Yukinori Ando

Pathogenesis of periventricular white matter hemorrhages in preterm infants

Periventricular white matter hemorrhage (PWMH) was frequently found in very low-birth weight infants with perinatal asphyxia or respiratory distress. Primary PWMH with or without intraventricular rupture was found at the deep arterial borderzones of the frontal or occipital lobes. The ischemic tissue damage induced by hypoperfusion may be a predisposing factor for PWMH. However, the high incidence of visceral intravascular thrombi and the fan-shaped appearance of hemorrhage suggested venous hemorrhagic infarction. Venous thrombosis with coagulopathy may be an important factor for the pathogenesis of PWMH.

Cerebral Palsy in Tottori, Japan

From the changing incidence of cerebral palsy (CP) in the Tottori joint study, the absolute number of saved non-CP babies in the period 1955–1984 in the whole of Japan was calculated as about 33,000. The significant decrease of the incidence in the period 1955–1980 was mainly related to the advances made in perinatal medicine. In contrast, the recent reincrease is attributable to low-birth-weight CP. As for the risk factors for quadriplegia or double hemiplegia of CP, maternal toxemia, low Apgar scores and neonatal abnormal signs were important. Diplegia and paraplegia were significantly correlated with low birth weight. Among the babies weighing below 2,000 g, there was a more than 40-fold increased risk of CP compared with that in the general population. As for the risk for low-birth-weight diplegic CP, the number of abnormal signs in the neonatal period is correlated with the brain damage. The next step in preventing perinatal brain damage might be to give more attention to fetal deprivation and to well-balanced and sensible neonatal care of risk babies.

Relationship between periventricular hemorrhage, leukomalacia and brainstem lesions in prematurely born infants.

The brain pathology in very prematurely born infants with intraventricular hemorrhage (IVH) was studied particularly as to the severity and site of the complicated brain lesions responsible for the prognosis. A high frequency of leukomalacia, pontosubicular necrosis and/or olivocerebellar neuronal loss was found in the cases of IVH, and these non-hemorrhagic brain lesions showed an increasing frequency with the grade of IVH. However, there was marked reduction of IVH, periventricular leukomalacia and, in particular, brainstem lesions in prematurely born cases of sudden infant death. These IVH and associated conditions have different pathogenesis, but factors responsible for their occurrence may be present together in each case.

Comparison of brain imaging and neuropathology in cases of trisomy 18 and 13

SummaryA comparative study of intracranial imaging and brain pathology in cases of trisomy 18 and 13 was performed. Computed tomography (CT) and ultrasonography (US) revealed disproportional dilatation of the lateral ventricles, a wide Sylvian fissure and a large extracerebellar space with a small cerebellum in each case. In addition, it was characteristic that the occipital poles of the cerebrum protruded in the infero-posterior direction in trisomy 18, and the pontine basis was relatively wide in trisomy 13. The brain pathology in trisomy 18 and 13 demonstrated that the large extracerebellar space is due to the cerebellar dysplasia and protruding occipital poles, the wide Sylvian fissures due to the temporal lobes or external capsular dysplasia, and the relatively wide pontine basis due to meningeal glioneuronal heterotopia. Thus, the characteristic intracranial image in trisomy 18 and 13 suggest microdysgenesis of the brain and might be useful for understanding the pathological structure of the central nervous system in these conditions.

Postnatal Changes of Cerebral Blood Flow Velocity In Normal Term Neonates

Postnatal changes of cerebral blood flow velocity were studied in 43 healthy term neonates using a continuous waveform bidirectional Doppler flowmeter and an ultrasonograph with a pulsed Doppler unit. Pulsatility Index (PI) values of anterior cerebral artery were high within 6 hours after birth, and then decreased in the neonates born by means of both vaginal delivery and caesarean section. These postnatal changes of PI observed with the continuous waveform bidirectional Doppler flowmeter were identical with those with pulsed Doppler technique. The sequential measurement of right radial artery blood flow showed a marked decrease of diastolic flow velocity, which may be due to transient postnatal patent ductus arteriosus. Therefore, this postnatal transient patent ductus arteriosus may be one of the pathogenetic factors for high PI values shortly after birth.

Hypoxic-ischemic brain damage and cerebral blood flow changes in young rabbits

Hypoxic-ischemic cerebral damage was demonstrated in the cerebral cortex of 2-week-old rabbits at 3 to 5 days after bilateral carotid artery ligation and reperfusion during hypoxemia. Carotid ligation and reperfusion had little effect on cortical blood flow during normoxemia, but the former suppressed a blood flow increase to hypoxemia and the latter suppressed a blood flow decrease to hyperoxemia. These results suggest a relative ischemia or vascular dysfunction which may play a part in the pathogenesis of the hypoxic-ischemic cortical necrosis.

Cerebral blood flow velocities in postasphyxiai term neonates

Blood flow velocities of the anterior cerebral artery and right radial artery were studied in 15 postasphyxiai term neonates using a continuous waveform bidirectional Doppler flowmeter. Pulsatility index (PI) values of most mild asphyxic infants were within the normal range. However, the infants with anoxic encephalopathy showed high or low PI values. The minimal flow velocities of the right radial artery (RRA) showed markedly retrograde flow velocity shortly after birth in comparison with those of the controls. The high PI values may be mainly due to a marked decrease of diastolic flow velocity representing retrograde flow in RRA. The low PI values indicated the poor prognosis in the postasphyxiai infants. In low PI cases the cerebrovascular autoregulation may be presumed to be impaired, and arterioles to be markedly dilated.

Cerebral blood flow velocity in preterm neonates

The postnatal changes of cerebral blood flow velocity in 35 preterm neonates with or without complications were measured with a bidirectional Doppler flow meter. In the cases without complications, the pulsatility index for the anterior cerebral artery (ACA-PI) was high shortly after birth, and gradually decreased after 6 hrs as that in normal term neonates. However ACA-PI showed large variations in the cases with respiratory distress. On the other hand, ACA-PI in the cases with subependymal hemorrhage (SEH) was low during the first 6 hrs after birth, and thereafter showed no significant changes. ACA-PI in the cases with intraventricular hemorrhage (IVH) was high during the first 6 hrs after birth and then decreased when IVH was found on ultrasound scanning. ACA-PI increased gradually with progression of post-hemorrhagic ventricular dilatation. The difference of high PI in IVH and low PI in SEH during the first few hrs after birth suggests that the pathogenesis of SEH may be different from the mechanism of intraventricular rupture from SEH. Low PI values in the infants with SEH may be related to intrapartum events, while the changing patterns of high to low PI in the infants with IVH suggest postnatal hemodynamic changes.

Measurement of endotoxin in cerebrospinal fluid from neonates and infants using a new endotoxin-specific chromogenic test.

Masumi Inagaki a, Masako Nakajima a, Yukinori Ando a, Sachio Takashima a, Kenzo Takeshita a, Shigenori Tanaka b, Hiroshi Tamura b and Taminori Obayashi ’ a Division of Child Neurology, lnstiiute of Neurological Sciences, Tottori University School of Medicine, Yonago, ’ Tokyo Research Institute, Seikagaku Kogyo Co., Ltd., Higashiyamato, Tokyo and ’ Department of Clinical Pathology, Jichi Medical School, Tochigi-ken (Japan)

Reflectance spectrophotometry, cerebral blood flow and congestion in young rabbit brain

Reflectance spectrophotometry was applied to examine experimental cerebral oxygenation and hemodynamics in young rabbits. The estimated brain tissue SO2 level (ISO2) showed a prompt response to acute hypoxemia. The estimated brain tissue hemoglobin concentration (IHb) showed good correlation with CBF changes, estimated by the H2 clearance method, on hypoxemia or hypercarbia, and with cerebral congestion on neck venous compression. Moreover, trend recording of IHb and ISO2 was useful for monitoring the cerebral oxygenation and hemodynamic changes, including CBF as well as congestion.