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When to do a lumbar puncture

2002; BMJ; Volume: 87; Issue: 3 Linguagem: Inglês

10.1136/adc.87.3.235

1468-2044

F.A.I. Riordan,

Streptococcal Infections and Treatments

If you suspect meningitis, unless there is a specific contraindication Lumbar puncture has long been a key investigation. The “classical signs” of meningitis are often absent in infants in the first year of life. Lumbar puncture is thus advocated for any infant who is drowsy or ill, without awaiting the development of meningeal signs.1 Concerns about the perceived dangers of lumbar puncture2 and a suggestion that it has little diagnostic value in meningococcal disease3 have led to fewer lumbar punctures being performed.4 Some experts have expressed concerns that not enough lumbar punctures are being performed, since the consequences of missing meningitis may be disastrous.5 A review of the indications for lumbar puncture is thus timely, and papers in this issue by McMaster and colleagues6 and Carroll and Brookfield7 contribute to this debate. Critical questions include: In most cases lumbar puncture confirms or excludes bacterial meningitis. It is rare for microscopy of cerebrospinal fluid obtained at lumbar puncture to be normal, and a pathogen to be grown later. This occurs most often in meningococcal meningitis (up to 8%).4 These children have clinical signs of meningitis or septicaemia (rash) and should receive antibiotics in spite of a “normal” cerebrospinal fluid. Children rarely develop meningitis some hours after a normal lumbar puncture. The suggestion that the lumbar puncture itself performed during bacteraemia may cause meningitis remains controversial and unproven.8 Initial Gram staining of cerebrospinal fluid reveals an organism in 68–80% of cases of meningitis,9 allowing appropriate choice of antibiotics. …