Biomedical subjects
Publications and source records attributed to Luc Picard.
Aneurysm diagnosis has evolved considerably over the last years. Technological advances have brought CT angiography and MR angiography to the forefront of ruptured and nonruptured intracranial aneurysm diagnosis. This article highlights current diagnostic modalities for intracranial aneurysms.
Explore the source record for details and available documents.
PURPOSE: To report the results of arc-therapy radiosurgery for cerebral arteriovenous malformation (AVM) and to compare the adverse event rate with the rate expected from the natural history. METHODS AND MATERIALS: We performed a retrospective study of our 118 first patients with a mean follow-up of 46 months (range, 5-105 months). The AVMs had features indicating a poor prognosis at initial presentation and had already been treated by previous embolizations in 88% of patients. The mean volume of the targets was 7.4 cm3 (range, 0.3-28.3 cm3). The mean minimal and maximal dose was 17.7 Gy (range, 10-25 Gy) and 24.5 Gy (range, 17-36 Gy), respectively. RESULTS: The crude and 5-year actuarial rate of cure (total obstruction of the AVM shunt at angiography) was 54% (60 of 112) and 77%, respectively. The only independent prognostic factor of cure was the AVM volume (crude cure rate 67% for <7 cm3 vs. 35% for > or =7 cm3; p = 0.001). No patient died. Transient and permanent complications and hemorrhage occurred in 5%, 1.7%, and 6% of patients, respectively. The annual risk of an adverse event (hemorrhage or complication) was 3.9%. CONCLUSION: The results of our series showed that radiosurgery, performed alone or after prior shrinkage of the AVM by embolization, is both effective and well tolerated, with a rate of adverse events comparable to that expected from the natural history.
OBJECTIVE: To analyze the treatment options in hemorrhagic intracranial dissections. METHODS: This study involved a retrospective review of 27 patients with 29 dissections treated during a 16-year period, mainly by endovascular treatment (EVT). RESULTS: EVT was performed in the acute stage in 12 of the 29 dissections, and occlusion was performed using coils at the dissection site in six dissections and with proximal balloon occlusion in six dissections. Wrapping was performed in one case. In the remaining 16 dissections, which were not treated, mainly for anatomic reasons, three patients died, one from rebleeding. Angiographic follow-up performed in the 13 surviving patients demonstrated an initially misdiagnosed lesion in one and worsening lesions in five that led to delayed EVT in five and surgical clipping in one. One of these dissections, which was located on a dominant vertebral artery, was treated after subsequent rupture using a stent and coils to preserve the patency of the parent vessel. Four ischemic complications related to EVT resulted in a moderate disability in two patients. No rebleeding occurred after EVT, but one patient died because of a poor initial clinical status; the other patients improved. In the 10 patients treated conservatively, four died, three from a poor initial clinical status and one from rebleeding, and six patients had a good clinical outcome. Of the 27 patients, three had rebleeding and one died as a result of that rebleeding. Seventeen patients (63%) had a good recovery, six (22%) had a moderate disability, and four (15%) died. CONCLUSION: EVT provides effective protection against rebleeding. When possible, occlusion with coils at the dissection site is the current method of choice. Another option is parent artery occlusion with balloons, and the use of a stent may preserve vessel permeability in specific cases.
It has recently been proposed that the Ca(2+) uptake by the SR is inhibited by blocking Cl(-) and/or K(+) movements across this intracellular membrane. We have characterised the functional and pharmacological profile of the SR K(+) channel derived from human and sheep atrial cells. Mammalian atrial SR preparations were subjected to [(3)H]-ryanodine binding assays, SDS-PAGE analysis and channel protein reconstitution into planar lipid bilayers. Assessment of [(3)H]-ryanodine binding on the SR Ca(2+) release channel revealed that it was inhibited by both Ruthenium Red and Mg(2+) with IC(50) values of 4.11 microM and 9.12 m M, respectively. In crude populations as well as in all SR-enriched fractions, activity of K(+) selective channels was recorded. This channel displayed a high conductance value of 193 and 185 pS for human and sheep preparations respectively. Gating and conducting behaviours of this channel were unaffected by the addition of up to 5m M 4-Aminopyridine (4-AP), 100 n M Iberiotoxin (IbTX), 10 microM E-4031 and 30 microM amiodarone. However, 100n M Dendrotoxin (gamma-DTX) largely increase the occurrence of the SR K(+) channel subconducting states without an effect on the main unitary conductance. These results demonstrate that the SR K(+) channel, present in all mammalian atrial SR membranes tested (as assessed by [(3)H]-ryanodine binding and its typical inhibition by ruthenium red and the magnesium), displays different properties than those classically described for cardiac sarcolemmal K(+) channels. Despite the fact that the biophysical properties of the SR K(+) channel are well known, its molecular identity remains to be ascertained.
BACKGROUND AND PURPOSE: Controversy still surrounds the question of when and how to manage cases of subarachnoid hemorrhage of Hunt and Hess grade IV and V aneurysms. Several authors are in favor of surgical treatment, reporting improved clinical outcomes and lower mortality rates. Considering that endovascular procedures are currently being increasingly used to treat aneurysms, we investigated their use in the management of subarachnoid bleeding in a retrospective review of 80 patients. METHODS: Eighty patients were admitted to our hospital between October 1992 and October 1998 with subarachnoid hemorrhage of Hunt and Hess grade IV and V aneurysms. Patients received standard resuscitation treatment, nimodipine to prevent vasospasm, CSF shunt when necessary, and selective occlusion with Guglielmi detachable coil. They were subsequently followed up for at least 1 year. Aneurysm occlusion was monitored with MR angiography and/or angiography at 6 months and at 1 year. RESULTS: Of the 80 patients, 42 (52.5%) did well (Glasgow Outcome Scale score of 1 or 2) (62% of the 56 patients with grade IV and 25% of the 24 patients with grade V aneurysms), seven (8.75%) presented with poor neurologic status (Glasgow Outcome Scale score of 3), and 30 (37.5%) died during the first 6 months (26.7% of the patients with grade IV and 62% of the patients with grade V aneurysms). One patient was lost to follow-up. The main causes of death were consequences of initial bleeding in the patients with grade V aneurysms and vasospasm in the patients with grade IV aneurysms. CONCLUSION: The results are at least as encouraging as the outcomes reported for the surgical series and suggest that early endovascular treatment of high grade hemorrhage is a feasible option, especially because endovascular maneuvers can be performed at any time, even during vasospasm.