Neurosonography of hydrocephalus in infants

Relationship between biparietal diameter/ventricular ratio and neurodevelopmental outcomes in non-handicapped very preterm infants

PURPOSE

Preterm infants are at high risk for brain damage and long-term neurodevelopmental problems. Cranial ultrasonography is the main neuroimaging technique for very low birth weight infants. Ventricle size and its ratio to brain volume contribute very important information about the central nervous system of preterm babies. We calculated biparietal diameter/ventricular ratio of preterm infants using cranial ultrasonography and evaluate the relationship between this ratio and neurodevelopment.

METHODS

Cranial measurements were derived using routine ultrasonographic scanning. Transverse brain length, or biparietal diameter (BPD), was considered a representation of the total brain, ventricular index (VI) and thalamo-occipital distance (TOD) length were used to represent the ventricles, and their ratio was accepted as a measure of the tissue portion of the brain. The ratio of BPD to the sum of left and right VI and TOD values was recorded as BPD/(VI+TOD) ratio.

RESULTS

Data from a total of 482 patients were analyzed. The mean gestational age was 27.6 (24-29.6) weeks and the mean birth weight was 1010 (350-1390) g. The mean BPD/(VI+TOD) ratio was 32.90 (± 2.32). At 24 months corrected age, the patients' mean MDI score was 78.64 (± 13.29) and mean PDI score was 79.49 (± 14.31). When patients with and without NDI were compared, there were significant differences between the groups in terms of BPD/(VI+TOD) ratio, MDI, and PDI (p < 0.001, p < 0.001, p < 0.001, respectively).

CONCLUSION

The BPD/ventricle ratio can be calculated using two-dimensional measurements in VLBW infants and reduced BPD/ventricle ratio was associated with poor neurodevelopmental outcomes.

TRIAL REGISTRATION

NCT02848755.

Sonographic assessment of posthemorrhagic ventricular dilatation

Sonography plays a key role in the initial evaluation and monitoring of ventricular dilatation in the newborn. The use of supplemental imaging approaches by the mastoid fontanelle and foramen magnum can help identify the cause and location of obstruction. Duplex Doppler of intracranial vessels during anterior fontanelle compression is a useful indicator of altered cranial compliance in these infants. Additional views of the thoracolumbar spine can help identify which infants will likely benefit from lumbar puncture for therapy of progressive ventricular dilatation.

Reference ranges for the linear dimensions of the intracranial ventricles in preterm neonates

AIMS

To establish normal ranges, in preterm infants < 33 weeks' gestation, for measurements of the lateral, third, and fourth ventricles and to assess intra-observer and inter-observer reliability. To assess the effect of head position during scanning on lateral ventricle size. To determine whether sex influences ventricle size.

METHODS

A prospective study involving infants < 33 weeks' gestational age (GA) at birth. Cranial ultrasound scans were done during the first 3 days of life. Linear dimensions of the anterior horn width and thalamo-occipital distance of the lateral ventricles, the width of the third ventricle, and the width and length of the fourth ventricle were measured. Measurements were plotted against GA and reference ranges produced. All measurements were tested for intra-observer and inter-observer reliability. Head position and sex differences were studied.

RESULTS

120 infants with known GA (23(+1) to 32(+6) weeks) had their intracranial ventricles measured. Reference ranges obtained were-anterior horn width: 0-2.9 mm; thalamo-occipital distance: 8.7-24.7 mm; third ventricle width: 0-2.6 mm; fourth ventricle width: 3.3-7.4 mm; fourth ventricle length: 2.6-6.9 mm. Dependent and non-dependent lateral ventricles did not differ significantly in size. There was no clinically significant difference in ventricular size between sexes.

CONCLUSIONS

Reference ranges for the measurement of the intracranial ventricles in preterm infants from 23 to 33 weeks' GA are provided and can be used in the diagnosis and assessment of ventricular enlargement in preterm infants. All measurements have good intra-observer and inter-observer reliability. Head position at the time of scanning does not influence the asymmetry of the lateral ventricular measurements. The infant's sex does not influence ventricular size.

Dynamic and three-dimensional transcranial sonography studies of an asymptomatic, cerebral convexity arachnoid cyst

Dynamic and three-dimensional transcranial sonography (dTCS and 3D-TCCS) examinations are complementary, noninvasive methods used in the assessment and follow up of patients with cerebrospinal fluid (CSF) circulation disorders.

A 16-year-old female patient who presented with a space-occupying, cerebral convexity arachnoid cyst and recurrent tension-type headache underwent examination for raised intracranial pressure (ICP) by using a standard color-coded duplex sonography system attached to a personal computer–based system for 3D data acquisition. Conventional TCS identified the outer arachnoid membrane of the cyst, which undulated freely after short rotation of the head (“headshake maneuver”). The undulation was documented as a QuickTime movie that is included with this article. A 3D dataset was acquired and, by using a multiplanar reformatting reconstruction algorithm, the authors obtained images with excellent resolution that corresponded to an initial magnetic resonance (MR) imaging study. No differences on dTCS and 3D-TCS were detectable at follow up 9 months later, indicating normal ICP and a stable, benign condition.

The use of 3D-TCCS and dTCS ultrasonography may complement other diagnostic procedures such as MR imaging and, thus, can improve management and therapeutic strategies for patients with CSF circulation disorders. In this report the authors present evidence of the excellent fine resolution and exact reproducibility of reconstructed ultrasound image planes derived from 3D datasets and the additional biomedical information from dynamic imaging.

[Transfontanellar Doppler ultrasound measurement of cerebral blood velocity before and after surgical treatment of hydrocephalus]

Twenty-seven children with hydrocephalus of different etiologies diagnosed by clinical examination, neurosonography and computerized brain tomography were submitted to transfontanellar US-Doppler evaluation for measurement of blood flow velocity and for the calculation of resistance index (RI) in the anterior and middle cerebral arteries and internal carotids. All children were submitted to evaluation before surgery and on the 1st, 30th and 60th postoperative days. We conclude that neurosonography and US-Doppler technique is useful for determination of hydrocephalus, indication and control of cerebrospinal fluid shunts and monitoring of changes in RI, comparing data obtained immediately before and after surgery and during the late postoperative period. The results obtained when comparing the RI values for the various arteries during the different stages of the study also permitted us to conclude that the anterior cerebral arteries are representative of the maximal alterations that occur in cerebral vascular resistance in pediatric patients with hydrocephalus.

Identification of ventricular enlargement and estimation of intracranial pressure by transcranial color-coded real-time sonography

Transcranial color-coded real-time sonography (TCCS) was applied to 26 patients with ventricular enlargement to quantify the ventricular size and to estimate intracranial pressure. Intracranial pressures, as determined by lumbar, epidural, or ventricular tonometry, ranged from 6.5 to 55 cm H2O (8 patients had pressures > 18 cm H2O). The widths of the third ventricle and the frontal horns of both lateral ventricles depicted by TCCS were compared to corresponding computed tomography data: TCCS and computed tomography findings correlated well for the third ventricle (r = 0.96) and for the right (r = 0.86) and left (r = 0.92) frontal horns. The capability of the septum pellucidum to undulate relative to the ventricular wall during short (20-degree) rotatory movements of the head was related to intracranial pressure. In all patients with intracranial pressure below 17 cm H2O, rotatory head movements induced septum pellucidum undulation; no lateral deflection of the septum pellucidum was found in patients with an intracranial pressure above 21 cm H2O. Therefore, TCCS may be employed to quantify and follow-up ventricular enlargement. Dynamic neurosonographic tests may allow a gross estimation of intracranial pressure.

Duplex color ultrasound study of infantile progressive ventriculomegaly

Sequential measurements of ventricular sizes and Doppler variables of anterior cerebral artery (ACA) by duplex color ultrasound were performed on 14 ventriculomegalic infants (mean age: 3.4 months): 9 were postmeningitic, 3 posthemorrhagic, and 2 congenital. According to changes of the frontal horn radius (FHR) after shunts, the FHR was decreased greater than 30% (n = 9) in group I and less than or equal to 10% (n = 5) in group II. Before shunting, Pourcelot index (PI) in group I was greater than in group II (P less than 0.01), but FHR in group II was higher than in group I (P less than 0.01). The intracranial pressure did not vary between groups. Serial preshunt examinations showed a significant correlation between the degree of cerebrovascular resistance and the degree of ventricular dilation only in group I. After surgery, significant changes of end-diastolic velocity, the area under the velocity curve, and PI were found only in group I. The reservoir pumping test performed on 2 cases of recurrent ventriculomegaly in group I and 3 cases in group II showed a decreased PI only in group I, in which the outcome was better. PI is useful in differentiating between hydrocephalic and atrophic ventriculomegaly. These data suggest that a ventriculomegalic infant with an unelevated PI value hardly benefits from a ventricular shunt.

Cranial ultrasonography in the evaluation of macrocrania in infancy

Cranial ultrasonography was used in the initial evaluation of 40 infants with macrocrania. Three of the infants had normal findings. The other 37 had evidence of various types of abnormality: intraventricular obstructive hydrocephalus, external hydrocephalus, arrested hydrocephalus with atrophy, or mild ventriculomegaly. All the infants were given neurological and developmental examinations at the time of presentation and were followed up for one year. Sonograms and head-circumference and intracranial pressure measurements were done at intervals, according to the initial ultrasound findings and the clinical status of the children. Neurodevelopmental outcome was related to the type of abnormality. The majority of children with external hydrocephalus were neurodevelopmentally normal at follow-up. In contrast, those with obstructive or arrested hydrocephalus had unfavourable outcomes, which may be related to the significant perinatal insult causing the hydrocephalus. CT confirmation was available for 16 of the infants.