Guillain-Barre syndrome with concurrent posterior reversible encephalopathy syndrome and hyponatraemia: mere coincidence or rare coexistence.

A 61-year-old Caucasian woman with a history of hypertension presented with a week's history of confusion falls and back pain was found to have hyponatraemia from secretion of antidiuretic hormone and treated appropriately. Given her persistent symptoms, despite a normal CT head on presentation, an MRI head was obtained, showing vasogenic oedema in line with posterior reversible encephalopathy syndrome (PRES). Despite aggressive antihypertensives and supportive measures, unfortunately, her condition deteriorated, with increased confusion, new left-sided flaccid paresis, paraesthesias and worsening of the back pain. Following further testing including a cerebrospinal fluid analysis, finally diagnosed with an atypical presentation of Guillain-Barre syndrome (GBS), and prompt management with intravenous immunoglobulins was initiated. She recovered clinically and returned to near-normal function on follow-up. We use this case to suggest the importance of dysautonomia in GBS and various clinical manifestations it can present with, including PRES and hyponatraemia.