The ‘Ring Sign’: Is it a reliable indicator for cerebral spinal fluid?

doi:10.1016/S0196-0644(05)81855-4

Annals of Emergency Medicine

Volume 22, Issue 4, April 1993, Pages 718-720

https://doi.org/10.1016/S0196-0644(05)81855-4 Get rights and content

Study objective:

To study the development of a ring sign when blood is mixed with various fluids.

Methods:

One drop of blood and one drop of either spinal fluid, saline, tap water, or rhinorrhea fluid were placed simultaneously on filter paper, and the specimens were examined after ten minutes for the development of a ring. A variety of filter paper agents were used, including standard laboratory filter paper, paper towels, coffee filters, and bed linens.

Results:

All fluids, when mixed with blood, gave rise to a ring sign; blood alone did not. The type of filter paper did not affect the development of a ring.

Conclusion:

In this experimental setting, the ring or halo sign is reliable for detecting cerebrospinal fluids but is not exclusive for cerebrospinal fluid.

References (7)

American College of Surgeons
GordonK
Head and neck trauma
McLaurinRL
Diagnosis and treatment of head injury in infants and children

There are more references available in the full text version of this article.

Cited by (24)

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Cerebrospinal fluid (CSF) fistulas are a rare phenomenon, that can lead to life-threatening complications if left untreated. Presenting as rhinorrhea or otorrhea, they can be difficult to diagnose due to admixture of other bodily fluids. Typically, CSF fistulas develop after trauma, but in rare instances, they can be diagnosed in patients with a neoplastic lesion.
To discuss several steps in diagnosing CSF fistulas.
A fifty-year-old female with an intra-osseous temporal bone meningioma.
For diagnosing CSF admixture in fluids, two tests are looked into: beta-2 transferrin (β2T) and beta-trace protein (βTP) testing.
Testing for βTP is a highly sensitive, quick and non-invasive method to assess CSF admixture in middle ear effusion. Because of its lower cost, faster results and easy sample collection, βTP testing has in our clinic replaced β2T testing. The current case illustrates a rare etiology of a CSF fistula, where β2T testing presumably showed false-negative results and βTP testing showed true-positive results.
An unusual case of otorrhagia
2012, Journal of Emergency Medicine
Citation Excerpt :
However, as demonstrated by this case, a history of trauma and the presence of otorrhagia do not always correlate with a basilar skull fracture diagnosis. Even the hallowed “halo” or “ring” sign does not cinch the diagnosis because other fluids mixed with blood will form a “halo” as well (8,9). According to the consulting oromaxillofacial and neurosurgical colleagues, the blood-tinged fluid flowing from our patient's ears was due to a cochlear otolymph/blood mixture.
Fracture of the external auditory canal mimicking basilar skull fracture
2012, Journal of Emergency Medicine
Citation Excerpt :
When there is doubt about the origin of the blood, the diagnosis of a basilar skull fracture must be excluded. Distinguishing blood due to a basilar skull fracture from cutaneous bleeding using the “halo sign” (applying a drop of blood to a filter paper looking for more rapidly diffusing cerebrospinal fluid surrounding the blood), is often cited but unreliable (3–5). In this patient, based on the history of direct mandibular impact, mandibular trauma with EAC fractures was presumed to be the cause of bleeding.
Halo Sign Is Neither Sensitive Nor Specific For Cerebrospinal Fluid Leak
2009, Annals of Emergency Medicine
Basal skull fracture and the halo sign
2013, CMAJ. Canadian Medical Association Journal
Management of the Postoperative Leak
2023, Skull Base Reconstruction: Management of Cerebrospinal Fluid Leaks and Skull Base Defects

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Brief reportThe ‘Ring Sign’: Is it a reliable indicator for cerebral spinal fluid?

Study objective:

Methods:

Results:

Conclusion:

Head and neck trauma

Diagnosis and treatment of head injury in infants and children

Brief report
The ‘Ring Sign’: Is it a reliable indicator for cerebral spinal fluid?