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Neuronal Protection Against Excitotoxicity

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Occipitoaxial spinal interarticular stabilization with vertebral artery preservation for atlantal lateral mass failure

Lukas Bobinski, Marc Levivier, and John M. Duff

The treatment of craniocervical instability caused by diverse conditions remains challenging. Different techniques have been described to stabilize the craniocervical junction. The authors present 2 cases in which tumoral destruction of the C-1 lateral mass caused craniocervical instability. A one-stage occipitoaxial spinal interarticular stabilization (OASIS) technique with titanium cages and posterior occipitocervical instrumentation was used to reconstruct the C-1 lateral mass and stabilize the craniocervical junction. The ipsilateral vertebral artery was preserved.

The OASIS technique offers single-stage tumor resection, C-1 lateral mass reconstruction, and stabilization with a loadsharing construct. It could be an option in the treatment of select cases of C-1 lateral mass failure.

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Gamma knife radiosurgery for brainstem arteriovenous malformations: preliminary results

Nicolas Massager, Jean Régis, Douglas Kondziolka, Théodore Njee, and Marc Levivier

Object. This study was undertaken to assess the efficacy and safety of gamma knife radiosurgery (GKS) for the treatment of arteriovenous malformations (AVMs) located within the brainstem.

Methods. The results of GKS performed in 87 patients with brainstem AVMs at two centers with experienced physicians are reviewed. The mean patient age was 37 years and the population included 19 children. The male/female ratio was 56:31. The malformation was located in the upper brainstem in 52 patients. Seventy-four percent of the patients had suffered a hemorrhage before GKS. For 70% of the patients no other treatment had been proposed before GKS. The mean AVM volume was 1.3 cm3. The lesions were treated with one to eight isocenters, with a margin dose ranging between 11.5 Gy and 30 Gy. The mean clinical follow-up period was 3.2 years. Ninety-five percent of the patients improved or remained neurologically stable. Rebleeding occurred in three patients at 3, 6, and 16 months, respectively, after GKS. Two patients in whom rebleeding occured recovered, and one died. The AVM obliteration rate was 63% at 2 years and 73% at 3 years after GKS. A second GKS was performed in six patients in whom only partial obliteration was demonstrated on angiography 3 years after the first procedure.

Conclusions. Gamma knife radiosurgery may be a valuable first-choice therapy for the treatment of AVMs located within the brainstem.

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Radiation Necrosis or Recurrence

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Morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery

György T. Szeifert, Nicolas Massager, Jacques Brotchi, and Marc Levivier

Object. The purpose of this study was to demonstrate positron emission tomography (PET), histological, and immunohistochemical data supporting the notion of morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery (GKS).

Methods. The 11C- methionine-PET activity, Ki-67 labeling index (LI), and p53 protein expression were examined using immunohistochemical methods to assess tumor proliferative capacity. Tissue samples were obtained before and after radiosurgery in a patient with a malignant (Grade III) cerebellar astrocytoma.

Positron emission tomography scans obtained 5.5 months following radiosurgery were suggestive of decreased tumor proliferative capacity and radionecrosis. Histological examination of tumor tissue removed 42 months before GKS was characteristic of a diffuse Grade III astrocytoma in every part of the resected tumor. Similar material removed 6 months after GKS was consistent with a Grade II astrocytoma in the great majority of the resected tumor.

Conclusions. Histopathological examination showed positive phenotypic modification (redifferentiation) consistent with a Grade II astrocytoma in the majority of tumor specimens after radiosurgery. After GKS both the Ki-67 LI and p53 reaction decreased considerably as did 11C methionine uptake. Because p53 is one of the essential genes involved in the radiation response, mutations induced by the ionizing effect of gamma rays might promote partial repair of this gene's tumor suppressor function.

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Synovial cysts of the lumbar spine: surgery-related results and outcome

Benoit Pirotte, Nicolay Gabrovsky, Nicolas Massager, Marc Levivier, Philippe David, and Jacques Brotchi

Object

The authors conducted a study to determine the surgery-related results and outcomes in patients with synovial cysts of the lumbar spine. They emphasize several specific characteristics useful in clinical management.

Methods

Forty-six consecutive patients with 54 lumbar synovial cysts underwent surgery between 1990 and 2001. A retrospective analysis of the clinical presentation and follow-up data, radiological findings, and surgical techniques was performed. Clinical presentation was dominated by acute or subacute sciatic pain. No specific symptom allowed differentiation of synovial cyst from a lumbar disc herniation. Computerized tomography scanning aided in establishing the correct diagnosis in 19 of 30 cases and magnetic resonance (MR) imaging did so in all cases. Three of the 46 patients presented with bilateral lumbar synovial cysts. The L4–5 level was affected in 61%, and radiological signs of disc degeneration/spondylosis were observed in 54% of the patients. Immediate symptom relief without local recurrence was obtained by complete microsurgical excision in which bipolar coagulation was used to remove the synovial membrane and in which the interapophysial joint was preserved. During the 1st postoperative year, a newly formed symptomatic synovial cyst developed on the contralateral side or at a superior vertebral level in five patients. They underwent surgery; results were good and there was no recurrence.

Conclusions

The findings in this series suggest that synovial cysts can occur at multiple lumbar sites within a short period of time and could be predisposed to developing in certain individuals, predominantly in women older than 40 years of age. Postoperative follow up is recommended and MR imaging mandatory in cases of recurrent sciatica.

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The Zeiss-MKM system for frameless image-guided approach in epidural motor cortex stimulation for central neuropathic pain

Benoit Pirotte, Philippe Voordecker, Freddy Joffroy, Nicolas Massager, David Wikler, Danielle Baleriaux, Marc Levivier, and Jacques Brotchi

Object

Twelve patients (seven female, and five male, mean age 55.6 years) suffering from refractory central (ischemic/traumatic [eight cases]) and neuropathic pain (trigeminal neuropathy [four cases]) underwent surgery for the implantation of an epidural motor cortex stimulation (MCS) device in which the authors used a frameless neuronavigation system, the Zeiss-MKM microscope.

Methods

The authors assessed the spatial accuracy of the neuronavigation system and its potential contribution to improve the quality of targeting pain. In these patients, the positions of the central sulcus, defined by stereotactic magnetic resonance MR imaging, intraoperative somatosensory evoked potentials (SSEPs) and subdural visual verification, were correlated into the stereotactic neuronavigation planning procedure. The mean spatial accuracy of distance between (MR) imaging–defined and actual central sulcus was 2.4 mm (range 5–10 mm). The intraoperative SSEP-defined central sulcus was close to that defined by MR imaging (mean distance 6.4 mm). Although very precise, intra-operative SSEP recordings were impaired by artifacts and wave attenuation in six of the 12 patients. Stereotactic correlations between anatomical and functional data in the navigation system corrected final targeting in 10 of 12 cases. Pain relief was obtained in eight patients. Indeed, inappropriate targeting probably explains the reported variable success rate of MCS and certainly underestimates the actual efficacy.

Conclusions

Since intraoperative SSEP monitoring has, for many years, been considered the standard procedure to approach motor target, the development of an accurate stereotactic image guidance system could help to increase the efficacy of MCS on the alleviation of pain. The excellent spatial accuracy provided by the Zeiss-MKM navigation system allows precise data correlations that represent a remarkable means to validate functional MR imaging as an alternative to SSEP. The authors believe that developing stereotactic image guidance with such a navigation system could improve the success rate of MCS.

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Use of the Leksell gamma knife C with automatic positioning system for the treatment of meningioma and vestibular schwannoma

Marc Levivier, Jose Lorenzoni, Nicolas Massager, Salvador Ruiz, Daniel Devriendt, and Jacques Brotchi

Object

The authors report their experience using the Leksell gamma knife C (GK-C) for the treatment of meningioma and vestibular schwannoma (VS).

Methods

In December 1999, the first commercially available clinical GK-C was installed at the Université Libre de Bruxelles (Erasme Hospital, Brussels, Belgium). In January 2000, the system was upgraded and equipped with the automatic positioning system (APS). Between February 2000 and February 2003, the APS-equipped GK-C was used to perform 532 radiosurgical treatments, including those in 97 meningiomas and 101 VSs.

Meningioma and VS represent 18 and 19%, respectively, of lesions in patients treated with GK-C at the authors' center. The mean number of isocenters per lesion was 9.5 (range 1–36): 18.1 (range 1–36) for meningioma and 12.8 (range 1–27) for VS. In 77.6% of the cases, the authors used a single helmet of collimators (55.5% in meningioma and 74.3% in VS). The most frequently used collimator size was 4 mm (46.7%). Whereas it was 4 mm in cases of VS (64.3%), it was 8 mm in cases of meningioma (41.6%). The APS could be used in 86% of the cases, either alone (79%) or in combination with trunnions (7%). There was a difference in the APS-based treatment success rate in meningiomas (85%) and VSs (94%). A significant difference was also noted in the conformity of the radiosurgical treatments between the two lesions.

Conclusions

The APS-equipped GK-C represents an evolutionary step in radiosurgery. It requires adjustments by the treating team for its specific limitations, which vary among indications, as exemplified by the differences inherent between meningioma and VS in this series.

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Systematic review and meta-analysis of the technique of subtotal resection and stereotactic radiosurgery for large vestibular schwannomas: a “nerve-centered” approach

Daniele Starnoni, Roy Thomas Daniel, Constantin Tuleasca, Mercy George, Marc Levivier, and Mahmoud Messerer

OBJECTIVE

During the last decade, the primary objective for large vestibular schwannoma (VS) management has progressively shifted, from tumor excision to nerve preservation by using a combined microsurgical and radiosurgical approach. The aim of this study was to provide a systematic review and meta-analysis of the available literature regarding the combined strategy of subtotal resection (STR) followed by stereotactic radiosurgery (SRS) for large VSs.

METHODS

The authors performed a systematic review and meta-analysis in compliance with the PRISMA guidelines for article identification and inclusion using the PubMed, Embase, and Cochrane databases. Established inclusion criteria were used to screen all identified relevant articles published before September 2017 without backward date limit.

RESULTS

The authors included 9 studies (248 patients). With a weighted mean follow-up of 46 months (range 28–68.8 months), the pooled rate of overall tumor control was 93.9% (95% CI 91.0%–96.8%). Salvage treatment (second STR and/or SRS) was necessary in only 13 (5.24%) of 18 patients who experienced initial treatment failure. According to the House-Brackmann (HB) grading scale, functional facial nerve preservation (HB grade I–II) was achieved in 96.1% of patients (95% CI 93.7%–98.5%). Serviceable hearing after the combined approach was preserved in 59.9% (95% CI 36.5%–83.2%).

CONCLUSIONS

A combined approach of STR followed by SRS was shown to have excellent clinical and functional outcomes while still achieving a tumor control rate comparable to that obtained with a total resection. Longer-term follow-up and larger patient cohorts are necessary to fully evaluate the rate of tumor control achieved with this approach.

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Gamma knife surgery for idiopathic trigeminal neuralgia performed using a far-anterior cisternal target and a high dose of radiation

Nicolas Massager, José Lorenzoni, Daniel Devriendt, Françoise Desmedt, Jacques Brotchi, and Marc Levivier

Object. Gamma knife surgery (GKS) has emerged as a suitable treatment of pharmacologically resistant idiopathic trigeminal neuralgia. The optimal radiation dose and target for this therapy, however, remain to be defined. The authors analyzed the results of GKS in which a high dose of radiation and a distal target was used, to determine the best parameters for this treatment.

Methods. The authors evaluated results in 47 patients who were treated with this approach. All patients underwent clinical and magnetic resonance imaging examinations at 6 weeks, 6 months, and 1 year post-GKS. Fifteen potential prognostic factors associated with favorable pain control were studied.

The mean follow-up period was 16 months (range 6–42 months). The initial pain relief was excellent (100% pain control) in 32 patients, good (90–99% pain control) in seven patients, fair (50–89% pain control) in three patients, and poor (< 50% pain control) in five patients. The actuarial curve of pain relief displayed a 59% rate of excellent pain control and a 71% excellent or good pain control at 42 months after radiosurgery. Radiosurgery-induced facial numbness was bothersome for two patients and mild for 18 patients. Three prognostic factors were found to be statistically significant factors for successful pain relief: a shorter distance between the target and the brainstem, a higher radiation dose delivered to the brainstem, and the development of a facial sensory disturbance after radiosurgery.

Conclusions. To optimize pain control and minimize complications of this therapy, we recommend that the nerve be targeted at a distance of 5 to 8 mm from the brainstem.