Underlying neuropathies combined with amyotrophic lateral sclerosis (ALS) cast doubt on the diagnosis of ALS when present.Abnormal sural nerve conductions were found in 3 patients with clinically definite ALS. Pathologically demyelinating, axonal, or vasculitic neuropathy was suggested respectively. High dose oral corticosteroid had no effect and clinical courses were deteriorating in all the patients.The causes of combined neuropathies were unclear. Possibility of direct consequence of ALS, concomitant neuropathies, or rare variants of ALS should be considered in these cases.
