✓ The management of 21 parasagittal meningiomas is described; three were located in the anterior third of the sinus, 14 in the middle third, and four in the posterior third. Of these, four meningiomas were attached only to the lateral wall, two invaded the external layer of only one sinus wall, two involved the lateral recess of the sinus, and seven invaded one or two sinus walls. The remaining six tumors invaded the three walls of the sinus, which was completely blocked. There were bilateral meningiomas in four cases. Complete excision of the meningioma with preservation of the venous flow in the sinus and its collateral veins was attempted in each case. In the first eight cases it was possible to preserve the patency of the sinus without graft. In six of the next seven cases the removal of the two invaded walls permitted preservation of the third healthy wall and entailed the repair of the two involved walls by a partial graft, either dural graft (three cases) or venous graft (three cases). In one of the last six cases, a total vein graft was performed after complete excision of the invaded sinus. Two cortical veins were sutured to a collateral branch of the autogenous vein graft. The surgical technique of the partial and the total vein graft is described and clinical results and angiographic controls are discussed.
Joel Bonnal and Jacques Brotchi
Jacques Brotchi and Georges Fischer
Ependymomas are the most frequent spinal cord tumors in adult patients. Although magnetic resonance imaging can be a highly accurate diagnostic tool, it does not always provide accurate differentiation between ependymomas and astrocytomas. This is why the authors recommend surgical resection and histological evaluation in all intraspinal cord tumors. It cannot be said that a tumor is unresectable without first attempting to remove it. Complete removal should be accomplished whenever possible, and patients should undergo operation before they become neurologically impaired. Quality of life depends on preoperative neurological status. Postoperative radiotherapy should be avoided in all low-grade ependymomas even after partial removal. Radiotherapy may be used to treat anaplastic ependymomas, which are quite rare in the spinal cord. Patients with low-grade ependymomas must be followed for years and undergo reoperation if necessary. In our experience treating 93 spinal cord ependymomas, complete removal was achieved in 86 patients and only one patient underwent reoperation 18 years later for tumor recurrence. The gold standard in treatment protocol is gross-total resection without adjunctive radiation therapy. Good long-term outcomes have been achieved by using this strategy.
Joël Bonnal, André Thibaut, Jacques Brotchi and Jacques Born
✓ The authors report a series of 34 meningiomas of the sphenoid ridge. Eight tumors were totally removed uneventfully: two from the middle sphenoid ridge and six from the pterion or Sylvian point. Five tumors were not operated on because of their extensions or the patient's age. Twenty-one tumors raised serious surgical problems, resulting in a classification into three groups: deep or clinoidal, invading beyond the sphenoid wings, and a combination of both. Histological study of the hyperostotic bone showed meningiomatous cells in the bone in 12 of 13 cases so examined.
Surgical limitations included invasion of the cavernous sinus (15 cases), of the dura mater of the sella turcica (seven cases), of the lateral part of the sphenoid body at the insertion point of the ala magna (seven cases), and of the common tendinous annulus of Zinn in the orbit (five cases), and basilar extracranial extension, particularly in the pterygomaxillary fossa (three cases). Following extensive removal, there were no early recurrences and three late recurrences (9 years and more). In 13 cases with a follow-up period of 1 to 8 years, there were no clinical recurrences. In only two cases was the meningioma totally removed. There were three postoperative deaths, two cases of hemiparesis with aphasia and epilepsy, one case with a frontal lobe syndrome, and nine with slight oculomotor, visual, or esthetic sequelae.
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.
Marc Levivier, Jose Lorenzoni, Nicolas Massager, Salvador Ruiz, Daniel Devriendt and Jacques Brotchi
The authors report their experience using the Leksell gamma knife C (GK-C) for the treatment of meningioma and vestibular schwannoma (VS).
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.
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.
Benoit Pirotte, Nicolay Gabrovsky, Nicolas Massager, Marc Levivier, Philippe David and Jacques Brotchi
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.
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.
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.
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.
Daniele Morelli, Benoit Pirotte, Alphonse Lubansu, Dominique Detemmerman, Alec Aeby, Christophe Fricx, Jacques Berré, Philippe David and Jacques Brotchi
The authors evaluate the incidence of persistent hydrocephalus after early surgical management of pediatric posterior fossa tumors and the indicators for routine preoperative endoscopic third ventriculostomy (ETV).
Between 1989 and 2004, 160 children with a posterior fossa tumor were treated at Erasme Hospital in Brussels, Belgium. Hydrocephalus was present at admission in 114 of the patients. Thirty-one patients had severe hydrocephalus (Evans index [EI] > 0.4). Twenty-four of these and the 83 patients with mild hydrocephalus (EI between 0.3 and 0.4) were treated with early posterior fossa surgery (Group 1; 107 patients). In this group, 93 patients underwent a total or subtotal tumor resection associated with external ventricular drainage (Group 1A), and 14 underwent a stereotactic biopsy associated with an ETV (Group 1B). The 53 remaining patients underwent elective posterior fossa surgery (Group 2).
Early tumor resection (Group 1A) resolved hydrocephalus in 85 (91%) of 93 patients, whereas an ETV resolved intracranial hypertension in 11 patients (Group 1B). In Group 1, persistent hydrocephalus affected 11 (10%) of 107 patients, seven of whom had symptoms and were treated (three with shunts and four with ETVs). Persistent hydrocephalus was more frequent in children with severe preoperative hydrocephalus (p = 0.002) and with medulloblastomas (p = 0.0154). A total of 22 technically successful ETV procedures were performed. The ETV success rate for controlling hydrocephalus was 81% (18 of 22) and the rate of severe complications was 9% (two of 22).
An ETV is an efficient procedure for controlling hydrocephalus associated with posterior fossa tumor. The authors confirm that a routine postoperative ETV is indicated for treating persistent hydrocephalus. For preventing it, however, they recommend early posterior fossa surgery whenever possible. The low rate of persistent hydrocephalus does not justify adopting routine preoperative ETVs.