Doppler sonographic diagnosis of increased intracranial pressure through comparison of flow velocities between the extra- and intracranial section ofthe internal carotid artery. Part 2: Infants with increased intracranial pressure.

Aim: We investigated the correlation between intracranial pressure and flow parameters by simultaneous Doppler sonographic flow measurements in the in ternal carotid arteries and estimation of the intracranial pressure over th e anterior fontanelle. Method: 12 infants (7 boys and 5 girls) with increas ed intracranial pressure were investigated. The corrected gestational age a t investigation was 42 +/- 14 weeks, the weight was 3080 +/- 2540 g. Intrac ranial pressure was measured by applanation tonometry over the anterior fon tanelle. The infants were subdivided into two groups: Group 1 (9 infants) w ith slightly increased intracranial pressure (16.9 +/- 3.3 cm H2O) and grou p 2 (3 infants) with moderately increased intracranial pressure (21.6 +/- 3 .3 cm H2O). In all infants Doppler sonographic flow measurements within the intra- and extracranial segments of the internal carotid arteries were per formed. From the flow profile, the peak systolic flow velocity Vs, the endd iastolic flow velocity Ved as well as the time average flow velocity TAV an d the resistance index RI were measured. From the flow velocities, the I/E- ratio was calculated. The measured variables were compared with the values of matched pairs of a healthy control group of similar age and weight. Resu lts: Group 1 with slightly increased intracranial pressure displayed no sig nificant difference of the RI within intracranial and extracranial sections of the internal carotid artery and the control group. The flow velocities, however, showed a significant increase within the intracranial segment of the internal carotid artery in comparison with the extracranial part of the internal carotid artery as well as the healthy control group. I/E-ratio fo r Vs increased significantly to 1.29 +/- 0.19, for Ved to 1.24 +/- 0.27 and for TAV to 1.08 +/- 0.27. Group 2 with moderately increased intracranial p ressure displayed a significant increase of RI within the intracranial sect ion of the internal carotid artery to 0.89 +/- 0.08 in comparison to the ex tracranial section with 0.79 +/- 0.07 and to the healthy control group with 0.75 +/- 0.07. All flow velocities decreased significantly within the intr acranial section of the internal carotid artery in comparison to the extrac ranial part of the internal carotid artery and the healthy control group. T he I/E-ratio was significantly reduced in group 2 with 0.76 +/- 0.11 for Vs , 0.38 +/- 0.21 for Ved, and 0.58 +/- 0.16 for TAV. Conclusion: Flow measur ements in extra- and intracranial sections of the internal carotid arteries are an accurate method for semiquantitative estimation of increased intrac ranial pressure. This method is superior to the measurement of the RI. Slig htly increased intracranial pressures below 20 cm H2O cause an increase of the I/E-ratio above 1, whereas the RI does not change. Moderately increase of the intracranial pressure above 20 cm H2O lowers the I/E-ratio significa ntly below normal values of 0.8, whereas the RI increases.