Peripheral nerve atrophy together with higher cerebrospinal fluid progranulin indicate axonal damage in amyotrophic lateral sclerosis

ABSTRACT Introduction We aimed to investigate whether sonographic peripheral cross‐sectional nerve area (CSA) and progranulin (PGRN), a neuritic growth factor, are related to each other and whether they interact to predict clinical and paraclinical measures in amyotrophic lateral sclerosis (ALS). Methods We included 55 ALS patients who had forearm median and ulnar nerve CSA, cerebrospinal fluid (CSF) PGRN, and serum PGRN measures available. CSF PGRN was normalized against the CSF / serum albumin ratio (Qalb). Using age, sex, height, and weight adjusted general linear models, we examined CSA × CSF PGRN interaction effects on various measures. Results There was a medium‐effect size inverse relationship between CSA and CSF PGRN, but not between CSA and serum PGRN. Lower CSA values together with higher CSF PGRN levels were linked to smaller motor amplitudes. Discussion In ALS, the constellation of peripheral nerve atrophy together with higher CSF PGRN levels indicates pronounced axonal damage. Muscle Nerve 57: 273–278, 2018