Cerebrospinal Fluid Leakage, Spinal Needles, and Postdural Puncture Headache (PDPH)

To the Editor: I read with interest the article by Westbrook et al. [1] reporting the results of their study showing that pencil-point needles reduce the leakage of cerebrospinal fluid (CSF) compared with Quincke point needles. I would like to discuss their conclusion. They state that "pencil-point needles require more force to pierce dura but subsequently leak less CSF when compared to Quincke needles, confirming their superiority in reducing the incidence of PDPH." This claim is invalid. I agree that their study convincingly demonstrates that pencil-point needles reduce the leak of CSF compared with Quincke point needles. It is also true that, for a similar gauge, pencil-point needles do reduce the incidence of PDPH [2]. However, their study does not look at PDPH, and no one has directly correlated CSF leakage rate with the incidence of headache. How the two variables of rate and duration of leakage interact in the pathogenesis of the headache is also unknown [3]. Factors such as recoil of dural fibers [4], the anatomy of the epidural space, and the rate of CSF production are also important. It is therefore a leap of faith for them to state that their study confirms the "superiority" of pencil-point needles in reducing the incidence of PDPH. Alasdair R. Maclean, FRCA Department of Anaesthesia, St. James's University Hospital, Leeds LS9 7TF, England