Quantitative lateral flow immunoassay for rapid detection and monitoring of cerebrospinal fluid leakage following incidental durotomy

Cerebrospinal fluid (CSF) leakage due to incidental durotomy is an inherent complication of spine surgery. With appropriate treatment, complications of CSF leakage, such as headache and even meningitis, can be reduced. CSF leakage could be detected on the basis of correlated clinical symptoms; diagnosis should be based on these symptoms and appropriate imaging studies. However, the diagnosis of CSF leakage remains a challenge, especially if incidental durotomy is unrecognized during surgery; even if incidental durotomy is detected and repaired intraoperatively, the severity of the leakage and quality of the primary dural repair are difficult to evaluate postoperatively. Rapid, inexpensive, and safe methods of detecting CSF-containing samples are currently lacking; hence, the development of a point-of-care test (POCT) method to improve diagnostic efficiency is necessary. We developed a high-sensitivity lateral flow immunoassay with a stacking pad (sLFIA) for quantitative detection of β-trace protein (BTP), a specific CSF marker. The BTP concentration in 39 clinical samples was calculated using a calibration equation for test-line intensity and evaluated by a standard laboratory method. To avoid the hook effect, we diluted each sample prior to testing. The correlation coefficient between the enzyme-linked immunosorbent assay and our BTP sLFIA method was 0.991 A 75-fold sample dilution was applied owing to the hook effect point, identified as 175 ng mL^-1. We established an optimal sample-specific cutoff point at a value of 4.0 μg mL^-1 for CSF leakage in subfascial drainage samples following spinal posterior decompression. The sensitivity and specificity of the BTP sLFIA method were 90% and 97%, respectively, according to a receiver operating characteristic curve analysis. In addition, clinical samples from patients who underwent primary dural repair intraoperatively were tested, and CSF leakage was successfully diagnosed using our method. Finally, the quantitation of BTP in samples collected daily provided an accurate assessment of the severity of the residual leakage. Our results demonstrate that the BTP sLFIA method possesses the potential to serve as a POCT method for screening and monitoring postoperative CSF leakage.