Objective:

To describe peripheral neuropathies in patients with spinocerebellar ataxias (SCAs).

Background:

SCAs are autosomal dominant hereditary diseases characterized by heterogeneous clinical manifestations with peripheral neuropathies reported across different SCAs subtypes. Although several SCAs have been reported in Peru, the occurrence of peripheral neuropathies remains unknown in this population.

Design/Methods:

We conducted a retrospective cross-sectional study reviewing medical records of genetically confirmed SCA patients followed at the national referral ataxia outpatient clinic in Peru.. 

Results:

We analyzed 135 individuals (48.9% female), mean age at evaluation 47 ± 14.9 years, mean age at onset 35.4 ± 13.7 years, and mean disease duration 11.6 ± 8.4 years. Subtypes distribution was SCA10 (69.6%), followed by SCA2 (19.3%), MJD/SCA3 (6.7%), SCA7 (2.2%), SCA6 (1.5%), and SCA1 (0.7%). Neuropathy symptoms were common across the cohort, affecting up to 73% of patients. Nerve conduction studies (NCS) were available for a subset of patients (67/135). Among them, peripheral neuropathy was confirmed in 22 cases (11 SCA2, 6 MJD/SC3, 4 SCA10, 1 SCA6) predominantly of the axonal type. Polyneuropathy prevalence differed across subtypes (SCA10 8.7%, SCA2 78.6%, MJD/SCA3 100%, SCA6 100%). In an exploratory analysis, NESSCA score were higher in patients with polyneuropathy (12.0 vs 9.9; p = 0.031), whereas SARA (14.3 vs 13.1; p = 0.11) and age at onset (34.2 vs 35.3 years; p = 0.55) showed no significant differences. CAG repeat length (major allele) showed no association with polyneuropathy (p = 0.760).

Conclusions:

In this Peruvian cohort, neuropathy symptoms were common, and one third of tested patients showed  predominantly axonal polyneuropathy, with higher prevalence in SCA2 and MJD/SCA3. Higher NESSCA scores correlated with polyneuropathy occurrence.