Transcranial Doppler (TCD) ultrasonography in patients with ventriculomegaly: Investigation of additional parameters for qualifying shunt implantation
Background: Ventriculomegaly without increased intracranial pressure is observed both in normal-pressure hydrocephalus (NPH) and idiopathic cerebral atrophy (CA). Investigating additional parameters to differentiate these diseases is important for a good qualification of shunt implantation. The study presents the influence of intravenous administration of acetazolamide on cerebral blood flow velocity (BFV) and cerebrovascular reactivity (CVR) in 23 patients with ventriculomegaly and symptoms of cognitive function disorders. The aim was to establish the differences in the dynamic cerebral hemodynamics parameters in NPH and CA patients. Material/Methods: Measurement of BFV was performed in 23 patients using transcranial Doppler (TCD) ultrasonography before and 20 minutes after intravenous administration of 1000 mg acetazolamide. CVR was calculated as the percent change from the baseline mean BFV value and assessed bilaterally in the middle (MCA), anterior (ACA), posterior (PCA), and internal carotid cerebral (ICA) arteries in the intracranial part. Additionally, BFV was evaluated in selected patients during a lumbar infusion test. The patients were divided into 2 groups: those with NPH and those with CA. Results: BFV values were decreased both in the NPH and the CA group compared with the control group (healthy volunteers of the same age). There were no significant differences between the two groups. In the CA group a complete lack of CVR was observed in all examined arteries. In the NPH group, CVR was maintained, while mean BFV (MFV) changed 37±4% in the MCA, 26±6% in the ACA, 33±5% in the PCA, and 30±4% in the ICA. There were statistically significant differences in CVR values between the groups. A decrease in initial BFV in all examined intracranial arteries and a complete lack of CVR is characteristic of the CA group. Conclusions: Maintenance of CVR and a simultaneous decrease in BFV is a characteristic of the NPH group, but among the patients in that group we found differences in cerebrovascular response to acetozolamide. In both groups there were no significant differences in BFV in the MCA during the lumbar infusion test. The acetazolamide test appears as an additional factor in the differential diagnosis of NPH and CA.
