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Three Part Question

In [patients with suspected subarachnoid haemorrhage but a negative CT and LP] where [suspicion of subarachnoid haemorrhage remains high] [what is the prognosis]

Clinical Scenario

A 39 year old woman presents to the emergency department with a thunderclap headache. She has not suffered from anything like this before. You suspect a subarachnoid haemorrrhage. You send her for urgent CT scan which comes back negative. You then wait until 12 hours after the onset of the symtoms and do a lumbar puncture which also comes back negative. You are worried about discharging her because you have heard horror stories about the consequences of misdiagnosis of SAH. You feel you have done everything you can you know want to know if you can dicharge this patient

Search Strategy

Medline 1966 to July week 1 2006,
Embase 1980 to 2006 week 28,
CINAHL 1982 to July Week 2 2006
Cochrane
Medline
[{exp Intracranial Aneurysm/ or exp Subarachnoid Hemorrhage/} OR {(subarachnoid adj (hemorrhage$ or haemorrhage$ or bleed$)).mp.} OR {SAH.mp.}] AND [{Tomography, X-Ray Computed/} OR {(CT adj scan$).mp.} OR {(computer$ adj tomography$ adj scan$).mp.}] AND [{exp Spinal Puncture/} OR {((lumbar$ adj puncture$) or LP or Spinal$ tap$ or spinal$ puncture$).mp.} OR [{exp Cerebrospinal Fluid/} OR {((Cerebrospinal$ adj fluid$) or csf).mp.}]. Limit search to humans and English Language
Embase and CINAHL
[{exp Intracranial Aneurysm/ or exp Subarachnoid Hemorrhage/} OR {(subarachnoid adj (hemorrhage$ or haemorrhage$ or bleed$)).mp.} OR {SAH.mp.}] AND [{Tomography, X-Ray Computed/} OR {(CT adj scan$).mp.} OR {(computer$ adj tomography$ adj scan$).mp.}] AND [{exp Spinal Puncture/} OR {((lumbar$ adj puncture$) or LP or Spinal$ tap$ or spinal$ puncture$).mp.}]. Limit search to humans and English Language.
Cocharane
[{Mesh Descriptor Subarachnoid Hemorrhage explode all trees} OR {( subarachnoid* hemorrhage*) OR (subarachnoid* haemorrhage*) OR (SAH)}] AND [{Mesh Descriptor Spinal Puncture explode all trees} OR {(lumbar* puncture*) OR (lp) OR (spinal* puncture*) OR (spinal* tap*)}]

Search Outcome

Medline 308 papers 2 relevant
Embase 220 papers 0 relevant papers
CINAHL 22 papers 0 relevant
Cochrane 22 papers found 0 relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Harling DW et al 1989 Norway	14 patients with sudden headache suggestive of SAH but with negative CT scans and lumbar puncture	Prospective cohort study. Level of evidence 2b.	Is CTA necessary for patients with sudden severe headache.	At an 18 month follow up of these patients found: 1 patient had had no subsequent headache; 4 were thought to have had the headache due to musculoskeletal pain; 5 patients were thought to have headaches of psychogenic origin; 4 were found to suffer from migranous headaches.	Very small number of patients. Does not say how the CSF is analysed (naked eye or spectroscopy). The CSF was only analysed after 2 hours which is far too short a period of time. The data is not compared with controls or statistically analysed.
Wijdicks EMF et al 1988 Netherlands	71 patients with severe and unusual headaches but with a normal CT scans and lumbar punctures	Prospective cohort study. Level 3b	Is there a need for CTA in patients with no abnormalities detected by CT or LP	Over the average 3.3 years follow up, twelve had a similar episode of which four had negative CT, LP and CTA investigations. 31 patients went on to develop either tension or migrainous headache.	Small study sample. There is no statistical analysis of data and very little information is given. Exact numbers for data are not always given. Whilst it implies no one had an SAH it does not state this clearly. It also doesn't state which method was used to test the CSF.

Comment(s)

The evidence from these papers is very weak as the study groups are very small, there are no control groups and the results have not been statically analysed. Neither of the reports have mentioned what was looked for in the CSF. A previous bet has recommended the analysis of CSF for xanthochromia. It recommends the lumbar puncture is done at least 12 hours after the episode. I further recommend that CSF spectophotometry is used to analyse the sample.

Clinical Bottom Line

In patients with a negative CT and LP it is safe to discharge them if CT negative and CSF negative, after 12 hours, without further follow up.

References

1. Harling DW et al Thunderclap Headache: Is It Migraine? Cephalgia 1989;87-90
2. Wijdicks EMF et al Long-Term Follow Up of 71 Patients With Thunderclap Headache Mimicking Subarachnoid Haemorrhage. The Lancet 1988;68-70