Value of transcranial Doppler indices in predicting raised ICP in infantile hydrocephalus
ABSTRACT Cerebral hemodynamic changes in infants with progressive hydrocephalus have been studied with the transcranial Doppler (TCD) technique. Several authors have referred to the correlation between the hemodynamic changes and increased intracranial pressure (ICP). Despite conflicting conclusions on the value of pulsatility index (PI) measurements for monitoring infantile hydrocephalus, these pulsatility indices are the most commonly used for this purpose. Although clinical signs of raised ICP are highly variable and unreliable in infants, assumptions have been made in most of the studies about the presence of elevated ICP on the basis of the patient's clinical state. Few studies have reported on actual ICP values, however, and a direct relationship between ICP and TCD changes has never been adequately demonstrated. In the present study, this relationship was investigated in long-term simultaneous TCD/ICP measurements, in an attempt to develop a noninvasive method of monitoring the effect of ICP on intracranial hemodynamics. Two groups of data sets were established. Group I consisted of pre- and postoperative (shunt implantation) TCD/ICP measurements. Group II were long-term simultaneous TCD/ICP recordings showing significant ICP variations. In most of the postoperative measurements there was a decrease in the average PI and RI values. The correlation between PI or RI and ICP in the long-term simultaneous recordings, however, was generally poor. The risk of obtaining false positive or false negative PI or RI values in short-term measurements was also demonstrated. It can be concluded from our results, besides the wide range of reference values for the Doppler indices and extracranial influences upon them, that the present Doppler indices are inadequate for monitoring the complex intracranial dynamic responses in patients with raised ICP.
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ABSTRACT: Intracranial pressure and cerebrospinal fluid hypoxanthine and xanthine concentrations were measured in hydrocephalic children with suspected raised intracranial pressure. There was a highly significant correlation between intracranial pressure and cerebrospinal fluid hypoxanthine and xanthine levels.Journal of Neurology Neurosurgery & Psychiatry 08/1984; 47(7):730-3. · 4.92 Impact Factor
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ABSTRACT: Because transcranial Doppler ultrasound is a blind procedure, it is not possible to routinely correct for insonation angle errors, which are presumed to be small. In anatomically normal brains this is a valid assumption; however, in some patients with distorted vascular anatomy (as in hydrocephalus) a small insonation angle cannot be assumed, and measurements of flow velocity may be misleadingly low. The orientation of the middle cerebral arteries was studied on magnetic resonance images of 17 control patients and three patients with hydrocephalus, and estimates of insonation angle errors in velocity measurements were made. When asymmetrical vessel distortion is present, relative flow to each hemisphere may not be accurately reflected in the measured velocities. Under these circumstances, the resistivity index may be a more reliable hemodynamic parameter.Journal of Neurosurgery 11/1990; 73(4):572-5. · 3.15 Impact Factor
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ABSTRACT: Previous studies have demonstrated a high correlation between hydrocephalus and the resistive index (RI), as determined by transcranial Doppler ultrasonography. Measurements of RI, calculated by dividing the difference between the peak systolic velocity and the end-diastolic velocity by the peak systolic velocity, were attempted in 55 pediatric patients during evaluations for ventriculoperitoneal shunt malfunctions; values were obtained in 52. Indications of shunt malfunction included both clinical and radiographic evidence of increased intracranial pressure. Eleven patients, determined to have functional shunts both by clinical criteria and subsequent outcome, had RIs of 47 +/- 5 (average +/- 1 standard deviation). Shunt malfunctions were confirmed in 41 patients. Prior to shunt revisions, these 41 patients had RIs of 71 +/- 10%; following revision, the RIs fell to 53 +/- 12%. Nine patients had had pre-malfunction RIs of 48 +/- 11% obtained during routine follow-ups; when they subsequently had shunt malfunctions, their RIs had significantly increased. Four of the 41 patients with shunt malfunctions had essentially normal RIs (52 +/- 7%), but had fluid tracking along the shunt; in these, RIs were essentially unaffected by shunt revision. For comparison, 119 pediatric patients with clinically functional ventriculoperitoneal shunts had RIs of 50 +/- 9%. The data, statistically significant with a P value of less than 0.001, showed a correlation between elevated RIs and shunt malfunction; thus, transcranial Doppler ultrasonography is a practical, non-invasive technique useful in the diagnosis of ventriculoperitoneal shunt malfunction.Child s Nervous System 03/1991; 7(1):27-30. · 1.24 Impact Factor