Phosphorus spectroscopy in acute TBI demonstrates metabolic changes that relate to outcome in the presence of normal structural MRI.

Metabolic dysfunction is a key pathophysiological process in the acute phase of traumatic brain injury (TBI). Although changes in brain glucose metabolism and extracellular lactate/pyruvate ratio are well known, it was hitherto unknown whether these translate to downstream changes in ATP metabolism and intracellular pH. We have performed the first clinical voxel-based in vivo phosphorus magnetic resonance spectroscopy (31P MRS) in 13 acute-phase major TBI patients versus 10 healthy controls (HCs), at 3T, focusing on eight central 2.5 × 2.5 × 2.5 cm3 voxels per subject. PCr/γATP ratio (a measure of energy status) in TBI patients was significantly higher (median = 1.09) than that of HCs (median = 0.93) (p < 0.0001), due to changes in both PCr and ATP. There was no significant difference in PCr/γATP between TBI patients with favourable and unfavourable outcome. Cerebral intracellular pH of TBI patients was significantly higher (median = 7.04) than that of HCs (median = 7.00) (p = 0.04). Alkalosis was limited to patients with unfavourable outcome (median = 7.07) (p < 0.0001). These changes persisted after excluding voxels with > 5% radiologically visible injury. This is the first clinical demonstration of brain alkalosis and elevated PCr/γATP ratio acutely after major TBI. 31P MRS has potential for non-invasively assessing brain injury in the absence of structural injury, predicting outcome and monitoring therapy response.

[Renovascular hypertension due to unilateral renal artery stenosis with hypokalemic alkalosis, the salt-losing syndrome and reversible hyperechogenicity of the contralateral kidney. A study of 2 infants]. / Hipertensión renovascular por estenosis unilateral de la arteria renal con alcalosis hipocaliémica, síndrome de pérdida salina e hiperecogenicidad reversible del riñón contralateral. Estudio de dos lactantes.

This report describes two infants with severe arterial hypertension secondary to unilateral renal artery stenosis which was manifested by polyuria, polydipsia, hypokalemic alkalosis, hyponatremia, increased natriuresis and increased plasma values of rennin and aldosterone. On sonographic examination, the contralateral non-stenotic kidney of both patients appeared enlarged and hyperechogenic mimicking parenchymal lesion. When the patients became normotensive, their sodium and potassium balance became normal and their contralateral non-stenotic kidney also became normal in size and echogenicity. The increase of the filtration and the natriuresis observed in the contralateral non-stenotic kidney of the patients with renovascular hypertension due to renal artery stenosis might be responsible for the hyperechogenicity. When the patients became normotensive, the filtration and excretion of sodium of the contralateral kidney also became normal and the increase of echogenicity also disappeared. The reversibility of the sonographic findings suggest a functional origin.