A method of treating a sinus cavity of a subject includes advancing a distal portion of a light source through a drainage pathway of a sinus cavity and into the sinus cavity and visually observing a transdermal light emitted from the light source. A distal portion of a substantially rigid inner guide member of a balloon dilation catheter is advanced into the drainage pathway, the balloon dilation catheter including a movable shaft including a balloon that is slidably mounted on the substantially rigid inner guide member. The movable shaft and balloon are advanced distally over the substantially rigid inner guide member to place a portion of the balloon in the drainage pathway whereby the balloon is inflated.