Subdural hygroma is a rare pathology most commonly encountered in post-traumatic patients. Even more rarely, it has been described as a complication of cerebellopontine angle tumor requiring surgical evacuation. CASE DESCRIPTION: This report discusses two patients who underwent surgery for cerebellopontine angle tumor and who both developed symptomatic subdural hygromas a few days later. Both became highly symptomatic but symptoms resolved spontaneously and promptly before planned surgery. CONCLUSIONS: These two cases highlight the two principal pathogenesis theories for the development of subdural hygromas, arachnoid tear and effusion, and suggest a theory for their sudden and spontaneous resolution, the pressure-equilibrium opening the valve created by the arachnoid tear. As surgical treatment remains the recommended attitude, these cases show that a conservative treatment can be an option in some cases ¹⁾.