Sample-dependent diagnostic accuracy of prostaglandin D synthase in cerebrospinal fluid leak

CSF or middle ear effusion? Diagnostical dilemmas in a patient with temporal bone meningioma: A case report

Introduction

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.

Objective

To discuss several steps in diagnosing CSF fistulas.

Patient

A fifty-year-old female with an intra-osseous temporal bone meningioma.

Interventions

For diagnosing CSF admixture in fluids, two tests are looked into: beta-2 transferrin (β2T) and beta-trace protein (βTP) testing.

Conclusion

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.

Cut-off value for β-trace protein (β-TP) as a rapid diagnostic of cerebrospinal fluid (CSF) leak detection

Objective

To find an adequate cut-off point for beta trace protein (β-TP) in nasal secretion (NS) and validate this diagnostic test with a large sample of patients. Likewise, we evaluated β-TP test efficacy to confirm the cerebrospinal fluid (CSF) leakage closure after treatment.

Methods

We performed a retrospective analysis with 207 samples from 162 patients with suspected CSF leakage received in the Hospital Universitario Virgen de la Arrixaca between 2010 and 2016. Twenty-five samples were included in the control group. Samples were obtained from NS through a swab to determine β-TP using a nephelometry-based assay. Sensitivity, specificity, and area under the curve (AUC) for β-TP in NS were assessed using the receiver operator characteristic (ROC) analysis.

Results

Using imaging techniques, the diagnosis of CSF leak was confirmed in 57 patients (35.19%), while 105 had a negative diagnosis (64.81%). Patients with CSF leakage had significantly higher β-TP values in NS (16.07 ± 16.94 mg/L, p < .001) than the control group (0.33 ± 0.12 mg/L) and patients without CSF leakage (0.61 ± 2.34 mg/L). Applying a 1 mg/L cut-off point resulted in 96.5% sensitivity and 97.1% specificity. Positive and negative predictive values (PPV and NPV) at this cut-off were 94.9% and 98.6%, respectively. Finally, this cut-off point yields a test efficacy for CSF leak diagnosis of 97% (95% CI 92.9-98.9).

Conclusion

Our study has established a 1 mg/L β-TP concentration in NS as a cut-off point for CSF leakage diagnosis with high sensibility and specificity. These results suggest that β-TP analysis could be useful to check CSF leak resolution.

Level of Evidence

4.

Rapid Diagnostic Test Kit for Point-of-Care Cerebrospinal Fluid Leak Detection

Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial cavities and the external environment. They are a common and serious complication of numerous procedures in otolaryngology, and if not treated, persistent leaks can increase a patient's risk of developing life-threatening complications such as meningitis. As it is not uncommon for patients to exhibit increased secretions postoperatively, distinguishing normal secretions from those containing CSF can be difficult. Currently, there are no proven, available tests that allow a medical provider concerned about a CSF leak to inexpensively, rapidly, and noninvasively rule out the presence of a leak. The gold standard laboratory-based test requires that a sample be sent to a tertiary site for analysis, where days to weeks may pass before results return. To address this, our group recently developed a semiquantitative, barcode-style lateral-flow immunoassay (LFA) for the quantification of the beta-trace protein, which has been reported to be an indicator of the presence of CSF leaks. In the work presented here, we created a rapid diagnostic test kit composed of our LFA, a collection swab, dilution buffers, disposable pipettes, and instructions. Validation studies demonstrated excellent predictive capabilities of this kit in distinguishing between clinical specimens containing CSF and those that did not. Our diagnostic kit for CSF leak detection can be operated by an untrained user, does not require any external equipment, and can be performed in approximately 20 min, making it well suited for use at the point of care. This kit has the potential to transform patient outcomes.

Point-of-Care Cerebrospinal Fluid Detection

OBJECTIVE

A cerebrospinal fluid leak is one of the most serious complications in otolaryngology. It may occur as a result of injury to the skull base, typically traumatic or iatrogenic. While the presence of a leak is often discerned in the emergent setting, distinguishing normal secretions from those containing cerebrospinal fluid can be difficult during postoperative visits in the clinic. As most current laboratory-based assays are labor intensive and require several days to result, we aim to develop a more user-friendly and rapid point-of-care cerebrospinal fluid detection device.

STUDY DESIGN

Our laboratory developed a barcode-style lateral-flow immunoassay utilizing antibodies for beta-trace protein, a protein abundant in and specific for cerebrospinal fluid, with a concentration of 1.3 mg/L delineating a positive result.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Tests with known concentrations of resuspended beta-trace protein and the contents of discarded lumbar drains (presumed to contain cerebrospinal fluid) were performed to validate our novel device.

RESULTS

Our results demonstrate the ability of our device to semiquantitatively identify concentrations of beta-trace protein from 0.3-90 mg/L, which is within the required range to diagnose a leak, thus making beta-trace protein an excellent target for rapid clinical detection.

CONCLUSION

Herein we detail the creation and initial validation of the first point-of-care cerebrospinal fluid detection device. This device is a feasible method to more efficiently and cost-effectively identify cerebrospinal fluid leaks, minimize costs, and improve patient outcomes.

Tau protein as a possible marker of cerebrospinal fluid leakage in cerebrospinal fluid rhinorrhoea: A pilot study

Introduction

The management of posttraumatic cerebrospinal fluid (CSF) rhinorrhoea remains a clinical challenge. Cerebrospinal fistula is a dural defect responsible for possible CSF leakage into the contiguous air-filled cavities located at the skull base. The risk of central nervous system infection in these conditions is severe and can be life threatening. Consequently, a specific CSF biomarker might be used in case of difficult diagnosis of CSF rhinorrhoea. CSF Tau protein is a neuronal protein, commonly assessed for diagnosis of Alzheimer Disease (AD). The aim of this study was to determine whether the Tau protein could be a relevant marker of CSF leakage.

Materials and methods

Tau protein measurement was performed by enzyme-linked immunosorbent assay in 13 patients with CSF leakage (CSF rhinorrhoea group), and 8 patients with spontaneous aqueous rhinorrhoea (non-CSF leakage group). The serum concentration of Tau protein was measured by ELISA in both CSF rhinorrhoea group and non-CSF leakage group.

Results

In patients with CSF leakage, CSF Tau protein median concentration was 479 ng/L (197 - 2325 ng/L). On the other hand, the Tau protein concentration was below the lower limit of quantification (LLoQ) (< 87 ng/L) in non-CSF leakage group. Serum Tau protein concentration by ELISA was also below LLoQ (< 87 ng/L) for all subjects.

Conclusion

ELISA measurement of Tau protein in rhinorrhoea fluid may be a reliable and relevant marker for detecting the presence of CSF in the nasal discharge and sign the existence of a CSF leakage.