Elevated Neurofilament Light Chain in Cerebrospinal Fluid and Plasma Reflect Inflammatory MRI Activity in Neurosarcoidosis.

BACKGROUND

Damage to axonal cells releases neurofilament light chain (NFL) into the cerebrospinal fluid and plasma. The objective of this study was to investigate NFL as a potential biomarker of disease activity in neurosarcoidosis. MRIs were graded according to enhancing lesions at different central nervous system (CNS) sites.

RESULTS

In cerebrospinal fluid, levels of NFL were higher in neurosarcoidosis patients (n = 20) median 2304 pg/mL (interquartile range (IQR) 630-19,612) compared to 426 pg/mL (IQR 261-571) in extra-neurologic sarcoidosis patients (n = 20) and 336 pg/mL (IQR 194-402) in healthy controls (n = 11) (p = 0.0002). In plasma, levels of NFL were higher in neurosarcoidosis patients median 28.2 pg/mL (IQR 11.5-49.3) compared to 6.2 pg/mL (IQR 4.3-8.2) in extra-neurologic sarcoidosis patients and 7.1 pg/mL (IQR 6.2-9.0) in healthy controls (p = 0.0001). Levels in both cerebrospinal fluid and plasma were higher in neurosarcoidosis patients with moderate/severe enhancement than patients with mild enhancement on MRI (p = 0.009 and p = 0.005, respectively). To distinguish neurosarcoidosis patients from extra-neurologic patients and healthy controls, a cut-off level of 630 pg/mL in cerebrospinal fluid had 94% specificity and 79% sensitivity, while a cut-off level of 11.4 pg/mL in plasma had 97% specificity and 75% sensitivity.

CONCLUSIONS

NFL levels in cerebrospinal fluid and plasma are significantly higher in neurosarcoidosis patients compared to extra-neurologic patients and healthy controls, and the levels correlate to the extent of inflammation on MRI.