Persons with cardiovascular diseases or risk factors seem to be at lower risk of ALS. Although these diseases are apparently somehow protective regarding ALS susceptibility, their presence did not modify disease progression and survival in patients with ALS. Our study further confirms the well-known continuum between ALS and dementia. It also suggests a link with other neurodegenerative diseases such as Parkinson's disease.

We retrospectively screened a large cohort of 554 ALS patients with regard to documented nerve compression syndromes and identified 23 patients, mostly with carpal tunnel syndrome. Patients could be subdivided into three groups. Group A comprised 13 patients in whom nerve compression was apparently confused with early ALS signs. Group B consisted of six patients diagnosed with carpal tunnel syndrome who had experienced improvement after surgery years before they eventually developed ALS. Group C consisted of four patients who, after diagnosis of ALS, additionally developed a nerve compression syndrome. Altogether, the frequency of true nerve compression syndromes in our ALS cohort (1.8%) was no higher than in the general population (0.3-10.8%). In group A, the initial confusion with a nerve compression syndrome led to a slight though not significant delay (15.2 vs. 12.9 months; p = 0.32) of the diagnosis of ALS. Survival was no different between group A and the cohort. It can also be concluded that the misdiagnoses could have been avoided by thorough electrophysiological examination using a standardized protocol.