Yasushi Fujii

Measurement of lumbar spinal bone mineral density in preterm infants by dual-energy X-ray absorptiometry.

Lumbar spinal bone mineral density (BMD) was measured in 40 preterm infants by dual-energy X-ray absorptiometry (DXA). During the first several months of life, their BMD was considerably lower than that of normal term infants and the osteopenia was more pronounced in the more preterm and smaller infants. Weak (inverse) correlations were found between the BMD and urinary calcium/creatinine or tubular phosphorus reabsorption ratio. Rickets-like changes in the forearm bones did not predict the greater spinal osteopenia. Follow-up study was performed in 10 preterms. In 3 of the 4 who underwent the last DXA between 8 and 12 months, BMD had improved remarkably. Our present study shows the potential of DXA for the assessment and management of osteopenia of prematurity.

Bone Mineral Status in Preterm-Born Children: Assessment by Dual-Energy X-Ray Absorptiometry

To elucidate the long-term consequences of osteopenia of prematurity, lumbar spinal bone mass was measured in 21 preterm-born children aged 3-4 years by dual-energy X-ray absorptiometry. Their mineral intake remained low during early life, and all 11 infants previously studied were osteopenic at term postconception. At the age of 3-4 years, however, all 21 children were found to have normal bone mineral content and density with slightly elevated serum osteocalcin levels. Our results show that in preterm-born children spontaneous resolution of lumbar spinal osteopenia occurs during early childhood.

Lipoma on surface of centroparietal lobes

A 4-year-old Japanese boy with an intracranial lipoma above the surface of the left centroparietal lobes is reported. Paresthesia occurred in the right lower extremity. This symptom continued for 30 min and recurred several times a day. Three weeks after onset, the paresthesia disappeared spontaneously. Ten months after onset, generalized tonic seizures occurred. Routine cranial computed tomography at onset revealed no remarkable lesion, but subsequently full scans, including the slice at the top of the cerebrum, revealed low-density areas on the surface of the left centroparietal lobes. T1-weighted magnetic resonance imaging revealed a hyperintense area in the same regions. The intensity of these areas was decreased by the fat saturation technique; therefore, an intracranial lipoma at a very rare site was diagnosed.

Periventricular hyperintensity detected by magnetic resonance imaging in infancy

Twenty-one infants younger than 12 months of age were diagnosed as having periventricular hyperintensity (PVH) on T2-weighted magnetic resonance imaging. Ten infants had experienced neonatal asphyxia, 6 intracranial hemorrhage, 2 bacterial meningitis, and 3 apnea. PVH was classified according to its extent. Round foci of PVH surrounding the frontal and occipital horns of the lateral ventricles were observed in 4 infants (PVH pattern I). Continuous PVH was observed in 17 infants (PVH patterns II and III). Fourteen infants with continuous PVH had spastic diplegia or quadriplegia. Developmental delay was demonstrated in 15 infants with continuous PVH. No PVH pattern I infants had cerebral palsy; only 1 such infant had mild developmental delay. Our study suggests that the extent of PVH reflects the severity of brain damage in neonates with cerebral injuries.

MRI assessment of myelination patterns in high-risk infants

Magnetic resonance imaging (MRI) was used in high-risk infants to assess the myelination process and its relationship with neurologic outcome. The time period when delayed myelination is best detected by MRI was also studied. MRI was performed in 39 high-risk infants (i.e., preterm infants, infants with respiratory distress syndrome, or with neonatal convulsions and asphyxia). In 10 of 11 infants with normal development, MRI revealed a normal myelination pattern before 2 months of age, and in 11 of 13 infants after 2 months of age. Conversely, in infants with poor outcomes, MRI demonstrated delayed myelination patterns in only 1 of 4 infants before 2 months of age but in 9 of 11 infants after 2 months of age. In patients with poor outcomes, delayed myelination was found more frequently after rather than before 2 months of age. These findings demonstrate that delayed myelination detected by MRI is useful in predicting the neurologic outcome of high-risk infants, especially after 2 months of age.

Developmental features of the brain in preterm and fullterm infants on MR imaging

Normal development and maturation in pre- and postnatal periods were studied using MR imaging. For this purpose, we performed MR imaging at a postmenstrual age of 37-44 weeks in both low-risk preterm and fullterm infants and assessed the myelination pattern and the dimension of the pituitary gland, corpus callosum, pons and cerebellar vermis. There were no differences in stages of myelination and the size of these structures in both groups. MR imaging was also performed in infants with various cerebral injuries. Focal or diffuse areas of hyperintensity on T2-weighted images and delayed myelination were the commonly observed abnormal findings in these infants.

MRI and SPECT in influenzal encephalitis

Repeated magnetic resonance imaging studies were performed in a 22-month-old boy with influenzal encephalitis. T2-weighted magnetic resonance images disclosed multifocal hyperintense areas in the cortex and subcortical white matter of the left frontal, temporal, parietal, and right frontal lobes. 123I single photon emission computed tomography (SPECT) brain images demonstrated decreased uptake in the same regions. SPECT revealed larger areas of decreased uptake as compared with magnetic resonance imaging. One year after the onset of encephalitis, these brain lesions continue to be observed, although the patient has no apparent neurologic sequelae.

Effects of ACTH on brain midline structures in infants with infantile spasms

Changes of the midline structures of the brain, including the pons, cerebellar vermis, and corpus callosum, induced by adrenocorticotropic hormone (ACTH) therapy in 7 infants with infantile spasms were investigated using magnetic resonance imaging. Decreased volume of these parts of the brain was induced in almost all infants. Decreased volume of the pons was thought to be closely related to sleep disturbance during ACTH therapy. These results may demonstrate that the cessation of convulsive episodes in infants with infantile spasms treated with ACTH is due to its direct action on the brainstem.

Urinary excretion of aquaporin-2 in term and preterm infants

Aquaporin-2 (AQP-2) is a vasopressin-regulated water channel of the renal collecting duct and is excreted in human urine. We measured the urinary excretion of AQP-2 by radioimmunoassay in 14 term and 12 preterm infants aged 1 month. Excretion of AQP-2 was low compared with adults, and correlated significantly with urine osmolality in preterm infants. Our results demonstrate that AQP-2 water channels are expressed in the renal collecting duct of both term and preterm infants.

Corpus callosum in developmentally retarded infants

The development of the corpus callosum was examined by magnetic resonance imaging in developmentally retarded infants ranging in age from 1-13 months. Results were compared with those of normal infants. Eighteen magnetic resonance imaging studies were performed on 18 developmentally retarded infants. Fifty-four magnetic resonance imaging studies were performed on 38 normally developed infants. The thickness of the corpus callosum was measured at a point one-third of the length of the entire corpus callosum from the most anterior aspect of the genu. The development of the corpus callosum was related to aging in both groups. There was significant difference in the thickening of the corpus callosum between normal and developmentally retarded infants.