80. Small fiber neuropathy in Amyotrophic Lateral Sclerosis: Contribution of laser-evoked potentials and skin biopsy

Abstract

Increasing evidence suggests that amyotrophic lateral sclerosis (ALS) is a multisystem neurodegenerative disorder, also determining a small fiber neuropathy (SFN) as recognized by skin biopsy studies in distal legs, irrespective of the disease duration. This study aimed at evaluating the performance of a battery of neurophysiological and morphological tests assessing the small fiber loss occurring in ALS. We recruited 10 consecutive ALS patients (5 M, age 64.9 ± 7.3, duration of symptoms 29.1 ± 20.7 months). All patients had undergone skin biopsy (from thigh and lower leg) and LEPs using a Nd-YAP laser (1340 nm) by stimulating hand, foot and face skin surface. Intraepidermal nerve fiber density was altered in 100% of patients. 80% of ALS patients showed abnormalities in LEPs. Comparing face, hand and foot, Aδ-LEPs were more often abnormal recording from foot. Interestingly, C fibers in the trigeminal territory showed the highest abnormalities (40% of patients). Our study has confirmed a small fiber involvement in ALS patients. To our knowledge this is the first study using Nd:YAG LEPs and skin biopsy in a ALS cohort. However, our findings need to be extended to a larger number of patients in order to evaluate the possibility of a higher involvement of C fibers rather than A-δ in SFN associated to ALS.