VALUE OF TRANSCRANIAL DOPPLER INDEXES IN PREDICTING RAISED ICP IN INFANTILE HYDROCEPHALUS - A STUDY WITH REVIEW OF THE LITERATURE

Cerebral hemodynamic changes in infants with progressive hydrocephalus have been studied with the transcranial Doppler (TCD) technique. Seve ral authors have referred to the correlation between the hemodynamic c hanges and increased intracranial pressure (ICP). Despite conflicting conclusions on the value of pulsatility index (PI) and resistance inde x (RI) measurements for monitoring infantile hydrocephalus, these puls atility indices are the most commonly used for this purpose. Although clinical signs of raised ICP are highly variable and unreliable in inf ants, assumptions have been made in most of the studies about the pres ence of elevated ICP on the basis of the patient's clinical state. Few studies have reported on actual ICP values, however, and a direct rel ationship between ICP and TCD changes has never been adequately demons trated. In the present study, this relationship was investigated in lo ngterm simultaneous TCD/ICP measurements, in an attempt to develop a n oninvasive method of monitoring the effect of ICP on intracranial hemo dynamics. Two groups of data sets were established. Group I consisted of pre- and postoperative (shunt implantation) TCD/ICP measurements. G roup II were long-term simultaneous TCD/ICP recordings showing signifi cant ICP variations. In most of the postoperative measurements there w as a decrease in the average PI and RI values. The correlation between PI or RI and ICP in the long-term simultaneous recordings, however, w as generally poor. The risk of obtaining false positive or false negat ive PI or RI values in short-term measurements was also demonstrated. It can be concluded from our results, besides the wide range of refere nce values for the Doppler indices and extracranial influences upon th em, that the present Doppler indices are inadequate for monitoring the complex intracranial dynamic responses in patients with raised ICP.