Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Adult-onset Alexander disease is neurodegenerative disorder caused by a mutation in the glial fibrillary acidic protein gene (GFAP). The adult form is clinical, and radiologically, completely different from the infantile form. A palatal myoclonus is highly suggestive clinically, but frequently not present. Other presenting symptoms are non-specific and include a progressive history of brain stem disturbances, ataxia, or spastic paraparesis. MRI might be the first hint to the correct diagnosis. Adult-onset Alexander disease shows highly characteristic MRI findings with severe atrophy of the medulla oblongata and upper cervical spinal cord (A, arrows) accompanied by high signal in the anterior medulla oblongata (B, arrow). Additionally, high signal in the hilum of the dentate nucleus can be seen (C, arrows).