The Pulsator syringe for epidural injection has a plunger that can be pulled back beyond a stop tab, and if the operator is unaware the plunger is so engaged, can experience "bounce" of the plunger when advancing with no loss of resistance. The needle can be driven all the way across the spinal canal (don't ask me how I know....fortunately mine was lumbar and other than a transient spinal headache, no foul). If the needle is advanced with the plunger in this position and if "danger view" fluoroscopy is not used (lateral in the thoracic and lumbar, Pullitz line or lateral in the cervical), then significant damage to the cord, dura, spinal nerves, annulus fibrosis can occur. On the other hand, glass syringes, even when pre-wetted, can bind at the most inopportune moments.. Moral of the story: use lateral view fluoro guidance (or modification) for advancement of an interlaminar needle, otherwise it is just a blind epidural stick.