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BMJ No 7119 Volume 315 Editorial Saturday 22 November 1997
Lumbar puncture needn't be a headacheUse blunt needles and no bed restLumbar puncture is an investigation that patients often fear. Headache afterwards is the commonest complication, occurring in over 30% of patients when a 20 G bevelled needle is used.(1) The headache is typically occipital and related to posture. It can be severe in up to a third of patients, rendering the individual immobile. Characteristically, the headache starts 24-48 hours after lumbar puncture and usually lasts one to two days but may be more prolonged. The headache is related to low cerebrospinal fluid pressure resulting from spinal fluid leaking through the hole cut in the dura by bevelled spinal needles.(2,3) Traditionally, manoeuvres such as bed rest and posture have been used to prevent headache. Despite the popularity of bed rest, evidence of its effectiveness is weak, and British clinicians are ignoring the most effective means of preventing headache after lumbar puncture. Two randomised controlled trials have considered bed rest, comparing four(4) and six(5) hours' bed rest with immediate mobilisation, only one using blinded assessors.(5) Neither study found any difference in the rate of headache, or in the rate of disabling headache.(5) Bed rest is thus not of proven benefit. Lumbar puncture is most commonly performed in administering spinal anaesthesia and in diagnosing neurological disease. In anaesthetics much effort has gone into reducing the incidence of headache after lumbar puncture. Finer bore spinal needles have been used in an attempt to reduce the volume of the cerebrospinal fluid leak(2,3) and have succeeded in reducing the incidence of headache to around 14% with a 25 G needle and just over 2% with a 27 G needle.(6) In addition "blunt" needles (pencil point and bullet tipped) have been found to separate rather than cut dural fibres, thereby further reducing the rate of leakage.(7) Using such needles with bores of 25 G or smaller reduces the incidence of headache to around 1%.(3) In diagnostic neurology many of the traditional investigations necessitating lumbar puncture such as myelography, where the incidence of headache is higher,(2) have been superseded by newer techniques. Nevertheless, lumbar puncture to allow examination of the cerebrospinal fluid remains an important investigation. The requirements of diagnostic lumbar puncture differ from those in anaesthetics: spinal fluid must be removed and the pressure measured. Thus very fine needles cannot be used. Needles smaller than 22 G take longer than six minutes to collect 2 ml of fluid.(6) A similar period is required to measure pressure, and even then the measurement may be inaccurate.(6) In practice therefore a 22 G needle is the smallest size that can be used for diagnostic lumbar puncture. Blunt needles have recently been shown to reduce the incidence of headache after diagnostic lumbar puncture in neurological practice in double blind controlled randomised trials.(8,9) A 22 G blunt needle gave rise to an incidence of headache of only 5%,(8,9) similar to the incidence quoted in anaesthetic series for this type of needle.(6) This evidence has not yet changed practice in British neurological and medical units, where a 20 G needle remains the standard and bed rest is routine.(10,11) The incidence of headache could be reduced sixfold (30% to 5%) if clinicians switched to 22 G blunt spinal needles. The newer needles are more expensive, but theoretical calculations indicate that the higher cost of the needles is more than offset by the potential saving from treating fewer patients with severe post-lumbar puncture headache.(10) In the light of this evidence neurological and medical units should review which lumbar puncture needles they use and consider limiting the use of bed rest. Simon A Broadley
Registrar
Department of Neurology,
References
1 Kuntz K M, Kokmen E, Stevens J C, Miller P, Offord K P, Ho
M M. Post- lumbar puncture headaches: experience in 501 consecutive
procedures. Neurology 1992;42:1884-7.
2 Peterman S B. Postmyelography headache: a review.
Radiology 1996;200:765-70.
3 Morewood G H. A rational approach to the cause, prevention and
treatment of postdural puncture headache. Can Med Assoc
J 1993;149:1087-93.
4 Spriggs D A, Burn D J, French J, Cartlidge N E F, Bates D. Is
bed rest useful after diagnostic lumbar puncture? Postgrad Med
J 1992;68:581-3.
5 Vilming S T, Schrader H, Monstad I. Post lumbar puncture
headache: the significance of body posture. A controlled study of 300
patients. Cephalalgia 1988;8:75-8.
6 Carson D, Serpell M. Choosing the best needle for diagnostic
lumbar puncture. Neurology 1996;47:33-7.
7 Westbrook J L, Uncles D R, Sitzman B T, Carrie L E S.
Comparison of the force required for dural puncture with different
spinal needles and subsequent leakage of cerebrospinal fluid.
Anaesth Analg 1994;79:769-72.
8 Muller B, Adelt K, Reichmann H, Toyka K. Atraumatic needle
reduces the incidence of post-lumbar puncture syndrome. J
Neurol 1994;241:376-80.
9 Braune H J, Huffmann G . A prospective double-blind clinical
trial, comparing the sharp Quincke needle (22G) with an
"atraumatic" needle (22G) in the induction of post-lumbar puncture
headache. Acta Neurol Scand 1992;86:50-4.
10 Broadley S A, Fuller G N. Audit of lumber puncture practice in
United Kingdom neurology centres. J Neurol Neurosurg Psychiatry
1997;63:266
11 McSwiney M, Phillips J. Post dural puncture headache.
Acta Anaesthesiol Scand 1995;39:990-5.
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