Superficial siderosis of the central nervous system: report of three cases and review of the literature.

We present 3 cases and a review of the literature to demonstrate the current state of clinical diagnosis and therapy of superficial siderosis of the central nervous system. Typical symptoms were progressive cerebellar ataxia, spasticity and hearing loss. Repeated subarachnoid hemorrhage was indicated by persistent xanthochromia of the cerebrospinal fluid and confirmed by the presence of erythrophages, siderophages and iron-containing pigments. Deposition of free iron and hemosiderin in pial and subpial structures leads to intoxication of the central nervous system and represents the pathophysiological mechanism of superficial siderosis. Hypointensity of the marginal zones of the central nervous system on T2 weighted MR images indicates an iron-induced susceptibility effect and seems pathognomonic for superficial siderosis. In 39 of the 43 previously described cases superficial siderosis was verified by biopsy or autopsy. Today magnetic resonance imaging enables diagnosis at an early stage of the disease. Therapeutic management requires the elimination of any potential source of bleeding. In patients with unknown etiology no proofed therapy is yet available.     

Resistance to insulin mediated glucose disposal in obese subjects: respective effect of lipid metabolism and glycemia.

The present study was designed to assess the respective effect of altered lipid metabolism and hyperglycemia on glucose metabolism in vivo in obese subjects. Six young obese non-diabetic volunteers were studied on four occasions during hyperinsulinemic clamp, twice during euglycemia and twice during hyperglycemia, with or without the infusion of beta-pyridylcarbinol, an inhibitor of lipid metabolism. Glucose oxidation was calculated from continuous respiratory exchange measurements, and glucose storage was obtained as the difference between total glucose disposal and glucose oxidation. Two-way analysis of variance (with interaction term) demonstrated (i) a significant increase for total glucose disposal with beta-pyridylcarbinol but no significant effect of hyperglycemia and no interaction between the two treatments, and (ii) an important increase of beta-pyridylcarbinol to enhance glucose storage but no significant effect of hyperglycemia and no interaction between the two treatments. These results show that obese people, at physiological insulinemia, enhance their glucose disposal and glucose storage when lipid oxidation is artificially lowered. This suggests that enhanced lipid oxidation is related to insulin resistance in these patients. However, hyperglycemia in these patients failed to compensate for defective glucose disposal or storage.