Plasma Glial Fibrillary Acidic Protein (GFAP) as a Biomarker of Acute Focal Brain Injury

ObjectiveThe validation of acute brain injury biomarkers has encountered challenges such as the absence of pre-insult measurements, variability in injury timing and location, and interindividual differences. In this study, we addressed these limitations by using Magnetic Resonance-guided High-Intensity Focused Ultrasound (MRgHIFU) thalamotomy to assess plasma biomarker changes after an acute focal brain injury. MethodsThis prospective study included 30 essential tremor (ET) and tremor-dominant Parkinsons disease (TDPD) patients undergoing MRgHIFU thalamotomy at a single academic institution. Blood samples were collected at three specific time points: pre-procedure, 1-hour post-procedure, and 48 hours post-procedure. Plasma levels of glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), amyloid-beta (A{beta}40 and A{beta}42), and phosphorylated tau 181 (pTau-181) were measured using the Quanterix Single Molecule Arrays (SiMoA) assay. ResultsGFAP levels significantly increased 48 hours post-MRgHIFU in all patients with a thalamotomy lesion. GFAP levels were highly sensitive (89.7%) and specific (96.6%) in detecting the presence of a HIFU lesion with a cutoff value of 216.2 pg/ml. NfL, A{beta}40, and A{beta}42, also showed statistically significant increases post-procedure but were less robust than GFAP. No changes were observed in pTau-181 levels post-MRgHIFU. ConclusionPlasma GFAP emerged as a highly sensitive and reliable biomarker for detecting acute brain injury following MRgHIFU thalamotomy. The significant post-procedure elevation of GFAP suggests its potential as an early diagnostic tool for focal brain injuries, particularly in acute stroke. Further research is needed to validate the GFAP injury cutoff identified in this study and to explore its broader clinical utility in the early detection of focal brain lesions.