Jacques Brotchi

Objective: To evaluate retrospectively our surgical technique and results in the management of anterolateral foramen magnum (FM) meningioma with the posterolateral (far-lateral) retrocondylar or partial transcondylar approach, and to adapt our prospective management regarding surgical indication, epidural transposition of the vertebral artery (VA), drilling of the occipital condyle, and extent of tumor resection. Methods: From 1992–2008, 16 women and 10 men (ages 28–82 years) were referred for anterolateral FM meningiomas (10 anterior, 16 lateral). All patients were symptomatic, and all meningiomas inserted at C0 (FM rim); they extended to the clivus in 4 patients, to the cervical canal in 10, and to both in 12. The tumor was located above the VA in 7 cases, below in 9, and on both sides in 10 (Lariboisière classification). Twenty-two patients were operated on using the posterolateral (far-lateral) transcondylar approach described by Bertalanffy and Gilsbach in 1996, which included: C1–C3 laminectomy; occipital hemicraniectomy; C1 transverse foramen opening; medial epidural VA exposure and transposition (in 19 of 22 cases); and partial (from one third to one half) drilling of the occipital condyle (in 10 of 22 cases), with the amount of drilling depending on the position of the meningioma on the FM rim and the wish to reach the very anterior pole of the tumor. We analyzed: (1) surgical indications; (2) utility of VA transposition and condyle drilling; (3) quality of access and view; (4) microsurgical technical difficulties according to tumor location, extent, and consistency; (5) microsurgical challenges at the tumor to spinal cord, cranial nerves, and vessels interface; and (6) morbidity and total removal rate. Results: Four patients older than 70 years were not operated on (3 had only a few symptoms, and 1 had an enormous tumor), and their follow-up at 2–3 years showed stable clinical status. Operatively, VA transposition (in 19 of 22) enlarged the access, but it was only helpful for accessing the lower clivus and intradural VA anteriorly. Condyle drilling of up to 50% did not induce instability and enlarged the intradural view to the anterior FM rim, but it did not improve tumor dissection and removal; therefore, systematic drilling decreased with experience and was only kept for small anterior meningiomas. Total removal was achieved in 16 of 22 (73%). We learned from experience that tumor consistency (calcified and fibrous meningiomas generally lengthened dissection), VA encasement (inclusion/stretching of VA), and tumor invasiveness (adherences to cranial nerves) represented prognostic factors increasing complications (1 death, 5 permanent deficits). Conclusion: Our study illustrates that the posterolateral (far-lateral) transcondylar approach with VA transposition offers a large view to accurately manage the anterior FM rim and lower clivus. With surgical experience, however, we learned to: (1) measure indication according to age and severity of symptoms; (2) consider the transcondylar approach in anterior cases only, although it neither significantly improved our surgical results nor induced instability in our series; (3) consider the retrocondylar approach as sufficient for lateral meningiomas.

The etiological factors involved in idiopathic intracranial hypertension are not easy to identify. This case of idiopathic intracranial hypertension was associated with a capillary hemangioma growing in the lumen of the superior sagittal sinus. A 10-year-old girl had experienced progressive headaches and abdominal pain. Fundoscopic examination disclosed bilateral papilledema and high intrathecal pressure, suggesting idiopathic intracranial hypertension. Magnetic resonance imaging, including magnetic resonance angiography as well as digital angiography, revealed a 3-cm mass protruding into the superior sagittal sinus lumen above the torcular. A capillary hemangioma attached to the internal dural wall of the sagittal sinus lumen was microsurgically removed. The symptoms resolved in several days and no additional treatment was required. A tumor growing into a venous sinus is a rare cause of venous outflow impairment and may generate the clinical signs of idiopathic intracranial hypertension. This case emphasizes the importance of multiple complementary imaging modalities and the efficacy of a direct surgical approach, which allowed resolution of symptoms.

We compared the contributions of the labeled tracers (11)C-methionine (Met) and (18)F-FDG for PET-guided stereotactic biopsy of brain gliomas. In 32 patients with glioma, stereotactic Met PET and (18)F-FDG PET were integrated in the planning of stereotactic brain biopsy. PET images were analyzed to determine which tracer offered the best information for target definition. The stereotactic coregistration of PET images allowed accurate comparison of the level, distribution, and extent of uptake for both tracers according to tumor location and grade. A histologic diagnosis was obtained for all patients. All gliomas had an area of abnormal Met uptake, and 27 showed abnormal (18)F-FDG uptake. (18)F-FDG was used for target selection when its uptake was higher in tumor than in gray matter (14 gliomas). Seven were in the basal ganglia or brain stem. Met was used for target selection when there was no (18)F-FDG uptake or when (18)F-FDG uptake was equivalent to that in the gray matter (18 gliomas). Thirteen were in the cortex. Sixty-one of the 70 stereotactic trajectories obtained from the 32 patients were based on PET-defined targets and had an area of abnormal Met uptake. These 61 Met-positive trajectories always yielded a diagnosis of tumor. All nondiagnostic trajectories (n = 9) were obtained in areas with no increased uptake of Met. In all patients with increased uptake of both tracers, the focus of highest Met uptake corresponded to the focus of highest (18)F-FDG uptake. However, the extent of uptake of both tracers was variable. Distributions of highest Met and (18)F-FDG uptake are similar in brain gliomas. Because Met provides a more sensitive signal, it is the molecule of choice for single-tracer PET-guided neurosurgical procedures in gliomas.

We developed a technique that allows the routine integration of PET in stereotactic neurosurgery, including radiosurgery. We report our clinical experience with the combined use of metabolic (i.e., PET) and anatomic (i.e., MRI and CT) images for the radiosurgical treatment of brain tumors. We propose a classification describing the relative role of the information provided by PET in this multimodality image-guided approach. Between December 1999 and March 2003, 57 patients had stereotactic PET as part of their image acquisition for the planning of gamma knife radiosurgery. Together with stereotactic MRI and CT, stereotactic PET images were acquired on the same day using either (18)F-FDG or (11)C-methionine. PET images were imported in the planning software for the radiosurgery dosimetry, and the target volume was defined using the combined information of PET and MRI or CT. To analyze the specific contribution of the PET findings, we propose a classification that reflects the strategy used to define the target volume. The patients were offered radiosurgery with PET guidance when their tumor was ill-defined and we anticipated some limitation of target definition on MRI alone. This represents 10% of the radiosurgery procedures performed in our center during the same period of time. There were 40 primary brain lesions, 7 metastases, and 10 pituitary adenomas. Abnormal PET uptake was found in 62 of 72 targets (86%), and this information altered significantly the MRI-defined tumor in 43 targets (69%). The integration of PET in radiosurgery provides additional information that opens new perspectives for the optimization of the treatment of brain tumors.

SPINAL CORD TUMORS are more frequently detected than in the past, because of progress in neuroradiology. Many neurosurgeons must now decide how to treat such lesions. The recent neurosurgical literature contains many case reports, few series, and different strategies. This article describes the surgical method I have developed in a period of 15 years, with Georges Fischer in Lyon, on the basis of experience with more than 260 patients and 300 operations. The standard treatment is complete resection whenever possible, but we must learn when and where to stop to preserve the quality of life. I have several useful strategies, which are explained in this report. For gliomas (ependymomas and astrocytomas), I favor a midline approach; for most vascular tumors (such as hemangioblastomas and cavernomas), however, I prefer to proceed from the point at which the lesion is observed through the microscope and to dissect the lesion in one piece. Meticulous nonbleeding surgery and experience are the keys to success.

OBJECTIVE AND IMPORTANCE: Lhermitte-Duclos disease (LDD) represents a focally indolent dysplastic growth of the cerebellar cortex. The 106 cases reported previously in the literature show an extremely slow evolution, and the operative indications and techniques for this disease entity are still controversial. The authors present the first case of LDD studied with positron emission tomography using the labeled tracers [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) and 11C-labeled methionine ([11C]Met) to study the glucose and protein metabolism of the lesion. CLINICAL PRESENTATION: A 40-year-old woman suddenly became unconscious then completely recovered 5 minutes later. Magnetic resonance imaging of her brain showed a well-delineated 10 × 5-cm abnormal area with enlarged cerebellar folia, which led to the diagnosis of LDD. TECHNIQUE: On positron emission tomographic scans, [18F]FDG and [11C]Met uptake in the normal cerebral and cerebellar cortex appeared higher than normal, reaching levels found in patients with primary malignant brain tumors. Moreover, the uptake of both tracers was heterogeneous, in contrast to the homogeneous uptake visualized on magnetic resonance imaging scans. The areas of greatest [11C]Met and [18F]FDG uptake were discordant. Some areas of greater than normal [18F]FDG uptake corresponded to areas of moderate or low [11C]Met uptake. Because of the important mass effect in the posterior fossa, total surgical resection was performed. A histological examination confirmed the diagnosis of LDD. CONCLUSION: This first reported metabolic study of LDD supports the view that LDD is an active and evolving disease. These data should prompt reevaluation of the indications for surgery in patients with this disease as well as the timing of surgery.

Opened on November 1st, 2001, the Department of Neurosurgery has progressively grown to become worldwide renown in a few years. All the pathologies are covered, from lumbar disc hernia to intracranial tumors and vascular malformations. But the originality stays into the exceptional environment by the concentration of logistic resources and the ability of clinician and researchers who daily collaborate with the neurosurgical team. The Department of Neurosurgery has a strong reputation in several fields like intraspinal cord tumors or Pet-guided Neurosurgery in stereotactic biopsies, neuronavigation and Gamma Knife and, generally speaking, in the original approach of the treatment and follow-up of brain tumors. Neurodegenerative diseases also benefit of modern approaches trough the Gamma Knife, deep brain stimulation or fetal cell grafting into the brain in Parkinson and soon in Huntington diseases. Last but not least, the arrival for the 25th anniversary of Erasme Hospital of an interventional MRI will allow to follow in real-time the resection of brain tumors with an obvious benefit for the surgical performances and the quality of life of the patients. It will also open a new window for neurosurgical research through combination with functional MRI and Pet-Scan, reinforcing the reputation of Erasme Neurosurgical Department who has been distinguished in 1997 by the World Health Organisation as "WHO Collaborating Center for Research and Training in Neurosurgery" and nominated again in 2002 for a new 4-year period, which is unique in the Neurosurgical World.