Teaching Point: Iatrogenic overdrainage of cerebrospinal fluid may cause intracranial hypotension with secondary engorgement of the epidural venous plexus, resulting in potentially reversible ...compression radiculopathy or myelopathy.
We report on a patient with a history of Ewing sarcoma who underwent surgery and subsequent adjuvant chemotherapy and radiotherapy. He developed low-back pain 6 months after the end of the ...radiotherapy and during consolidation chemotherapy. Magnetic resonance imaging showed evidence of myositis corresponding to the ‘radiation-recall phenomenon’, an inflammatory reaction of irradiated tissue.
Abstract Purpose Microcystic meningioma is a rare morphological variant of meningioma with multiple radiological presentations. To date only the findings on CT and conventional MRI have been ...described. We report two cases of microcystic meningioma examined with perfusion-weighted MR. Methods Two patients with a cystic meningioma were examined with gradient-echo perfusion MR. Results A convexity microcystic meningioma showed low rCBV in one patient. In the other patient with a microcystic falx meningioma high rCBV was noted, probably reflecting hypervascularity, but also impaired venous outflow and contrast-medium leakage. The vascularity of the tumor as demonstrated by perfusion MR correlated well with the intra-operative findings. Conclusion The vascularity of microcystic menigioma seems variable and multifactorial. In our two patients rCBV correlated well with intra-operative findings. Further larger studies will have to confirm that perfusion MR can predict the vascularity of a meningioma with cystic appearance.
Saturation curves for substrate interaction with an acceptor (enzyme, binding or carrier protein) are often analysed on the assumption that the amount of acceptor-bound substrate is negligible ...compared to its total amount. Analytical criteria permitting one to decide whether the assumption is justified or not for systems described by a single Michaelis-Menten equation have been derived previously. For more complicated systems, error formulae often cannot be obtained in closed form, and, if obtainable, are unwieldy. How this more complicated problem can be tackled is shown for mixtures of acceptor sites described by a sum of several Michaelis-Menten terms, without or with an additional term for 'non-specific' uptake or binding. In particular, it is shown that the maximum error, for which simple analytical expressions are obtained, provides a valid criterion for assessing whether substrate depletion is negligible or not.
