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Biomedical subjects

B George

Publications and source records attributed to B George.

At least 109 records · Page 6Linked to original sources
PubMed1995

Anterolateral and posterolateral approaches to the foramen magnum: technical description and experience from 97 cases.

Over a 12-year period (1981-1993), 97 lesions located in the foramen magnum area were treated using either the posterolateral or the anterolateral approach. The former is a lateral extent of the midline posterior approach; the latter is the technique of exposure of the cervical vertebral artery applied at the C-1 to C-2 level. The choice between the two types of lateral approaches was made following three modes of localization: anteroposterior attachment, relation to the dura, and relation to the vertebral artery. Both techniques are described in detail, with special attention paid to the bone and dural openings, which vary according to the localization.The treated lesions include 91 tumors, 4 craniocervical junction malformations, 1 synovial cyst, and 1 abcess. A complete resection was realized in 95% of the tumoral cases, with a very limited morbidity and mortality (3%).

Journal Article↗
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↗
PubMed1994

Spinal epidural haematoma: report of 11 cases and review of the literature.

Spinal epidural haematomas (SEH) are rare; most are caused by trauma, anticoagulant therapy, vascular anomalies, hypertension, blood dyscrasias, epidural anaesthesia or, rarely, spinal surgery. We report 11 cases and review the literature (16 cases). The clinical picture is that of acute spinal cord compression. MRI characteristics are quite specific. On sagittal sections, the SEH appears as a biconvex mass, dorsal to the thecal sac, clearly outlined and with tapering superior and inferior margins. The dura mater is seen as curvilinear low signal separating the haematoma from the cord. Within 24 h of onset, the haematoma is isointense with the cord on T1-weighted images and heterogeneous on T2-weighted images. Later, it gives high signal on both T1- and T2-weighted images. Differential diagnosis must include subdural haematoma, epidural neoplasm and abscess. Complete neurological recovery rapidly follows laminectomy and removal of the clot. In three of our cases, the haematoma resolved spontaneously. MRI is the best examination for diagnostic and follow-up.

Adult↗
PubMed1994

Superolateral approach to orbital tumors.

The conventional lateral approach to the orbit (Krönlein) does not allow a satisfactory view of the superior part of the orbit and the operative field is rather narrow. Therefore, large tumors which have developed not only laterally but also superiorly are usually approached transcranially. The craniotomy and exposure of the dura may be avoided when the tumor does not extend too far posteriorly and medially, by turning a larger orbital bone flap than the Krönlein's one. This technique was described by Nakamura as "type I orbitotomy" and can be referred to as a superolateral approach. After a bicoronal skin incision, a free orbital bone flap is cut. It includes the lateral orbital rim, a large external part of the superior orbital rim, and the lateral orbital wall. From 1985 to 1990 this approach was performed on 23 patients presenting with lacrimal gland tumors in 14 cases (11 pleomorphic adenomas, 2 adenoid cystic carcinomas, 1 adenocarcinoma), schwannomas in 2 cases, dermoid cyst in 1 case, hydatic cyst in 1 case, cavernous hemangiomas in 2 cases, inflammatory pseudotumor in 1 case, and mucoceles in 2 cases. This superolateral approach provides a wider exposure to the superolateral orbit than the classical Krönlein's approach and avoids the drawbacks of a craniotomy. A direct incision through the eyebrow can be used for bald people or for patients in poor condition.

Follow-Up Studies↗
PubMed1994

Oblique transcorporeal drilling to treat anterior compression of the spinal cord at the cervical level.

Oblique transcorporeal drilling is a new surgical technique in which the transverse foramina with the vertebral artery and lateral aspects of the bodies of the cervical vertebrae are exposed; it allows to drill out obliquely from the antero-lateral to the opposite postero-lateral corner, half of one or several cervical vertebral bodies. The technique is shortly described and its indications are discussed. It can mainly be applied to release osteophytic compression and to remove anteriorly developed tumors. The advantages are to work in a wide field with all important structures kept medially and protected and to keep a sufficient portion of the vertebral bodies to preserve the spine stability. This technique has been used in 39 cases with spondylosis in 27 cases, tumor in 11 cases and kyphosis in 2 cases including one with neurofibroma. Results in term of decompression were excellent in all cases. Mortality was none and morbidity was limited to a transient Horner's syndrome in almost all cases and to a CSF leak in three cases. This technique is therefore alternative to the anterior transcorporeal approach. In our experience, the oblique transcorporeal drilling provides a wider and safer access to lesions located anterior to the spinal cord.

Adult↗
PubMed1994

Intratumoral embolization of intracranial and extracranial tumors: technical note.

A new technique of intratumoral embolization is described. An intratumoral injection of N-butylcyanoacrylate is performed either perioperatively by direct puncture of the tumor or preoperatively through the nose or through the skin. The indications for this technique are hypervascularized tumors, such as juvenile angiofibroma, hemangiopericytoma, or paraganglioma. This technique has been applied in 21 patients with excellent results in terms of devascularization.

Aged↗
PubMed1994

Devascularization of craniofacial tumors by percutaneous tumor puncture.

PURPOSE: To present and evaluate a devascularization technique for hypervascular tumors of the head and neck by direct tumor puncture. METHODS: Tumor puncture was performed percutaneously or via natural orifices (nose and mouth). In one case, an intrasellar tumor was embolized via a transseptosphenoidal surgical approach. The embolization material used was NBCA, lipiodol, and tungsten in the majority of tumors (14 out of 17) and alcohol for 3 metastases of the calvarium. We used this technique to embolize 10 nasopharyngeal fibromas, 4 tumors of the calvarium (3 metastases and 1 hemangiopericytoma), 1 intrasellar hemangiopericytoma, and 2 glomus tumors. Reflux of blood was obtained in every case after direct puncture of the tumor. Direct injection of contrast agent into the tumor revealed local parenchymography followed by local and regional venous drainage without extravasation. RESULTS: Total devascularization was obtained in 14 cases, and devascularization greater than 90% was obtained in 3 cases. Thirteen tumors were totally resected without requiring blood transfusion. During surgery, the limits of the exsanguinated tumor were very well defined in every case by the black staining induced by tungsten. Of the 4 tumors embolized but not operated on (3 metastases and 1 glomus tumor), 2 metastases needed retreatment after 6 and 8 months of remission, respectively. The other metastasis is still in remission after 3 months, and the volume of the glomus tumor decreased by 80% remains unchanged after 8 months. CONCLUSION: This technique was initially used to devascularize tumors with difficult or dangerous intravascular access, but in view of the hemodynamic and surgical results obtained, we believe that the indications for this technique can be extended to hypervascular tumors accessible to conventional embolization.

Angiofibroma↗
PubMed1994

Vertebral arteriovenous fistulas: a study of 49 cases and review of the literature.

The experience is reported with 50 vertebral fistulas treated by the authors in a joint radiological and surgical team. Of the 28 fistulas that were traumatic, 18 occurred after incidental iatrogenic puncture, and 22 were spontaneous, of which four presented in patients displaying angiographic features of fibromuscular dysplasia. Eleven patients were operated on and 33 had endovascular treatment. In nine patients who were either symptom-free or in poor health, no treatment was advised. The fistula was occluded in 38 (93%) of the treated patients, and the vertebral artery patency was preserved in 32 (78%). A total of 224 published cases were reviewed: 152 were traumatic, most after a penetrating injury; 72 were spontaneous, with three age peaks (at 7, 26 and 52 years). Treatment has evolved considerably and endovascular occlusion is now the treatment of choice, surgery being reserved for specific indications.

Adolescent↗
PubMed1993

[Intracranial cavernoma. 30 cases].

During the last few years, as a result of improved neurodiagnostic procedure there has been an increase in the number of intracranial cavernous angioma. We present 30 cases totalling 32 cavernous angiomas. Twenty-one received a successful surgical treatment. Twenty-four angiomas were supratentorial (75 percent) and 8 subtentorial (25 percent). Cavernous angiomas are congenital vascular malformations, usually of small size, with multiple vascular cavities surrounded by fibrous walls. They are often found in young adults (mean age 35 years in our series), most frequently located in the supratentorial white matter. The presenting symptoms were epilepsy, haemorrhage and an expanding mass syndrome. In this series, 16 patients had epilepsy (53 percent), 7 had haemorrhage (23.5 percent) and 7 had a mass syndrome (23.5 percent). The diagnosis of this lesion, usually obtained with angiography, has been dramatically improved by CT scan and, particularly, MRI. The natural history of cavernous angiomas is still poorly understood: the major complication is haemorrhage. Total surgical excision is the treatment of choice: it avoids a possible haemorrhage and is effective in relieving epileptic seizures. The indication for surgery depends on the clinical symptom and the location of the lesion. The post-operative morbidity in our 21 operated cases was fairly low due to minor sequelae. In only 2 of the 16 patients who had epilepsy the clinical seizures persisted after surgery, but they were less frequent. The literature is reviewed.

Adolescent↗
PubMed1993

Binding of a murine proteinase inhibitor to the acrosome region of the human sperm head.

Proteinase inhibitors are present in the various glands, tissues, and secretions of the male reproductive tract. Some of these inhibitors bind to the acrosomal region of the sperm, and their release during in vitro or in utero incubation suggests that they may play a role in capacitation. In the mouse, the binding site for a trypsin-acrosin inhibitor, the acceptor, has been implicated in capacitation, zona binding, and the acrosome reaction. This presentation demonstrates that a component, molecular weight approximately 20,000, on the human sperm head may recognize the murine inhibitor. Furthermore, the acrosome reaction can be induced in capacitated human sperm by immunoaggregation of bound murine inhibitor. The data indicate that the proteinase inhibitor binding site on the human sperm head may, as with a similar site on murine sperm, play a role in the early events of fertilization.

Acrosome↗
PubMed1993

Pyogenic parenchymatous and nidus infection after embolization of an arteriovenous malformation. An unusual complication. Case report.

Infectious complications of cerebral angiography and of therapeutic angiographic procedures are very seldom reported. The case of an infected embolized arteriovenous malformation (AVM) by staphylococcus aureus is reported. Abscess formation became manifest seven months after the endovascular procedures. Antibiotherapy was initially started after puncturing the abscess, but finally the cure of the lesion could only be obtained by radical excision of the infected and embolized AVM, as if the persisting embolization material was promoting the infection. The modalities of infection after cerebral endovascular procedures are discussed.

Adult↗