Lumbar Puncture

Lumbar Puncture Needle Selection

The issue of needle selection is almost resolved. The most up to date recommendation from the American Academy of Neurology is that 22 guage atraumatic needles should be used, as they are asociated with the lowest risk of an LPs most frequent complication - the post-LP headache. 

The evidence for this comes mostly from anaesthetic literature, but there is little doubt from e.g. good quality studies that an atraumatic needle may reduce post-LP headache from 24% to 12%.

However, not all doctors have ever used atraumatic needles, and the lower risk of post-LP headache should be measured against the risk of a poor patient experience caused by an operator using a needle with which they are not experienced.  A misdirected LP needle can be very painful, particularly if the needle comes into contact with bone (periosteum) or nerve root. This may seem silly i.e. surely all needles are the same?  In actual fact you do get used to the feel of certain needles.  A fine needle is more flexible, whereas you have more control over the direction of a thicker/broader needle. 

There are potentially other methods of preventing post-LP headache.  An interesting way, but not widely accepted, is to insert the needle tangentially i.e. deliberately placing the needle at an angle instead of perpendicular to the surface of the back (see Dr Hatfalvi’s article published in Regional Anesthesia 1995. Tangential insertion also requires training and anatomical knowledge, and image guidance, such as ultrasound, may help less experienced operators.

A preference must surely be for correct use of 22 guage atraumatic needles, but for those of us who are confident with existing cutting or traumatic needles, we will need to justify our continued use of these with evidence of minimal patient discomfort at the actual time of their LP.