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BET 1: Does a normal D-dimer rule out cerebral venous sinus thrombosis (CVST)?
  1. Emma Smith,
  2. Varun Kumar
  1. Nottingham University Hospitals NHS Trust, Nottingham, UK
  1. Correspondence to Emma Smith; production.emj{at}bmjgroup.com

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Clinical scenario

A 32-year-old woman presented to the emergency department (ED) with a history of occipital headache and intermittent blurred vision for the past 3 weeks. D-dimer performed on admission is within normal range. Can you safely rule out cerebral venous sinus thrombosis (CVST)?

Three-part question

In (patients presenting to and ED with suspected CVST) does a (normal D-dimer) rule out this condition?

Search strategy

NICE Healthcare interface Medline 1966–November 2016

[ddimer.ti,ab] AND [exp INTRACRANIAL EMBOLISM/OR exp INTRACRANIAL THROMBOSIS/OR exp SINUS THROMBOSIS, INTRACRANIAL/OR exp CAVERNOUS SINUS THROMBOSIS/OR exp INTRACRANIAL EMBOLISM AND THROMBOSIS/OR exp LATERAL SINUS THROMBOSIS/OR exp SAGITTAL SINUS THROMBOSIS/OR (cerebral AND venous AND sinus AND thrombosis).ti,ab/OR (sinus AND thrombosis).ti,ab] AND [exp DIAGNOSIS/OR (rule AND out).ti,ab/OR exclu*.ti,ab/OR normal.ti,ab/OR negative.ti,ab/OR sensitivity.ti,ab/OR diagnosis.ti,ab]

Search outcome

Seventy-one papers were identified, of which 52 were irrelevant and 7 were of insufficient quality for inclusion.

Twelve papers were included for use in final review. This included two systematic reviews that covered eight of the previously identified papers. Therefore, these two systematic reviews, along with the remaining two studies, are detailed in this Best Evidence Topic (BET) (table 1).

Table 1

Relevant papers

Comments

CVST is a relatively rare disease with high morbidity and mortality if undiagnosed. It is likely that the array of imaging techniques available has increased CVST incidence; however, it remains a diagnostic challenge for clinicians due to the wide, sometimes vague, spectrum of symptoms with which it can present. D-dimer is an inexpensive, readily accessible test that is already used to rule out deep vein thrombosis with high sensitivity. If D-dimer could be similarly used to rule out CVST, it has the potential to aid clinical diagnosis, while avoiding unnecessary costly, and potentially harmful imaging studies. There is a lack of high-quality data to assess the role of D-dimer in predicting CVST. Studies are observational in nature, and as a result, their design varies widely. In addition, a relatively low number of patients have been studied, which may reflect the rarity of the disease. Although not directly relevant to the BET question, it is noteworthy that the included studies have suggested that a number of clinical variables affect D-dimer level. These include: symptom duration, signs/symptoms and the number of sinuses affected. Symptoms of >30-day duration had statistically significant lower D-dimer levels than acute and subacute presentations. In addition, an isolated headache and single sinus involvement were significantly associated with a lower D-dimer level.

Clinical bottom line

A normal D-dimer does not safely rule out CVST. However, the research suggests D-dimer level may help predict the risk of CVST when combined with other factors, such as clinical presentation and risk factors for thrombosis. This could negate the need for further imaging in low-risk patients. Therefore, there is potential for D-dimer to be used as part of a preimaging probability score in the context of CVST. To answer this question, larger, higher quality studies would need to be performed.

References

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Footnotes

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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