The traditional neurological method consists of first deducing, from the symptoms and signs, ‘Where is the lesion?’, and then from additional history such as the temporal course, general medical and family history, deducing ‘What is the lesion?’. In a patient with a movement disorder, no matter what the symptoms and signs, localisation ends up back in the basal ganglia and one is no further along the diagnostic process. Therefore, a different diagnostic approach is needed. First, one assesses the phenomenology and then formulates a syndromic diagnosis, which in turn allows the generation of an aetiological differential diagnosis which forms the basis of further investigations and management.1 For example, the differential diagnosis of a patient presenting with myoclonus and dystonia varies from that of a patient presenting with chorea and dystonia.

It is in the context of the neurological method described above that the article by …