Volumetric study of brain MRI in a cohort of patients with neurotransmitter disorders.

Purpose: Inborn errors of neurotransmitters are rare monogenic diseases. In general, conventional neuroimaging is not useful for diagnosis. Nevertheless, advanced neuroimaging techniques could provide novel diagnosis and prognosis biomarkers. We aim to describe cerebral volumetric findings in a group of Spanish patients with neurotransmitter disorders.

Methods: Fifteen 3D T1-weighted brain images from the International Working Group on Neurotransmitter related Disorders Spanish cohort were assessed (eight with monoamine and seven with amino acid disorders). Volumes of cortical and subcortical brain structures were obtained for each patient and then compared with those of two healthy individuals matched by sex and age.

Results: Regardless of the underlying disease, patients showed a smaller total cerebral tissue volume, which was apparently associated with clinical severity. A characteristic volumetric deficit pattern, including the right Heschl gyrus and the bilateral occipital gyrus, was identified. In severe cases, a distinctive pattern comprised the middle and posterior portions of the right cingulate, the left superior motor area and the cerebellum. In succinate semialdehyde dehydrogenase deficiency, volumetric affection seems to worsen over life.

Conclusion: Despite the heterogeneity and limited size of our cohort, we found novel and relevant data. Total volume deficit appears to be a marker of severity, regardless of the specific neurotransmitter disease and irrespective of the information obtained from conventional neuroimaging. Volumetric assessment of individual brain structures could provide a deeper knowledge about pathophysiology, disease severity and specific clinical traits.