Guillaume Lot

Intradural Perimedullary Arteriovenous Fistulae: Results of Surgical and Endovascular Treatment in a Series of 35 Cases

A series of 35 patients treated for an intradural perimedullary arteriovenous fistula (AVF) between 1970 and 1990 is reported. Angiography was performed on all of the patients, leading to the diagnosis. The patients were classified into Type I (4 patients), Type II (9 patients), and Type III (22 patients). One Type I patient was not treated, two others underwent surgery, and the last one was embolized. All of the Type II AVFs were treated, two by embolization, four by direct surgery, and three by surgery after incomplete embolization. All of the Type III AVFs were treated by endovascular detachable silicone balloon. Complete occlusion of the AVF was achieved in all treated cases of Types I and II AVF and in 15 cases of Type III AVF; for the 6 other cases of Type III AVF, incomplete occlusion was achieved. In the Types I and II AVFs, partial improvement was clinically observed in only half of the patients; the others remained unchanged. The 15 patients whose Type III AVF was completely embolized recovered completely, and four patients with Type III AVF who were incompletely embolized remained unchanged; 2 other patients with Type III AVF worsened after incomplete occlusion, and 1 additional patient died a few hours after an attempt of endovascular occlusion of a cervical Type III AVF. The place of the perimedullary AVFs among the other vascular malformations involving the spinal cord is discussed according to this classification into three types. Their specific diagnostic and therapeutic difficulties are discussed, resulting in a simplified classification including two types of perimedullary AVF.

Cervical Neuromas with Extradural Components: Surgical Management in a Series of 57 Patients

OBJECTIVEnCervical neuromas with extradural components (intraextradural or strictly extradural forms) are rare. Their resection raises the problems of nerve root preservation, vertebral artery (VA) control, and spinal stability.nnnMETHODSnA series of 57 patients with neuromas (29 neurofibromas, 23 schwannomas, 4 neurofibrosarcomas, and 1 plexiform neurofibroma) was treated during the period of 1980 to 1995, using one of the lateral approaches (antero- or posterolateral approach). The VA was always controlled before resection of the tumor. In cases of intraextradural forms, the intradural component was removed by a complementary laminectomy (three patients) in the early period and then by an oblique corpectomy through the same lateral approach (five patients) in the late period. A laminectomy had been performed in 15 other patients (11 patients with intraextradural neuromas) before they were referred to us. These patients included seven with recurrent neuromas, occurring after an average period of 4.1 years (1-9 yr).nnnRESULTSnComplete resection was achieved in all except two patients, in whom the nerve root reacted positively to intraoperative stimulation and could not be separated from the tumor. One of the patients was subsequently operated on after 2 years. Another recurrence was observed in another patient at 1 year. The four patients with sarcomas died from recurrence within 2 years. The rate of root preservation included an average of 28%, including 43.5% for schwannomas, 18% for neurofibromas, 44% for lower cervical neuromas (C4-C8), and 4.5% for upper cervical neuromas (C1-C3). Worsening of preoperative neurological deficits was observed in only two patients. The VA was always preserved, except in one patient with a sarcoma that was preoperatively occluded. No instability was observed in any of the patients.nnnCONCLUSIONnComplete resection with good neurological results can be achieved in most patients harboring cervical neuromas each with an extradural component by using a lateral approach and VA control. If the root cannot be separated from the tumor, especially in patients with neurofibromas, intraoperative stimulation can help decide whether the root may be divided without incurring postoperative deficit. The lateral approach permits the resection of the extradural as well as the intradural component by a complementary oblique corpectomy. There was no morbidity in relation to VA control as well as no postoperative instability.

Foramen Magnum Meningiomas: A Review from Personal Experience of 37 Cases and from a Cooperative Study of 106 Cases

Summary:Foramen magnum (FM) meningiomas are reviewed from our personal experience of 37 cases over 12 years and a cooperative study done in 1993 in which patients were collected from 21 French departments of neurosurgery over the period 1982–1992. FM meningiomas account for 6.5% of posterior fossa meningiomas and 1.5% of all intracranial meningeal tumors. Historical background and clinical features are presented first. Then reported are the histological and radiological data. Finally, the surgical technique is described, detailing postoperative clinical condition and extent of resection. Important specific points are emphasized: (a) the limits of what is defined as the FM area, which is generally not described in the literature; (b) the high frequency (56%) of psamommatous tumors; and (c) the great value of magnetic resonance imaging (MRI) and angio-MRI in defining the localization regarding the dura (14% of FM meningiomas have an extradural extension), the vertebral artery (48% of FM meningiomas are developed above the vertebral artery), and the anteroposterior location (31% of FM meningiomas are anterior and 56% are lateral). These points are fundamental to choosing the best surgical technique. The technique always includes drilling of the FM lateral wall according to tumor localization, thus providing lateral access to the premedullary spaces. This lateral approach can be posterolateral (a lateral extension of the standard midline approach mainly used to excise intradural tumors) or anterolateral (applied in the excision of extradural tumors). The lateral approach is currently the technique that permits the most complete resection (96%) with minimal mortality and morbidity.