[Primary intracranial hypotension associated with chronic subdural hematoma--report of 2 cases].

Low spinal fluid pressure syndrome is characterized by orthostatic headache aggravated in upright position. It is classified into two from etiological standpoint i.e. primary and secondary (most often seen after lumbar puncture). On the other hand, low spinal fluid pressure is one of the promoting factors of chronic subdural hematoma. We report 2 cases of primary low spinal fluid pressure syndrome (primary intracranial hypotension) associated with chronic subdural hematoma. Case 1 is a 47-year-old man who was admitted with disorientation following 2 week history of orthostatic headache. Spinal fluid pressure was 7mmH2O in the lateral recumbent position. CT scan revealed bilateral isodense chronic subdural hematoma. The subdural hematoma reaccumulated 17 days after the first operation. Case 2 is a 31-year-old woman who was admitted with 4 week history of progressive orthostatic headache accompanied by nausea and vomiting. Spinal fluid pressure was 0 mmH2O. CT scan and cerebral angiography showed bilateral chronic subdural hematoma. The hematoma reaccumulated 20 days after the first operation. Six cases including our two cases of primary intracranial hypotention associated with chronic subdural hematoma have been reported. When changes of characters of headache, especially mental symptoms and disturbances of consciousness occurred in patients with chronic orthostatic headache, association of chronic subdural hematoma should be suspected. In cases with chronic subdural hematoma associated with low spinal fluid pressure syndrome, the reaccumulation of hematoma tends to occur after burr hole opening and irrigation of hematoma.