Cerebral hemodynamics on MR perfusion images before and after bypass surgery in patients with giant intracranial aneurysms.

BACKGROUND AND PURPOSE: Preoperative assessment of the anatomy and dynamics of cerebral circulation for patients with giant intracranial aneurysm can improve both outcome prediction and therapeutic approach. The aim of our study was to use perfusion MR imaging to evaluate cerebral hemodynamics in such patients before and after extraintracranial high-flow bypass surgery. METHODS: Five patients with a giant aneurysm of the intracranial internal carotid artery underwent MR studies before, 1 week after, and 1 month after high-flow bypass surgery. We performed MR and digital subtraction angiography, and conventional and functional MR sequences (diffusion and perfusion). Surgery consisted of middle cerebral artery (MCA)-internal carotid artery bypass with saphenous vein grafts (n = 4) or MCA-external carotid artery bypass (n = 1). RESULTS: In four patients, MR perfusion study showed impaired hemodynamics in the vascular territory supplied by the MCA of the aneurysm side, characterized by significantly reduced mean cerebral blood flow (CBF), whereas mean transit time (MTT) and regional cerebral blood volume (rCBV) were either preserved, reduced, or increased. After surgery, angiography showed good canalization of the bypass graft. MR perfusion data obtained after surgery showed improved cerebral hemodynamics in all cases, with a return of CBF index (CBFi), MTT, and rCBV to nearly normal values. CONCLUSION: Increased MTT with increased or preserved rCBV can be interpreted as a compensatory vasodilatory response to reduced perfusion pressure, presumably from compression and disturbed flow in the giant aneurysmal sac. When maximal vasodilation has occurred, however, the brain can no longer compensate for diminished perfusion by vasodilation, and rCBV and CBFi diminish. Bypass surgery improves hemodynamics, increasing perfusion pressure and, thus, CBFi. Perfusion MR imaging can be used to evaluate cerebral hemodynamics in patients with intracranial giant aneurysm.

Intradural lumbar disc hernia: description of three cases.

Three new cases of intradural lumbar disc hernia are added to the 25 previously published cases. The clinical features of the lesion, which usually occurs at the level of the cauda equina, and its pathogenesis are discussed.

Multiple intracranial meningiomas.

The authors report 14 cases of multiple intracranial meningiomas representing 1.1% of all meningiomas operated on at their hospital in the past 35 years. Differentiation of multiple meningiomas, especially from meningiomatosis, must be strict. Since the introduction of computerized tomography scanning, the frequency of these cases has risen from 0.58% to 4.5% in the authors' meningioma series. Despite the multiplicity of sites, multiple meningiomas do not differ in prognosis from benign solitary meningiomas.

Treatment of aneurysms unsuitable for clipping or endovascular therapy.

A small percentage of aneurysms cannot be treated by traditional techniques. The majority of these are giant aneurysms, whose dimensions exceed 2.5 cm, which are particularly difficult to treat because of their anatomical characteristics. Clinically, they may present with compressive, ischemic or hemorrhagic symptoms. Treatment of intracavernous aneurysms and those of the pre- and intrapetrous segment of the internal carotid artery represent a challenge for the neurosurgeon and on occasion may not be suitable for clipping or endovascular techniques. This is true for aneurysms without a well-defined neck and fusiform aneurysms, for which extra-intracranial bypass using a graft of saphenous vein plays a fundamental role. The method used for bypass depends on whether there is sufficient collateral flow. The authors emphasize that it is not possible to identify patients who can be submitted to therapeutic occlusion of the internal carotid artery without the risk of late ischemic attacks or de novo aneurysm formation.

Acrylic prosthesis of the fifth cervical vertebra in cervical chordoma. Case report and review of the literature.

Description of a two-stage surgical treatment of a case of chordoma of the fifth cervical vertebra mainly affecting the vertebral body. In the first stage the cervical column was immobilized employing a posterior approach and a small portion of the tumour in the right lamina was removed. In the second stage the whole of the body of C5 was removed by an anterior route and replaced with an acrylic prosthesis. The advantages of acrylic resin and the literature on vertebral prostheses are discussed.

Small aneurysm clips for surgery of neck vessels.

Surgery of the internal carotid artery and the extracranial vertebral artery is of a fundamentally preventive nature, and justifiable when intra and postoperative complications (intraoperative stroke, postoperative vessel occlusion, postoperative TIA and/or stroke) remain within very low limits (less than 5% according to major case-series'). To minimize damage to the arterial wall that could cause vessel occlusion and even neurological damage, the authors propose the use of intracranial aneurysm clips for temporary closure of the neck vessels, explaining the methods used for selection of these clips.

Primary chiasmatic lymphoma.

We report a case of primary cerebral lymphoma in an unusual site, the chiasma, and with a unique combination of symptoms. We review the salient published data on lymphomas in this site.

Fronto-temporo-orbito-zygomatic approach and variants. Surgical technique and indications.

AIM: In the last decade, development and refìnement of skull base surgery have widened the surgical options available for treatment of mtracramal lesions. Despite the enormous advances made m microsurgical technique, the bony phase is still extremely important for achievmg optimal exposure of vascular and tumoral skull base lesions. The role of anterolateral approaches for such lesions is discussed. METHODS: We collected 87 consecutive patients with 74 neoplasms and 13 vascular lesions involving the floor of the antenor and/or middle cranial fossae, cavernous sinus, orbit, petrous bone, clivus, parasellar region and infratemporal fossa operated throughout 8 and a half years by means of an anterolateral approach and we evaluated the results obtained employing different craniotomies. RESULTS: To simplify the parameters for evaluation of outcome, we considered 2 main aspects: comparison between pre- and postoperative neurological status and the extent of tumour removal on MR imaging. For vascular lesions, we took into consideration the neurological outcome and the successful clipping of the aneurysm or disappearance of the AVM (l case) on postoperative angiography. Satisfactory surgical results were obtained with each type of craniotomy employed (fronto-teniporo-orbito-zygomatic, fronto-temporo-orbital, fronto-temporo-zygomatic, fronto-orbito-zygomatic). CONCLUSION: On the whole, surgical results were satisfactory. By deliberately excluding the microsurgical aspects of the lesions treated, we can observe that the fronto-temporo-orbito-zygomatic approach is principally indicated for lesions requiring a multidirectional approach such as spheno-petro-clival tumours, aneurysms of the basilar tip and intracavemous lesions while the fronto-temporo-orbital approach proved excellent for more medial lesions such as meningiomas of the luberculum sellae and cramopharyngiomas. The fronto-temporo-zygomatic approach is our 1(st) choice for neoplasms involving the Gassenan ganglion and the intratemporal fossa. For lesions of the orbital apex, a fronto-orbito-zygomatic approach can be successfully employed. Introduction of these approaches is relatively recent but promises a further refinement of their indications and surgical technique aimed at mimmismg postoperative morbidity.

Postoperative spondylodiscitis from Aspergillus fumigatus in immunocompetent subjects.

The authors describe a case of spondylodiscitis from Aspergillus fumigatus which occurred subsequent to surgery for lumbar disc herniation in a non-immunodepressed patient. The results obtained by combined medical and surgical treatment are discussed.

Primary intracranial lymphomas.

We present 20 cases of primary intracranial lymphoma and review the most important published series on this subject. The clinical patterns and the differential diagnosis from other intracranial space-occupying lesions on the CT and angiographic evidence are discussed. Surgical treatment was given in 19 of our cases, followed in 17 cases by radiotherapy and in 4 by chemotherapy. One patient was treated by a ventriculo-peritoneal shunt. The effectiveness of the various modalities of treatment is discussed in the light of survival.

Considerations on a case of intranasal cerebral ectopia.

The Authors report a case of intranasal cerebral ectopia; the problems concerning the nosographic and diagnostic definition of this condition as well as the differences from other similar pathologies with the same location (such as meningoencephalocele and nasal glioma) are discussed. Particular attention is payed to the various surgical techniques that can be used in these cases.

[Neurinomas and ependymomas of the cauda equina. A review of the clinical characteristics]. / Neurinomi ed ependimomi della cauda equina. Revisione delle caratteristiche cliniche.

A retrospective review of 603 cases of intradural benign tumors of the cauda equina are presented (283 schwannomas and 320 ependymomas). For each tumor, the clinical course and long-term postoperative results were analyzed: it emerged that differential diagnosis between neurinomas and non tumoral lesions is not possible if based on clinical findings alone and that neuroradiological diagnosis is more accurate when MRI is employed. Long-term prognosis of neurinomas was always favourable, while in the ependymomas, early diagnosis gives excellent results because prognosis is apparently directly correlated to the length of preoperative clinical history.

How to set up a microsurgical laboratory on small animal models: organization, techniques, and impact on residency training.

Microsurgical training is mandatory for the optimal education of modern neurosurgeons. Even though this is a widely acknowledged statement and a lot of institutions around the world practice training in laboratory, the recent literature lacks tip and tricks on how to start a laboratory from scratch, what would be a convenient anesthesia, and what kind of exercises are appropriate. We present our experience in 16 microsurgical training courses settled up at our institutions. Two hundred eleven rodents were dissected. We will describe the organization of the laboratory and of the training courses and we will discuss its practical impact on the residency program.