Evidence & Methods
According to the authors, the use of atraumatic needles is uncommon in diagnostic lumbar punctures. Utilization of atraumatic needles has been linked to lower rates of post–lumbar puncture headache. The authors performed a prospective, randomized, single-blinded clinical trial to define the incidence post–lumbar puncture headaches based on the needle types used to perform the lumbar puncture.
Patients were randomized to receive lumbar puncture with a traumatic or atraumatic needle. Analysis was performed as treated, with 30 patients randomized to the atraumatic group receiving lumbar puncture with a traumatic needle. The rate of post–lumbar puncture headache was significantly lower among patients punctured with an atraumatic needle. The duration of headaches was also significantly shorter in the atraumatic group.
The ideal means of performing this analysis would have been along intent-to-treat lines, rather than as treated. Nonetheless, this investigation provides evidence in support of the use of atraumatic needles in lumbar puncture, although their utilization may be technically challenging. Readers should consider the authors’ inclusion criteria, as well as socio-cultural differences that may exist between their patients and those who participated in this study, before they apply the findings of this work to clinical practice.
—The Editors
Postdural puncture headache (PDPH) is the most common complication of lumbar puncture (LP), occurring in about 40% of times [1], [2]. According to the International Classification of Headache Disorders (ICHD-III), it is defined as a bifrontal and/or occipital headache that appears within 5 days after LP, which occurs or worsens when upright position is assumed and improves or disappears lying down. It may be accompanied by tinnitus, hearing loss, photophobia, or nausea. Usually, it resolves spontaneously within 1 week [3]. In most cases, PDPH resolves spontaneously with an estimated remission rate of 72% at 5 days [4]. Conservative methods of treatment of PDPH include bed rest, analgesia, and hydration. When this management fails, oral or intravenous caffeine is helpful, but if the PDPH is severe, it is best treated with an epidural blood patch [5].
The pathophysiology is unclear, and there are probably different and not mutually exclusive mechanisms. The needle produces a dural defect and consequent spinal fluid leakage into the epidural space, resulting in a decrease of the cerebrospinal fluid (CSF) pressure and volume. Then, when the patient assumes the upright position, he experiences traction on pain-sensitive structures (meningeal membranes, blood vessels and nerves). Other theories explain the PDPH based on a compensatory intracranial vasodilatation, according to the Monro-Kellie doctrine (the constant volume of the skull contents), to alleviate the lower CSF pressure [6], [7], [8].
Postdural puncture headache is more frequent in the female gender, younger age, and patients with lower body mass index (BMI) [9], [10], [11]. The three technical factors that have been discussed as possibly reducing the incidence of PDPH are the smaller needle diameter or gauge (G), which is the most important, the insertion of the needle with the bevel parallel to the long axis of the spine, rather than in a perpendicular direction, and the reinsertion of the stylet before needle withdrawal [6], [12], [13]. An extensive meta-analysis has shown the ineffectiveness of bed rest after LP [14]. However, the needle design is a less-known factor in the development of PDPH. Spinal needles can be either cutting (traumatic) or pencil point (atraumatic). According to the histologic studies, atraumatic needles (Sprotte [S] or Whitacre [W] type) have a blunt tip, which produces tearing of the dura fibers creating a smaller hole that closes rapidly and results in relatively small CSF leakage. However, the traumatic needle (Quincke [Q] type) has a sharp tip, which cuts the dura fibers in multiple directions and creates a larger hole that heals more slowly and is associated with a greater CSF leakage [10]. Hence, the atraumatic needle produces a smaller dural defect, which closes rapidly and results in lower incidence of PDPH [6]. Although the S-type needle is slightly more expensive than the Q-type needle, a cost-efficacy analysis showed the first one to be more efficient when the additional expenses because of the PDPH were included [15].
In the field of anaesthesiology, thinner needles are used for LP, and the advantage of atraumatic needles in reducing postdural puncture headache is well established. In fact, the frequency of PDPH appears to be doubled in the diagnostic punctures in relation to the anaesthetics one [16]. However, in diagnostic LP, the use of 25G spinal needles, customary in spinal anesthesia, could be an obstacle to receive CSF enough for diagnostic purposes, and the ordinary small diameter used is 22G.
In contrast with the experience in anaesthesiology, the type of needle factor is less studied in diagnostic LP. Up to date, seven comparative and methodologically correct studies investigate the influence of needle type in PDPH [1], [10], [17], [18], [19], [20], [21], and three of them showed a lower incidence of PLPH with atraumatic needle, as presented in Table 1. However, neurologists use atraumatic needles in less than 2% of their patients [22].
It is justified to do additional and methodologically correct studies to support the recommendation of the use of atraumatic needle because PLPH is an important cause of iatrogenic morbidity after an LP, and its use is still limited in standard neurological practice [23]. To define the impact of needle type on PDPH, we performed a prospective, randomized, and simple-blinded trial comparing the incidence of PDPH in patients undergoing LPs with traumatic or Q-type versus atraumatic or S-type 22G needles.