Late-onset presentation of ornithine transcarbamylase deficiency in a young woman with hyperammonemic coma

A, Magnetic resonance images obtained during the acute phase of the encephalopathy. A diffuse swelling of both frontal and temporal lobes, insulae (arrowheads), and pallidal nuclei (arrows) characterized by a marked hyperintensity caused by the higher amount of water in the pathologic tissues is evident. The ventricular cavities are normal. B, Magnetic resonance images obtained 1 year after the beginning of the disease. MRI shows diffuse cortical and subcortical gliotic and atrophic changes associated with cerebrospinal fluid ventricular and extracerebral space enlargement. These alterations represent the chronic evolution of the previous episodes of hyperammonemia.

Schematic representation of the major sources of ammonemia. GI, Gastrointestinal; TIPS, total implantable portocaval shunt

The most common causes of hyperammonemia in adult patients.¹⁶