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Biomedical subjects

J E Jan

Publications and source records attributed to J E Jan.

At least 55 records · Page 3Linked to original sources
PubMed1990

Light-gazing by visually impaired children.

This study assessed the prevalence and characteristics of light-gazing by all visually impaired children referred during a 2 1/2-year period. Light-gazing (compulsive staring into lights) is one of the many clinical signs of cortical visual impairment (CVI), and in the present study it occurred in 60 per cent of children with CVI. The authors believe that light-gazing by any child with ocular lesions indicates some degree of CNS involvement. Visually impaired children who flicker their fingers in front of their eyes against a light source demonstrate an extension of this compulsive behaviour. This and other studies suggest that blind mannerisms have specific neuropathological substrata and therefore are useful clinical signs.

Blindness↗
PubMed1990

Head shaking by visually impaired children: a voluntary neurovisual adaptation which can be confused with spasmus nutans.

Rapid, horizontal, pendular head oscillations were observed in 18 visually impaired children with nystagmus during intense visual fixation, and the characteristics of this behaviour were analysed. Head tilting and eye deviations also occurred in 14 of the children. Their symptoms and signs resembled spasmus nutans. Head shaking appeared to be a voluntary, learned, neurovisual adaptation to improve visual acuity. Accurate simultaneous recordings of eye and head movements are required to understand the pathophysiological significance of these head oscillations.

Adolescent↗
PubMed1990

Habilitation and rehabilitation of visually impaired and blind children.

Important neurological, developmental and cognitive differences exist between the visually impaired and the sighted. Unless parents, health professionals, educators and other caregivers understand the differences, serious problems may arise. Certain aspects of development in visually impaired children have consequences for habilitation and rehabilitation.

Blindness↗
PubMed1990

Computed tomography of the brains of children with cortical visual impairment.

Computed tomography (CT) of the brains of 70 children with permanent cortical visual impairment (CVI) and of 25 children who recovered from their cortical visual loss were analysed and the findings were correlated with clinical signs and symptoms. The 70 children with CVI were divided into groups depending on the known or suspected pathophysiology of CVI. Asphyxia caused permanent CVI in 34 children, of whom 16 were preterm, 17 were term and one lost vision later in life. Congenital brain malformations were the second largest group, followed by trauma, infections and shunt failure. 25 children recovered their visual acuities, but six of them were left with homonymous hemianopia. The results identified various clinical characteristics of the groups. CT scanning was helpful in understanding the pathophysiology of CVI, and provided useful information for the prognosis of visual recovery.

Adolescent↗
PubMed1989

Joubert's syndrome associated with congenital ocular fibrosis and histidinemia.

We describe a 16-month-old girl with Joubert's syndrome (JS), congenital ocular fibrosis, and histidinemia. Abnormal respiration, ptosis, and minimal eye movements were observed in the neonatal period. Intraoperative examination of the eyes later demonstrated severely restricted eye movements and abnormal insertions and fibrosis of the extraocular muscles. Computed tomography of the head revealed absence of the corpus callosum and brain stem. Histidine levels were elevated in the blood, urine, and cerebrospinal fluid. The patient was ataxic and developmentally delayed. To our knowledge, the association of JS with congenital ocular fibrosis has not previously been described. This report indicates that jerky eye movements are not an invariable finding in JS.

Ataxia↗
PubMed1989

Neurological and developmental findings in children with cataracts.

Ninety-seven children who were born between 1954 and 1986 and presented to the Visually Impaired Program of British Columbia's Children's Hospital, Vancouver, Canada, with a primary ophthalmologic diagnosis of cataracts, were assessed neurologically, ophthalmologically, audiologically, and developmentally. Causal factors included prenatal infection (35 cases), hereditary cataracts (22 cases), various syndromes and metabolic disorders (9 cases), trauma (1 case), and unknown (30 cases). Ninety children were diagnosed to have congenital cataracts while 7 acquired them. Findings indicated that prenatal infection continues to be a cause of infantile cataracts, despite rubella immunization; that prematurity is not, as has been stated in the past, a cause of infantile cataract; and that careful neurological, audiological, and developmental examination is vital in the assessment of likely causes of this condition.

Adolescent↗
PubMed1989

Quantitative VEP analysis in children with cortical visual impairment.

Children with cortical visual impairment (CVI) usually have a typical clinical presentation. However, in some cases, it may be useful to have confirmatory evidence based on objective electrophysiologic information. To achieve this, we examined some mathematically derived parameters constructed from 20 channel visual evoked potential (VEP). A group of 30 children diagnosed with CVI by clinical and CT findings was compared to a normal control group of 52 children. Each recorded VEP was mathematically transformed using Hjorth's source derivation, to reduce reference contamination and enhance local features. The area under the response curve, computed for each channel within a fixed time window, was used as a measure of the response activity at that channel. These areas were then used to construct several parameters ("R values") describing ratios of activities between different recording electrode areas. Some of these ratios provided good separation between patient and control groups, especially for children older than 5 years of age; in particular CVI patients were found to have a low occipital-to-parietal activity ratio. This finding, together with the observed age independence of the R values in the normal population, their ease of computation and possible physiological interpretability, suggest that R values could be used as confirmatory diagnostic measures.

Adolescent↗
PubMed1988

The unequal nystagmus test.

In children who exhibit nystagmus secondary to visual impairment, the better eye determines the quality of the nystagmus. 40 children with different visual acuities and 10 with the same vision in each eye were studied. By inspecting the behaviour of the nystagmus in each eye, while covering the other, it was possible to identify which eye had better foveal vision. This so-called 'unequal nystagmus test' is very simple to do and it offers valuable information.

Adolescent↗
PubMed1988

Behaviour of the alpha rhythm in electroencephalograms of visually impaired children.

One hundred and thirty-eight electroencephalograms (EEGs) of 104 children with ocular visual loss were studied and the findings correlated with clinical information. Records of blind children without other neurological deficits did not contain posterior slowing or occipital spikes. The frequency, reactivity and regulation of alpha rhythm were affected only when vision was at the level of finger-counting. Therefore the EEGs of the majority of 'normal' visually impaired children showed normal alpha behaviour. Although most totally blind children's records lacked alpha, five had spontaneously appearing and disappearing alpha rhythm. The EEG is a valuable tool in the evaluation of visually impaired children, provided the findings are interpreted appropriately. The earlier theory that visual deprivation can cause electrical abnormalities over the visual cortex was not supported by these data.

Adolescent↗
PubMed1988

Changing pattern of retinopathy of prematurity: a 37-year clinic experience.

A retrospective analysis was done of multi-disciplinary neurodevelopmental assessments in 70 children who were legally blind because of cicatricial retinopathy of prematurity. The subjects lived in British Columbia and were born during a 37-year period between 1951 and 1987. The purpose of the study was to investigate changes in the perinatal characteristics and to evaluate the associated handicaps. All patients were assessed at least once in the Visually Impaired Program, British Columbia Children's Hospital. In the majority, the visual loss was profound. Since 1951, blinding retinopathy of prematurity has become a disease of progressively smaller and less mature infants. Since 1981, it has been almost entirely confined to infants of birth weight less than 1,000 g in British Columbia. The diagnosis of mild spastic diplegia was made more commonly in patients born after 1980 but, despite the progressive reduction in birth weight and gestational age during the study period, the number of patients without other associated handicaps remained constant (approximately 30%) during each successive decade.

Birth Weight↗
PubMed1987

Visual recovery from hypoxic cortical blindness during childhood. Computed tomographic and magnetic resonance imaging predictors.

We reviewed the clinical courses and computed tomographic (CT) and magnetic resonance imaging (MRI) scans of 30 infants and children with cortical blindness following hypoxic insults. The degree of injury to the striate and parastriate cortices and the area of the optic radiations were graded from 0 to 4 by a neuroradiologist. Only two children had normal scans of the posterior visual pathway and both had favorable visual outcomes. The visual recovery differed significantly with respect to the age at which the hypoxic insult occurred and CT and MRI abnormalities in the area of the optic radiations, but not with abnormalities in the striate or parastriate cortices. Our results suggest that CT and MRI scanning are helpful in prognosticating the visual potential of children with hypoxic cortical blindness.

Age Factors↗
PubMed1987

Congenital ocular blindness in children, 1945 to 1984.

A total of 676 children born in British Columbia with congenital ocular blindness during the years 1945 through 1984 were studied. The birth prevalence rate of congenital blindness has decreased from eight per 10,000 live births in the late 1940s to three per 10,000 live births. Retinopathy of prematurity was replaced by genetic ocular disorders as the leading cause of congenital blindness, although the former is reemerging. The rate of congenital rubella infection also declined. There has been a significant increase in the rate of births with optic nerve lesions during the past 15 years, while the rate of births with lesions of the lens fell, reflecting the decline in the rate of maternal rubella infection. There are fewer children with congenital ocular legal blindness who have no light perception today, and they also have fewer associated handicaps.

Blindness↗
PubMed1987

Behavioural characteristics of children with permanent cortical visual impairment.

The common behavioral features of 50 children with permanent cortical visual impairment (CVI) are described. CVI is frequently associated with specific behavioural characteristics. The majority of these children have residual vision, but they all have variable and inconsistent visual performance, including visual acuity. They see better in familiar environments and when they understand what to look for and where to look for it. They often use touch to identify objects. Their ability to identify colours is much stronger than their perception of form. Many turn their heads to the side when they are reaching. Nystagmus and visual self-stimulation are exceptionally rare. They appear to have great difficulty with the cognitive evaluation of visual perception in spatial terms. Head elevation is worst in those with least vision, and without head elevation the possibility of visual stimulation is further restricted.

Adolescent↗