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Biomedical subjects

B George

Publications and source records attributed to B George.

At least 19 recordsLinked to original sources
PubMed1997

Constitutional inversion of chromosome 7 and hematologic cancers.

Nonrandom aberrations of chromosome 7 have been described in various hematopoietic disorders. We describe here two unrelated families with the same constitutional inversion of chromosome 7 [inv(7)(q11.2q22)]. The probands in both families had acute leukemia and cytogenetic analysis revealed that the inversion was the sole cytogenetic abnormality in the bone marrow at diagnosis. There is a history of hematologic diseases in one of these families that included a son who is a carrier of this constitutional inversion. The distal inversion breakpoint lies within the common region of chromosome loss identified in some myeloid diseases. These observations raise the possibility that this inherited chromosome rearrangement could result in a mutation of a tumor suppressor gene and possibly represent a predisposing event for the development of leukemia in these individuals.

Aged↗
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↗
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↗
PubMed1995

Comparison of propofol and midazolam for sedation in intensive care unit patients.

OBJECTIVES: To evaluate the comparative safety and effectiveness of intravenous infusion of propofol or midazolam when used for 12 to 24 hrs of sedation and to evaluate the quality of sedation during stimulation. DESIGN: An open, comparative, prospective, randomized study. SETTING: Surgical intensive care unit (ICU) in a university hospital. PATIENTS: Postoperative, intubated, general surgical, and orthopedic patients requiring mechanical ventilation (n = 60). INTERVENTIONS: None. MEASUREMENTS: Assessments were made at baseline (0 time), 5, 10, 15, 30, 45, and 60 mins; at 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 hrs; and at the end of sedation. The assessments included systolic, mean, and diastolic blood pressures, heart rate, two-lead electrocardiogram, pulse oximetry oxygen saturation, FIO2, end-tidal CO2, respiratory rate, ventilator rate, tidal volume, and sedation scale. Vital signs and the sedation scale were obtained at 30, 60, and 90 mins and at 2, 4, 12, and 24 hrs after the end of sedation. At approximately 8 hrs and 24 hrs (or at the end of sedation), the patient's CO2 production was calculated over a 5-min interval. Every 4 hrs, the nurse would summarize and rate patient response during stimulation as well as the overall rating of the sedation and patient ability to tolerate the ICU setting. MAIN RESULTS: There were no significant differences in pulse oximetry, arterial blood gas values, or respiratory measurements during sedation with propofol or midazolam. The mean heart rate was slower in the propofol group throughout the sedation and postsedation periods. The rating of sedation and tolerance of the ICU environment were significantly better for the propofol-treated group. Postsedation, the propofol group woke up faster on discontinuation of the sedative. CONCLUSIONS: Propofol was as safe and as efficacious as midazolam for continuous intravenous sedation. The quality of sedation was better in the propofol group.

Procedural Sedation↗
PubMed1995

Neurinomas of the first two cervical nerve roots: a series of 42 cases.

A group of 42 patients with C-1 and C-2 neurinomas treated during the 10-year period 1982 to 1992 has been collected, including 25 cases from 20 French neurosurgical departments and 17 personal cases from the Neurosurgical Department of the Lariboisière University Hospital, Paris. Analysis of this series reveals some interesting findings relating to multiplicity of tumors, extradural extension, and neurofibromatosis. There were seven patients with multiple lesions (bilateral C-2 neurinomas in six cases and two neurinomas at C-2 and one at C-1 in one case). In the 35 other cases, 16 lesions were entirely extradural and 19 had an hourglass configuration. Thirteen patients presented signs of neurofibromatosis. One lesion had a melanotic form and another was a radiation-induced schwannoma. Surgical results were excellent in most cases with no immediate postoperative death. Best results in terms of complete removal and neurological condition were achieved with posterolateral or anterolateral surgical approaches (17 cases) as compared with the standard midline posterior route (25 cases).

Adolescent↗
PubMed1995

Pentylenetetrazol-induced kindling in animals: protective effect of BR-16A.

Repeated administration of pentylenetetrazol (PTZ, 30 mg/kg, thrice a week) to mice for 9 weeks and subsequent challenge of the animals with the same dose of PTZ on the last chronic dose produced chemical kindling. The mice showed myoclonic jerks, clonus, Straub's tail, falling back response and full blown convulsions. The anticonvulsant profile of chronic administration of BR-16A (100 and 500 mg/kg) was studied in this model of epilepsy. BR-16A offered protection against PTZ-induced chemical kindling. The per cent animals showing myoclonic jerks and clonus was reduced to 40 and 34 with 100 mg/kg and 54 and 27 with 500 mg/kg of BR-16A, respectively. The protective effect was compared with diazepam (1 mg/kg, ip). The results demonstrated GABAA receptor mediated PTZ-induced kindling and protective effect of BR-16A therein.

Animals↗
PubMed1995

Lithium-pilocarpine neurotoxicity: a potential model of status epilepticus.

Convulsive status epilepticus (SE) is clinically defined as prolonged electrical and clinical seizure activity in which the patient does not regain consciousness to a normal alert state between repeated tonic-clonic attacks. The disorder is a neurological emergency associated with a mortality rate of 10-12% and an even greater morbidity. Seizures represent one of the most severe in vivo stimulatory stresses that the brain is exposed to and generalized status epilepticus represents a very severe form of seizures. The International Classification of Seizures has defined this condition as "a condition characterized by an epileptic seizure that is so frequent or so prolonged as to create a fixed and lasting condition". During SE, high-amplitude, high-frequency electrical activity lasting at least 5 min is seen in the EEG. Continuous seizure activity in itself will result in progressive brain injury. The longer the condition of SE, the more difficult it is to control and the more likely it is to result in permanent neuronal damage. Therefore, SE is an emergency situation requiring prompt medical attention if severe permanent brain damage or death is to be prevented. SE often occurs in individuals with a history of seizures, in whom there are neural substrates already predisposed towards supporting seizure activity.

Animals↗