EXPANDABLE CEREBROVASCULAR SHEATH

Disclosed is an expandable transluminal sheath, for introduction into the body while in a first, small cross-sectional area configuration, and subsequent expansion of at least a part of the distal end of the sheath to a second, enlarged cross-sectional configuration. The sheath is configured for use in the upper vascular system and has utility in the introduction and removal of therapeutic or diagnostic microcatheters. The access route is through the femoral arteries or the iliac arteries to the cerebrovasculature. The distal end of the sheath is maintained in the first, low cross-sectional configuration during advancement to the cerebrovasculature. The distal end of the sheath is subsequently expanded using a radial dilatation device, which is removed prior to the introduction of microcatheters. The sheath can be inserted in a first, small cross-sectional configuration, be expanded diametrically to a second, larger cross-sectional configuration, and then be reduced to a diametrically smaller size for removal.