Optic neuritis (ON) is the first clinical manifestation in approximately 20% of patients with multiple sclerosis (MS). The inflammation and demyelination of the optic nerve are characterized by symptomatic visual impairment and retrobulbar pain, and associated with decreased visual acuity, decreased colour and contrast sensitivity, delayed visual evoked potentials and visual field defects. Spontaneous recovery of vision typically occurs within weeks or months after onset, depending on the resolution of inflammation, remyelination, restoration of conduction in axons which persist demyelinated and neuronal plasticity in the cortical and subcortical visual pathways. To assess where recovery takes place along the visual pathway, visual activation was studied in the lateral geniculate nucleus (LGN), the main thalamic relay nucleus in the visual pathway and in three areas of the visual cortex: the lateral occipital complexes (LOC), V1 and V2. We conducted a longitudinal functional magnetic resonance imaging (fMRI) study of regions of interest (ROI) of activation in LGN and visual cortex in 19 patients with acute ON at onset, 3 and 6 months from presentation. With fMRI we measured the activation in the ROIs and compared activation during monocular stimulation of the affected and unaffected eye. In the acute phase the activation of LGN during visual stimulation of the affected eye was significantly reduced (P < 0.01) compared to the unaffected eye. This difference in LGN activation between the affected and unaffected eye diminished during recovery, and after 180 days the difference was no longer significant (P = 0.59). The decreased difference during recovery was mainly due to an increase in the fMRI signal when stimulating the affected eye, but included a component of a decreasing fMRI signal from LGN when stimulating the unaffected eye. In LOC, V1 and V2 activation during visual stimulation of the affected eye in the acute phase was significantly reduced (P < 0.01) compared to the unaffected eye, and during recovery the difference diminished with no significant differences left after 180 days. As the pattern of activation in LOC, V1 and V2 resembled the development in LGN we found no evidence of additional cortical adaptive changes. The reduced activation of the LGN to stimulation of the unaffected eye is interpreted as a shift away from early compensatory changes established in the acute phase in LGN and may indicate very early plasticity of the visual pathways.

BackgroundFabry disease is a rare metabolic glycosphingolipid storage disease caused by deficiency of the lysosomal enzyme α-galactosidase A—leading to cellular accumulation of globotriasylceramide in different organs, vessels, tissues, and nerves. The disease is associated with an increased risk of cerebrovascular disease at a young age in addition to heart and kidney failure.ObjectiveThe objective of this study was to assess brain function and structure in the Danish cohort of patients with Fabry disease in a prospective way using 18-fluoro-deoxyglucose (F-18 FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI).PatientsForty patients with Fabry disease (14 males, 26 females, age at inclusion: 10–66 years, median: 39 years) underwent a brain F-18-FDG-PET-scan at inclusion, and 31 patients were followed with FDG-PET biannually for up to seven years. All patients (except one) had a brain MRI-scan at inclusion, and 34 patients were followed with MRI biannually for up to nine years.Image AnalysisThe FDG-PET-images were inspected visually and analysed using a quantitative 3-dimensional stereotactic surface projection analysis (Neurostat). MRI images were also inspected visually and severity of white matter lesions (WMLs) was graded using a visual rating scale.ResultsIn 28 patients brain-FDG-PET was normal; in 23 of these 28 patients brain MRI was normal—of the remaining five patients in this group, four patients had WMLs and one patient never had an MRI-scan. In 10 patients hypometabolic areas were observed on brain-FDG-PET; all of these patients had cerebral infarcts/hemorrhages visualized on MRI corresponding to the main hypometabolic areas. In two patients brain-FDG-PET was ambiguous, while MRI was normal in one and abnormal in the other.ConclusionOur data indicated that, in patients with Fabry disease, MRI is the preferable clinical modality—if applicable—when monitoring cerebral status, as no additional major brain-pathology was detected with FDG-PET.

For a subpopulation of drug-resistant epilepsies, a ketogenic diet constitutes the treatment of choice. A ketogenic diet is a high-fat, low-protein, and low-carbohydrate diet, which induces ketosis. Despite the use in treatment of epilepsy since 1924, the clinical efficacy was not demonstrated in a controlled, randomized trial until 2008, showing its capability of reducing seizure frequency with more than 50%. However, the exact mechanism of this form of treatment is still unknown. We report here a patient with drug-resistant epilepsy on a ketogenic diet, where a brain 18F-FDG PET examination demonstrated a severely decreased uptake in the cerebral cortex bilaterally.