stylet replacement ？

Risk factors for the occurrence of PDPH are divided into non-modifiable and modifiable. Non-modifiable risk factors include (1) age (highest risk at age 20–30, rare over the age of 60), (2) female gender, (3) low BMI, (4) history of prior PDPH, and (5) history of chronic headache. Modifiable risk factors include (1) size of the spinal needle, (2) needle shape,(3) bevel orientation and angle of insertion, (4) stylet replacement, and (5) operator experience.

PDPH发生的危险因素分为不可改变和可改变。不可改变的危险因素包括(1)年龄(20-30岁风险最高，60岁以上少见)，(2)女性，(3)低BMI，(4)既往PDPH病史，(5)慢性头痛病史。可矫正的危险因素包括(1)脊椎针的大小，(2)针的形状，(3)斜面方向和插入角度，(4)stylet replacement，(5)操作者经验。

stylet replacement  插管芯置换？就是不合适的管芯？还是打麻药的时候把针芯抽掉的？抽掉针芯的过程就叫stylet replacement？但是抽掉针芯的过程大家不都是一样的吗？