Magnetic resonance spectroscopy findings in a case of hyperglycaemic hemianopia

Patients with nonketotic hyperglycaemia may present with neurological manifestations, including hemianopia. Thus far, the pathophysiology of such neurological events remains unknown, although the findings on magnetic resonance imaging (MRI) may help to elucidate the underlying mechanisms.

This report describes a patient who had an episode of homonymous hemianopia, which coincided with a state of nonketotic hyperglycaemia. Initial MRI showed hypointense areas on T2-weighted and FLAIR sequences, involving the internal portion of the right occipital cortex and adjacent white matter, with mild hyperintensity on diffusion-weighted imaging. Magnetic resonance spectroscopy revealed significant increases in cerebral metabolites. Dramatic clinical and neuroimaging improvements were progressively observed over 3 weeks, following rehydration and normalization of blood glucose levels with insulin therapy.

In this patient, magnetic resonance spectroscopy was used in combination with other neuroimaging methods and clinical evidence to suggest that hyperosmolality leading to intracellular dehydration in localized brain regions should be considered a potential underlying mechanism responsible for reversible neurological symptoms in nonketotic hyperglycaemia.