabitants. Clinical features essentially include visual disturbances, endocrine deficiencies, and neurological signs. Initial signs are often visual loss and increased intracranial pressure in children, growth and pubertal delay in teenagers, visual disturbances or cognitive impairment in adults. Diagnosis is made on MRI and CT scan, demonstrating a sellar or suprasellar tumor, heterogeneous, with frequent calcifications. Craniopharyngiomas can be classified depending on their locations from the sella, the diaphragma sellae, and upon their origins from the pituitary stalk or the infundibulum. They can also be classified depending on the location from the optic chiasm and the third ventricle. This classification allows surgical series comparison, which is of importance since developments and extensions of the tumor can explain surgical difficulties. The management of this lesion is still controversial. Because it is an extra-cerebral benign lesion, the ideal goal of treatment should be complete tumor removal with improvement of altered visual functions, minimal deterioration of endocrine function, and no neuropsychological impairment. But the situation of the tumor, its relationship with third ventricle, hypothalamus, optic tract, vascular structures make its removal often difficult. However, great progresses have been realized in surgical treatment, resulting in a dramatic improvement of the prognosis of craniopharyngiomas. Nowadays, one can expect total removal in 60 to 70% of patients, subtotal removal in 20 to 30%, and partial removal in 10%. When total removal is impossible, radiotherapy may reduce the risk of a poor evolution. Recurrences are a problem in 15% of patients with total removal, 35% in subtotal removal, 70% in partial removal. If radiotherapy has not been performed as first treatment, it is efficient in 80% of recurrences. Long term follow up is necessary in these patients, due to medical management of endocrine, visual and psychological problems, and risk of late recurrence. With close involvement in this management, most of patients may enjoy a good outcome, 80% being able to return to normal active life.