Abstract
Ninety four neurologists in the United Kingdom, China, and West Germany responded to two structured questionnaires. The first assessed the diagnostic weighting assigned to a number of symptoms, signs, and clinical investigations ascertained from classical descriptions and case notes of patients with motor neuron disease (MND). The second tested the likelihood and consistency of diagnosis in a series of case summaries representing the clinical data of 10 patients with clinically and pathologically documented motor neuron disease. There was a wide measure of agreement concerning the common clinical features of the disease, especially regarding fasciculation of the tongue, fasciculation associated with weakness seen in more than one limb, and dysphagia. In the case summaries, however, there was clear variation in the ranked likelihood of the diagnosis of MND and in the consistency of diagnostic behaviour in the different groups of neurologists. These findings support the need for internationally agreed criteria in the diagnosis of MND. Any such criteria will need to be tested against a standardised data set to establish their validity.