Less than 50 years since tau was first isolated from a porcine brain, its detection in femtolitre concentrations in biological fluids is revolutionizing the diagnosis of neurodegenerative diseases. This review highlights the molecular and technological advances that have catapulted tau from obscurity to the forefront of biomarker diagnostics. Comprehensive updates are provided describing the burgeoning clinical applications of tau as a biomarker of neurodegeneration. For the clinician, tau not only enhances diagnostic accuracy, but holds promise as a predictor of clinical progression, phenotype, and response to drug therapy. For patients living with neurodegenerative disorders, characterization of tau dysregulation could provide much-needed clarity to a notoriously murky diagnostic landscape.

Objectives: To identify clinical factors that may assist emergency physicians to delineate between patients with new onset seizures (NOS) versus patients with recurrent undiagnosed seizures (RUS) among those presenting with apparent 'first seizures' to EDs. In addition, to provide a summary of current evidence-based guidelines regarding the workup of seizure presentations to ED. Methods: This retrospective cohort study included patients aged over 17 years who presented to a tertiary hospital ED between 1 January 2008 and 30 November 2016 with seizurerelated ICD-10-AM discharge codes. Exclusion criteria included pre-existing epilepsy and non-seizure diagnoses. Medical records were reviewed and relevant data extracted. Results: Seventy-five patients had NOS (54.7% [41/75] female, median age 71 years) and 22 patients had RUS (59.1% [13/22] female, median age 64 years). Non-motor index seizures were more than four times as common among RUS patients (27.3% [6/22] RUS vs 6.7% [5/75] NOS; P = 0.015). 95.5% (21/22) of RUS patients met epilepsy diagnostic criteria compared to 44.0% (33/75) of NOS patients (P < 0.001). No differences in patient demographics, seizure aetiology or seizure risk factors were identified. Conclusions: Emergency physicians should be wary of patients presenting with non-motor 'first seizures': they are more likely to have experienced prior seizures (the 'recurrent untreated seizure' group), and thus meet epilepsy diagnostic criteria. Almost half of those with actual NOS may also meet epilepsy criteria, largely driven by abnormal neuroimaging. Distinguishing RUS from NOS patients in the ED allows accurate prognostication and timely initiation of appropriate therapy.