Philippe Mercier

Local and sustained delivery of 5‐fluorouracil from biodegradable microspheres for the radiosensitization of glioblastoma

The authors have developed a new method of drug delivery into the brain using implantable biodegradable microspheres. In this study, this method was used to provide localized and sustained delivery of 5‐fluorouracil (5‐FU) after the surgical resection of glioblastoma. This antimetabolite and radiosensitizing drug was selected in an attempt to decrease the rate of local recurrence of the tumor.

Drug Targeting into the Central Nervous System by Stereotactic Implantation of Biodegradable Microspheres

Controlled drug release in the central nervous system through an implantable polymeric vector has been developed in recent years. For this purpose, different polymeric devices composed primarily of synthetic biocompatible and biodegradable polymers have been investigated. The first polymeric devices developed were macroscopic implants (monolithic devices), which required open surgery for implantation. Microencapsulation methods, however, allow the production of microparticles or nanoparticles loaded with neuroactive drugs. Because of their size, these micro- or nanoparticles may be easily implanted by stereotaxy in discrete, precise, and functional areas of the brain without causing damage to the surrounding tissue. Presently, this method is most frequently applied in the fields of neuro-oncology and neurodegenerative diseases, but neurologically, the potential applications of drug targeting by stereotactic implantation of drug-loaded particles are legion.

Dermal sinus and intramedullary spinal cord abscess Report of two cases and review of the literature

Abstract Intramedullary abscesses of the spinal cord are uncommon. Most of them occur in association with heart, pulmonary or urogenital infections. We report two cases of intramedullary spinal cord abscesses secondary to congenital dermal sinus. Only 14 cases of such an association have previously been reported. In our cases, dermal sinus was associated with an epidermoid tumour. The clinical presentation, pathogenesis, magnetic resonance imaging findings, surgical management and outcome are discussed.

Recurrent intrinsic brain stem epidermoid cyst

The authors report the case of a 14-month-old baby boy with an epidermoid cyst located entirely within the pons and medulla, without an exophytic component. The lesion was examined by computed tomography and magnetic resonance imaging. The child was operated upon three times after two recurrences of the lesion. A suboccipital, subtonsillar approach was used for the first and second procedures and a transtemporal approach for the last one. Excision was thought to be complete the first time, since a solid tumor was found and removed in a large cyst. The cyst wall was not identified. No tumor was found during the second procedure despite recurrence of the cyst, which was drained without an attempt to remove the cyst wall. Finally the cyst recurred with a large tumor in the cyst wall which was again totally removed. Consistent with the high mortality of brain stem epidermoid cysts in the literature, the child eventually died. The therapeutic problems, surgical options, and consequences are discussed.

Are the calcium antagonists really useful in cerebral aneurysmal surgery? A retrospective study.

From 1983 to 1990, 234 patients with one or several cerebral arterial aneurysms were surgically treated in our department. Since 1983, we have been performing surgery as early as possible. As soon as the subarachnoid hemorrhage diagnosis is confirmed by computed tomography (or if unconfirmed, by lumbar puncture), we assume that each patient may have an aneurysm. Between 1987 and 1990, 111 patients were treated by vascular volume expansion (maintenance of central venous pressure above 5 cm H2O with 4% albumin or Ringer-lactate or, if necessary, with 20% albumin), which we supplemented with calcium antagonists (nimodipine in 60 patients and nicardipine in 51 patients). Two months after being discharged, each patient is examined by a neurosurgeon and, on the same day, is subjected to a neuropsychological evaluation and a computed tomographic scan of the brain. A few months after this consultation, a working-position/family-activities questionnaire is issued to the patient. All of the results studied on the basis of postoperative mortality, second-month computed tomographic scan ischemia, neuropsychological evaluation, and return to work show no significant difference between the groups with or without calcium antagonists or between the nimodipine and nicardipine subgroups.

Ideal intraspinal implantation site for the repair of ventral root avulsion after brachial plexus injury in humans. A preliminary anatomical study

The advances made to date in root reimplantation for avulsion of the brachial plexus are modest considering that there are only reports from ten patients in the literature. However, the results are promising and should be applauded. The problem with reimplantation, in addition to the difficult surgical exposure, is to determine the ideal intraspinal implantation site for the graft. Given the non-permissive substrate properties of the CNS white matter, the outcome of grafts elsewhere in the spinal cord need to be evaluated. An inappropriate implantation site might explain the still modest recovery in this challenging group of patients. Consequently the microscopic anatomy of the cervical spinal cord segments C5 to T1 was studied. The aims were to 1- determine the relationships between the ventral gray horn and the ventrolateral sulcus of the spinal cord, and 2-analyse the location and course of the motoneuron fibres passing through the white matter to reach the ventral root. On the basis of the present findings it is proposed that reimplantation of nerve grafts or rootlets should be performed directly through the ventral root exit zone in contact with the ventromedial region of the ventral gray horn at a depth of 2 mm, rather than into the white matter of the lateral aspect of the cord. Initially we used a posterior approach with total facetectomies. An anterior approach is now evaluated for current use.

Anatomic and radioanatomic study of the lateral genicular arteries: application to prevention of postoperative hemarthrosis after arthroscopic lateral retinacular release

Arthroscopic lateral retinacular release can be complicated by hemarthrosis in 10 to 18% of cases. The vascular structures involved are the lateral vascular pedicles of the knee. This study examines the topography of these pedicles. Anatomic and radioanatomic studies carried out in 50 specimens defined the route of the vascular pedicles at the lateral aspect of the knee. From the measurements carried out, we noted the relative homogeneity of the routes taken by the different proximo-lateral vascular pedicles, which are highly vulnerable, and the variability of the disto-lateral arterial routes. A tracing-paper study identified two distinct routes for the disto-lateral vascular pedicle and evaluated the risk of injury to it in surgical approaches to the lateral aspect of the knee. Finally, the topographic data of the study suggest the possibility of preventive hemostasis of the proximo-lateral pedicle via a minimal approach close to the patella. Furthermore, it seems possible to avoid cutting the disto-lateral pedicle if it is localised by cutaneous trans-illumination at the beginning of the operation.

Persistent sciatic artery: report of an original aneurysm-associated case.

Persistent sciatic artery (PSA) is a rare embryologic abnormality and can sometimes be bilateral. It may be discovered because of a gluteal aneurysm or ischemic or embolic complications in the lower limb. The case we report was a unilateral type III aneurysm-associated PSA. Since the abnormal artery may be the only source of blood supply to the lower limb, a thorough knowledge of the artery and its embryologic origins is essential.

Cavernomas of the spinal cord: Report of two patients

Two operated cases of spinal cord cavernomas are presented. Since spinal angiography is usually normal and myelography not specific, the contribution of magnetic resonance imaging to the diagnosis is emphasized. Surgical considerations of treatment are discussed.

Pseudotumoral demyelination: a diagnosis pitfall (report of three cases)

Rare forms of demyelinating disease such as Balòs concentric sclerosis or Schilders disease may simulate brain tumors, both clinically and on the computed tomography (CT) and magnetic resonance imaging (MRI). Even the histopathological diagnosis after a biopsy is not entirely reliable. We report three cases of pseudotumoral demyelinating disorders having required a stereotaxic biopsy, one of which was erroneously diagnosed as a malignant astrocytoma. We describe MRI especially the intense contrast enhancement with ill-defined margins, and the mild mass effect. We then detail the histopathological processes upon which differential diagnosis with a tumor can be based.