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Biomedical subjects

A Kriss

Publications and source records attributed to A Kriss.

At least 73 records · Page 4Linked to original sources
PubMed1989

Leber's congenital amaurosis--a new syndrome with a cardiomyopathy.

Seven members of four families had nystagmus noted by 4 months of age, poor vision, photophobia, and a markedly reduced or absent electroretinogram. Six of these patients had a life threatening episode of cardiac failure in infancy. There were also two neonatal deaths, and one of the affected children died at 2 years and one at 19 years. The five surviving children are well, remain with nystagmus, and have visual acuities of less than 6/60, with the eldest two having lost perception of light. They have a short obese habitus distinct from that of their unaffected siblings and parents.

Blindness↗
PubMed1989

Visual evoked potentials in dissociated vertical deviation: a reappraisal.

Pattern reversal and flash evoked potentials were recorded in 13 children with dissociated vertical deviation (DVD). No electrophysiological evidence was found to support the notion that patients with DVD have an anomalous (albinoid) projection of visual fibres originating from the temporal retina of each eye. However, DVD patients had significantly smaller monocular and binocular pattern evoked responses than age matched controls. Explanations are given for this finding and for the occipital VEP asymmetries reported by other workers.

Adolescent↗
PubMed1988

Pattern- and flash-evoked potentials in patients with dissociated vertical deviation.

Pattern reversal and flash evoked potentials were recorded in 13 children with dissociated vertical deviation. We found no evidence of anomalous responses to pattern reversal half-field stimulation and no asymmetries in flash responses as reported to occur in albinism. However, we found that patients with dissociated vertical deviation had significantly smaller monocular and binocular pattern responses compared to a group of age-matched control subjects.

Adolescent↗
PubMed1988

Recovery after optic neuritis in childhood.

Thirty-nine children who presented with optic neuritis in childhood were reviewed after a follow up period from 3 months to 29 years (mean 8.8 years). At follow-up, 30 out of 39 (77%) of the children had had no further episodes and in three (8%) there was recurrence of optic neuritis alone. Multiple sclerosis had developed in six patients (15%), a much lower frequency than after optic neuritis in adult life. Regardless of the initial degree of visual impairment or neurological outcome, the visual prognosis was excellent. Pattern evoked potentials at follow-up were much more frequently normal (55%) than in adults (10%) after optic neuritis.

Adolescent↗
PubMed1988

Lumbar and cortical somatosensory evoked potentials in rats with vitamin E deficiency.

Somatosensory evoked potentials (SEPs) from lumbar and cortical areas and electromyographic activity (EMG) were recorded in 40-42 week vitamin E deficient rats and in age matched controls. A significant increase in the latency (p less than 0.001) of the cortical SEP and a significant reduction in the lumbar to cortical conduction velocity (p less than 0.001) were observed in vitamin E deficient rats compared with controls. No significant differences were obtained in the latency of the lumbar SEP or in the peripheral conduction velocity from the ankle to lumbar region. All the vitamin E deficient rats had abnormal EMG findings (fibrillation potentials, positive sharp waves and polyphasic activity), whereas none of the controls showed any of these signs of dysfunction.

Afferent Pathways↗
PubMed1987

Central and peripheral SEP defects in neurologically symptomatic and asymptomatic subjects with low vitamin B12 levels.

Somatosensory evoked potentials (SEPs) following median nerve stimulation were abnormal in 7 patients with sensory impairment due to vitamin B12 deficiency. Extensor plantar reflexes indicated a central sensory pathway lesion in 4 cases and absent tendon jerks suggested peripheral neuropathy in 4, but median nerve SEPs indicated a predominantly central lesion without marked peripheral nerve involvement in 6 and an axonal neuropathy without CNS involvement in 1. The latter had evidence of central slowing of conduction in SEPs following posterior tibial nerve stimulation. Consequently, it is suggested that the brunt of sensory pathway involvement usually falls on the CNS, although peripheral neuropathy may occur as the major abnormality in some cases. In 2 patients SEPs showed a marked improvement following treatment with vitamin B12 injections, one consistent with restored central conduction and the other with recovery from peripheral neuropathy. No peripheral or central SEP abnormalities were seen in 18 dairy-produce eating vegetarians with low vitamin B12 levels, although 6 reported mild sensory symptoms suggestive of peripheral neuropathy and 3 had corroborative clinical signs.

Adolescent↗
PubMed1986

Disseminated lesions at presentation in patients with optic neuritis.

Thirty five adults and two children with clinically isolated optic neuritis were examined by magnetic resonance imaging (MRI) to determine the presence of disseminated lesions within the brain at presentation and to compare these findings with the results of evoked potential studies. Of the adult patients, 61% showed lesions on the scans whereas the evoked potentials suggested the presence of lesions outside the visual system in 30%. MRI is a sensitive method for the demonstration of clinically unsuspected lesions in patients with uncomplicated optic neuritis.

Adolescent↗
PubMed1985

A study of the relationship between neurological function and serum vitamin E concentrations in patients with cystic fibrosis.

A patient with cystic fibrosis and undetectable serum vitamin E concentrations is described who developed a progressive spinocerebellar syndrome and pigmentary retinopathy with abnormal somatosensory and visual evoked potentials (SSEPs and VEPs). In order to assess the relationship between neurological function and serum vitamin E concentrations in cystic fibrosis, 29 unselected patients who had no neurological symptoms were examined neurologically. Ten were randomly selected for neurophysiological assessment by recording SSEPs and VEPs. Electroretinograms (ERGs) were also performed in five cases. The findings were correlated with serum vitamin E concentrations which were unknown to the neurological investigators prior to completion of the study. Only one patient had definite reflex and sensory abnormalities, and the remaining 28 were clinically normal. The ERG was abnormal in two cases, one of whom had abnormal VEPs. SSEPs were normal in all 10 cases. Twenty six patients had serum vitamin E concentrations below the normal range. In two of the three patients who had definite neurological or electrophysiological abnormalities serum vitamin E concentrations were below the median value for the whole group.

Adult↗
PubMed1985

Pattern- and flash-evoked potentials in the assessment and management of optic nerve gliomas.

Visual evoked potentials were recorded in 25 young patients with optic nerve glioma. In only eight patients could pattern responses be recorded from the affected eyes and these were invariably abnormal. In nine cases with no pattern responses it was still possible to elicit flash responses from the affected eyes. Six patients showed pattern evoked potential changes indicating involvement of fibres from the fellow eye crossing at the chiasm. Serial recording showed a remarkable improvement in the pattern responses of two patients. Flash responses were far less sensitive and less reliable than pattern responses in monitoring patients.

Adolescent↗
PubMed1980

Evoked potentials following unilateral ECT. I. The somatosensory evoked potential.

The somatosensory evoked potential (SEP) was recorded in 14 patients undergoing unilateral ECT for the treatment of depression. All patients received right-sided ECT. One patient was studied on a second occasion during leftsided ECT. The index and middle fingers of each hand were electrically stimulated 1/sec throughout anaesthesia, the fit and the 0.5 h period following the fit. During barbiturate anaesthesia the SEP showed the characteristic change of the P49 component and enhancement of P32, while during the seizure induced by right ECT, the SEP was seen more clearly on the left side of the head, despite the high voltage epileptic activity. No significant asymmetries of any of the SEP components were seen post-ictally, the response returning rapidly on both sides. The subjective threshold to electrical stimulation of the fingers of each hand was significantly raised following ECT.

Adult↗
PubMed1980

Evoked potentials following unilateral ECT. II. The flash evoked potential.

The flash evoked potential (VEP) was recorded in 16 depressed patients before, during and for 0.5 h following administration of unilateral ECT. In 14 the recordings were made following right ECT and in 3 following left ECT. One patient was recorded after right- and left-sided treatments administered on separate occasions. While the patients were conscious, responses were averaged with eyes open and eyes closed. During anaesthesia, ictus and post-ictal coma the response to repetitive stimulation through closed eyes was recorded continuously in sequential runs. Consistent latency differences between VEPs with eyes open and closed were established in the runs prior to treatment. In postictal coma there was a marked asymmetry in the response from the two sides. Component P140, in particular, was significantly smaller and later over the side which received ECT. On average, these asymmetries lasted less than 15 min following the treatment. A significant latency increase, common to both hemispheres, was found at the end of the recording session.

Adult↗
PubMed1980

The incidence and nature of visual pathway involvement in Friedreich's ataxia. A clinical and visual evoked potential study of 22 patients.

Pattern-reversal visual evoked potentials (VEP) were recorded from 22 patients (mean age 33.7 years) with Friedreich's ataxia, 15 of whom also had a detailed neuro-ophthalmological assessment prior to the VEP examination. None had noted symptomatic visual impairment. Eleven of the 15 (73 per cent) examined clinically had one or more neuro-ophthalmic abnormality and 14/22 (64 per cent) had an abnormal VEP study which was always binocular and comprised absent responses, or most commonly, increased P100 component latencies. The maximum P100 latency was 143 ms and the group mean was 118 ms. The P100 amplitude was also generally reduced particularly in those patients with latencies less than 115 ms (upper limit of normal), while in those with latencies above the normal range there was a significant inverse correlation between the P100 amplitude and latency. The waveform, temporal dispersion and interocular differences were normal in almost all patients with identifiable responses, including those with prolonged VEP latencies. Electroretinograms recorded from three selected patients were either normal or minimally abnormal and suggested secondary rather than primary retinal involvement. The only VEP parameter to correlate with either the duration of the generalized disease or the visual acuity was the P100 amplitude. A good correlation was found between the VEP and the clinical neuro-ophthalmic findings. Temporal pallor of the optic disc was most often associated with an abnormal VEP result and impaired visual acuity or colour vision were uncommon in the absence of VEP abnormalities. The VEP changes and those obtained from 24 age- and acuity-matched cases of demyelinating optic neuritis are contrasted and the probable pathophysiology is discussed. Two main conclusions emerge from this study. First, there is a high incidence of asymptomatic visual pathway involvement in Friedreich's ataxia which can be demonstrated by both clinical and VEP examination. Secondly, the VEP changes in Friedreich's ataxia differ from those found in typical demyelinating optic neuropathy and are consistent with progressive nerve fibre loss and associated slowing of conduction, indicating that the visual pathway is affected by the same widespread process of axonal degeneration found throughout the nervous system.

Adult↗
PubMed1978

The effect of experimental 'scotomata' on the ipsilateral and contralateral responses to pattern-reversal in one half-field.

The averaged cortical responses to a reversing checkerboard pattern presented monocularly in either left or right visual half-fields have been recorded from the occipital scalp using a transverse chain of widely spaced electrodes referred to a common mid-frontal electrode. The half-field responses showed a consistent asymmetry, the dominant feature of which was a positive wave (P100) that was widespread on the ipsilateral scalp and maximally recorded from the midline and ipsilateral electrodes. This formed part of the triphasic negative-positive-negative complex, the other two components being an N75 and an N145. On the contralateral scalp it was generally possible to record a triphasic complex of opposite polarity, but this was usually of smaller amplitude and its components (P75, N105, P135) showed greater variation in latency and morphology than the ipsilateral components. With progressive occlusion of the pattern stimulus from the central regions of the visual half-field, the ipsilateral positive wave (P100) was increasingly attenuated, while components of the contralateral complex were relatively unaffected, or, in some cases, enhanced. By contrast, reducing the radius of the stimulated area had relatively little effect on the ipsilateral P100, while the contralaterally recorded response was attenuated. These differential effects on the half-field response components are discussed in relation to the anatomy of the central and paracentral cortical representation of the visual field. The implications for the interpretation of evoked potential recordings in patients with field defects are considered.

Adolescent↗
PubMed1978

EEG immediately after unilateral ECT.

EEG was continuously recorded in 15 patients for a period extending from just before to 1/2 hour after unilateral ECT. Fourier analysis was performed on the EEG following 15 right-sided treatments and five left-sided treatments. During the induced seizure, epileptic slow-wave activity had significantly greater power on the treated side. Immediately after the seizure, there was significantly more delta activity and less alpha and beta activity on the treated side. This asymmetry, though becoming less marked, was usually still present at the end of the recording period. Analysis of other variables associated with the treatment showed that there was a significant correlation between the time to eye-opening after ECT and both the duration of the seizure and the amount of anaesthetic administered. The similarity between these induced unilateral seizures and unilateral seizures occurring spontaneously in some epileptics is discussed.

Adolescent↗