Effect of prenatal betamethasone/thyrotropin releasing hormone treatment on somatosensory evoked potentials in preterm newborns

The maternal administration of betamethasone and thyrotropin releasing hormone (TRH) to accelerate the maturation of the fetus is an increasingly adopted strategy to prevent neonatal morbidity in preterm infants. The effect of this prenatal treatment on the neural maturation of the infant was assessed by measuring somatosensory evoked potentials (SEP) in preterm infants (gestational age 29-36 wk) on the 1st postnatal day, at the age of 1 wk, and before discharge. The N1 latency values of the SEP obtained in 14 infants who were exposed prenatally to betamethasone/TRH were compared with the N1 latencies measured in 12 control infants. On the 1st postnatal day, the N1 latencies in the betamethasone/TRH-treated infants were strikingly shorter (p less than 0.01) than in the controls. However, at the age of 1 wk and at discharge, the N1 latency values of both groups were similar. In conclusion, the present study provides the first solid evidence for the concept that the prenatal exposure to betamethasone/TRH accelerates the SEP-assessed neural maturation of the human fetus, that this prenatal acceleration is followed by a compensatory relative deceleration during the early neonatal period, and that the subsequent SEP-assessed neural maturation proceeds at a normal velocity.

Unilateral thalamic haemorrhage in the pre-term and full-term newborn

One full-term and three premature newborns with a unilateral thalamic haemorrhage are reported. The lesion was diagnosed using cranial ultrasonography and confirmed in three using magnetic resonance imaging. Severe perinatal asphyxia occurred in all infants. The neonatal clinical history, subsequent neuro-developmental outcome and neuroimaging findings are discussed. As the prognosis appears to be much better than for infants with bilateral thalamic densities, it is important that this type of lesion is recognised as a separate entity.

Brain oxygen transport related to levels of fetal haemoglobin in stable preterm infants

The relative amount of regional cerebral oxygen transport was compared between different preterm infants by performing measurements of cerebral blood flow velocity, mean arterial blood pressure, whole blood viscosity and haemoglobin content for each individual. In addition the percentage of fetal haemoglobin was determined. On 25 occasions measurements of fetal haemoglobin and cerebral oxygen transport have been performed prior to and following a blood transfusion with adult red blood cells. Comparison of the data for cerebral oxygen transport suggests that the actual amount of cerebral oxygen transport is lowest at fetal haemoglobin levels below 30% and will increase progressively as soon as the percentage of fetal haemoglobin rises about 30%. Thus, at increasing fetal haemoglobin levels, cerebral haemodynamic mechanisms in the human neonate cause elevations of regional cerebral blood flow and oxygen transport. The found increase of cerebral blood flow and oxygen transport at high fetal haemoglobin levels will minimize the impeded dissociation and delivery of oxygen to brain tissues.

Near-infrared spectroscopy in newborn infants

Neonatal encephalopathy of early onset, plausibly related to hypoxia and ischemia remains one of the main problems in perinatal medicine. Efforts are necessary to find new non-invasive methods for assessing brain oxygenation. Near-infrared spectroscopy (NIRS) provides information on the concentrations of the oxygenated and reduced forms of hemoglobin, as well as the redox state of cytochrome aa3. Different important variables can be derived through hemoglobin measurement, such as cerebral blood volume and flow, and the responses of these to changes in pCO2. Changes in cytochrome aa3 may provide immediate information on intracellular oxygen utilization. Various studies have shown the feasibility of NIRS in preterm infants. Methodological and technical problems of this method are discussed.

The diaphragm of the newborn infant: anatomical and ultrasonographic studies

In the newborn infant, the diaphragm seems badly adapted to perform the burden of respiratory work. Indeed, due to the large angle of insertion on the rib cage and the small area of apposition, the flat diaphragm of the newborn infant seems better designed to suck in the rib cage rather than air. To better understand this paradox, and get insight in the structure-function relationship, the anatomical connections between the diaphragm and the rib cage were studied in 16 infants of various postmenstrual and postnatal ages. It was concluded (1) that the diaphragm inserts on the rib cage border only in the anterior costo-diaphragmatic triangle. From antero-laterally to posteriorly it inserts at increasingly greater distance from the rib cage border; (2) that the dorsal diaphragm ends its free course at the 11th rib and continues caudally as a spur ending between the 12th rib and the crista iliaca. From echographic studies of the right diaphragm with simultaneous measurement of the caudad displacement of the diaphragm and abdominal circumference change, the dynamics of the diaphragmatic movements could be better understood. It was concluded that, in contrast with the adult diaphragm, acting as a piston within the rib cage, the diaphragm of the newborn infant acts as a below moving mainly in the posterior part.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of early somatosensory evoked potentials for adverse outcome in full-term infants with birth asphyxia

SEPs were examined during the first weeks of life in 34 infants with mild to severe birth asphyxia, in an attempt to provide a more accurate prediction of neurodevelopmental outcome. Normal, delayed and absent responses were compared with the infant's acute clinical condition, imaging findings using different imaging techniques and neurodevelopmental outcome. All infants with normal SEPs were normal at follow-up. All but two of the infants with a delayed or absent response died or suffered from severe neurological sequelae. A delayed or absent N1 latency carried a risk for death or severe handicap of 71 and 100%, respectively, compared with 25 and 89% for moderate or severe encephalopathy on neurological assessment, and 29 and 85% for moderate or severe changes seen using different imaging techniques. SEPs may provide useful additional information when assessing the infant with birth asphyxia.

MR findings in leukodystrophy

Up to 5 years ago, the radiological diagnosis of leukodystrophy was based on computed tomography (CT). More recently, magnetic resonance imaging (MRI) has been used to study pathology of the white matter with great success. The abnormalities in eight patients with different types of leukodystrophy are described, using high-field MRI. CT and MRI show comparable sensitivity in detecting the pathological changes of leukodystrophy. MRI seems to be superior in visualizing the extent of the lesions, their precise anatomical location and any involvement of the brain stem and cerebellum. Differential diagnosis among the three types of leukodystrophy by MRI is difficult but may be attempted by some features. Specific diagnosis can be achieved only by laboratory examination or histology. The role of MRI should be to suggest the proper biochemical test at an earlier stage.

Conservative versus neurosurgical treatment of tethered cord patients

We compared the outcome of neurosurgical release of a tethered spinal cord in 20 children with the neurological evolution of 21 other children known iwth a tethered spinal cord on nuclear magnetic resonance scan (NMR). Neurosurgery yielded stabilisation of the symptoms without any lasting improvement. Pre-operative conservative medical treatment had to be continued in all operated children. Three of the 20 operated children are showing signs of retethering despite appropriate neurosurgery, indicating that retethering should be considered as a major and frequent complication. In the majority of our children, symptomatic (re)tethering was recognised by the appearance of increased tendon reflexes and a progressive pes cavus, suggestive of an upper motor neuron disease involvement.

Cerebrovascular occlusive complications in osteopetrosis major

We report the case of a 16-year-old patient with osteopetrosis major, complaining of transient sensory and motor disturbances in the left upper limb and dizziness on changing the position of his head. Selective angiography of the cerebral vessels showed severe narrowing of the internal carotid artery within the petrous carotid canal and in its supraclinoid portion. The cervical vertebral arteries showed multiple stenosis within the vertebral canal. These findings are explained by narrowing of the basal foramina by the osteopetrotic bone.

Upper limits of brain blood flow autoregulation in stable infants of various conceptional age

In healthy adults cerebral blood flow is autoregulated and kept constant over a wide range of mean arterial blood pressures (MAP) between 60 and 150 mmHg. In 27 stable infants with different conceptional ages ranging from 33 to 50 weeks, Doppler measurements of mean flow velocity at the anterior cerebral artery have been recorded simultaneously with mean arterial blood pressures (MAP) during a period of 6 h. The range of autoregulation and its upper limit could thus be determined. The upper limit was found to increase with advancing age. In the infants with conceptional ages between 33 and 35 weeks, the upper limit of autoregulation varied between 45 and 60 mmHg, while the upper limit shifted to a MAP of 100 mmHg at 47 weeks conceptional age. A significant positive linear relationship existed between the upper limit of autoregulation and conceptional age.

The role of short latency somatosensory evoked responses in infants with rapidly progressive ventricular dilatation

The effect of hydrocephalus on somatosensory evoked potentials was studied in nine infants. An increase in N1 latency was found in five infants studied longitudinally during a period of progressive ventricular dilatation. A marked decrease in N1 latency was noted in 7 infants, within one week following shunt insertion and in two infants who showed spontaneous arrest of ventricular growth. A correlation was found between cerebrospinal fluid pressure and the delay in N1 latency, but the number of infants studied is still small. SEPs appear to be a useful additional test when assessing infants with progressive ventricular dilatation. Once a baseline value for N1 has been obtained following shunt insertion, SEPs may subsequently be useful when assessing a child with possible shunt dysfunction.

Alobar holoprosencephaly, diabetes insipidus and coloboma without craniofacial abnormalities: a case report

An infant is described with coloboma of the right eye, holoprosencephaly and diabetes insipidus without craniofacial malformations. The association is discussed in view of the development of the prosencephalon and its relation to the development of craniofacial structures.

The role of high resolution ultrasound and MRI in the investigation of infants with macrocephaly

External hydrocephalus was diagnosed using computed tomography in seven children presenting with macrocephaly. The value of different imaging techniques in distinguishing between subdural effusions and external hydrocephalus was investigated. High resolution ultrasonography combined with magnetic resonance imaging appeared to provide enough information to make a distinction between these two conditions. Radionuclide cisternography was still required to assess the flow pattern of the cerebrospinal fluid (CSF) which was important when placement of a lumboperitoneal shunt was considered.

Infant feeding and cardiorespiratory maturation

134 preterm infants were investigated in their ability to coordinate sucking and breathing. Of those infants who did not coordinate, 79% showed immature cardiorespiratory control whereas of those who suck and breathe simultaneously only 12% had poor cardiorespiratory control. This finding suggests that in infants with poor coordination of sucking and breathing an investigation of cardiorespiratory control might be indicated.

[Moyamoya. Diagnosis using MRI and NMR angiography]

A case of Moya-Moya disease confirmed by cerebral angiography in a 10-year-old girl is reported. Hypertrophic collateral circulation is easily visualized by MRI. MR angiography very accurately demonstrated the vascular obstruction and the collateral circulation. As MR angiography is not invasive, it promises to become a valuable alternative to conventional angiography in the diagnosis of Moya-Moya.

Somatosensory evoked potentials and adaptation to extrauterine life: a longitudinal study

In order to compare longitudinal data with existing cross sectional extrauterine life data on somatosensory evoked potentials (SEPs), two groups of appropriate for gestational age optimal premature infants were studied. Group A consisted of 8 infants born between 34 and 36 weeks gestational age (GA). In this group, SEPs were recorded within 24 hours after delivery and then every 48-72 hours until discharge. Group B consisted of 7 infants born between 29 and 33 weeks GA. In these infants, SEPs were recorded at weekly intervals from the second week onwards. In group A, a marked decreased in the N1 latency was seen during the first week of life. Six infants had initial values above the normal range. During the second week of life this decrease paralleled the cross sectional data. In group B all the infants had a N1 latency within the normal range and the longitudinal data paralleled the cross sectional data. These findings must be taken into consideration when SEPs are used to assess the neurological integrity of the newborn during the first week of life.

Review: Normal and abnormal central nervous system GABA metabolism in childhood

The metabolism and function of central nervous system GABA is briefly reviewed. Hereditary disorders of the GABA metabolism presenting in childhood are discussed with particular emphasis on the recently identified succinic semialdehyde dehydrogenase deficiency and GABA-transaminase deficiency, and on diseases associated with low CSF GABA which await further unravelling. Low CSF GABA concentrations are not always associated with convulsions. A separate section is devoted to the CSF as a tool in the diagnosis of these disorders. Finally, we present a few diagnostic and therapeutic guidelines.