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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neuronal organization of the motor cortex of a 19-month old child with Down's syndrome (mongolism) has been studied with the rapid Golgi method. This congenital syndrome, also known as 21 Trisomy is caused by a chromosomal abnormality consisting of the presence of an extra chromosome in the group 21. Various structural abnormalities have been found in the dendritic spines (postsynaptic structures) of the pyramidal neurons of the motor cortex of this child. The axo-spinous synapses of these neurons are considered to be altered by these spine abnormalities. In addition, a peculiar form of intrinsic vacuolar change affecting the dendrites and scattered neuronal fragmentation and necrosis have also been found. At least three different types of abnormality involving the spines--(the unusually long spine, the very short spine and a reduction in the number of spines)--are recognized among the pyramidal cells of the motor cortex. It is postulated herein: that a basic anomaly, possibly related to the genetic disorder affects primarily some cortical neurons which undergo progressive degenerative changes terminating in cell fragmentation and death. The different spine abnormalities are considered to represent various developmental stages of the common genetic anomaly. These changes might be structural correlates of the motor incoordination and mental retardation which are characteristic of this genetic disorder, but, final conclusions should await the investigation of other cases with this or similar methods capable of demonstrating the normal as well as the abnormal structural organization of the human cerebral cortex.
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PMID:Pyramidal cell abnormalities in the motor cortex of a child with Down's syndrome. A Golgi study. 13 10

A review is presented of a variety of human pathologic conditions, including some forms of mental retardation, and of experimental situations involving the nervous system proved (with the Golgi method) to be associated with detectable morphologic abnormalities. The postsynaptic elements (the dendritic spines) have been found to be especially sensitive and frequently they are found to be structurally abnormal. Structural abnormalities involving one of the synaptic components could result in synaptic dysfunction which could explain some degree of mental or motor retardation or incoordination. It is hoped that this review will stimulate and encourage the use of the Golgi method in the study of abnormal conditions (clinical or experimental) affecting the nervous system.
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PMID:Abnormal neuronal differentiation (functional maturation) in mental retardation. 76 96

Areas of increased signal seen on magnetic resonance imaging (MRI) of the brain are frequently present in neurofibromatosis and are considered possible areas of dysplasia or heterotopias. Since Rosman and Pearce [Brain 1967; 90:829-838] have shown that neuronal heterotopias in deep cerebral white matter are associated with mental retardation in neurofibromatosis type 1 (NF-1), we hypothesized that these areas of increased signal seen on MRI should be associated with learning difficulties or incoordination in children with NF-1. Using MRI, we studied 31 children with NF-1 and attempted to correlate the presence of areas of increased signal with learning difficulties or incoordination. We found no association. This suggests that either these areas of increased signal are heterotopias which are not associated with learning difficulties or incoordination, or these areas of increased signal are not heterotopias and are not relevant to the study of learning problems or incoordination in children with NF-1.
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PMID:Magnetic resonance imaging evaluation of learning difficulties and incoordination in neurofibromatosis. 251 20

A clinical, neurological and electroencephalographic investigation was undertaken in 29 previously cytogenetically verified hemizygous males with the fra(X) form of mental retardation (age range 3.5 to 59 years); in addition, 6 heterozygous females were examined. All male patients displayed the known physical aspects of this syndrome together with associated abnormalities of the palate, skeleton, connective tissue and endocrine system. The most prominent neurological features were different forms of oculomotor disturbances, minor motor and pyramidal signs, incoordination, muscle hypotonia, gait and speech abnormalities. There was no increased frequency either in seizures or in epileptic EEG discharges. Some patients had a slowing of background activity in EEG. About 50% of all patients displayed autistic-like behaviour, short attention span and/or hyperactivity. In accordance with the literature, the findings indicate that there are no neurological, electroencephalographic or neuroradiological features which occur specifically in this syndrome. The need to differentiate the findings from those resulting from encephalopathic mechanisms during the gestational and perinatal period is stressed. A distinct typing of seizures and EEG changes is needed in each patient, before definite conclusions about an association of seizures and fra(X) syndrome are drawn. In view of the lack of correlation between IQ and the clinical-neurological measures, a more practical approach to quantifying the mental impairment is proposed.
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PMID:Clinico-neurological investigations in the fra(X) form of mental retardation. 270 58

We report two brothers with previously unexplained mental retardation and seizures who had dysmorphic facial features, macro-orchidism, and a fragile site at the X chromosome. This recently described syndrome is the second most common chromosome aberration associated with mental retardation after Down's syndrome. In order to determine the prevalence of seizures and the frequency of specific neurological features, we studied a total of 17 patients with the fragile X syndrome. 41% had grand mal seizures; 41% had extensor plantar responses; 47% had hyperactive behaviour and 65% exhibited stereotypics; 59% had incoordination and 35% had blepharospasm. We emphasise the need for chromosome analysis of patients with unexplained mental retardation, specific phenotypic abnormalities, and large testes.
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PMID:Neurological findings in patients with the fragile-X syndrome. 392 Mar 55

The fragile X syndrome is a relatively common form of mental retardation that tends to affect boys more severely than girls. The syndrome is associated with a fragile site at q27 on the X chromosome and with physical features including large or prominent ears and macro-orchidism. Four boys had physical and cytogenetic features of the fragile X syndrome. However, the IQ scores of these patients extended into the normal range. All four patients demonstrated similar learning difficulties that included hyperactivity, visuomotor incoordination, language deficits, and academic delays in mathematics. The fragile X syndrome should be considered in the differential diagnosis of learning disabled children.
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PMID:Learning disabilities and attentional problems in boys with the fragile X syndrome. 401 89

The clinical, radiological, and neuropathological findings in early onset Cockayne syndrome are illustrated in identical twins and their brother. Their appearance of dwarfism with small head and prominent beaked nose strongly resembled that seen in the Seckel syndrome, but unlike patients with that syndrome they had a normal birth weight (for twins), thick cranial vaults, intracranial calcification, and a severe degree of mental retardation. The twins were deaf and blind, with optic atrophy and retinal pigmentation, while their brother had cataracts. Their hands and feet were large in proportion to their small trunk. They had cutaneous sensitivity to any slight exposure to ultraviolet light and severe neurologic problems with incoordination and spasticity. Radiologic findings included microcephaly, a thick cranial vault, a small pelvis, coxa valga, and "ivory epiphyses" in terminal phalanges of hands and feet. Pathologic findings included atrophy of white matter with widespread patchy demyelination, and massive siderocalcific deposits in the brain, particularly in the basal ganglia and cerebellum. While autosomal recessive inheritance is most likely, formally X-linked inheritance cannot be excluded.
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PMID:Identical male twins and brother with Cockayne syndrome. 689 Mar 11

Two siblings with different degrees of mental retardation, skeletal dysplasia, coarse facies, delayed speech, motor incoordination, recurrent respiratory infections, and immunological abnormalities, were found to have deficient alpha-mannosidase activity. Cultured skin fibroblasts in one sib were markedly deficient in alpha-mannosidase while all other lysosomal enzymes tested were within the normal range. The more severely affected sib came to autopsy and was found to have "washed-out" appearing cortical neurons and marked histiocytosis effacing lymph node architecture and partially replacing the bone marrow. The post-mortem brain and liver samples demonstrated a deficiency in alpha-mannosidase relative to the elevations of other lysosomal enzymes. Although the patterns of abnormalities in the two cases closely match those of descriptions of "type II" and "type I" mannosidosis respectively, the variation should be due to genetic modifiers or environmental effects since the brothers must have shared similar alpha-mannosidase mutations. Immunologic abnormalities present in the more severely affected sib suggest that the differential survival seen in mannosidosis types I and II may be due to differences in their immune systems.
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PMID:Mannosidosis: two brothers with different degrees of disease severity. 730 17

This is the first reported case of dystonia with a partial deletion of the long arm (q) of chromosome 18. Neurologic findings in the 18q- syndrome include mental retardation, seizures, nystagmus, incoordination, tremor, and chorea. A 36-year-old woman with an 18q terminal deletion [karyotype 46,XX,del(18)(q22.2)] had hypothyroidism, diabetes mellitus, borderline intelligence, short stature, short neck, sensorineural hearing loss, and sensorimotor axonal neuropathy. Parents' karyotypes were normal. She had had incoordination and writing difficulty since childhood. Posturing and tremor of the head began at age 16, followed by arm tremors. She had jaw deviation and tremor, neck tremor with retrocollis, involuntary pronation of the right arm, coarse postural and severe action tremor, and tight pen grip with dystonic wrist extension on writing. The 18q- syndrome should be added to the list of genetic causes of secondary dystonia. A karyotype analysis should be considered in secondary dystonias, particularly when there are associated features such as short stature and endocrinopathies.
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PMID:Dystonia in a patient with deletion of 18q. 756 32

We report a case of dystonia with a partial deletion of the short arm (p) of chromosome 18 and androgen insensitivity. Neurologic findings in the 18p syndrome are reported to include mental retardation, seizures, incoordination, tremor, and chorea. A 15-year-old girl with a denovo 18p deletion [karyotype 46, XY, del (18)(p11.1)] developed progressive asymmetric dystonia. She had oromotor apraxia and partial expressive aphasia since childhood, and she was able to partially communicate through elementary sign language. At the age of 15 years, she developed subacute and progressive choreic movements of the right arm, severe dystonic posturing of the left arm, and spastic dystonia in both legs. Her response to parenteral or oral benzodiazepines, oral trihexyphenidyl, benztropine mesylate, baclofen, and L-dopa were brief and inadequate. The response to intrathecal baclofen has been sustained over 18 months. In all likelihood, the 18p deletion syndrome affecting this patient is significant in the pathogenesis of her acquired dystonia. Chronic intrathecal baclofen therapy via pump has been effective in this case and should be considered as a treatment modality in carefully selected patients with dystonia.
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PMID:Progressive dystonia in a child with chromosome 18p deletion, treated with intrathecal baclofen. 1007 26


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