Neonatal subependymal cysts detected by sonography: prevalence, sonographic findings, and clinical significance

OBJECTIVE

Cranial sonography in neonates occasionally shows subependymal cysts. These cysts may be due to a variety of pathologic disorders, but they also occur as an "isolated" condition without an obvious cause in some patients. Assessment of the clinical significance of these lesions has been difficult because of the limited duration of follow-up, the informal nature of neurodevelopmental evaluation, and the heterogeneous cohort of patients previously reported. Accordingly, the purposes of this study were to provide more complete and longer neurodevelopmental followup and to describe the prevalence and sonographic characteristics of isolated subependymal cysts detected on cranial sonograms in neonates.

MATERIALS AND METHODS

In a 4 1/2-year period, more than 4000 cranial sonograms were obtained at our institution. We retrospectively determined that 17 neonates (59 studies) had sonographic evidence of an isolated subependymal cyst. A high-resolution real-time mechanical sector transducer was used to obtain the sonograms. No subjects had clinical or sonographic evidence of intercurrent hemorrhage, infarct, infection, or congenital abnormalities. Neurodevelopmental outcome was independently determined. In particular, premature infants who weighed less than 1500 g at birth were longitudinally assessed by a multidisciplinary developmental team. A general quotient was derived in nine subjects by using the Griffith Mental Developmental Scales.

RESULTS

Subependymal cysts were often tear shaped, 2-11 mm in size, and located either at the caudothalamic groove or along the anterior aspect of the caudate nucleus. Most subjects (n = 15) who had the cysts were born prematurely (mean gestational age, 31 weeks; range, 25-34 weeks). Results of follow-up were available in 14 infants 2-41 months old (mean, 22 months; median, 21 months). Development was considered to be normal in 13 of the 14 subjects; one term infant referred because of mild dysmorphic features had a mild global delay. The general quotient for corrected age, determined in nine subjects, had a mean of 111 (range, 103-120; normal, > 83). Fifteen neonates had at least two cranial sonographic examinations. In seven patients, serial examinations showed that cysts had resolved or diminished in size (on average 23 weeks after the initial sonographic study). In the other eight, no change in the size of the cyst was observed, but the mean interval between the first and last sonograms was only 14 days.

CONCLUSION

Cranial sonograms of neonates occasionally show isolated subependymal cysts, usually in premature infants. In most cases, no serious neurodevelopmental complications occur. Many cysts resolve after a variable period.

Barth syndrome: clinical features and confirmation of gene localisation to distal Xq28

Barth syndrome is an X-linked disorder characterised by cardioskeletal myopathy of variable severity usually fatal in childhood, and neutropenia. We ascertained a large pedigree with affected males in 3 generations. All affected males had dilated cardiomyopathy, with endocardial fibroelastosis (EFE) in some. The locus for Barth syndrome in this family was found to be closely linked to DXS52 (z = 2.78, theta = 0.0). The family was nonrecombinant for DXS52 in distal Xq28, but recombinant for DXS374 which maps proximal to DXS52. This localised Barth syndrome distal to DXS374, confirming a previous localisation to distal Xq28. As yet there is no evidence for genetic heterogeneity of Barth syndrome.

Treatment with hypertonic dextrose and insulin in severe hyperkalaemia of immature infants

Over a three-year period, 12 infants received dextrose/insulin infusions for severe hyperkalaemia from a mean age of 24 h. The infants were born after 24 to 26 weeks of gestation and weighed 730 +/- 172 g (mean +/- SD) at birth. Serum potassium concentration ranged from 7.4 to 8.4 mmol/l (7.7 +/- 0.4 mmol/l; mean +/- SD). Four had cardiac arrhythmias. All infants showed an initial response, serum potassium concentration decreased below 6.5 mmol/l in 5 +/- 2 h. In two infants, rebound hyperkalaemia occurred and was resistant to treatment; both infants died, one during an exchange transfusion. In the other 10 infants, infusions were ceased at a mean postnatal age of 53 h. Hyperglycaemia was the major problem during infusion and was resistant to increases in insulin concentrations. Normoglycaemia was achieved in 10 infants. The hypertonic solution consisted of a dextrose/insulin ratio of 2.2 +/- 0.6 g/IU, which delivered glucose at a rate of 0.46 +/- 0.15 g/kg/h, in addition to the pre-existing stable maintenance glucose intake.

Necrotizing enterocolitis in a perinatal centre

Thirty-five neonates developed radiologically proven necrotizing enterocolitis (NEC) over a 40 month period. They were 28 +/- 2 weeks gestation, and weighted 1094 +/- 411 g at birth. Eighteen infants (51%) required surgery and three (8.5%) died. The incidence was 6.7% in the very low birthweight (VLBW) infants. A large proportion of NEC (60%) presented beyond 10 days of life. An inverse relationship between gestation and age of onset was observed. The age of presentation was 22 +/- 13 days (range 10-53 days) for the 18 infants less than or equal to 28 weeks compared with 7 +/- 5 days for those over 28 weeks (P less than 0.01). Five NEC infants had bacteraemia which occurred 2-7 days prior to gastrointestinal symptoms of NEC, and four were staphylococcal. Compared with infants controlled for gestation, there was no significant differences observed in perinatal events or feeding history. We concluded that an immature gastrointestinal system is vulnerable to NEC even beyond the early neonatal period.

Effect of short-term muscle relaxation on neonatal plasma volume

OBJECTIVES

To study the effect of pancuronium-induced muscle relaxation on circulating plasma volume.

DESIGN

A prospective, controlled study. Consecutive infants who were paralyzed with pancuronium and a comparative group who were not paralyzed during mechanical ventilation were studied.

SETTING

Neonatal ICU of a regional referral university-affiliated hospital.

PATIENTS

Newborn infants weighing greater than 1700 g who required respiratory assistance within 24 hrs of birth and who were free of congenital heart disease, sepsis, or blood loss were eligible for entry into the study. Infants who received colloid infusions during the study period were excluded. A total of 17 consecutive infants (nine paralyzed and eight nonparalyzed control infants) were studied. Four paralyzed infants and one nonparalyzed infant received colloid infusions before the completion of the study and were excluded from the final analysis.

MEASUREMENTS

Plasma volume was measured three times in the paralyzed infants: a) immediately before the first dose of pancuronium, b) after 12 to 24 hrs, and c) greater than or equal to 12 hrs after the return of muscle activity, but before extubation. Plasma volume in the nonparalyzed, control infants was measured at the time of intubation, 12 to 24 hrs after commencing mechanical ventilation, and 12 hrs after extubation. Plasma volume was measured using the Evans blue dye dilution technique.

RESULTS

There were no changes in the plasma volume or blood volume in the three measurements among both the paralyzed and nonparalyzed infants.

CONCLUSION

Pancuronium-induced muscle relaxation in mechanically ventilated newborn infants weighing greater than 1700 g did not alter circulating plasma volume in 24 hrs.

Evaluation of bayesian forecasting for individualized gentamicin dosage in infants weighing 1000 g or less

We evaluated the use of Bayesian forecasting for gentamicin therapy in outborn infants weighing 1000 g or less irrespective of postnatal age. Dosages were individualized using a computer program, guided by early serum gentamicin assays after a loading dose and a database of population kinetics. Steady-state gentamicin levels achieved were compared with those from a regimen based on guidelines. A total of 26 gentamicin courses were individualized in 19 infants of 22 to 33 weeks' gestation, weighing 500 to 1000 g at 1 to 41 days of age. All steady-state trough levels were between 1 and 2.4 mg/L; peak levels were between 4.4 and 9.3 mg/L. The 95% confidence intervals were in almost identical ranges. The prevalence of toxic and suboptimal trough levels was less when compared with that of 23 gentamicin courses based on guidelines in 17 control infants. We conclude that early individualized gentamicin dosage over a range of postnatal age is a practical alternative and serum level distributions appear superior.

A new system for location of endotracheal tube in preterm and term neonates

A randomized, controlled trial was conducted to evaluate a new noninvasive system for placement of the endotracheal tube, based on a magnetic field interference-sensing technique. Seventy-two neonates treated by the standard technique were compared with 70 treated by the new system (TRACH MATE), with radiographic localization as the standard. As judged by the author(s) on the morning after the intubation, correct initial placement was achieved in 69 (78%) of 88 intubations using the new system, compared with 71 (66%) of 107 using the standard technique (Fisher's Test, one-tailed, P = .044). Repositioning was actually done in 23 (26%) of 88 TRACH MATE intubations, compared with 42 (39%) of 107 standard intubations (Fisher's test, one-tailed; P = .037). Intubation of the right main bronchus occurred in 7 standard intubations, but in none of the TRACH MATE intubations (Fisher's test, one-tailed; P = .014). Endotracheal tube position (high, low, or appropriate) was correctly determined by TRACH MATE in 77 (90%) of 85 intubations; the position was not recorded on three occasions. No differences in the number of complications (eg, unplanned extubations, distal displacement, subglottic stenosis) were found between the two groups. It is concluded that the TRACH MATE technique is superior to the standard clinical method in initial placement of the endotracheal tube.

Widened subarachnoid space in pre-discharge cranial ultrasound: evidence of cerebral atrophy in immature infants?

The authors examined the incidence of widened subarachnoid spaces (SAS) among 75 infants with birthweights less than or equal to 1250g, and their significance in developmental outcome. Nine of 30 infants with gestations less than or equal to 27 weeks had widened SAS in their pre-discharge ultrasound scans. Three of the nine, including two with periventricular leukomalacia (PVL), had late-onset ventricular enlargement, unrelated to intraventricular haemorrhage (IVH): all three were developmentally impaired. The other six infants without ventricular enlargement developed normally, including one with IVH. Five of the remaining 21 infants with gestations less than or equal to 27 weeks and without widened SAS were developmentally impaired. Widened SAS was not associated with a significantly increased risk of developmental impairment; ventricular enlargement and PVL were the only significant factors. The authors conclude that an isolated finding of widened SAS is not predictive of impairment in immature infants.

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.

Collodion babies with Gaucher's disease

Two neonates with acute infantile cerebral Gaucher's disease had prominent collodion skin. Ichthyosis has been described in some cases of metabolic lipid disorders, however, this is the first report of the association of lamellar desquamation of the newborn (collodion baby) with Gaucher's disease.