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Biomedical subjects

R J Lemire

Publications and source records attributed to R J Lemire.

At least 19 recordsLinked to original sources
PubMed1995

Epidemiology, etiologic factors, and prenatal diagnosis of open spinal dysraphism.

The caudal neural tube closes late in the first month after fertilization and failure of it results in myelomeningocele. Epidemiologic studies have shown differences in prevalence at birth based on ethnic-racial backgrounds and geography. Etiologic factors include the drug valproic acid or carbamazepine. Periconceptional folic acid supplementation appears to decrease the prevalence of neural tube defects. Numerous modalities allow for prenatal diagnosis of myelomeningocele. A cesarean section, before rupture of amniotic membranes and onset of labor, decreases the degree of paralysis.

Cesarean Section↗
PubMed1990

Management and long-term follow-up review of children with lipomyelomeningocele, 1952-1987.

The medical records of patients at Children's Hospital and Medical Center treated for lipomyelomeningocele repair were reviewed to assess the long-term outcome of surgery. In total, 108 children were cared for between 1952 and 1987, and long-term data are available for 80 of 96 children who underwent surgery. Cutaneous manifestations and associated malformations were common. Surgical repair was performed at ages 1 week to 17 years; there was no operative mortality. Thirty-five of 38 children with normal preoperative examination were without deficits on long-term follow-up review. Bowel and bladder paralysis was present in 42 children and did not recover after release of cord tethering. Eleven children had return of symptoms and were reexplored 3 to 8 years after initial surgery. Surgical repair with release of cord tethering at the time of diagnosis is advocated, regardless of patient age.

Adolescent↗
PubMed1990

Anencephaly: its spectrum and relationship to neural tube defects.

Anencephaly patients are of renewed interest because they are regarded as a potential source of organ donation. While there has been a longstanding scientific curiosity on this subject, studies have frequently included such cases as part of the larger spectrum of neural tube defects (NTDs). This paper will discuss some unusual features of anencephaly. Following a review of classification and pathogenesis, associated malformations, growth parameters (organ size and anthropometric measurements), and associations with other entities are discussed. Finally, the relationship of anencephaly to NTDs is presented.

Abnormalities, Multiple↗
PubMed1990

Aberrant morphogenesis of the central nervous system.

This overview of congenital defects of the CNS has emphasized pathogenesis. As developmental pathways continue to be elucidated, this approach remains to an extent hypothetical. When, however, an understanding of the features of morphogenesis and dysmorphogenesis helps to indicate time of onset or to elucidate causal factors, important steps toward the prevention of birth defects are taken.

Central Nervous System↗
PubMed1987

Atelencephalic microcephaly: craniofacial anatomy and morphologic comparisons with holoprosencephaly and anencephaly.

This is the first detailed report of the craniofacial anatomy of atelencephaly. Comparisons were made with a control specimen and others with holoprosencephaly, anencephaly, and anencephaly with holoprosencephalic facial features. In the atelencephalic fetus, severe microcephaly, flattened calvaria, and partial synostosis of the metopic suture were apparent. The cranial fossae were much smaller than usual; lesser wings of the sphenoid were folded into a rounded basal mass. Facial features were pronounced, and orbits were hyperteloric, lowset, and rounded. Ethmoidal cartilages, nasal bones, and maxillary structures were distorted and elongated. The secondary palate was displaced inferiorly and cleft. Because major components of the craniofacial complex were generally present, although misshapen, changes in the atelencephalic skull seem to be deformations rather than malformations. Differences in the cranial morphology of associated disorders--holoprosencephaly and anencephaly--can be construed as aberrations of separate developmental fields. Relationships between atelencephaly and these fields are unclear.

Abnormalities, Multiple↗
PubMed1986

Atelencephalic microcephaly in a 21-week human fetus.

Atelencephalic microcephaly, a rare and extreme disorder, is known morphologically by only six cases. Derivatives of the telencephalon are absent or dysplastic, while more caudal structures are normal or mildly deformed. A more extensive form, aprosencephaly, involves structures of the diencephalon and may be associated with holoprosencephalic facies. Extracranial anomalies may be present in both atelencephaly and aprosencephaly. We describe the seventh and youngest specimen, a 21-week female with atelencephaly. Maternal and gestational histories were unremarkable; the fetus was obtained by therapeutic abortion following diagnosis of a severe cranial malformation by ultrasound. A small and depressed, but intact, calvarium covered the brain. The forebrain was rounded and showed fused hemispheres, absent gyri, olfactory bulbs, and tracts. Caudal structures were mildly deformed. An oval mass of bone filled much of the middle cranial fossa. By light microscopy, several dysplastic changes were apparent in the forebrain. Ventricles were not present; small round cells resembling those of the germinal matrix were prominent in the forebrain. Pyramidal tracts were absent at all levels. The process responsible for these changes cannot be established with certainty; the changes are, however, in keeping with previous damage, such as that accepted for other encephaloclastic disorders. The insult in atelencephaly presumably occurs after closure of the rostral neuropore; earlier damage, with more widespread consequences, is possible for aprosencephaly. As with other destructive processes, etiology in atelencephaly and aprosencephaly is most likely heterogeneous.

Brain↗
PubMed1984

Arteriovenous malformations of the brain: a teratologic challenge.

Congenital arteriovenous malformations of the brain are lesions which are well-known to neurologists and neurosurgeons but are puzzling to teratologists because they occur sporadically and are unassociated with congenital malformations outside the central nervous system. They are recommended to teratologists as a field of etiologic and pathogenetic research.

Abnormalities, Multiple↗
PubMed1984

Coma scale for use in brain-injured children.

The association between admission coma score and eventual outcome was assessed using a coma scale developed for children with a variety of central nervous system injuries. As opposed to the Glasgow coma scale, this scale does not demand assessment of verbalization, and thus can be applied to the preverbal or previously intubated child. Cortical function is graded from 6 (purposeful, spontaneous movements) to 0 (flaccid), and brainstem function is graded from 3 (intact) to 0 (absent and apneic). Maximum total score is 9. In 91 children treated for intracranial hypertension, the association was moderately good. The scale was better in predicting the outcome of patients with hypoxic encephalopathy and head trauma than that of patients with Reye's syndrome, meningitis, or encephalitis. No child with a score of less than 3 survived in spite of intensive therapy. Most of these children were flaccid with depressed or absent brainstem reflexes. No child with flaccidity on admission survived.

Brain Injuries↗
PubMed1983

Neural tube defects: clinical correlations.

There are several approaches that can be applied to the analysis of malformations of the CNS. One practical way in making clinical correlations is to divide neural tube defects into those that arise during the period of neurulation and those that arise thereafter. This concept applies to cranial and spinal lesions and makes it possible to interpret clinical findings with embryological events. Malformations of the CNS that arise during the period of neurulation are not covered by skin and can be diagnosed prenatally by amniocentesis. Postneurulation CNS malformations are skin-covered and have differing patterns of associated malformation and etiologies. There is an overlap of the latter group with congenital tumors, and for the most part these malformations are not apt to be diagnosed prenatally.

Anencephaly↗
PubMed1982

Syndromes with cephaloceles.

Encephaloceles may occur as isolated malformations or together with other anomalies making up various syndromes or associations. With the possible exception of the aberrant tissue band syndrome and the Meckel syndrome, little attention has been paid to syndromes with encephaloceles as a group. This paper discusses syndromes of known genesis, including the aberrant tissue band syndrome, Chemke syndrome, cryptophthalmos syndrome, dyssegmental dwarfism, frontonasal dysplasia, Knobloch syndrome, Meckel syndrome, pseudo-Meckel syndrome, von Voss syndrome, and warfarin syndrome. Associations include a wide range of anomalies that may occur with encephalocele. Some abnormalities are secondary to encephalocele formation; others represent primary noncontiguous embryonic malformations. Associated anomalies include absent corpus callosum, orofacial clefting, craniostenosis, Dandy-Walker defect, Arnold-Chiari defect, ectrodactyly, hemifacial microsomia, hypothalamic-pituitary dysfunction, Klippel-Feil anomaly, iniencephaly, and myelomeningocele. Finally, several other conditions with encephalocele are discussed. Some may represent true low-frequency associations; others are spurious.

Agenesis of Corpus Callosum↗
PubMed1982

Pathogenesis of congenital tumors and malformations of the sacrococcygeal region.

Skin-covered lesions in the sacrococcygeal region include an unusual array of congenital tumors and malformations. Excluding the easily recognized meningomyelocele, there are over 50 other conditions that occur, many of which seem to be important in linking the disciplines of teratology and oncology. While it is impossible to precisely determine the manner in which these arise, there is suggestive evidence that early structures incorporated within the caudal cell mass of the embryonic tail may play an important role. The present paper reviews the basis for this speculation from both the literature and a series of 136 cases.

Ependyma↗
PubMed1981

The facial features of holoprosencephaly in anencephalic human specimens. I. Historical review and associated malformations.

At least 19 human anencephalic specimens have been published which have the facial features of holoprosencephaly. All categories of holoprosencephaly are represented except ethmocephaly, the rarest form. Because of current scientific and clinical interest in both neural tube defects and holoprosencephaly it seems important to establish whether or not this association occurs by chance alone. The study of human embryos with holoprosencephaly by Matsunaga and Shiota ('78) and the anencephalic collection of Lemire et al ('78) suggests the association may be real.

Abnormalities, Severe Teratoid↗
PubMed1981

The facial features of holoprosencephaly in anencephalic human specimens. II. Craniofacial anatomy.

The craniofacial anatomy of two anencephalic human specimens with the facial features of holoprosencephaly is reported. Many of the malformations have distinctly holoprosencephalic or anencephalic features. Absence of the entire ethmoid complex, observed in both specimens of the present study, has rarely been described and, to our knowledge, has never been confirmed histologically. The significance of agenesis of the ethmoid bone in the development of normal and holoprosencephalic facial features has not been considered previously. On the basis of several morphological variations in the two specimens described, it is evident that the ethmoid bone provides integral support in multiple planes for tissues of the median face. It is postulated that the spatial relationships of the bony and soft tissue components of the median face are guided and maintained by the ethmoid complex during morphogenesis. Specifically, hypotelorism and superiorly displaced structures of the nose and upper lip may well represent migration of embryonic tissues into areas normally occupied by the ethmoid bone. Absence of the sella turcica and pituitary gland is ascribed to the holoprosencephalic process. A variant of choanal atresia, due to collapse of the pterygoid plates, is described.

Anencephaly↗
PubMed1980

The association of spinal retroflexion with limb anomalies.

The spectrum of conditions in which retroflexion of the spine occurs includes anencephaly, iniencephaly, and Klippel-Feil syndrome. It was suggested by Gimour ('41) that a continuum may exist linking the latter two entities. The present paper attempts to reopen this question by reporting two specimens which have none of the above conditions, yet have spinal retroflexion and limb malformations. Combined with other isolated case reports, they show that spinal retroflexion can arise over a variable period of time.

Abnormalities, Multiple↗
PubMed1975

Studies of the development of congenital anomalies in rats. III. Effects of inhibition of mitochondrial energy systems on embryonic development.

Pregnant rats were treated with various inhibitors of mitochondrial oxidative energy metabolism and with lowered oxygen tension, and the embryo fetuses examined for the occurrence of congenital malformations and for changes in enzymatic activities. Treatment with all agents tested resulted in the production of skeletal anomalies. Sodium phenobarbital was the most teratogenic of the drugs tested and produced a high incidence of malformations which included cleft palate, tail anomalies, spinal retroflexion, domed head, and facial hypoplasia. Diphenylhydantoin produced a low incidence of syndactyly and oligodactyly. In addition to its effects on fetal growth and development chloramphenicol appeared to interfere with implantation. Tissue preparations from embryos exposed to sodium phenobarbital and chloramphenicol showed markedly lowered levels of DPNH oxidase activity. Cytochrome oxidase activity was also markedly lowered in the preparations from chloramphenicol-exposed embryos. Enzyme activities in preparations from embryos exposed to malonate and diphenylhydantoin appeared unaffected, although the drugs are strong inhibitors of electron transport in vitro; the lack of apparent effect may be due to the fact that both drugs do not bind to the enzyme preparations and were diluted 100- to 200-fold during preparation and assay of the tissue homogenates.

Abnormalities, Drug-Induced↗