O-020 Modifying Flow in the ICA Bifurcation: Pipeline Deployment from the supraclinoid ICA Extending into the M1 Segment: Clinical and Anatomical Results

BACKGROUND: Utility of the pipeline embolization device (PED) extending to the M1 segment as well as its clinical and flow consequences at the ICA bifurcation, has not clearly described. We describe clinical and anatomical flow modifications results at the ICA bifurcation. METHODS: In this retrospective analysis of patients treated for distal supraclinoid carotid aneurysms, a single PED was deployed from the proximal M1 segment to the distal supraclinoid carotid. Flow assessment prior to the procedure, to predict the competence of the ACA/AcomA complex, was achieved by formal DSA angiography and occasional manual cross compression. In all cases a single PED was deployed over the ostium of the A1, while treating a single or multiple aneurysms. Anatomical vessels diameters and ratios between the size of the proximal segments of the A1 and M1 as well as the distal ICA were assessed. Relationships between the PED nominal diameter and the diameters of the vessels at the landing zones were obtained. All measurements were evaluated in respect to flow modifications and size regression of the A1 in the immediate postoperative images, at 3 month MRI/MRA and at 6-9 month formal DSA angiography. Immediate and mid-term clinical results were assessed. RESULTS: We treated seven patients using this technique. Median age was 62. Four patients were treated for multiple aneurysms. The following aneurysms were treated: 3 posterior communicating artery aneurysms, 3 anterior choroidal artery aneurysms, 4 ICA bifurcation aneurysms and one A1 segment aneurysm. 6/7 patients demonstrated no change of flow in ACA/AComA complex at the immediate post embolization angiography. One patient demonstrated immediate antegrade flow retardation in the ipsilateral A1 segment. Five patients underwent 3-4 month MRA follow up. All demonstrated size regression of the ipsilateral A1 segment and occlusion of the neurysms. Five patients underwent mid-term follow-up angiography (5.5-12 month). Complete reversal of flow in the ipsilateral A1, was noted in 4/5 patients (Figure 1). One patient did not demonstrate any flow modification. This patient had a dominant ipsilateral A1 segment. Interestingly, ratios of the vessels participating in this bifurcation demonstrated a unique configuration of a higher A1/M1, A1/ICA ratios and a lower M1/ICA ratio, possibly in favor of maintaining patency of the ipsilateral A1. In this specific patient, a minimal length (0.97 mm) of PED was deployed in the M1 segment. This was the most oversized PED in respect to the M1 segment. All patients were stable in the post-procedural period and with no new neurological deficits. There were no clinical nor radiographic signs of ischemia. One patient experienced asymptomatic angiographic in-stent stenosis at the M1 segment. CONCLUSIONS: We found that the deployment of PED from the distal supraclinoid carotid to the M1 segment may result in reversal of flow in the ACA/AcomA complex as well as regression of the ipsilateral A1 segment. Preoperative anatomical disposition and sizing of the PED may predict the flow modification results. This modification of flow is safe and effective, based on pre-embolization flow assessments, and may be useful in treating distal ICA aneurysm by a flow diverter. DISCLOSURES: E. Nossek: None. D. Chalif: None. S. Chakraborty: None. A. Setton: None

Internal Maxillary Artery-Middle Cerebral Artery Bypass: Infratemporal Approach for Subcranial-Intracranial (SC-IC) Bypass

BACKGROUND:Internal maxillary artery (IMax)-middle cerebral artery (MCA) bypass has been recently described as an alternative to cervical extracranial-intracranial bypass. This technique uses a keyhole craniectomy in the temporal fossa that requires a technically challenging end-to-side anastomosis.OBJECTIVE:To describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax to facilitate bypass.METHODS:Orbitozygomatic osteotomy is used followed by frontotemporal craniotomy and subsequently laterotemporal fossa craniectomy, reaching its medial border at a virtual line connecting the foramen rotundum and foramen ovale. The IMax was identified by using established anatomic landmarks, neuronavigation, and micro Doppler probe (Mizuho Inc. Tokyo, Japan). Additionally, we studied the approach in a cadaveric specimen in preparation for microsurgical bypass.RESULTS:There were 4 cases in which the technique was used. One bypass was performed for flow augmentation in a hypoperfused hemisphere. The other 3 were performed as part of treatment paradigms for giant middle cerebral artery aneurysms. Vein grafts were used in all patients. The proximal anastomosis was performed in an end-to-side fashion in 1 patient and end-to-end in 3 patients. Intraoperative graft flow measured with the Transonic flow probe ranged from 20 to 60 mL/min. Postoperative angiography demonstrated good filling of the graft with robust distal flow in all cases. All patients tolerated the procedure well.CONCLUSION:IMax to middle cerebral artery subcranial-intracranial bypass is safe and efficacious. The laterotemporal fossa craniectomy technique resulted in reliable identification and wide exposure of the IMax, facilitating the proximal anastomosis

Thermoelectric effect in very thin film Pt∕Au thermocouples

The thickness dependence of the thermoelectric power of Pt films of variable thickness on a reference Au film has been determined for the case when the Pt film thickness, t, is not large compared to the charge carrier mean free path, {ell}, that is, t/{ell}. Pt film thicknesses down to 2.2 nm were investigated. We find that {Delta}S{sub F} = S{sub B}-S{sub F} (where S{sub B} and S{sub F} are the thermopowers of the Pt bulk and film, respectively) does not vary linearly as 1/t as is the case for thin film thermocouples when the film thickness is large compared to the charge carrier mean free path

Inverse scale space decomposition

We investigate the inverse scale space flow as a decomposition method for decomposing data into generalised singular vectors. We show that the inverse scale space flow, based on convex and absolutely one-homogeneous regularisation functionals, can decompose data represented by the application of a forward operator to a linear combination of generalised singular vectors into its individual singular vectors. We verify that for this decomposition to hold true, two additional conditions on the singular vectors are sufficient: orthogonality in the data space and inclusion of partial sums of the subgradients of the singular vectors in the subdifferential of the regularisation functional at zero. We also address the converse question of when the inverse scale space flow returns a generalised singular vector given that the initial data is arbitrary (and therefore not necessarily in the range of the forward operator). We prove that the inverse scale space flow is guaranteed to return a singular vector if the data satisfies a novel dual singular vector condition. We conclude the paper with numerical results that validate the theoretical results and that demonstrate the importance of the additional conditions required to guarantee the decomposition result

The art of cerebral aneurysms-3 decades of postoperative drawings: review, classification, and efficacy for training

OBJECTIVE: To focus on postoperative drawings of aneurysms, which serve as visual records and teaching tools for neurosurgeons and reinforce three-dimensional vascular configurations that are specific for different cerebral aneurysms, and examine experience with this technique, particularly in regard to the training of neurosurgical residents. METHODS: After performing craniotomy for aneurysm treatment, formal postoperative drawings were created and reviewed. Microsurgical issues graphically highlighted included the totality of aneurysmal dome anatomy, position of visible and hidden branch vessels, rupture points, clipping techniques, and location of adjacent cranial nerves. Drawings were cataloged and categorized according to location. RESULTS: Over a 28-year period, during a continuous series of 1480 microsurgically treated aneurysms, 619 drawings (221 of anterior cerebral artery, 154 of middle cerebral artery, 214 of internal carotid artery, 30 of posterior circulation) were created. Postoperative drawings in each location were presented and reviewed. Drawings demonstrated site-specific microsurgical approaches, morphologies, and points of obscuration and rupture. CONCLUSIONS: Creation and review of postoperative drawings are important adjuncts for the development of three-dimensional understanding of aneurysmal anatomy. This classic art has impact in the digital age and allows patterns of morphology, projection, and anatomy to be reinforced. Surgical atlases created from postoperative drawings function as reference and teaching tools. The creation of postoperative drawings should be a routine part of the training and methodology of vascular neurosurgeons

Agonistic Behavior in Female Wolf Spiders (Araneae, Lycosidae)

Volume: 11Start Page: 407End Page: 42