Encephalopathy with Guillain-Barré syndrome: seek a different cause.

A 30-year-old woman developed symptoms, signs and neurophysiology consistent with Guillain-Barré syndrome and was admitted to the neurosciences intensive care unit owing to respiratory compromise. Here, she received a clonidine infusion for agitation, complicated by a minor hypotensive episode, following which she became unconscious. MR scan of the brain showed changes compatible with hypoxic brain injury. Urinary amino acids showed increased urinary α-ketoglutarate. Genetic testing using whole-exome sequencing identified pathogenic variants in the gene known to be associated with an acute reversible leukoencephalopathy with increased urinary α-ketoglutarate. The case highlights the importance of considering inborn errors of metabolism in cases of unexplained encephalopathy.