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Biomedical subjects

B George

Publications and source records attributed to B George.

At least 91 records · Page 5Linked to original sources
PubMed1997

Meningioma of the foramen magnum: a series of 40 cases.

BACKGROUND: Surgical treatment of foramen magnum meningiomas (FM meningiomas) has been improved by the recently developed posterolateral and anterolateral approaches. The choice of these approaches and the extent of bone resection, however, need to be defined according to the tumor location. METHODS: Over a short period (1980-1993), 40 cases of FM meningiomas were treated either by the posterolateral (N = 31), the anterolateral (N = 5), or the midline posterior approaches (N = 4). The choice of surgical technique (surgical approach, extent of bone drilling, and dural opening) was made according to the tumor location, which is defined by three parameters: the horizontal plane (anterior N = 18, lateral N = 21, and posterior N = 1); the vertebral artery (above N = 4, below N = 20, and on both sides N = 16); the dura mater (intradural N = 24, extradural N = 2, and intraextradural N = 4). RESULTS: Intradural anterior and lateral FM meningiomas were operated by the posterolateral approach. The bone drilling was limited either to the occipital condyle or to the lateral mass of the atlas, depending on whether the tumor location is above or below the vertebral artery, respectively. Intradural posterior meningiomas were treated by the midline posterior approach. FM meningiomas with an extradural component were resected by the anterolateral approach alone or combined with a midline posterior approach. The rate of complete resection was 94% for intradural FM meningiomas and 50% for the extradural ones. FM meningiomas with an extradural component generally have aggressive features invading the adjacent bone and soft tissues; this explains the difficulty of performing a complete resection. The clinical condition improved in 90%, worsened in 7.5%, and did not change in 2.5%. The worsened group consisted of three deaths (one case of air embolism, one case of pulmonary embolism, and one case with preoperative coma and tetraplegia). Similar results were obtained in both anterior and lateral locations. CONCLUSION: FM meningiomas can be completely and safely removed in most cases, using an appropriate surgical technique. The technique must be chosen after precise and correct analysis of the tumor location. The lateral approaches are very effective in the treatment of lateral and anterior FM meningiomas.

Adolescent↗
PubMed1997

Cervical neuromas with extradural components: surgical management in a series of 57 patients.

OBJECTIVE: Cervical 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. METHODS: A 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). RESULTS: Complete 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. CONCLUSION: Complete 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.

Adult↗
PubMed1997

[Malignant tumors of the ethmoid sinuses. A homogeneous series of 41 cases operated on by mixed approaches].

A series of 41 malignant tumors including 31 adenocarcinomas invading the ethmoid sinuses were treated by a combined transcranial-transfacial approach. Management, by the same team, of these consecutive cases permitted to analyze the technical problems and the carcinologic results. Chemotherapy was given to 21 patients pre-operative followed by surgical resection by a combined transbasal and paralateronasal routes and then, by a post-operative radiotherapy. Post-operative complications were more frequent (52%) in case of reconstruction of the anterior skull base and especially with madroporic corals. In the other cases where the double dural closure was only packed with abdominal subcutaneous fat, the rate of post-operative problems was only 20%. Noticeably, infection at the cranial base was observed in 6 cases (4 cases needing a reoperation) with bone reconstruction and in none without reconstruction. Actuarial survival rate was 84% at 1 year, 53% at 3 years and 36% at 5 years whatever the pathology (whole series or subgroup of adenocarcinomas). Mortality is related to incidental problems (3 cases), another malignant primary disease (3 cases), metastasis (8 cases) and local recurrence (4 cases). A longer survival was observed in the group of patients without skull base invasion (survival rate 100%, 83%, 50% at 1, 3 and 5 years respectively).

Combined Modality Therapy↗
PubMed1997

Modulation of lithium-pilocarpine-induced status epilepticus by adenosinergic agents.

Effect of adenosinergic agents were investigated in lithium-pilocarpine-induced status epilepticus (SE) in rats. Adenosinergic agents such as adenosine (50, 100 mg/kg), 2-choloroadenosine (1, 2 mg/kg), carbamazepine (20, 80 mg/kg), N6-cyclohexyladenosine (1, 2 mg/kg) and dipyridamole (10, 20 mg/kg) produced theophylline-sensitive protective effects as they dose-dependently prolonged the latencies for onset of forelimb clonus with rearing. Pretreatment with Ro 5-4864 (20 mg/kg i.p.) did not offer any protection. These results indicate the possible involvement of adenosinergic mechanism in preventing lithium-pilocarpine-induced SE and mortality.

2-Chloroadenosine↗
PubMed1997

Dopaminergic modulation of lithium/pilocarpine-induced status epilepticus in rats.

The effects of selective dopaminergic agonists and antagonists on epileptic activity were tested in rats using the lithium/pilocarpine seizure model. Systemic administration of the D1 agonist SKF-38,393 reduced the latency of onset of forelimb clonus with rearing, whereas the D1 antagonist SCH-23,390 and the D2 agonist B-HT 920 prevented the convulsive activity in a dose-dependent manner. Mixed agonists like apomorphine offered partial protection. Haloperidol (D1, D2 blocker, with antimuscarinic property) reduced the threshold for convulsions. The effects of SKF-38,393 and B-HT 920 could be partially blocked by pretreating the rats with SCH-23,390 and sulpiride, respectively. Neither D1 nor D2 antagonists could alter the limbic stereotypies induced by lithium/pilocarpine. These results indicate that dopamine receptor subtypes exert opposite effects on the regulation of convulsive activity. Lipid peroxidation levels (MDA formed) in rat brain homogenates were found to be concomitant with the development of epileptiform activity.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1996

Giant-cell tumour of the sphenoid bone: case report.

We report an 18-year-old woman with a giant cell tumour of the sphenoid bone. CT demonstrated a lytic soft-tissue mass arising from the sphenoid body, extending to the left petrous apex and into the nasopharynx. On MRI the tumour had nonspecific signal intensity, but there was contrast enhancement on both examinations. CT was better for showing the extent of the osseous disease, whereas MRI was more accurate as regards soft-tissue extension.

Adolescent↗
PubMed1996

Treatment of brain arteriovenous malformations by embolization and radiosurgery.

Embolization was used to reduce the size of brain arteriovenous malformations (AVMs) prior to radiosurgical treatment in 125 patients who were poor surgical candidates or had refused surgery. Of these patients, 81% had suffered hemorrhage, and 22.4% had undergone treatment at another institution. According to the Spetzler-Martin scale, the AVMs were Grade II in 9.6%, Grade III in 31.2%, Grade IV in 30.4%, and Grades V to VI in 28.8% of the cases. Most embolizations were performed using cyanoacrylate delivered by flow-guided microcatheters. Radiosurgery was performed using a linear accelerator in 62 patients treated by the authors, and 34 patients were treated at other institutions using various methods. Embolization produced total occlusion in 11.2% of AVMs and reduced 76% of AVMs enough to allow radiosurgery. Radiosurgery produced total occlusion in 65% of the partially embolized AVMs (79% when the residual nidus was < 2 cm in diameter). Embolizations resulted in a mortality rate of 1.6% and a morbidity rate of 12.8%. No complications were associated with radiosurgery. The hemorrhage rate for partially embolized AVMs was 3% per year. No patient with a completely occluded AVM experienced rehemorrhage. Angiographic follow-up review of AVMs embolized with cyanoacrylate demonstrated a 11.8% revascularization rate, occurring within 1 year. It is concluded that after partial embolization with cyanoacrylate, the risk of hemorrhage from the residual nidus is comparable to the natural history of AVMs and that the residual nidus can be irradiated with results almost as good as for a native AVM of the same size.

Adolescent↗
PubMed1996

[Therapeutic management of craniocervical chordoma].

Chordomas are rare neoplasms of notochordal origin that arise along the vertebral axis. In the cervicofacial area, they show a marked proclivity for the sphenooccipital region. These slow-growing and infiltrating tumors are often discovered because of neglected symptoms related to the ENT field such as nasal obstruction, snoring, dyspnea or dysphagia in the case of anterior development, serous otitis media, cervical pain, or even palsy of the X, XI, or XII cranial nerves when the tumor develops toward the foramen jugulare or the foramen magnum. Prognosis is usually poor because of local malignancy, proximity to critical central nervous system structures, and volume of the tumor. Surgery is the preferred treatment for these extradural tumors, but most authors recommend postoperative irradiation because of surgical spillage or residual tumor. However, conventional irradiation is limited by the sensitivity of surrounding structures, which results in a poor rate of local control. We present 9 cases of histologically proven diagnosis of chordoma treated from 1984 to 1994 at our institution. Prognosis and therapeutic modalities are discussed. Therapeutic improvement might be brought the protontherapie, which ensures a better local control, and therefore may transform the prognosis of the disease.

Adolescent↗
PubMed1996

Protective effects of GABAergic drugs and other anticonvulsants in lithium-pilocarpine-induced status epilepticus.

Administration of subconvulsive dose of pilocarpine (30 mg/kg s.c.) to rats pretreated with lithium chloride (3 meq/kg i.p.) produced a state of status epilepticus in animals. The animals showed characteristic symptoms of generalized convulsions, wet dog shakes (WDS), forelimb clonus and falling back. The symptoms of status epilepticus (SE) developed within 26.8 +/- 3.6 min after administering pilocarpine and these symptoms continued uninterrupted. The phenomenon was totally reproducible, with a consistent latency of onset of seizures and a high mortality rate. The symptoms were blocked by atropine, scopolamine and the GABAergic agents GABA, sodium valproate, (+)-baclofen and clonazepam when given prior to pilocarpine, but not when administered 30 min after pilocarpine administration.

Animals↗
PubMed1996

[Anterior and anterolateral surgery of the lower cervical spine (25 years after H. Verbiest). I: Technical bases].

The anterior approach to the cervical spine is currently a worldwide traditional surgical technique used by neurosurgeons or orthopedists in the treatment of traumatic, degenerative or tumoral cervical spinal lesions. Many original rules of these techniques were raised by pioneers as R. Cloward and H. Verbiest, and are still valid. Advances in the surgical armentarium and in bio-materials markedly improved the original technique and subsequently improved the clinical results. The present course was organized for the neurosurgery trainees by the French Speaking Neurosurgical Society, and was helded during the winter meeting in December 1995. The aim of this course is to recall the basic technical principles of the microsurgical anterior cervical approach, and to discuss the main indications of this surgical treatment. Many theoretical points are strengthened by the author's personal experience and comments. Part I presents the different anterior or antero-lateral approaches which any surgeon involved in cervical spine surgery actually needs to know. Secondly, the materials and technical basis needed to achieve an interbody graft or fusion or fixation are described. Lastly, some practical applications are detailed as a microdiscectomy, a medial or lateral cervical spine decompression, and the use of acrylic plastic or prothesis for a cervical vertebral replacement.

Bone Transplantation↗
PubMed1996

[Anterior and antero-lateral surgery of the lower cervical spine (25 years after H. Verbiest). 2: Indications, results, complications)].

The present course on the anterior and antero-lateral surgical approach of the lower cervical spine was organized for the neurosurgery trainees by the French Speaking Neurosurgical Society, and was held during the winter meeting in December 1995. The aim of this course was to recall the basic technical principles of the microsurgical anterior cervical approach, and to discuss the main indications of this surgical treatment. Many theoretical points were strengthened by the author's personal experience and comments. In Part I, the technical bases of the different anterior or antero-lateral approaches were presented (1996, 42 : 105-122). In the present Part II, the main indications of the anterior surgical approach to the cervical disk or the vertebral body are detailed, and the requirement of a bone graft and/or an osteosynthesis are discussed with their consequences on the final results. Secondly, variants of the surgical technics in use in case of cervical spinal instability are commented. Then various approaches to the cervical spinal tumors and to the vertebral artery are detailed and commented. Lastly, general and specific complications of the anterior cervical approach are listed with their rate of occurrence, and their prevention and management are discussed.

Cervical Vertebrae↗
PubMed1995

The juxtacondylar approach to the jugular foramen (without petrous bone drilling).

BACKGROUND: Surgical access to the jugular foramen is generally realized through the infratemporal approach, requires petrous bone drilling with facial nerve exposure and sometimes transposition. This is a rather complex and time-consuming technique that exposes the patient to complications such as deafness and facial nerve palsy. METHODS: The juxtacondylar approach we propose in this paper needs only a partial mastoidectomy and exposure of the distal cervical segment of the vertebral artery (above C2). The transverse process of the atlas is completely removed so as to permit progress upward along the lateral mass of the atlas and the occipital condyle. The vertebral artery rarely has to be transposed. RESULTS: The main indication for the juxtacondylar approach is neurinoma and meningioma of the jugular foramen. For tumors like paraganglioma extending into the petrous bone, the juxtacondylar approach can be combined with an infratemporal approach. The juxtacondylar approach has been used in seven cases including three neurinomas, three paragangliomas and one meningioma. Exposure was quite satisfactory on both intra- and extradural parts in all cases. CONCLUSIONS: The juxtacondylar approach is a different way to expose the jugular foramen region. Compared to the standard infratemporal approach, it is a complementary rather than an alternative technique; the exposure is rather on the posteroinferior side for the juxtacondylar approach and on the anterosuperior side for the infratemporal approach.

Adult↗