Resistance to Cerebrospinal Fluid Outflow and Intracranial Pressure in Patients with Hydrocephalus after Subarachnoid Haemorrhage
Resistance to CSF-outflow (Rout) and intracranial pressure (ICP) were measured in 33 patients with hydrocephalus after subarachnoid haemorrhage (SAH). Eleven patients examined between 10 to 30 days after SAH had high pressure hydrocephalus (HPH). Twenty-two patients had normal pressure hydrocephalus (NPH). All HPH-patients had ICP above 15 mm Hg, plateau waves and B-waves, a median Rout of 59 mm Hg×ml -1×min (range 29–100). All NPH-patients had a normal ICP level, no plateau waves, but long periods of B-waves and a median Rout of 22 mm Hg×ml -1×min (range 6–47). Early development of hydrocephalus after SAH is associated with a high Rout and a high ICP, whereas late (more than one month) hydrocephalus may be associated with normal ICP and high Rout. Patients with NPH and a high Rout have frequent B-waves and should be shunted. Patients with a long interval from SAH to the diagnosis of hydrocephalus often have a normal ICP, low frequency of B-waves, normal CSF-dynamics and need no shunting.