Fig. 2

Frequencies and timings of key neurological symptoms. Color-coded bars represent symptom occurrence (% patients) as initial isolated neurological symptoms, initial neurological symptoms (not isolated), or appearance during the course of neurological deterioration. This classification did not take into account vertical supranuclear gaze palsy (VSGP), cognitive developmental symptoms, or hearing loss (except for the hearing loss item). Cognitive and psychiatric symptoms were considered as a single category as they frequently overlap, and separating them according to age at onset can be arbitrary. Psychosis is contained within the Cognitive/Psychiatric category, but is also shown as a separate item due to its particular importance among adult/adolescent patients. N numbers above each bar are total numbers of patients analysed for each symptom. Mean ± SD ages at onset of each symptom are shown above each bar