Lumbar puncture: clinical features and physicians' predictions could not safely exclude a contraindication to lumbar puncture

Clinical bottom line (level 1b)

  1. One in forty patients had a contraindication to lumbar puncture.
  2. A physician's prediction of the presence of a contraindication to lumbar puncture was quite accurate (LR+19) .
  3. Physicians can predict fairly well patients with no contraindication to a lumbar puncture, (LR-0.0) but further testing is required to be certain.
  4. No clinical feature could safely diagnose or exclude an intracranial mass, though papilloedema (LR+11) , focal neurological signs (LR+4.3) and altered mentation (LR+2.2) made one more likely.
Gopal et al: Archives of Internal Medicine 1999; 159: 2681-2685
Expires April 2004

The study

Setting: university hospital, USA

111 patients (aged 17 to 99; median 42, ?% male) with an urgent need for lumbar puncture (to rule out meningitis, 37%; subarachnoid haemorrhage, 43% or other reasons)

Excluded if
  • incomplete data
  • aged < 18



    • Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Reference standard:
    • CT head: lumbar puncture contraindicated if any of
      • lateral shift of midline structures
      • loss of suprachiasmatic and basilar cisterns
      • obliteration of fourth ventricle
      • obliteration of superior cerebellar and quadrigeminal plate cisterns with sparing of the ambient cisterns
    Diagnostic test: clinical features

    The evidence

    pre-test probability of lumbar puncture contraindicated: 2.7%, (95% CI: 0.0% to 5.7%)
    pre-test probability of intracranial mass: 15%, (95% CI: 8.6% to 22%)

    diagnostic test lumbar puncture contraindicated no contraindication LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    physician's prediction of a contraindication 3 5 19
    (4.8 to 43)     		34% 0.0
    (0.0 to 0.7)     		0%
    total 3 108


    diagnostic test new intracranial lesion no intracranial lesion LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    papilloedema 3 1 11
    (1.1 to 120)     		67% 0.89
    (0.75 to 1.1)     		14%
    focal neurological examination 7 9 4.3
    (1.9 to 10)     		44% 0.64
    (0.38 to 1.0)     		10%
    altered mentation 13 33 2.2
    (1.5 to 3.2)     		28% 0.36
    (0.15 to 0.90)     		6%
    1 or more abnormality present 17 49 1.6
    (1.2 to 1.9)     		22% 0.0
    (0.0 to 0.6)     		0%
    physician's prediction of a new lesion 7 4 9.1
    (2.4 to 34)     		62% 0.63
    (0.4 to 1.0)     		10%
    total 17 94

    • None of the following features were found to predict intracranial lesions
      • HIV risk factors
      • HIV positive
      • immunosuppressed
      • malignant neoplasm
      • head trauma < 72 hours
      • prior CNS mass
      • seizures < 72 hours

    Comments

    1. In the emergency setting, it is contraindications to LP (rather than presence of intracranial masses) which is of clinical importance.
    2. The study is too small to show the diagnostic ability of most of the clinical features studied.
    3. Original numbers were not given, but calculated from data in the article and contact with the investigating clinician. A correction is being made to the original, triggered by the creation of this CAT.

    Citation

    1. Gopal AK, Whitehouse JD, Simel DL, et al: cranial computed tomography before lumbar puncture: a prospective clinical evaluation. Archives of Internal Medicine 1999; 159: 2681-2685
    Contributor: Chris Ball and Bob Phillips, April 2000
    Reviewer: Michael Nielsen

    Clinical Question.
    Patient requiring urgent lumbar puncture
    Intervention or Exposure clinical features
    Comparison CT head
    Outcome contraindication to lumbar puncture