Devices for treatment of vascular defects

A method for treating a cerebral aneurysm having an interior cavity and a neck, comprising the steps of:

• advancing an implant in a microcatheter to a region of interest in a cerebral artery, wherein the implant comprises:
• a permeable shell comprising a first layer, a second layer, a proximal end, a distal end, and a transitional section connecting the first and second layer, wherein the permeable shell has a radially constrained elongated state configured for delivery within a lumen of the microcatheter and an expanded state with a longitudinally shortened configuration relative to the radially constrained state,
• wherein the first and second layers are formed from a plurality of elongate filaments that are woven together to form a mesh, wherein each of the plurality of elongate filaments have a first end and a second end, wherein the first and second ends of each of the plurality of elongate filaments are gathered at the proximal end of the permeable shell in a proximal band, and
• wherein the transitional section of the permeable shell comprises a first end portion connected to a distal end of the first layer and a second end portion connected to a distal end of the second layer, wherein the second end portion is inverted, and wherein the intermediate portion of the plurality of elongate filaments is not surrounded by a band, wherein in an unconstrained configuration, the permeable shell further comprises a distal void space in a distal region of the permeable shell and a proximal void space in the proximal region of the permeable shell, and wherein the proximal void space is defined by a bottom surface of an expanded state of the second layer and an inner surface of a proximal region of the first layer;
• deploying the implant within the cerebral aneurysm, wherein the permeable shell expands to the expanded state in the interior cavity of the aneurysm;
• and
• withdrawing the microcatheter from the region of interest after deploying the implant.