[A case of primary low spinal fluid pressure syndrome complicated by bilateral subdural hematoma--study of the cerebrospinal fluid circulation].

A 43-year-old man with no history of trauma or neurosurgical procedure was admitted our hospital because of orthostatic headache made worse in upright position. Spinal fluid pressure was 0 mmH2O, and CT scan revealed wide cortical sulci and ventricles. In the 26th hospital day he had severe headache and CT scan revealed bilateral subdural hematoma, then neurosurgical procedure was done. About 2 months later, he was relieved of the headache and spinal fluid pressure returned to normal. We performed lumbar isotope cisternography and isotope choroid plexography in our case when low spinal fluid pressure and normalized pressure. Isotope cisternography revealed the radioactivity counts decreased rapidly in low pressure and normal in normal pressure. On the other hand isotope choroid plexography was almost no difference between low and normal pressure. Our data suggest that primary low spinal fluid pressure syndrome is not caused by hypoproduction, but by an undetectable leak from a minute tear in a spinal root sleeve or hyperabsorption at the spinal arachnoid membrane.