Research on Prematurity Impacts
Research
studies that all of us should have on hand to show the school, the pediatrician,
and any other institution or person who deals with our premature children.
By Helen Harrison
See Also: Helen Harrison's Bibliography
of the Long Term Effects of Prematurity
"Functional Assessment of a Multicenter Very Low-Birth Weight
Cohort at Age 5 Years" Palta, Sadek-Badai, Evans et al. Archives
of Pediatric and Adolescent Medicine, 2000;154:23-30.
"This is a multi-center study out of U of Wisconsin at Madison
and U of Iowa (Iowa City). The participants are more than 400,
predominantly Caucasian, very low birth weight preemies (under 1500
grams) born in the late 1980s and early 1990s. The average gestational
age is 29 weeks.
This study looks at differences in functional outcomes (mobility, self-care,
social) among preemie children who survived before and after the widespread
use of steroids and surfactant.
Because the teen studies I am also sending you come from the pre-surfactant
era of NICU care, there is always the question of whether or not such
studies are still relevant. Most people assume that outcomes have improved
in the more recent era, but this large and recent study shows that the
CP rate hasn't changed pre- or post-surfactant/steroids (13%), and that
functional outcomes such as mobility and social skills appear to have
worsened.
Although there is a current 13% CP rate, 30% of VLBW preemies
now have seriously subnormal "mobility" -- that is, they score
more than 2 standard deviations below the norm on tests of physical
functioning. This is the physical equivalent of retardation --
having an IQ below 70. 51% of VLBW preemies have scores 1 standard
deviation below the norm (the physical equivalent of an IQ of 84 or
below). That so large a percentage of physically compromised preemies
don't have a diagnosis should be of concern (IMHO).
32% of the VLBW children were one standard deviation below the norm
in self-care skills, and 39% had subnormal social skills."
"Developmental Coordination Disorder in Extremely Low Birthweight
Children( =/<800 grams) at 8.9 Years." Holsti, Grunau,
and Whitfield. Pediatric Research, 1999;45:245A, #1443. (The full
study has not been published yet to my knowledge.)
"In this study, out of U of British Columbia, Vancouver,
impaired physical functioning that wasn't considered to be cerebral
palsy, was referred to as "Developmental Coordination Disorder
(DCD)." The 114 children in the study were born between 1982 and
1987. 40 (35%) of the children had either CP and/or subnormal
IQ (below 85) and/or sensorineural problems and were *excluded* from
the study. Of the remaining 74 "normal"children, 51%
were classified as having DCD. DCD was defined as being one standard
deviation below the norm in tests of fine and large motor skills."
"Prediction of Written Output Ability in Extremely Low Birth
Weight (ELBW; =/<800g) Children from Age 4 to 8 Years." Grunau,
Whitfield, McConnell et al. Pediatric Research 1999;45:245A,
#1440. (The full study has not been published yet to my knowledge)
Also from Vancouver and involving the same children described above,
this study reports that difficulties with written work are 8 times more
common among "normal" preemies than among fullterm controls.
These problems (at age 8) were predicted by low scores at age 4 1/2
in numerical problem solving, pencil copying, and visual perception.
This study was presented at last year's Society for Pediatric Research
meeting in San Francisco. Sample essays by the preemies and the
fullterm children were displayed. The differences in handwriting,
continuity of thought, expression, etc., were striking.
The authors state: "This study highlights continuities in visual-motor
perceptual functioning and learning problems....Story writing is a complex
activity requiring multifaceted problem-solving in addition to pencil
skills."
"Emotional and Behavioral Adjustments of' Normal' Very Low Birth
Weight Children Compared to Controls at 7 Years of Age." Kamaya,
Moddemann, and Casiro. Pediatric Research. 1996;39:269A #1597.
(Not yet published to my knowledge.)
This study, from University of Manitoba in Winnipeg, looked at 48 "non-handicapped"
very low birthweight preemies and found they had intellectual, academic,
visual-spatial and attentional weaknesses compared to term controls.
Behavior and social competence of these children was rated lower by
parents and teachers with significant differences found in somatic complaints,
anxiety/depression, social problems, attention problems, and aggressive
behavior.
21% of the preemies had scores in the abnormal clinical range on Total
Behavior Problems; 19% were in the abnormal range on somatic complaints;
17% were in the abnormal clinical range on attention; 15% were in the
abnormal clinical range on "aggression."
"Visual-Motor, Visual-Perceptual, and Fine Motor Outcomes in
Very-Low-Birthweight Children at 5 Years. Goyen, Lui, and Woods. Developmental
Medicine and Child Neurology. 1998;40:76-81.
This study, from Westmead Hospital in NSW, Australia, of 83 "normal"
preemies showed that 71% had below average fine motor skills. Twenty-three
percent of these "normal" children were considered impaired
or seriously impaired by these problems.
"Neuropsychological Analysis of the Visuomotor Problems
in Children born Preterm at < or = 32 weeks of gestation: A Five Year
Prospective Follow-up." Luoma, Herrgard, and Martikainen. Developmental
Medicine and Child Neurology 1998;40:21-30.
This study, from Kuopio University Hospital in Finland, of 46 "normal"
preemies showed that they achieved lower scores in visuospatial and
sensorimotor functions compared to term born controls.
"They had most difficulty with drawing direction of lines and
in integrating two or more forms. They also had problems with
3-dimensional constructions as well as visual perception of rotated
shapes or slopes of lines."
"Short-term Memory and Language Outcomes After Extreme Prematurity
at Birth" Briscoe, Gathercole and Marlow. Journal of Speech,
Language and Hearing Research. 1998:41:654-66. University of Bristol,
England.
From the University of Bristol. 26 children born before 32 weeks gestation
were compared with 26 fullterm children on short-term memory and language
skills. The preterm children scored more poorly across the full
range of measures. 1/3 of the children showed large deficits and were
classified as "at risk" for persisting language difficulties.
"Psychological Findings in Preterm Children Related to Neurologic
Status and Magnetic Resonance Imaging." Olsen, Vainionpaa, Paakko
et al. Pediatrics.1998;102:329-36.
and
"Magnetic Resonance Imaging of Periventricular Leukomalacia and
its Clinical Correlation in Children." Olsen, Paakko, Vainionpaa
et al. Annals of Neurology 1997;41:754-61.
People often ask what an MRI can show about problems of prematurity.
These two studies that come from University of Oulu, Finland, and involve
42 "normal" children born <32 weeks and/or 1750 grams compared
with term controls. They show the following:
32% of the LBW and VLBW children showed signs of PVL
10% had CP, and all with CP had signs of PVL
31% of the preemies had "minor neurologic dysfunction" which
showed up on such tests as "deviations in tongue movements,"
"heel walking," "Fogs test results (don't know what this
is), and finger opposition as well as behavioral disturbances. 25% of
these children had evidence of PVL on MRI
However signs of PVL were also seen in 25% of preemie children considered
normal.
No signs of PVL or CP were seen in control children who were born at
term.
Children with PVL did worse on tests involving "heel walking"
and on the "Fogs test"
Children who performed poorly on tests of visuoperceptual and spatial
abilities often had signs of PVL, especially posterior ventricular enlargement.
Children who showed signs of "minor neurologic abnormalities"
were likely to have attention problems (whether or not they had abnormal
scans). They also had the most trouble at school.
Although MRI abnormalities are often related to learning and behavior
problems, the authors conclude that a thorough neurological examination
is superior to MRI. They recommend closer follow-up for children
with minor neurological disorders.
The studies found that although MRI findings were often related to
future problems they did not always predict learning and behavior problems.
The authors suggested that thorough tests of neurological functioning
were probably more useful.
"Cerebral MRI of Very Low Birth Weight Children at 6 Years of
Age Compared with the Findings at One Year" Skranes, Nilsen,
Smevik et al. Pediatric Radiology. 1998;28:471-5.
and
"Cerebral Magnetic Resonance Imaging and Mental and Motor Function
of Very Low Birth Weight Children at Six Years of Age." Skranes,
Vik, Nilsen et al. Neuropediatrics. 1997;28:149-54.
In the next two studies researchers from University Hospital of Trondheim,
Norway show that certain types of MRI abnormalities, which are extremely
common even in "normal" preemies, are closely related to certain
types of learning problems.
These two studies involve a one year geographical cohort of very low
birth weight (VLBW, born weighing less than 1500 grams) children at
age 6. Of 31 VLBW non-disabled survivors, 27 were examined by
MRI at age one and 20 of these were reexamined at age 6 and given various
motor, IQ, and psychological/educational tests.
At age one 21 of the 27 infants (78%) had abnormal myelination on MRI.
Myelination refers to the insulation of the nerve fibers with a fatty
substance known as myelin. Myelin helps conduct nerve impulses.
Many preemies show "delayed myelination," and there is always
the question with this finding of whether it reflects a true delay in
myelination or whether it is an indication of permanent brain damage.
Most of the abnormal or "delayed" myelination in these children
was located in the "central occipital white matter" and or
in the "centrum semiovale" (it may help to get a map of the
brain to get an idea precisely where these structures are located but
they are in the area of the ventricles).
12 of the 27 (44%) of the "non-disabled" infants, at age one,
had irregular and dilated ventricles. Ventricular malformation
and enlargement usually indicates that parts of the surrounding brain
tissue have died and that the ventricles have enlarged to fill in the
spaces. This condition is sometimes referred to as "hydrocephalus
ex vacuo." It is an indication of PVL (periventricular leukomalacia).
Only an estimated 30% of PVL is found on NICU ultrasound scans, so children
who left the NICU with a clean bill of neurological health have often
suffered undetected PVL (more about this when I review the study by
Stewart et al).
Only two of the "non-disabled" VLBW preemies had normal scans
at age 1.
At age 6, 20 of the 27 children were reexamined by MRI and other special
tests to try to determine whether the abnormalities seen at age 1 had
persisted and if so, what they meant.
Most of the children with abnormal MRIs at age 1 continued to have
abnormal MRIs at age 6.
Children who had abnormal myelination in the central occipital white
matter *combined with* abnormal myelination in the centrum semiovale
and/or ventricular enlargement now showed signs of "gliosis"
-- or scarring related to tissue death and loss in glial cells of the
brain. Glial cells are (I think) the cells that give support and structure
to the neurons. Gliosis is another indicator of PVL. 12 out of
13 children with these findings showed continued signs of PVL at age
6.
Abnormalities in the central occipital white matter alone had normalized
in two children and persisted as delayed myelination in 3 children at
age 6.
All the children with ventricular dilation (enlargement) at age 1 still
had it at age 6.
In all, 12 of 20 (60%) of these non-disabled preemies had signs of gliosis
(aka PVL).
The 20 children were then tested for IQ, motor, and perceptual functioning.
Gliosis in the centrum semiovale was related to lower scores on gross
motor skills and locomotion. Additional gliosis in the central
occipital white matter was related to both fine motor and gross motor
impairments. The authors speculate that damage has occurred to
both motor and visual pathways in these regions affecting eye-hand coordination
and balance.
Overall presence of MRI abnormality was not related to lower IQ, however
there was a significant relationship between gliosis [PVL] in both the
centrum semiovale and the central occipital white matter and low scores
on the performance part of the IQ test, as well as on tests of picture
completion and the Block design test. The authors state: "This
may indicate visual and spatial perceptual problems, caused by damage
to posterior visual pathways and occipito-thalamic tracts (get out your
brain maps!) dealing with visuo-motor integration."
"Executive Function of Children with Extremely Low Birthweight:
A Case Control Study" Harvey, O'Callaghan and Mohay. Developmental
Medicine and Child Neurology. 1999;41:292-7.
The studies by Skranes and others indicate that *most* VLBW preemies
have suffered white matter damage [PVL]. Recent research (not
included in the packet) shows that white matter loss [PVL] can negatively
affect gray matter development. Gray matter is what makes up the
frontal lobe, and the frontal lobe handles much of what is referred
to as "executive function" -- such
abilities as planning, sequencing, and inhibition of impulsive behavior.
This study from Mater Children's Hospital in South Brisbane, Australia,
tested 30 ELBW (<1000 g at birth) preemies at age 4 to 5 and compared
their abilities with 30 fullterm children of the same age. The
preemies scored significantly lower than their peers on all executive
tasks.
"Behavioural Adjustments in School of Very Low Birthweight Children"
Sykes, Hoy, Bill et al. Journal of Child Psychology and Psychiatry.
1997;38:315-25.
Not surprisingly, problems with "executive function" have
consequences for school adjustment. This study out of Queens University
in Belfast, Northern Ireland, looked at a cohort of 243 prematurely
born VLBW (<1500 g) children at age 7-8. The children, both
male and female, were rated by their teachers as expressing more behavioral
and school adjustment problems that controls. Environmental factors
such as high social class played no role in ameliorating these problems.
The authors speculate that the problem behaviors "reflect a failure
in self-regulatory [executive, or frontal lobe] functions."
Helen Harrison is the well known author
of The Premature Baby Book, often referred
to as the "Bible of Prematurity" by older preemie parents. These
observations are excerted with permission from posts to the prematurity
parents support internet mailing lists on prematurity: Preemie-child
and Preemie-L.
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