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Biomedical subjects

L M Dubowitz

Publications and source records attributed to L M Dubowitz.

At least 91 records · Page 5Linked to original sources
PubMed1982

Auditory brain stem response in neurologically normal preterm and full-term newborn infants.

A study has been completed on auditory brain stem responses (ABR) in preterm and full-term newborn infants. We have drawn up a regression score for latencies of waves I and V and the I-V interval both at 80 dB and 60 dB stimulation in infants considered neurologically optimal using stringent criteria on both clinical and sequential ultrasound assessment. The 80 dB stimulus gave more consistent results with a narrower standard deviation. Hearing thresholds were difficult to establish with consistency in this population. A parallel study of a neurologically suboptimal population with transient neurological abnormality showed deviations in the ABRs from those of the optimal population. This data should provide a baseline for assessment of abnormal infants.

Audiometry↗
PubMed1982

The development of visual function in normal and neurologically abnormal preterm and fullterm infants.

Pattern preference for four different pairs of patterns, and visual acuity based on the ability to distinguish black and white stripes of different widths, were compared in neurologically normal and abnormal preterm infants at 36 and 40 weeks postmenstrual age and in normal and abnormal fullterm infants in the newborn period and again at four and six weeks of age. The study aimed to chart the maturation process of these visual functions in the neonatal period and to assess their predictive value in the neurologically abnormal infant. Part I of the study deals with the normal infant and Part II with the abnormal infant. In Part I, the maturation process for both visual functions in newborn preterm infants of increasing gestational age is compared with longitudinal assessment of postnatal maturation of these functions in preterm infants up to 40 weeks postmenstrual age. Up to 36 weeks postmenstrual age the functions were comparable in the maturing preterm infants and the newborn infants of comparable postmenstrual age, but at 40 weeks the preterm infants did less well than the fullterm newborn infants. In Part II, the abnormal fullterm infants demonstrated a significantly poorer pattern preference at the initial and subsequent examination. Visual acuity was significantly poorer at the initial examination but less marked at follow-up. The abnormal preterm infants showed poorer pattern preference and visual acuity at both 36 and 40 weeks postmenstrual age. Compared with neurologically abnormal infants without intraventricular haemorrhage (IVH), preterm infants with IVH showed no significant difference in pattern preference at 36 and 40 weeks, but a significant deficit in visual acuity.

Cerebral Hemorrhage↗
PubMed1982

Developmental and neurological progress of preterm infants with intraventricular haemorrhage and ventricular dilatation.

A prospective neurological and developmental assessment was completed at ages 6, 9, and 12 months on 39 preterm infants under 34 weeks' gestation. In the newborn period each infant had an assessment of gestation and sequential neurological and ultrasound examinations and was placed in one of three groups: intraventricular haemorrhage (IVH) (n = 14), IVH followed by ventricular dilatation (n = 11), and control infants with no evidence of IVH (n = 14). When corrected for prematurity the Griffiths's developmental quotients (DQs) were normal at 6, 9, and 12 months for every infant except one aged 12 months. In contrast, the uncorrected DQs at 12 months were under 80 in only one of the 14 preterm infants without haemorrhage, compared with 2 of the 14 with IVH, and with 7 of the 9 with IVH and dilatation. There was also a higher incidence of neurological abnormality at each follow-up age in the infants with IVH plus ventricular dilatation, compared with those with IVH alone, or with infants without IVH. Similar differences were also demonstrated in 5 milestones reflecting gross motor, fine motor, and social or verbal development in the three groups at 6, 9, and 12 months. The neurological and developmental deficits seemed to relate more closely to the presence of post-haemorrhagic ventricular dilatation than to the size of the initial haemorrhage itself. These results may have important implications for therapeutic intervention in the management of newborn infants with IVH and ventricular dilatation.

Brain Diseases↗
PubMed1981

Neurologic signs in neonatal intraventricular hemorrhage: a correlation with real-time ultrasound.

A comprehensive neurologic assessment was applied sequentially in 100 consecutive unselected newborn infants in our neonatal unit in parallel with independent sequential real-time ultrasonic examination of the head. The results were analyzed in three separate gestational groups: Group I, 31 weeks and below (n = 29); Group II, 32 to 35 weeks (n = 39); Group III, 36 weeks and above (n = 25). In the remaining seven infants the ultrasonic examination was technically unsatisfactory. Deviant neurologic signs were correlated in each group with the presence of intraventricular hemorrhage recognized by ultrasound. Impaired visual tracking, an abnormal popliteal angle, and the later development of roving eye movements correlated strongly with the presence of IVH in Groups I and II. Decrease in tone and poor motility correlated with IVH in Group II infants only. In Group III the number of cases with IVH was small and none of the clinical signs reached statistical significance. The results suggest that our system of careful sequential neurologic examination in the newborn period is a sensitive means of detecting the development of intraventricular hemorrhage in the majority of immature infants, and of following its progress and resolution.

Cerebral Hemorrhage↗
PubMed1981

Assessment of gestation by ultrasound in various stages of pregnancy in infants differing in size and ethnic origin.

A clinical assessment of gestational age after birth has been compared with the ultrasound measurement in utero at various stages of pregnancy in a population of mixed socio-economic status and racial origin. In infants who were small-for-dates or large-for-dates at birth, accurate prediction from ultrasound measurement could only be achieved if the crown rump length or the biparietal diameter was measured before 20 weeks gestation. At this time, the infants destined to be small-for-dates or large-for-dates at birth show no growth retardation or acceleration. There is also no influence of racial origin on the measurements.

Birth Weight↗
PubMed1980

A new approach to the neurological assessment of the preterm and full-term newborn infant.

A method has been developed for the neurological assessment of the newborn infant comprising a carefully selected series of neurological and neurobehavioral items. It is applicable to preterm as well as full-term infants within 24 hours of birth, and can also be repeated sequentially on the same infant. The whole examination is recorded directly on a single sheet which also contains detailed instructions and diagrams. Individual items are scored on a 5-point scale, but no attempt has been made to compute a single total score, as it was thought more advantageous to document a pattern for individual groups of signs. Pilot studies have already demonstrated its sensitivity to perinatal factors such as drugs, asphyxia and infection. The examination can be rapidly documented by residents with no special training in newborn neurology. This method should provide a practical and objective means of monitoring the neurological status of the newborn infant, and also a baseline for longitudinal studies of neurological function in the newborn and developing infant.

Asphyxia Neonatorum↗
PubMed1980

Visual function in the newborn: a study of preterm and full-term infants.

Visual function has been studied in the preterm newborn infant by the visual orientation (tracking) technique of the Brazelton neurobehavioral assessment, and the pattern preference and fixation technique of Fantz. By both these methods we have been able to document the presence of discriminative visual function by 31-32 weeks gestation, and by 34 weeks the pattern reaches a maturity comparable to the full-term infant. Sequential studies at weekly intervals of preterm infants ranging in gestation from 28-32 weeks showed a similar pattern of development of visual function to the newborn infant of equivalent postconceptional age. Comparative studies of the two methods of assessment of visual function in the same infants have shown surprisingly little correlation. Assessment of visual function in the preterm newborn infant is a valuable milestone and, as in the case of other developmental milestones, aberrations may reflect a deficit in visual function itself, or a more broad based deficit in neurological function or a secondary response to a generalized illness in the newborn infant.

Choice Behavior↗
PubMed1980

Visual function in the preterm and fullterm newborn infant.

Visual function in the preterm newborn infant has been studied by the visual orientation (tracking) technique of the Brazelton neurobehavioural assessment, and by the pattern preference and fixation techniques of Frantz. Both these methods demonstrated the presence of discriminative visual function by 31 to 32 weeks gestation, which by 34 weeks reaches a maturity comparable to the pattern found in fullterm infants. Sequential studies at weekly intervals of preterm infants, ranging in gestation from 28 to 32 weeks, have shown a similar pattern of development of visual function to that of the newborn infant of equivalent postconceptional age. However, comparative studies of visual orientation and pattern preference in the same infants have not shown a close correlation. The assessment of visual function in the preterm newborn infant is a valuable milestone. Aberrations may reflect a dificit in visual function itself, a more broad-based deficit in neurological function, or possibly a response to a generalised illness.

Choice Behavior↗
PubMedDate not supplied

Evolution of periventricular leukomalacia during the neonatal period and infancy: correlation of imaging and postmortem findings.

Eighteen of 68 infants born over a 4-year period who had cranial ultrasound studies and later came to necropsy were found to have periventricular leukomalacia (PVL). Thirteen were diagnosed in life and there was one false positive diagnosis giving an accuracy of 91%, sensitivity of 72% and specificity of 98%. In 11 infants with sequential studies, who died at ages from 43 h to 3 years, the ultrasound findings were correlated with those at postmortem to establish the natural history of the condition. In infants who died within 7 days following the onset of the ultrasound changes, postmortem revealed early PVL without cysts: there were small haemorrhages into the affected areas in three of the four cases. In the five infants who died between 10 days and 9 weeks, cystic lesions were identified in life and at postmortem, but in two long-term survivors cysts resolved on ultrasound at 3-4 months of age. Correlation of ultrasound with postmortem findings demonstrated that, although the ultrasound lesions resolve, glial scarring and impaired myelination can still be demonstrated on careful pathological examination.

Brain↗
PubMedDate not supplied

Assessment of brain perfusion with MR imaging.

A technique for assessing brain perfusion with magnetic resonance (MR) imaging is described. This technique uses two spin echo sequences that are identical except that the second is sensitised to blood flow by use of a pair of unipolar gradients on either side of the 180 degree pulse. Differences in phase between the two sequences are displayed with a sensitivity to flow rates of +/- 0.5, +/- 1, and +/- 2 mm/s per full scale (+/- pi radians) deflection. The technique was validated for measurement of flow at these rates with a water phantom. Ten patients with cerebrovascular disease, multiple sclerosis, cerebral tumor, periventricular leukomalacia, and meningitis were studied. Differences between grey and white matter were normally seen in adults. Infants displayed differences between central and peripheral regions of the brain. Abnormalities were seen in all clinical cases. The technique will require further validation but it appears to provide a totally noninvasive method for assessing brain perfusion.

Adult↗
PubMedDate not supplied

Proton MR spectroscopy of the brain in infants.

Proton magnetic resonance spectroscopy (MRS) was used to study the brain of 2 normal and 15 abnormal infants aged from 33 weeks postmenstrual age (PMA) to 14 months postnatal age. Eleven of the infants were examined on at least two occasions. The principal clinical diagnoses in the abnormal infants were perinatal ischemic and hemorrhagic brain injury. All proton spectra demonstrated peaks that were assigned to N-acetylaspartate (NAA), choline containing compounds (Cho), and creatine plus phosphocreatine (Cr). The NAA/Cho and NAA/Cr ratios increased with age, while the Cho/Cr ratio decreased with age in the majority of infants. The NAA/Cho ratio was generally lower in abnormal infants, but the difference was not apparent before 40 weeks (PMA). This ratio was lowest in infants with the severest degree of neurological abnormality. Proton and phosphorus MRS was compared in seven infants. In those with severe brain lesions, early phosphorus spectra were abnormal. On follow-up the phosphorus spectra became normal, but the proton spectra showed persistently low NAA/Cho and NAA/Cr ratios. Proton MRS provides new information that may be complementary to phosphorus MRS in the diagnosis and monitoring of brain development in normal and neurologically damaged infants.

Asphyxia Neonatorum↗
PubMedDate not supplied

MR imaging of anisotropically restricted diffusion in the brain of neonates and infants.

Brain MR examinations were performed on one normal and 30 abnormal neonates and infants with a variety of clinical problems using pulsed gradient spin echo (PGSE) sequences sensitized in different directions to detect changes due to anisotropically restricted diffusion of water within the brain. Anisotropically restricted diffusion was demonstrated within white matter, which appeared to be myelinated with T1-weighted inversion recovery or spin echo sequences and within white matter where the presence of myelin was not demonstrated with these sequences. Cysts and fluid collections were recognised by their low signal intensity using PGSE sequences in the subcortical regions, lentiform nuclei, and periventricular regions. An intracerebral hematoma and a subdural hematoma showed a high signal intensity with PGSE sequences consistent with isotropically restricted diffusion. Chronic infarction displayed a low signal intensity consistent with relatively free isotropic diffusion. Patients with leukodystrophy associated with congenital muscular dystrophy showed an anisotropic pattern with different components of the abnormality present on images with sensitization in different directions. The corticospinal tracts failed to show highlighting in three cases where conventional imaging was normal. In several patients with a history of birth asphyxia, asymmetry and a relative reduction in signal intensity were seen in the corticospinal tracts.

Asphyxia Neonatorum↗
PubMedDate not supplied

A study of visual function in the premature infant.

Within the first week of life visual tracking and pattern differentiation were tested in 34 out of 47 premature infants born between 28--34 weeks of gestation. Positive results were achieved from 30 weeks onwards. Pattern differentiation was tested as soon as infants could be taken out of the incubator. Preference could be observed from 31 weeks post-conceptional age. Both functions showed comparable maturation to full-term controls by 34 weeks gestation.

Fixation, Ocular↗