"trauma (e.g. base of skull fractures, penetrating injury)"
"iatrogenic (e.g. lumbar puncture, surgery involving the dura)"
"congenital (e.g. some neural tube defects)"
"idiopathic/spontaneous (e.g. ventral dural defects, CSF-venous fistulas)"
"spinal meningeal cysts leaking into body spaces (e.g. pleura 4)"