硬膜関連病変―慢性硬膜下血腫，肥厚性硬膜炎と脳脊髄液漏出症

Dural related disease：Focusing on chronic subdural hematoma, hypertrophic pachymeningitis and CSF leak

慢性硬膜下血腫は，慢性的に硬膜下に生じる，被膜に被包化された血腫貯留状態である。被膜の脆弱な新生血管からの出血により血腫が貯留する。頭部外傷によって，架橋静脈が牽引，破綻して生じ，外傷後2〜3週間以上の経過で緩徐に発生すると考えられている。

It is important to understand the natural history of chronic subdural hematoma（CSDH）and carefully follow up patients with head injury, especially if it is associated with subdural hygroma, and the potential for the development of CSDH should be considered.

MRI of hypertrophic pachymeningitis shows localized dural thickening. Thickened areas are T2-hypointense to brain parenchyma. CSF leak shows diffuse pachymeningeal thickening and enhancement followed by dural venous engorgement, tonsillar herniation, and subdural collection. Many of the MRI abnormalities seen in CSF leak can be explained by the Monro-Kellie hypothesis.