Towards in vivo determination of peripheral nervous system immune activity in ALS.

INTRODUCTION: We aimed to identify ALS patients displaying suspected peripheral nervous system (PNS) inflammation, to compare them to those with suspected PNS degeneration.

METHODS: We measured sonographic median and ulnar nerve cross-sectional area (CSA) and CSF albumin/serum albumin ratio (Qalb ) in ALS patients, to classify them as having suspected PNS degeneration (small CSA/low Qalb ) or inflammation (larger CSA/high Qalb ).

RESULTS: 57% of patients had suspected PNS degeneration, 21% had suspected PNS inflammation, and 21% displayed suspected "normal PNS state". Suspected PNS degeneration was related to classic ALS, shorter disease duration and a smaller hypoechoic nerve area. Suspected PNS inflammation was associated with male sex, longer disease duration and a larger hypoechoic nerve area, and was the dominant finding in SOD1 mutation carriers.

DISCUSSION: Our simple approach might aid in the in vivo differentiation of two supposed ALS subtypes, those with suspected PNS degeneration vs. inflammation, for stratification in clinical trials. This article is protected by copyright. All rights reserved.