Nerve compression syndromes in ALS: a retrospective analysis in 554 patients.

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.