Cranial duplex sonography of the infant

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

Duplex Sonography of the Neonatal Brain

This article presents a review of intracranial Doppler techniques and their potential applications. Three approaches are described for interrogating major cerebral vessels: Sagittal and coronal anterior fontanelle, and axial transcranial approaches. Their advantages and limitations are discussed. The uses of pulsatility and flow velocity measurements in estimating blood flow are explored, with emphasis on the physiologic mechanisms that may alter these measures.

The ratio of flow velocities in the middle cerebral and internal carotid arteries for the prediction of cerebral palsy in term neonates

OBJECTIVE

This study evaluated whether the ratio of the mean flow velocities in the middle cerebral artery (MCA) and the internal carotid artery (ICA) of neonates in the first days of life can be used to identify future neurodevelopmental disabilities.

METHODS

We observed 127 term neonates without congenital malformations, chromosomal aberrations, intracranial hemorrhage, or early onset sepsis. The mean cerebral blood flow velocities were measured in the right and left ICAs and in the right and left MCAs with a Doppler flowmeter once from day 1 to day 3. The Vm ratio was defined as the mean velocity in the right and left MCAs/mean velocity in the right and left ICAs. Neurologic examinations were performed at 12 months of age in the outpatient follow-up clinic to detect cerebral palsy (CP), and the subjects were divided into 4 groups according to the diagnosis of hypoxic-ischemic encephalopathy (HIE) and neurologic prognosis: HIE- and normal neurologic function, HIE- and CP, HIE+ and normal neurologic function, and HIE+ and CP.

RESULTS

The Vm ratio in infants with the HIE- diagnosis and CP was significantly lower than that in infants with the HIE- diagnosis without CP (P < .05). There was no significant difference between the Vm ratios in infants with the HIE+ diagnosis without CP and infants with the HIE+ diagnosis and CP.

CONCLUSIONS

The Vm ratio might be a useful index in estimating neurologic outcome at birth, especially in neonates without the diagnosis of HIE.

Transcranial Doppler in infantile cerebrospinal fluid disorders: clinical validity

The present study was designed to investigate a possible relationship between transcranial Doppler sonography (TCD) parameters with infantile hydrocephalus and other types of cerebrospinal fluid (CSF) abnonnalities, i.e. arrested hydrocephalus and essential ventriculomegaly. TCD parameters in the major arteries of the circle of Willis were studied in hydrocephalic children (n = 12) before and after insertion of a ventricular shunt device. It was correlated with TCD parameters of children with CSF disorders (n = 13), in whom no surgery was performed. Also, TCD parameters were assessed in control cases (n = 10). Mean values for medial cerebral artery (MCA) flow velocities were higher in the essential ventriculomegaly (75.38 +/- 4.1) and in the control group (73.93 +/- 3.4) compared with hydrocephalic children (64.13 +/- 5.3). All hydrocephalic children had a higher mean MCA pulsatility index (RI) (1.08 +/- 0.13) and resistance index (RI) (0.64 +/- 0.17) values than the essential ventriculomegaly group (PI: 1.03 +/- 0.48; RI: 0.63 +/- 0.13) and the control group (PI: 0.84 +/- 0.32; RI: 0.57 +/- 0.23). Analysis of all TCD parameters disclosed its usefulness only after a particular and thorough evaluation of the TCD results with special emphasis in the clinical correlation of every case.

Color flow Doppler imaging and Doppler spectral analysis of the brain of neonatal dogs

Doppler ultrasonography was performed on the cerebral arteries of 19 neonatal dogs. Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed or examined under a stereomicroscope. Color flow Doppler imaging was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured in transverse images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.

Assessment of normal flow velocity in basal cerebral veins. A transcranial doppler ultrasound study

BACKGROUND AND PURPOSE

Transcranial Doppler ultrasound has not yet been applied systematically to the analysis of the venous system and cerebrovenous disorders. Assessment of the intracranial venous system, however, would contribute to the understanding of cerebral hemodynamics and thus allow new possibilities for clinical application of the Doppler technique. Therefore, we demonstrated the validity of the transcranial Doppler technique in analyzing the basal cerebral veins.

METHODS

Venous transcranial Doppler ultrasound was performed with a range-gated 2-MHz transducer in 60 healthy volunteers in patients without central nervous disorders ranging in age from 10 to 71 years (mean +/- SD, 41.9 +/- 15 years).

RESULTS

A venous signal away from the probe and adjacent to the posterior cerebral artery, considered to correspond to the basal vein of Rosenthal, was found in all subjects on at least one side. Mean blood flow velocity ranged from 4 to 17 cm/s (mean +/- SD, 10.1 +/- 2.3 cm/s). Analysis for age dependency revealed a trend of decreasing values with increasing age, exclusively caused by a significant reduction of velocity in men aged 40 years or older. No significant intraindividual side-to-side differences were found. A venous signal away from the probe and paralleling the middle cerebral artery, interpreted as corresponding to the deep middle cerebral vein, was found in 21.7% of the subjects with similar velocities.

CONCLUSIONS

We have shown that transcranial Doppler methods can also be used for evaluation of the basal cerebral veins in both sexes, in differing age groups, and without major difficulty. The cerebral basal veins could be identified on the basis of their anatomic relation to specific arteries.

Value of transcranial Doppler indices 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. 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) and resistance index (RI) 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.

Intracranial pressure and cerebral arterial flow velocity indices in childhood hydrocephalus: current review

Because of its noninvasive and repeatable nature, Doppler ultrasound has been increasingly used to assess changes in cerebral haemodynamics in infants and children with hydrocephalus. There is general agreement that a direct correlation exists between the intracranial pressure (from experimental, fontanometric and direct measurement evidence) and the resistance index. In addition, this increasing index has been predominantly due to a reduction in the end-diastolic velocity. Stable ventriculomegaly is associated with normal pulsatility. The cerebral blood flow velocity parameters change significantly following CSF drainage by tapping or shunting. The measurement of intracranial pressure and cerebral blood flow velocity are currently the best ways of assessing the need for CSF diversion and monitoring subsequent shunt function.

Monitoring intracranial dynamics by transcranial Doppler--a new Doppler index: trans systolic time

Since the introduction of transcranial Doppler sonography (TCD) several investigators have described the relationship between raised intracranial pressure (ICP) and Doppler waveform. This waveform has been expressed by several indices, such as the pulsatility index (PI) and the resistance index (RI). These indices are used to demonstrate the presence of raised ICP. In childhood hydrocephalus this information can be used to indicate the need for shunt implantation. However, PI and RI do prove to have certain disadvantages as both are strongly influenced by the heart rate. Moreover, both indices have a broad range of reference values, especially in children. Therefore, they are not very reliable for detecting insidious changes in the ICP. These drawbacks are due to the fact that these indices are composed of blood flow velocity measurements and do not embody the slope of the TCD waveform itself. An ideal TCD waveform analysis should be performed concerning the time-related changes of the velocities. We present a hydrodynamic model, with its electrical analogue, which shows the effects of raised ICP on the intracranial hemodynamic system. Based on these physical findings we define a new Doppler index, the Trans Systolic Time, reflecting specific changes in the TCD waveform induced by changes in the mean ICP. The applicability of this index, compared with PI and RI, is illustrated by consecutive simultaneous TCD and AFP measurements in three children with hydrocephalus.

Longitudinal quantitation of middle cerebral artery blood flow in normal human fetuses

OBJECTIVES

We attempted to quantify noninvasively blood flow of the middle cerebral artery in human fetuses during five distinct periods.

STUDY DESIGN

Twenty normal fetuses had color pulsed Doppler ultrasonography of the middle cerebral artery. A total of 68 studies were successfully done and are reported. The Doppler sample was placed as parallel to the direction of the vessel flow as possible. All waveforms were recorded on a strip chart at a preset speed of 100 mm/sec. Six Doppler waveforms were digitized for the time velocity integral (area under the curve is equal to time velocity integral) and averaged. Middle cerebral blood flow was obtained by multiplying the time velocity integral of the Doppler curve by the cross-sectional area of the vessel. The combined cardiac output was obtained by adding the right and left ventricular outputs, which were obtained by multiplying the time velocity integrals by the area of the corresponding annuli. Analysis of variance for repeated measurements was used to determine significance.

RESULTS

The diameter of the middle cerebral artery, the time velocity integral, and the peak flow velocity of the Doppler waveform increased significantly with advancing gestational age. Blood flow to the middle cerebral artery ranged from 23 ml/min at 19 weeks to 133 ml/min at term. Resistivity index values were not correlated with advancing gestational age. The percent of the cardiac output to one of the two middle cerebral arteries remained constant throughout gestation with a range between 3% and 7%.

CONCLUSIONS

(1) Time velocity integral, peak flow velocity, diameter, and blood flow of the middle cerebral artery increased significantly with gestational age; (2) the percent of the total cardiac output to the middle cerebral artery does not significantly change with gestational age.

The contribution of colour Doppler flow imaging to the study of cerebral haemodynamics in the neonate

We investigated the contribution of colour Doppler flow imaging (CDFI) to duplex-ultrasonography of the neonatal brain. In pre- and full-term infants, CDFI facilitated spectral analysis of blood flow velocity wave forms in most major intracranial arteries, enabling blood flow velocity measurements. Moreover CDFI depicted major deep and superficial veins, enabling venous blood flow velocity measurements. Smaller arteries could also be imaged in a substantial number of infants in regions with haemorrhagic or ischaemic lesions. The method may also offer the opportunity to assess regional cerebral blood flow in the neonatal brain, although further study is necessary to determine whether accurate, reproducible flow velocity measurements are possible in these vessels.

Remote congenital cerebral arteriovenous fistulae associated with aortic coarctation. Case report

A neonate presented with anatomically discrete cerebral arteriovenous fistulae located in the right sylvian fissure and the cerebellar vermis that were initially detected by prenatal ultrasonography. Following delivery of the baby by caesarean section, both malformations were treated by surgical obliteration. These intracranial vascular lesions were associated with cardiac anomalies and a periductal coarctation of the aorta, which was treated with a left subclavian rotational arterial pedicle repair. Follow-up examination of the infant at age 13 months demonstrated an excellent clinical result with normalization of the circulation. The pathophysiology of this syndrome is discussed and the literature reviewed.

Cerebrovascular resistive index assessed by duplex Doppler sonography and its relationship to intracranial pressure in infantile hydrocephalus

Duplex Doppler sonography and direct intracranial pressure (ICP) measurement were performed on 18 patients with infantile hydrocephalus. ICP was measured through a frontal reservoir or ventricular tap using a nondisplacement pressure transducer. The Pourcelot Resistive Index, RI = (peak systolic-end diastolic)/peak systolic velocity was obtained from pulsed-wave Doppler measurements of blood flow velocity in the anterior (ACA) and/or the middle cerebral (MCA) arteries. There was a statistically significant positive correlation between ICP and RIs in the MCA and ACA. Paired RI measurements in 7 patients with raised ICP decreased significantly from a mean of 0.90 pre-tap to 0.75 post-tap. Our results suggest that the RI provides a reliable measure of cerebrovascular resistance in hydrocephalus. Duplex Doppler ultrasonography thus is a useful noninvasive means of monitoring cerebrohaemodynamic change with simultaneous imaging of ventricular size in infantile hydrocephalus.

Maternal-fetal Doppler sonography: potential or reality

Doppler sonography, in its varying forms, has been used by numerous researchers to evaluate the maternal-fetal circulation. Unfortunately, as can be seen from this review, few sweeping conclusions can be drawn from the literature to date. Doppler certainly seems a worthwhile adjunct in the evaluation of patients with any of a number of abnormalities that affect maternal-fetal circulation. Unfortunately, considering the discrepancies in the literature and the recent controversy regarding the use of pulsed and color Doppler in pregnancy, the examination is often avoided. However, there are certainly instances where Doppler can provide unique and valuable information. In these situations, the prudent use of Doppler should be encouraged.

Transcranial Doppler ultrasound studies of cerebral autoregulation and subarachnoid hemorrhage in the rabbit

The authors describe a method for Doppler ultrasound recording of flow velocity in the basilar artery of normal rabbits and rabbits with experimental subarachnoid hemorrhage (SAH). With this transcranial Doppler (TCD) model, clinical assumptions regarding flow velocity/cerebral blood flow (CBF) relationships, autoregulatory responses, and Doppler spectral waveform analysis can be tested under controlled conditions and compared with established methods of CBF measurement (hydrogen clearance). The time course of changes in flow velocity following SAH (cerebral vasospasm) is successfully demonstrated using the experimental TCD method. There are significant differences in the flow velocity and CBF responses to hypercapnia, hypocapnia, and trimethaphan-induced hypotension which indicate that TCD cannot be considered a simple alternative to CBF measurement for the study of cerebrovascular reactivity and cerebral autoregulation.

Cerebral blood-flow velocity patterns in post-hemorrhagic ventricular dilation

To evaluate the effect of ventricular dilation (VD) on cerebral hemodynamics, serial cerebral bloodflow velocity patterns from the anterior and middle cerebral, and circle of Willis arteries were examined by range-gated, pulsed Doppler sonography in premature infants developing post-hemorrhagic VD. Nine infants (25 to 30 weeks gestation) without a patent ductus arteriosus were studied until resolution of VD. Forty-nine cranial sonograms from all nine infants were reviewed independently and grouped cross-sectionally into mild, moderate and severe VD prior to shunt. The corresponding pulsatility index (PI) showed a consistent trend of increase with VD in all three studied vessels. In six infants, absent or reversed diastolic flow was observed at the height of VD. Four of these infants required V-P shunt. Immediate fall in PI occurred in all three vessels. Serial measurement of PI during VD reflects global changes in cerebrovascular resistance. Results confirmed PI could be a useful index in monitoring cerebral hemodynamic changes.

Regional cerebral blood flow velocity patterns in newborn infants

Using range-gated pulsed Doppler sonography, cerebral blood flow velocity (CBFV) waveforms from the anterior cerebral artery (ACA), middle cerebral artery (MCA) and circle of Willis artery (CW) were examined in a total of 34 newborn infants. We compared the pulsatility index (PI) from the three cerebral arteries sampled in 10 term and 10 preterm (29 +/- 2 weeks) newborn infants without a history of perinatal asphyxia or intracranial pathology. The Pl in the ACA ranged from 0.60 to 1.03. There were no significant differences in Pl between the three vessels by paired comparisons. The Pl of the MCA differed from that of the ACA by 0.00 +/- 0.05. The variation coefficient (CV) was 7%. For CW with ACA, the difference was 0.00 +/- 0.04 and CV was 6%. Both intra- and interexaminer variation in Pl measurements were studied in another 14 infants. The variation coefficients were 5-8% for all three cerebral arteries. We showed that CBFV waveform patterns were similar in regional cerebral arteries, with Pl being a consistent CBFV index. In normal cerebral circulation, the intervessel Pl differences were within observer variations. Deviation from this may suggest abnormal regional cerebral haemodynamics.

The role of ultrasound in the management of vein of Galen aneurysms in infancy

Ultrasonography can be the key imaging modality for neonatal patients with vein of Galen aneurysms. Ultrasound can be used to diagnose the condition, monitor transtorcular embolization procedures, and follow-up these patients after embolization to assess the effectiveness of embolization and to check for complications.

Major pitfalls in Doppler investigations. Part II. Low flow velocities and colour Doppler applications

Many pitfalls result from the limited ability of Doppler instruments to record low flow velocities. These include a misleading resistance or pulsatility index due to diastolic cut-off and taking no signal to equal no flow assuming that no signal means no flow. Comparison of actual flow velocities as measured in an in-vitro system (range: 0.8 to 3.4 cm/s) with the lowest recordable spectral or colour signals in 3 Duplexscanners showed that reduced sensitivity to low flow velocities is not only dependent on the high pass ("wall") filter setting, Doppler frequency or angle of incidence, but also on factors such as vessel diameter, impairing the signal to noise ratio. Characteristic errors of colour flow mapping (misleading vascular anatomy, imitation of pathological findings, erroneous exclusion of flow) are due to partial volume effect, limited temporal and velocity resolution, changing angle of incidence, aliasing and failure to detect low flow velocities.

Major pitfalls in Doppler investigations with particular reference to the cerebral vascular system. Part I. Sources of error, resulting pitfalls and measures to prevent errors

Major pitfalls in Doppler investigations are presented based on 340 evaluated cerebral Doppler examinations in infants. Substantial pitfalls may result from: A. Physics of sound waves and Doppler instruments (errors due to high pass filter cut off, aliasing, rapid image update). B. Quality and adjustment of the Doppler instrument (errors due to low sensitivity, inappropriate adjustment of Doppler controls, inadequate wall filter). C. Examination technique (errors due to an unfavourable angle of incidence or due to transducer-induced pressure: decrease predominantly in diastolic flow velocity-increase in maximum flow velocity in the straight sinus). D. Hemodynamics (errors due to spatial or temporal variations of the flow profile, pulsatility, non-uniform distribution of cerebral blood flow/CBF). E. Cerebral vascular anatomy (errors due to an unfavourable probe position as related to the three-dimensional arrangement of vessels, inadequate separation of closely adjacent vessels). F. Interpretation (flow velocity or Resistance Index/RI is taken to equal CBF, RI is taken to equal peripheral vascular resistance, one artery is taken to represent the cerebral circulation). Pitfalls may be avoided by using adequate means (low wall filter adjustment, high Doppler frequency, critical assessment of velocity spectra) to reduce the likelihood of errors occurring.

Transcranial Doppler and real-time cranial sonography in neonatal hydrocephalus

Nine hydrocephalic infants who were less than 1 year old and 7 age-matched control subjects were examined by real-time and transcranial Doppler sonography to evaluate cerebral blood flow and to correlate it to ventricular size. These 16 infants were placed in one of three groups: infants in group 1 (n = 7) had a normal ventricular size, infants in group 2 (n = 3) had a progressively increasing ventricular size, and infants in group 3 (n = 6) had ventriculomegaly with either stable or decreasing ventricular size or a functioning ventriculoperitoneal shunt. All scans performed on group-2 infants showed markedly increased ventricular size and increased pulsatility index, while those on group-1 infants showed a normal ventricular size and pulsatility index. However, the scans of group-3 infants revealed increased ventricular size and pulsatility index for all groups. Regression analysis of the data showed rather weak correlations between ventricular size and pulsatility index for all groups. The regression data suggest that ventricular size is not the main determinant of cerebral blood flow in the neonate with hydrocephalus and that intracranial pressure may be a more critical factor. These data suggest that pulsatility index, as measured by transcranial Doppler, can be clinically more important than just the anatomical data alone in the evaluation of hydrocephaly. This points to a possible use of transcranial Doppler sonography in the evaluation of hydrocephalic patients for placement of ventriculoperitoneal shunts.

Duplex-scanning of the deep venous drainage in the evaluation of blood flow velocity of the cerebral vascular system in infants

Doppler investigations of the anterior cerebral (pericallosal) or internal carotid arteries have two major limitations: (1) flow velocity in one cerebral artery does not necessarily represent flow velocity in other cerebral arteries; (2) flow velocity spectra are influenced significantly by transducer-transferred pressure. Furthermore, there are substantial pitfalls in the interpretation of arterial flow velocity data. We therefore examined Doppler-shift waveforms of the deep venous drainage in addition to arterial flow velocity recordings in 186 infants, including a reference group of 49 infants without significant disease. In this group, mean values of peak velocities were 13.2 cm/s, 5.6 cm/s, 5.9 cm/s and 5.6 cm/s for the straight sinus, the vein of Galen, the right and the left basilar veins respectively. Venous flow velocities were increasing significantly with age, but not or only marginally with the weight at the time of examination. Three main flow velocity patterns were observed: (1) bandlike (straight sinus 25%, vein of Galen 59% and basilar veins 63%); (2) sinusoid and synchronous with arterial pulse (46%, 27% and 29% respectively; (3) intermittent (3%, 0% and 0% respectively). In contrast to the reference group, the intermittent pattern was common in severely ill premature infants and was associated with increased intrathoracic pressure and adverse outcome, indicating reduced venous volume flow irrespective of the arterial flow velocity pattern. Although difficult to perform, transcranial and transfontanellar Duplex-scanning of the deep cerebral veins might help to avoid pitfalls of arterial velocity interpretation, reveal further pathophysiological aspects of intensive care and be an important factor for the prediction of outcome.

The blood flow velocity waveform in the fetal internal carotid artery in the presence of hydrocephaly

The pulsatility index in the fetal internal carotid artery was studied in the presence of bilateral symmetrical hydrocephaly (n = 9) and unilateral hydrocephaly (n = 4). An elevated pulsatility index was demonstrated in five cases (38.5%) suggesting increased resistance to cerebral blood flow. In unilateral hydrocephaly a marked difference in pulsatility index was established between the normal and affected side. No relation could be established between the pulsatility index level and severity of ventriculomegaly or postnatal outcome. Both ventriculomegaly and increased intracranial pressure may play a role in the observed rise in pulsatility index.

Intracranial arterial duplex Doppler waveform analysis in infants

Duplex sonography of the brain was performed on 130 pediatric patients: 53 with normal brains, 22 with intracranial hemorrhage, 15 with hypoxic-ischemic encephalopathy, 29 with hydrocephalus requiring ventricular shunting, and 11 with ventriculomegaly without hemorrhage or shunting. Doppler arterial waveforms from the Circle of Willis showed increased pulsatility in 82% of patients with intracranial hemorrhage, 53% of patients with hypoxic-ischemic change, and in only 31% of patients with hydrocephalus requiring shunt and 36% of patients with ventriculomegaly without shunt or hemorrhage. Mean pulsatility was increased (p less than 0.05) in all groups except ventriculomegaly without hemorrhage or shunt. No statistical difference was found in the diagnostic efficiency of three indices of pulsatility (frequency index profile, pulsatility index, systolic to diastolic ratio).