Paraneoplastic neurological syndromes are diagnosed in patients affected by cancer, manifesting as complaints originating from the neurological system without a direct link to the developing tumour. Although the processes of development of the syndromes are not medically known, with the detection of onconeuronal antibodies it is possible to confirm a link between the symptoms that appear and the tumour, as the symptoms that are characteristic of this disease entity may be significantly ahead of the tumour diagnosis in time.