In vitro studies for stent-assisted coiling of terminus aneurysms by straight-on intra-aneurysmal stent deployment.

OBJECTIVE: Deployment of a Neuroform microstent (NFM; Boston Scientific/Target, Freemont, California, USA) within acutely angled geometry may result in substantial deformations. This in vitro study was conducted to validate a novel alternative technique, consisting of intentional deployment of a NFM straight on into a terminus aneurysm, by assessing the mechanics, feasibility, and stability of the coils. METHODS: Silicon models of wide-neck terminus aneurysms were constructed. Straight-on deployment of a NFM from the afferent vessel into the aneurysm was compared with conventional cross-neck deployment at a right angle position followed by Guglielmi detachable coil embolization simulation. The supporting forces of the two different methods of deployment were compared by the use of side-wall eccentric and en-face compression tests. RESULTS: Straight-on deployment of a NFM at a wide-neck terminus aneurysm was a relatively simple technique compared with cross-neck right angle deployment. Good stability of the coil mass was consistently achieved with adequate preservation of the parent vessel lumen. A larger residual neck space at the side without the stent and much coil mass protruding into the parent vessel were observed in cross-neck stent deployment. Compression tests revealed a larger supporting force of the NFM with straight-on deployment compared with the side-wall radial force (P < 0.05). A potential problem with this technique is the possible inability or difficulty in retrieving a partially deployed coil. CONCLUSIONS: Stent-assisted coiling of wide-neck terminus aneurysms with straight-on deployment of NFM consistently achieved a stable NFM-coil complex. The NFM also had a better supporting force in a straight position. Some technical difficulties may be encountered during subsequent coiling. This alternative technique to conventional cross-neck bridging appears to be another strategy for wide-neck terminus aneurysm coiling.

Experimental model evaluation of filter trapping after embolectomy using the Merci system: supplemental technique for Merci retrieval procedure.

Examination of embolectomy using the Merci Retrieval System using experimental stroke models demonstrated that aspiration is not adequate to remove larger clots. The effectiveness of filter trapping was examined using the same models. A silicone model of the carotid artery system with model blood clot was incorporated in a laboratory pulsatile flow system. Embolectomy was performed using the Merci Retrieval System. Any clot not evacuated through the balloon guide catheter was trapped with a distal protection filter device developed for cervical stenting. The clot could not be sucked into the guide catheter by the recommended procedures in nine of 15 trials. Trapping failed in only one trial, in which the clot passed through a gap between the edge of the filter orifice and the inner model lumen. A clot was withdrawn to the catheter tip trapped across the edge of the orifice frame in one trial, and a very large clot was trapped across the filter orifice in two trials. Even clots made by the same method showed variation in properties, especially hardness, which may affect the effectiveness of aspiration. The aspiration procedure recommended for the Merci Retrieval System did not remove the large clots formed by embolectomy. The trapping procedure using a filter device without an orifice frame was effective to solve this problem.

Evaluation of Merci Retriever by experimental modeling.

The Merci Retriever is the first device for mechanical embolus removal in patients with cerebral ischemia. Use of the device was evaluated using experimental models. Three stroke model systems were created: silicone embolism model with flow system, pig embolism model, and silicone-pig tortuous artery model. The series of extraction procedures (capture, retrieval, and aspiration) was examined in the models under flow control. Coagulated blood clot was adopted as embolic material, to simulate embolic stroke of the carotid or middle cerebral arteries. Retrieval of the clot was successful in only one of six trials in the silicone model of the carotid artery, as the clot easily worked free from the helical tip. Aspiration was successful in three of the six trials. Retrieval was successful in two of four trials in the middle cerebral artery and aspiration was successful in two. Retrieval was successful in all five trials in the pig embolism model, and three of five trials in the silicone-pig tortuous artery model. The Merci Retriever does not always retain the embolism, and the helix tends to distort in acute or rough lumen. Aspiration is not always successful.

Simulation of endovascular neurointervention using silicone models: imaging and manipulation.

Silicone models of cerebral aneurysm and stroke pathology were produced by copying the images of clinical cases to evaluate the simulation of endovascular procedures. Conventional silicone models, silicone suture models made from separate aneurysm sac and parent artery sutured together, and animal vascular models made from vessels obtained from pigs were made. The models were incorporated in the training system for simulation of endovascular procedures under digital subtraction angiography control using a portable angiography system. The conventional silicone models provided very close reproduction of the aneurysm and vessels, even the fine branches. However, greater resistance or impact was felt, especially when passing the device through curved vessels. Stroke models were insufficiently dilated by percutaneous transluminal angioplasty or stenting. The silicone suture model was useful to avoid damage to models of giant aneurysm or models with small orifices during the lost wax procedure, whereas the projection of domes was somewhat inaccurate. The animal vascular model could not provide accurate aneurysm shape and vessel diameter, although the feel during manipulation was much more realistic.

[Our current technique for basic pterional craniotomy].

Pterional cnaniotomy is frequently used in neurosurgical practice, but still poses significant cosmetic and functional drawbacks. Here, we describe our modified technique to overcome such problems as the sterilization of the scalp without brush and razor, preemptive analgesia, preservation of the periostium for reconstruction, retrograde dissection of the temporal muscle, and complete sphenoidotomy using chisel or drills. The tips of our pterional craniotomy offer suitable size and depth of working field around the paraclinoidal regions, maintaining cosmetic satisfaction of the patients.

De novo dissecting aneurysm in a patient with a ruptured saccular lesion. Case report.

Formation of a new saccular aneurysm after successful treatment of ruptured aneurysm has recently raised significant clinical concerns; however, de novo formation and rupture of a dissecting aneurysm has not been discussed. The authors report on a 42-year-old man who initially sought treatment for a ruptured saccular aneurysm of the right middle cerebral artery, which was successfully eliminated by surgical clipping of the aneurysm neck. Two years later, the patient presented with another subarachnoid hemorrhage and was found to have a dissecting aneurysm of the right vertebral artery, which arose from a previously angiographically documented normal artery. This rare association sheds light on the causes and growth of two distinct types of aneurysms, both clinically and pathologically.