All are predisposing causes of cerebral venous thrombosis except

*predisposing systemic causes for cerebral venous thrombosis: dehyration,pregnancy,Behcet's disease ,thrombophilia,hypotension,oral contraceptive use. *Local causes are:paranasal sinusitis,meningitis,subdural empyema,facial skin infection,otitis media,mastoiditis,skull fracture,penetrating head and eye wounds. Ref Harrison20th edition pg 2345