neurovasculature tortuous regions are defined as those vascular regions having bend exceeding 90 degrees and having a vascular diameter of 3 mm or less accordingly the distal end 16 has an outside diameter of 0 040 u2033 or less the distal end includes a delivery lumen with lumen walls the lumen walls being at least 0 0012 u2033 thick to withstand pressures associated with the delivery of viscous fluids 0043 fig2 shows the syringe 24 the syringe locknut 30 the luer fitting 18 the compression fitting 20 the catheter body 12 and the strain relief element 22 the syringe locknut 30 is one form of compression fitting there are other compression fittings however including compression fittings formed from thermal bonding techniques insert moldings and over moldings for examples these alternate forms of compression fittings can be substituted for the syringe locknut 30 in accordance with the present invention the syringe locknut 30 is hollow having a centrally defined opening 33 for receiving the needle 26 of the syringe 24 the syringe locknut 30 compresses against the needle 26 to hold and seal the needle 26 the syringe locknut 30 includes a threaded portion 31 and an angled section 37 the syringe locknut 30 rotates to thread the threaded portion 31 to the end 32 of the luer fitting 18 when the needle 26 inserts into the luer fitting 18 and the syringe locknut 30 slide forward in place with respect to the luer fitting 18 and rotates the needle 26 does not significantly deform instead the angled section 37 of the syringe locknut 30 radially compresses to hold the needle 26 within the opening 33 the compression fitting 20 according to one aspect of the invention is.