NEFL and respiratory failure: In the total patient cohort, CSF-NFL levels were found to correlate with the following parameters (Spearman’s R): age at disease onset (r = 0.45, p = 0.04), CRMP5/CV2 positivity (r = 0.58, p = 0.005), dysmetria (r = 0.4367, p = 0.05), cerebellar ataxia (r = 0.46, p = 0.04), balance disorder (r = 0.48, p = 0.03), respiratory failure (r = 0.58, p = 0.005), peripheral neuropathy (r = 0.65, p = 0.001), tumor presence (r = 0.71, p = 0.0003) and death (r = 0.6, p = 0.017).