[en] A classification of neurological or neurologically expressed disorders that occur in Western European cattle aged 12 month and over has been established on the basis of aetiology, frequency and conditions of appearance, age and type of animals concerned and the main clinical signs observed. Neurologically expressed disorders have been classified according to different groups of causes: biological, non-biological and non-specific or unknown. Differential diagnosis of neurologically expressed disorders is an essential element in the clinical epidemiological surveillance of bovine spongiform encephalopathy. A growing number of aetiologies are described in the scientific literature. The identification and centralised management of neurological disorders will make it possible, one the one hand, to take account of the inherent variability in the clinical forms encountered and in the diagnostic approaches of the observers and, on the other hand, to identify new risk factors in order to control them.