Serum NfL associated with anti-NMDA receptor encephalitis

Introduction: Neurofilament light chains (NfL) have been reported as potential markers for neuronal-axonal injury in neuroinflammatory diseases. In the current study, we describe serum NfL levels as a prognostic marker for anti-N-methyl-D-aspartate receptor encephalitis (NMDARE). Methods: Serum levels of NfL of 64 patients with anti-NMDARE and 84 healthy controls were measured by Simoa. The anti-NMDAR Encephalitis One-Year Functional Status (NEOS) score, Modified Rankin Scale (mRS) scores, and clinical and cerebrospinal fluid parameters were evaluated in patients with anti-NMDARE. Meanwhile, we performed a receiver-operator characteristic analysis to assess the power of the serum NFL in predicting the 1-year functional status. Results: Serum NfL levels were significantly elevated in patients with anti-NMDARE compared to healthy controls (p < 0.001, p_adjusted < 0.001), especially in patients with severe impairments (mRS > 3 vs ≤ 3, p = 0.035) or with limited response to treatment (vs. favorable outcome, p = 0.011). Serum NFL was positively associated with the initial admission mRS (r = 0.23, p = 0.072) and 1-year mRS (r = 0.29, p = 0.018). The AUC of serum NfL and NEOS score for 1-year poor functional status was 0.697 (95% CI 0.527–0.866, p = 0.011), 0.753 (95% CI 0.616–0.890, p = 0.001), respectively. Furthermore, AUC of the combination of serum NfL and NEOS was 0.815 (95% CI 0.680–0.950, p < 0.001). Conclusion: Our findings show that serum NfL levels evaluated in anti-NMDAR encephalitis may be a good predictor of the risk of 1-year poor functional status.