# Selective Alteration of the Left Arcuate Fasciculus in Two Patients Affected by Creatine Transporter Deficiency

## TL;DR

This paper shows that a brain pathway important for language is abnormally altered in two patients with a creatine transporter deficiency.

## Contribution

The study is the first to show a selective abnormality in the left arcuate fasciculus in creatine transporter deficiency.

## Key findings

- The left arcuate fasciculus showed a marked decrease in mean fractional anisotropy compared to healthy controls.
- The corticospinal tract FA values were similar to those of healthy controls.
- This suggests a region-specific impact of creatine deficiency on language-relevant brain structures.

## Abstract

(1) Background: In hereditary creatine transporter deficiency (CTD), there is an absence of creatine in the brain and neurological symptoms are present, including severe language impairment. However, the pathological changes caused by creatine deficiency that generate neuropsychological symptoms have been poorly studied. (2) Aims: To investigate if the language impairment in CTD is underpinned by possible pathological changes. (3) Methods: We used MRI tractography to investigate the trophism of the left arcuate fasciculus, a white matter bundle connecting Wernicke’s and Broca’s language areas that is specifically relevant for language establishment and maintenance, in two patients (28 and 18 y.o.). (4) Results: The T1 and T2 MRI imaging results were unremarkable, but the left arcuate fasciculus showed a marked decrease in mean fractional anisotropy (FA) compared to healthy controls. In contrast, the FA values in the corticospinal tract were similar to those of healthy controls. Although white matter atrophy has been reported in CTD, this is the first report to show a selective abnormality of the language-relevant arcuate fasciculus, suggesting a possible region-specific impact of creatine deficiency.