Shunt-dependent hydrocephalus after subarachnoid haemorrhage and aneurysm surgery: timing of surgery is not a risk factor.

Early hydrocephalus is a risk factor of shunt-dependent late hydrocephalus (SDHC). In the CT era 1980-1990 we had 835 consecutive patients operated on because of aneurysm and subarachnoid haemorrhage (SAH); 294 had an early hydrocephalus and 67 finally required a shunt. There were 14 patients with normal early CT and SDHC, in all 81 patients needed a shunt (10%). Patients with shunt did worse, they were older (53 vs 49) than the non-shunted group and there was a female preponderance. Pre-operative Grade correlated significantly with the need for a shunt operation; no one in Grade I developed SDHC, incidence in Grades III and IV was high (18% and 10%, respectively). Location was important; in vertebrobasilar area 28% and in anterior communicating area 14% but in middle cerebral area only 4% of the patients had SDHC. The amount of cisternal bleeding correlated significantly with SDHC; in 155 patients with non detectable or minimal cisternal blood only one developed SDHC, with severe cisternal bleeding the incidence was 16%. Ventricular bleeding increased the risk of SDHC, but intracerebral haematoma did not. Timing of surgery had no correlation with the risk of SDHC. Postoperative complications, haematomas and infections increased the risk of late SDHC. Delayed ischaemia correlated with the risk, but so did the treatment with nimodipine. Severe bleeding was the common predictor for the risk of SDHC. Location of the bleeding and postoperative problems are the other major causes. Outcome is, however, not so gloomy; 54% of patients with SDHC are independent one year later.