This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Expansion of the contrast filled space in myelography is seen in: 
Select and explain. 
A. Intramedullary tumor, B. Intradural extramedullary tumor, C. Spinal dysraphism, D. Extradural tumor
A: Intramedullary tumor
Answer: A: Intramedullary tumor 
Explanation: Ans: A. Intramedullary tumor(Ref Sutton 6/e p254: Neurology in Clinical Practice 4/e Vol I p579)Myelography:Expansion of contrast filled space (i.e. subarachnoid space) - Any intramedullaty extradural lesion (meningioma).Sometimes filling defect causing "meniscus sign" demonstrable.Levels of Block in MyelographySiteTypical AppearanceExtradural blockFeathered appearanceIntradural Extramedullary blockMeniscus signWidening of ipsilateral subarachnoid spaceIntramedullary blockWidening of the cordTrouser leg appearance