There are several articles in this special issue in which authors eloquently describe neurobehavioural and cognitive complications of multiple sclerosis with relevant neuropsychological assessments and neuroimaging findings. However behavioural and cognitive presentation of multiple sclerosis remains poorly understood. Two years ago, we reported a series of patients with multiple sclerosis who presented with neurobehavioural symptoms and had neuropsychological deficits consistent with cortical dysfunction. Based on previous case reports, pathological studies of cerebral cortex in multiple sclerosis and advanced neuroimaging studies we suggested that neurobehavioural presentation of multiple sclerosis represents a new variant called "cortical multiple sclerosis". The condition is characterised by predominant or exclusive cortical pathology presenting with neurobehavioural symptoms, such as depression, amnesia or distinct cortical syndromes. Since the publication of our report, there has been further neuroimaging and neuropathological findings that further supported the above concept. In addition, observation of more patients with this condition helped us to formulate a logical approach in the detection of these patients. This article focuses on their clinical characteristics.