AIM

The measurement of CSF flow in the aqueduct has been a focus of interest since the development of MR imaging (MRI) techniques for this purpose in diagnosing idiopathic normal-pressure hydrocephalus (iNPH).The purpose of this prospective study was to determine the ability of this diagnostic tool to replace invasive methods in establishing the diagnosis of iNPH.

PATIENTS AND METHODS

Between January 2003 and April 2005, 61 patients with the Hakim triad of clinical symptoms and dilated ventricular systems underwent the intrathecal infusion test, cerebrospinal tap test, and phase-contrast MRI to measure CSF flow rate in the aqueduct. Shunted patients were controlled 12 months postoperatively. Pre- and postoperative clinical symptoms were evaluated with the Kiefer score. Outcome was calculated according to the NPH recovery rate.

RESULTS

According to these criteria the patients were classified into groups of 41 with iNPH and 20 with brain atrophy. Of the iNPH patients, 39 were shunted and two did not agree to surgery. The mean Kiefer score of the shunted patients was statistically significantly lower after surgery. The aqueductal CSF flow rate of these patients was statistically analyzed and showed that a flow rate of more than 24.5 ml/min is 95% specific to iNPH.

CONCLUSIONS

Measurement of the CSF flow rate in the aqueduct using phase-contrast MRI is a highly specific preselective method for diagnosing iNPH.