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Biomedical subjects

G Laborde

Publications and source records attributed to G Laborde.

16 recordsLinked to original sources
PubMed1992

Experience with the infratentorial supracerebellar approach in lesions of the quadrigeminal region, posterior third ventricle, culmen cerebelli, and cerebellar peduncle.

We report about our experience with the infratentorial supracerebellar approach in 23 patients operated on for lesions located in the posterior part of the third ventricle, quadrigeminal plate, culmen cerebelli and cerebellar peduncle. Three patients had transient worsening of their deficits immediately after surgery. Three patients developed haemorrhages postoperatively requiring surgical evacuation. One of them died. None of the patients developed specific complications which could without any doubt be attributed to the approach. We concluded that in combination with intra-operative CSF drainage and the sitting position the infratentorial supracerebellar approach allows safe access to lesions situated in an area limited by the posterior part of the third ventricle, the fastigium level and both cerebellar peduncles.

Adolescent↗
PubMed1992

Computer assisted localizer for planning of surgery and intra-operative orientation.

There is discrepancy between the exact representation of anatomical structures and tumours in the CT or MRI scan and the more or less accurate intra-operative localisation methods based mostly upon landmarks of the skull and extracerebral space and visible abnormalities of the cerebral surface. To overcome these problems of exact intra-operative localisation a Computer Assisted Localizer (CAL) is presented which allows precise intra-operative orientation without these aids. It consists of a mechanically articulated arm with six degrees of freedom with a high precision digital incremental and an image processor for 3 D data of the head. MRI and/or CT investigation is done pre-operatively with four reference markers fixed on the patient's head. They are visible on the CT or MRI slices and are used as reference points during surgery for adjustment of the device. The co-ordinates of the digitalizer arm tip are projected into the corresponding axial, sagittal and coronal CT slices so that the system simultaneously presents three orthogonal multiplanar CT reconstructions with a reticule indicating the position of the tip of the arm. As the surgeon directs the arm to the region of interest the corresponding CT slices are displayed on the monitor at a rate of 20 slices/sec determined by the motion of the arm. The accuracy of measurement of the device itself lies within 1 mm. The accuracy is somewhat reduced however by the thickness of CT or MRI slices (routinely 2 mm slices were taken) and by deviations of the reference markers on the skin surface which amount up to 3 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Successful treatment of a haemangioblastoma in a 95 year-old patient. Case report.

Haemangioblastomas located in the posterior fossa have rarely been described in patients older than 60 years of age. The authors report a case of a 95 year-old man who presented with an obstructive hydrocephalus secondary to a posterior fossa tumour. Computed tomography and angiography suggested intracerebellar metastasis. Despite the advanced age of the patient and his poor general condition, surgery was performed with the patient in a supine position. A haemiangioblastoma was found and completely removed. The postoperative course was without complications. This case demonstrates that the combination of modern anaesthesia, supine operating position, and the use of microsurgical techniques allow successful operations on the posterior fossa even in very old patients.

Aged↗
PubMed1990

[Biomechanical behavior of the pulpectomized tooth].

No accurate information is in fact available regarding the biomechanical properties of devitalized teeth. The time frame seems to be a more significant factor than nature of the pulpectomy itself, as far as the risk of fracture is concerned. The use of a pivot or other form of root anchorage does not seem to play a determining role in the long-term reliability of restorations. Partial restorations can be substituted for full coronoperipheral reconstruction insofar as they protect the cusps. Each clinical situation must be matched with the appropriate reconstruction.

Crowns↗
PubMed1990

[Gingival thickening with a submerged connective tissue graft].

Gingival thickness is a clinical characteristic which should be given more consideration in evaluating muco-gingival problems. It is proposed that thick gingiva prevents gingival recession and is of particular significance when fixed prosthesis is being employed. The technique outlined includes a connective graft from the lamina propria of the palatal mucosa into the gingival connective tissue. A case report documents the technique.

Connective Tissue↗
PubMed1989

Microsurgical unilateral approaches for spinal tumour surgery: eight years' experience in 256 primary operated patients.

A series of 256 consecutive patients suffering from spinal tumours was studied with respect to the value of bilateral or unilateral surgical approaches. The case material included 152 extradural, 87 intradural, extramedullary and 17 intramedullary tumours. The cervical spinal cord was involved in 43, the thoracic in 152 and the lumbosacral region in 61 cases. Hemilaminectomy was chosen mainly for juxtamedullary tumours, while laminectomy was used for intramedullary tumours. No remarkable difference regarding the choice of approaches was found in extradural tumours. More than 60% of cervical or lumbosacral tumours were managed using unilateral procedures. A higher rate of surgical radicality but fewer complications, shorter stay in hospital and better early results were achieved using hemilaminectomy especially in patients with juxtamedullary tumours. From the observations it may be concluded that the results do not depend on the type of surgical approach but are closely related to the histology and location of tumours. Under the prerequisite of exact pre-operative definition of tumour location, unilateral approaches are advantageous for all kinds of spinal tumours especially for juxtamedullary benign tumours.

Adolescent↗
PubMed1989

Brain activity and blood flow velocity changes: a transcranial Doppler study.

Seventy volunteers with no sign of cerebral vascular disease performed two series of 6 cognitive tasks, 3 of which are assumed to be processed predominantly by the left and 3 by the right hemisphere. During the tasks, blood flow velocity changes in the middle cerebral artery were recorded every 3 seconds by the transcranial Doppler method (TCD). All tasks increased blood flow velocities in both MCAs, but only the "right hemispheric" tasks resulted in a statistically significantly higher increase than the left MCA. The time course of velocity changes reflects the increase in blood flow caused by increased brain metabolism during brain activity. During stimulation of the right and/or left visual field, blood flow velocity changes were recorded in the P2-segment of the corresponding hemisphere. In 76 volunteers, the study was performed. The time course of velocity changes was similar to that in the MCA study. Velocity rose as a result of increasing complexity of the visual stimulus. The velocity changes are similar to blood flow increases reported in the literature and rose by as much 2 to 25%. Assuming that the diameter of the large branches of the circle of Willis does not change during mental activity, blood flow velocity changes reflect blood flow volume changes. With the TCD method the close relationship among brain activity, metabolism, and blood flow can be reliably investigated. The high spatial resolution enables information to be given about the onset of autoregulation.

Adolescent↗
PubMed1988

The microvascular Doppler--an intraoperative tool for the treatment of large and giant aneurysms.

One of the problems especially associated with large and giant aneurysms is the control of the patency of the parent artery and the exclusion of the aneurysm. While the exclusion can be tested by puncture (which may sometimes be problematic), the patency can only be controlled by intraoperative angiography or recently, by microvascular intraoperative Doppler. The device we use has a high resolution and is equipped with probes as small as 0.3 mm with which all visible vessels with diameters of more than 0.1 mm can be investigated. Local stenoses above a diameter reduction of 40% can be easily detected by localized accelerations and changes in the pulse curves. Our recent experience with 11 giant and 13 large aneurysms has revealed marked discrepancies between an apparently well placed clip and an obviously open vessel on the one hand, and the haemodynamic reality revealed by the Doppler on the other. We were able to decide whether the flow was undisturbed, or whether there was an haemodynamically non-effective lumen reduction due to a tight clip, or if there was severe stenosis or a total occlusion. In five cases with severely disturbed flow after clipping, we had to change our strategy: we resected the aneurysms and sutured the neck, performed an end-to-end anastomosis, coated the aneurysm, or repositioned the clips. In cases in which we did not have full view of the neck, the Doppler guided us to a proper clip position. We conclude that especially for large and giant aneurysms, the microvascular interoperative Doppler is a valuable tool.

Adult↗
PubMed1988

Haemodynamic changes in arteriovenous malformations induced by superselective embolization: transcranial Doppler evaluation.

To reduce the intraoperative and postoperative complications in patients who suffer intracerebral arteriovenous malformations (AVM's), the slow reduction of the shunt flow to a brain perfusion flow has been tried by the use of several methods: microsurgical techniques, selective and superselective embolization, intraoperative embolization, staged operation. The risk of re-bleeding and intraoperative oedema increases in AVM's with two or more feeders. Our policy was to exclude such AVM's by primary superselective embolization. If there was only a small residual angioma, we tried to remove this by microsurgical techniques. The haemodynamics in AVM's could be examined by measuring the blood flow velocities in the feeding arteries and in the other parts of the circle of Willis by transcranial Doppler sonography (TCD). Signs of haemodynamic effective embolization could be measured by the reduction of flow velocities. After exclusion of an AVM the velocities in the brain and feeding arteries decreased to below normal values in the first days after the operation. In the feeding arteries this was due to the fact that the arteries were enlarged so that the velocity must be decreased when there was normal volume flow. The combination of superselective angiography and microsurgical resection of the residual angioma seemed to be the best way to treat AVM's which are fed by more than two arteries and which are 3 or more cm in diameter. TCD investigations were used to measure the haemodynamic changes before and after angioma superselective embolization and microsurgical operation.

Cerebral Angiography↗
PubMed1975

[Muscular work and its hyperemic phase in the patient with arteritis].

Already users of a method of functional assessment of the muscular circulation in the patients with peripheral artery disease by Xenon 133, the authors propose a radical modification of the performance of the exercise test. A quantified exercise test leads to a new and more objective interpretation of the radio-active tracer elimination curve. This new method permits the measurement of the total quantity of blood which passed during the hyperhaemic stage and its time distribution. The aim of this test is to form an opinion on the tenacity and the efficiency of the supplementary mechanisms when there is an occlusion of the arterial axis.

Adult↗