Aspiration catheter systems and methods of use

A method of performing a medical procedure at a treatment site within a cerebral vessel of a patient, the method comprising:

• assembling a system of devices comprising:
• a guidewire comprising a distal-most end;
• an outer catheter having a catheter lumen and a distal end;
• and
• a catheter advancement device having a working length configured to extend from outside a patient's body, through a femoral artery, and to the cerebral vessel, the catheter advancement device comprising:
• a flexible elongate body having a proximal end, a distal end, and a single lumen extending therebetween, the flexible elongate body comprising:
• a proximal segment configured to move the catheter advancement device bi-directionally within the catheter lumen of the outer catheter;
• an intermediate segment comprising a polymer having a first durometer;
• and
• a tip segment formed of a polymer different from the polymer of the intermediate segment, the polymer of the tip segment having a second durometer less than the first durometer, wherein the tip segment has a tapered portion that tapers distally from a first outer diameter to a second outer diameter,
• wherein, when assembled, the catheter advancement device extends within the catheter lumen of the outer catheter so that the tapered portion of the tip segment is positioned distal to the distal end of the outer catheter and the guidewire extends within the single lumen of the catheter advancement device so that the distal-most end of the guidewire is positioned proximal to a distal opening from the single lumen;
• and
• advancing the assembled system of devices together into the cerebral vessel.