Nociceptive R3 reflex in relapsing-remitting multiple sclerosis patients

Pain in multiple sclerosis (MS) patients has only recently been recognised as a genuine symptom of this disease. It is important to determine whether this pain is the consequence of another symptom of MS or whether it is due to a demyelinating lesion affecting pain pathways. A close relationship has been found between the R3 component of the blink reflex and the pain threshold. The aim of this work was to carry out an objective evaluation of the nociceptive system in MS patients by means of the R3 component of the blink reflex. The study was performed on 20 healthy volunteers and on 20 clinically defined relapsing-remitting MS patients with EDSS not > 3.5, normal R1 and R2 components of the blink-reflex, personal and family anamnesis negative for migraine and trigeminal neuralgia; the patients were not taking drugs at the time of the test. A significant difference was found, between healthy volunteers and patients, for R3 threshold, pain threshold and R3 latency.