Franko, E. | Search bioRxiv

bioRxiv2022

Diffusion MR imaging in the corticospinal tract of idiopathic scoliosis

Many studies have shown that idiopathic scoliosis is not only a deformity of the spine. It is often associated with neurological impairment without any macroscopic abnormality in the brain. In our previous diffusion MRI study, we demonstrated that children with right-thoracic idiopathic scoliosis had abnormal white matter microstructure of the crossing premotor fibres in the corpus callosum. Based on this, we hypothesized that similar microstructural changes could affect the main descending white matter tracts, the corticospinal tract. We compared the fractional anisotropy values along the corticospinal tracts in ten patients with right-thoracic and ten patients with left-thoracic idiopathic scoliosis to 49 healthy controls. We found abnormal left-right asymmetry of the fractional anisotropy values in scoliosis patients at the level of the pons. Whereas at upper levels the values were similar across all groups. Our results suggest that abnormal sensorimotor integration at the level of the pons is associated with the development of idiopathic scoliosis.

neuroscience↗

bioRxiv2019

Effect of nitrite on neural activity in the healthy brain

BackgroundNitrite is a major intravascular store for nitric oxide. The conversion of nitrite to the active nitric oxide occurs mainly under hypoxic conditions to increase blood flow where it is needed the most. The use of nitrite is, therefore, being evaluated widely to reduce the brain injury in conditions resulting in cerebral hypoxia, such as cardiac arrest, ischaemic stroke or subarachnoid haemorrhage. However, as it is still unknown how exogenous nitrite affects the brain activity of healthy individuals, it is difficult to clearly understand how it affects the ischaemic brain. ObjectiveHere we performed a double-blind placebo-controlled crossover study to investigate the effects of nitrite on neural activity in the healthy brain. MethodsTwenty-one healthy volunteers were recruited into the study. All participants received a continuous infusion of sodium nitrite (0.6mg/kg/h) on one occasion and placebo (sodium chloride) on another occasion. Electroencephalogram was recorded before the start and during the infusion. We computed the power spectrum density within the conventional frequency bands (delta, theta, alpha, beta), and the ratio of the power within the alpha and delta bands. We also measured peripheral cardiorespiratory physiology and cerebral blood flow. ResultsWe found no significant effect of nitrite on the power spectrum density in any frequency band. Similarly, the alpha-delta power ratio did not differ between the two conditions. However, nitrite infusion decreased the mean blood pressure and increased the methaemoglobin concentration in the blood. ConclusionOur study shows that exogenous sodium nitrite does not alter the electrical activity in the healthy brain. This might be because the sodium nitrite is converted to vasoactive nitric oxide in areas of hypoxia, and in the healthy brain there is no significant amount of conversion due to lack of hypoxia. However, this lack of change in the power spectrum density in healthy people emphasises the specificity of the brains response to nitrite in disease.

neuroscience↗