The hematological and electrophysiological effects of cobalamin. Deficiency secondary to vegetarian diets.
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Adult↗
Biomedical subjects
A Kriss
Publications and source records attributed to A Kriss.
Ophthalmologic assessment of young patients with Alport syndrome.
BACKGROUND: Alport syndrome is an X-linked disease affecting basement membrane collagen. It is characterized by nephritis associated with high-tone sensorineural hearing impairment and ophthalmic signs. Although ocular changes have been described in adults, few data exist regarding the incidence of abnormal ocular features in adolescence and childhood. METHODS: Fifteen male and five female patients with Alport syndrome underwent ophthalmologic, audiologic, and nephrologic assessments. All patients studied had hematuria and a positive family history of Alport syndrome. Thirteen patients had a renal biopsy that showed characteristic electron microscopic changes of the disease. Eleven patients had high-tone sensorineural impairment. Electrophysiologic investigations performed included electroretinography, visual-evoked potentials, and electro-oculography. RESULTS: Two patients had early signs of anterior lenticonus, three had flecks in the retina, and two patients also had posterior subcapsular cataracts. None of the patients had significant electrophysiologic abnormalities. CONCLUSION: These findings indicate that ocular changes are uncommon and subtle in young patients with Alport syndrome, and suggest that the signs increase in frequency and severity with age.
Adolescent↗
Electrophysiological assessment of visual pathway function in infants.
The flash ERG and VEP have conspicuous immature features during the first 4 months following birth. The most marked maturational changes occur in ERG amplitude and VEP latency. Concurrent recording of the skin ERG and VEP provides information which is very useful in helping to arrive at a diagnosis in the young infant with nystagmus who appears to be blind and has a fundus of normal appearance. ERG and VEP features associated with Leber's Amaurosis, congenital cone dysfunction, albinism, optic nerve hypoplasia and unilateral hemisphere dysfunction are described.
Electroretinography↗
Neonatal cataract: aetiology, pathogenesis and management.
We review the epidemiology, aetiology, pathogenetic mechanisms and clinical management of neonatal cataract. Visual development and the effects of visual deprivation in the infant with congenital cataract are discussed and related to the timing of surgery. Surgical techniques and the important operative and post-operative complications are discussed. We review post-operative management and compare the different techniques available for aphakic correction, and describe the VEP changes found in patients with monocular cataract.
Cataract↗
The electroretinogram in infants and young children.
Electroretinography (ERG), especially when combined with visual evoked potential recording, can provide valuable information to the pediatric clinician assessing a young child with nystagmus who appears not to see. ERG changes are described in clinical conditions affecting rod and/or cone function, vitreoretinal disease, maculopathies, and disorders involving the retina and central nervous system. The role of ERG in monitoring treatment, and in excluding retinal disease prior to eye surgery, is also covered.
Child↗
Aspects of albinism.
Genetic, clinical and electrophysiological aspects of albinism are described. Emphasis is placed on electrophysiological features which help to distinguish albinism from other clinical conditions, and on stimulating and recording factors which can affect the clarity of VEP results.
Albinism, Ocular↗
The use of video in assessing and illustrating abnormal eye movements in young children.
Eye movement studies can be useful in neuro-ophthalmological investigations of infants and young children. In our laboratory we use a combination of an electro-oculogram and video to record eye movements. A composite video image is created consisting of an image of the electro-oculographic eye movement trace superimposed on an image of the patient's eyes and face. This permits the qualitative clinical appearance of the case to be illustrated simultaneously with the quantitative eye movement trace.
Electrooculography↗
Abnormalities of the electroretinogram and visual-evoked potential in vitamin E deficient rats.
Flash electroretinograms, retinal oscillatory and cortical visual-evoked potentials were recorded in 10-month vitamin E deficient rats and in age-matched controls. A significant increase in the latency (P less than 0.0001) and decrease in amplitude (P less than 0.0001) of the electroretinogram a- and b-waves were observed in the vitamin E deficient rats compared with controls. The vitamin E deficient rats also showed a significant delay (P less than 0.002) in early oscillatory potentials. No significant group differences were obtained in the P1 latency or P1-N1 amplitude of the visual-evoked potential; however, the N1 peak was significantly delayed (P = 0.01) in the vitamin E deficient rats. This study shows, for the first time, that the electroretinogram and visual-evoked potential to flash stimulation provide a sensitive index for monitoring the visual effects of vitamin E deficiency in the rat.
Animals↗
Effects of pentobarbital and ketamine-xylazine anaesthesia on somatosensory, brainstem auditory and peripheral sensory-motor responses in the rat.
Somatosensory, brainstem auditory evoked and peripheral sensory-motor responses were recorded in rats anaesthetized with either pentobarbital or a ketamine-xylazine combination. This was carried out in order to assess which of these agents degraded responses to a lesser extent and thus would be more suitable for monitoring experimental effects. Neither of the anaesthetic agents affected peripheral sensory or motor conduction, nor were there any interpeak latency changes of the early components of the brainstem auditory response. However, pentobarbital anaesthesia resulted in an increase in latency of the initial positive component of the somatosensory cortical evoked potential and attenuation of the following negative component. During the recovery stages of ketamine-xylazine anaesthesia the longer latency evoked potential components were observed to emerge.
Animals↗
A longitudinal study of somatosensory, brainstem auditory and peripheral sensory-motor conduction during vitamin E deficiency in the rat.
A severe deficiency of vitamin E causes a characteristic neurological syndrome in man and experimental animals. In this study a number of electrophysiological modalities in vitamin E deficient and control rats have been investigated over a period of one year to define the time of onset and severity of the abnormalities associated with vitamin E deficiency in the rat. The mean velocities (n = 10) of the sensory evoked potentials were slower at all time points in the vitamin E deficient rats, with the central conduction velocities being more severely affected than the peripheral. Central conduction velocities, following both tibial and median nerve stimulation, were significantly delayed (P less than 0.005) after 8 months of deficiency. Differences in peripheral conduction following tibial stimulation became significantly delayed (P less than 0.005) after 11 months of deficiency. There were no significant differences in the brainstem auditory evoked potentials or peripheral sensory motor responses between the vitamin E deficient and control rats over the 1 year period. These results in the rat are essentially similar to those previously reported in vitamin E deficient man.
Animals↗
Detection of isolated occipital lobe anomalies during early childhood.
The authors report two children with isolated occipital lobe anomalies detected by visual evoked potentials (VEPs) and confirmed by MRI and CT scanning. Both had a markedly asymmetrical occipital distribution of flash and pattern VEPs. One child had acuity reduced to 6/36, and testing on confrontation suggested an homonymous hemianopia. The second child was visually inattentive to one side during infancy. Neither child had band atrophy of the optic disc or an afferent pupillary defect. Isolated abnormalities of the occipital lobes are difficult to detect by clinical examination during infancy and early childhood. Recording VEPs from a horizontal array of occipital electrodes can be helpful in detecting subtle occipital lobe abnormalities.
Child↗
Albinism in childhood: a flash VEP and ERG study.
Flash visual evoked potentials (F. VEPs) and electroretinograms (ERGs) were recorded in a total of 20 young children with albinism (age range 5 months to 11 years, mean 4 years). All recordings were made without sedation. There were 13 oculocutaneous cases (one with Hermansky-Pudlak syndrome) and seven ocular albinos. Monocular flash stimulation commonly elicited an asymmetrical occipital VEP distribution with a well lateralised component at around 80 ms which was of opposite polarity in a comparison of VEPs from each eye. None of the normally pigmented matched controls or obligate female carriers showed this anomalous distribution. The albino electroretinogram, compared with controls, recorded under fully darkened conditions had a significantly larger a wave and significantly shorter latencies for both a and b waves. The accentuated ERG and asymmetrical VEP recorded in infants and young children with albinism permits distinction of these patients from those with congenital cone dysfunction and idiopathic nystagmus, with whom they may be confused by a clinical examination only.
Albinism↗
Childhood albinism. Visual electrophysiological features.
Flash ERGs and VEPs, and VEPs to pattern onset and pattern reversal stimulation were recorded in young albino children and compared to age-matched, normally pigmented, controls. In albinos, the ERG had a significantly larger a-wave, and significantly shorter latencies for both the a-wave and b-wave. VEPs to flash, pattern onset and pattern reversal stimulation all showed an occipital crossed asymmetry when comparing responses from each eye. However, the findings for flash stimulation were more consistent and reliable than those to either form of pattern stimulation.
Albinism, Ocular↗
Follow-up and diagnostic reappraisal of 75 patients with Leber's congenital amaurosis.
We reexamined 75 children in whom Leber's congenital amaurosis had been previously diagnosed. On review, 30 of these patients had an ocular or systemic disorder other than Leber's congenital amaurosis. The most common of these revised diagnoses were congenital stationary night blindness, achromatopsia, infantile-onset retinitis pigmentosa, Joubert's syndrome, Zellweger syndrome, and infantile Refsum's disease. Of the 45 patients with Leber's congenital amaurosis, mental retardation occurred in six patients, and visual deterioration in six patients. Leber's congenital amaurosis should only be diagnosed if other known ocular and systemic disorders have been carefully excluded.
Blindness↗
Ocular manifestations of the congenital varicella syndrome.
Three children developed the congenital varicella syndrome following a maternal varicella infection during the second trimester of pregnancy. Systemic findings included a bulbar palsy, mild hemiparesis, cicatricial skin lesions, developmental delay, and learning difficulties. Ocular findings included chorioretinitis, atrophy and hypoplasia of the optic discs, a congenital cataract, and Horner's syndrome. Electroretinograms and pattern-reversal visual-evoked potentials recorded from the four eyes with chorioretinitis were attenuated and degraded. Two of the children had been misdiagnosed as having congenital toxoplasmosis. Chorioretinal scars probably occur more frequently with the congenital varicella syndrome than has been previously recognized and should be included in the differential diagnosis of congenital chorioretinal scars. Hypoplasia of the optic disc may develop after an intrauterine varicella infection during the 16th week of gestation. Children with the congenital varicella syndrome should be examined by an ophthalmologist to exclude ocular abnormalities. These abnormalities are often subtle and difficult to diagnose correctly.
Chickenpox↗
Joubert syndrome.
Joubert syndrome is an autosomal recessive condition in which there is a variable combination of central nervous system defects with a distinctive congenital retinal dystrophy, ocular motor abnormalities, and respiratory abnormalities in early infancy. The retinal dystrophy has been previously classified as a variant of Leber's congenital amaurosis. We report electrophysiologic and eye movement findings in a series of seven consecutive children with Joubert syndrome. Unlike patients with Leber's congenital amaurosis, all but one of these children had preserved flash and pattern-reversal visual evoked potentials. Six of the seven children had abnormalities of smooth pursuit, optokinetic nystagmus, and saccades. Six of the children had nystagmus: three had a pendular torsional nystagmus and three had a form of see-saw nystagmus. An alternating hyperdeviation was present in five of the patients, two of whom also had a tonic deviation of their eyes laterally. All seven patients had cerebellar vermis hypoplasia on a magnetic resonance imaging scan. Developmentally delayed children with an absent or highly attenuated electroretinogram should be investigated for Joubert syndrome.
Blindness↗
Delayed visual maturation. A longitudinal clinical and electrophysiological assessment.
Delayed visual maturation is an idiopathic condition characterized by visual inattention during infancy. The authors followed longitudinally nine children with an initial diagnosis of delayed visual maturation and compared their electroretinograms (ERGs) and visual evoked potentials with those of age-matched controls. Eight of the nine patients consistently had normal visual evoked potentials to flash and to pattern stimulation. All of the children had normal ERGs. Visually mediated behavior gradually developed in all of these children when they were between 3 and 8 months of age (mean, 5.5 months). Five patients also were delayed in other spheres of development. Visual evoked potentials are helpful in formulating a visual prognosis for children with delayed visual maturation.
Age Factors↗
Autosomal recessive microcephaly, mental retardation with nonpigmentary retinopathy and a distinctive electroretinogram.
The association of microcephaly and mental retardation with a non-pigmentary retinopathy is described in three siblings of consanguineous parents. The electroretinogram showed the distinctive appearance of markedly attenuated "b" wave but normal "a" wave suggestive of a retinal dystrophy primarily affecting post-receptoral elements in the inner retina. This appears to be an autosomal recessive condition which has not been previously reported.
Child↗