Intracranial pressure monitoring following hypoxic-ischaemic cerebral insults.
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Biomedical subjects
Publications and source records attributed to A Harden.
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Thiopentone anaesthesia was used in the treatment of seizures in 19 infants and young children. Nine had a pre-existing seizure disorder without acute cerebral injury and 10 had status epilepticus secondary to an acute cerebral illness. Clinical details, drug levels and findings from serial multichannel electroencephalograms (EEG) and continuous 1 to 2 channel signal processed EEGs using a Cerebral Function Analysing Monitor (CFAM) were reviewed to evaluate the contribution of these techniques to clinical management. Initial EEGs showed discharges that were not generalised in 16/19 patients. This necessitated the use of 7 different montages for continuous monitoring. Three different CFAM patterns representing particular EEG paroxysmal findings were seen. Acute seizure control was achieved in all 19 patients. All patients with a pre-existing seizure disorder survived, although 4/10 with an acute cerebral illness died. During treatment, patterns of burst-suppression to electrocerebral silence (ECS) were eventually seen in 16/19 patients and repeat EEGs demonstrated concordant multi-channel findings in 8/8. Although increasing thiopentone levels (13 patients) correlated with deeper suppression of cortical electrical activity, there was marked inter-patient variability. Inotropic support was not required during the period of treatment even when ECS was induced. In young children a combination of multi-channel EEG and continuous 1 to 2 channel monitoring has advantages over either method used alone. In individual patients on-line monitoring can be easily incorporated in a protocol of controlled cortical suppression and drug titration for seizure control.
EEG studies have been carried out on 52 girls with Rett syndrome, the majority of records being taken between two and 7 years of age. Discharges were a common feature, occurring in 43 patients, and did not appear to be related to the onset of seizures. The discharges, consisting of sharp waves or spikes, were characteristically most prominent around the middle third of the head, often occurring asymmetrically and could be infrequent or almost continuous. They were usually enhanced by light sleep and were seen only during sleep in 15 EEGs taken in 13 patients, most of whom were under four years of age. These EEG features when present may help confirm the diagnosis of Rett syndrome in the appropriate clinical setting and in particular are quite distinct from the usual EEG patterns seen in Angelman (Happy Puppet) syndrome.
The electroretinogram, findings, in response to a flash stimulus, was recorded from a skin electrode placed on the bridge of the nose in 4465 infants and children seen over a 10 year period. The electroretinogram was combined with a flash visual evoked potential. From this total, the electroretinographic findings in 240 patients, aged 1 day to 17 years, without suspected retinal pathology and with a normal visual evoked potential, were used as controls and normal electroretinographic parameters of different age groups defined. There were 332 patients who showed an absent or very reduced amplitude electroretinogram. They were divided into primarily ocular disorders (n = 195), neurodegenerative disorders (n = 94), and various syndromes (n = 43). Fundus examination did not always show any obvious abnormalities. The use of this simple and reliable technique for recording the electroretinogram made it possible to include this investigation as a routine procedure without the need for sedation in infants and uncooperative children. Electroretinographic studies, especially when combined with visual evoked potentials, and in some cases electroencephalography, may aid diagnosis in a wide variety of paediatric conditions, many of which have genetic implications.
An EEG study has been carried out on 19 children (including siblings in 3 families) with clinical features of Angelman syndrome. The age at time of the first EEG ranged from 11 months to 11 years with the majority under 5 years. Six children had no history of seizures at the time of the first EEG. One or more of the following EEG abnormalities were seen in all patients: 1. Persistent rhythmic 4-6/s activities reaching more than 200 microV not associated with drowsiness. 2. Prolonged runs of rhythmic 2-3/s activity (200-500 microV) often more prominent anteriorly, sometimes associated with discharges (ill-defined spike/wave complexes). 3. Spikes mixed with 3-4/s components usually more than 200 microV mainly posteriorly and facilitated by, or only seen with, eye closure. Two and sometimes three of these EEG features could be present in the same record particularly at a young age. The appearance of discharges mixed with slow components on eye closure was the commonest finding seen at some stage in 17 patients (aged from 11 months to over 12 years). The EEG features of Angelman syndrome appear to be sufficiently characteristic to help identify patients at an early age before the clinical features become obvious and at a time when genetic counselling may be particularly important.
Forty eight comatose children had electroencephalograms (EEG) recorded during the acute phase of their illnesses. These were classified according to a simple grading system and the findings correlated with the presence of seizures, deep coma, minimum cerebral perfusion pressure, and eventual neurological outcome. Serial EEGs proved important, particularly when slow activity was seen initially. None of the 20 patients who showed low amplitude EEG activity or electrocerebral silence at any stage of the acute illness did well. Discharges were seen in only 13 of the 29 patients with seizures and their presence did not correlate with outcome except in five patients with a distinctive pattern of discharges, none of whom had a good outcome. EEG findings associated with poor outcome did not always correlate with the clinical assessment of deep coma, emphasising the difficulties of neurological evaluation in these patients. Five of the patients with cerebral perfusion pressures greater than 42 mm Hg had a poor outcome that was predicted by serial EEGs. In nine patients with a minimum cerebral perfusion pressure in the borderline range 38-42 mm Hg the EEG was useful as an indication of the outcome. The EEG reflects changes in cerebral function which may be due to multifactorial or repeated insults. An EEG is therefore important in both the initial assessment and as an indicator of the neurological outcome, particularly in those patients in whom the cerebral perfusion pressure has apparently been adequate or within the borderline range.
The clinical features of eight children with infantile neuroaxonal dystrophy are presented. Diagnosis was established by brain biopsy (4 cases), conjunctival biopsy (1 case), and the family history (2 cases), while in one case a presumptive diagnosis was made on the combination of clinical and neurophysiological findings without histopathological confirmation. The pleomorphic clinical picture and variable neurophysiological findings make a firm diagnosis difficult without histopathological confirmation. However, in the appropriate clinical context, serial neurophysiological investigations (ERG, VEP, EEG, ENMG) may suggest the diagnosis after the age of 2 years. Conjunctival biopsy is not invariably helpful, and neuroaxonal spheroïds are not always demonstrated in brain biopsies by conventional techniques. However, they were consistently identified using a non-specific esterase stain and by electron microscopy. This technique is described, and the significance of ultrastructural and neuropathological findings in infantile neuroaxonal dystrophy is discussed.
A clinico-pathological entity of progressive neuronal degeneration of childhood with liver disease has now been recognised. Onset is in early childhood with intractable fits and progressive dementia. EEG/ERG/VEP studies have been carried out in 12 children with this condition. In most patients the EEG showed strikingly similar and unusual abnormal patterns (high amplitude slow activity together with smaller polyspikes). The flash VEP was usually abnormal and often asymmetrical. In the appropriate clinical setting the neurophysiological features are sufficiently characteristic to aid the clinician in early diagnosis of this autosomal recessive disorder.
The c-mos and c-myc proto-oncogenes have been assigned to bands q22 and q24, respectively, of human chromosome No. 8. A gain of chromosome No. 8 is the most common abnormality observed in myeloproliferative diseases. By using probes specific for the c-mos and c-myc genes, we have analysed the genomic DNA from peripheral blood and bone marrow samples from 15 patients with various malignant myeloid diseases, including leukemia and myelodysplasia, and from one patient with non-Hodgkin's lymphoma, all of whom have trisomy for chromosome No. 8. Except for one patient, the c-mos and c-myc genes were found in restriction fragments of germline size. In one patient with myelodysplasia, one c-myc allele was rearranged in a Hind III fragment, the other allele being normal. Thus, trisomy 8 associated with human hematologic neoplasia is generally not related to gross rearrangements of the c-mos or c-myc genes.
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Three unrelated patients with bilateral macular dysplasia ('colobomata') with no relevant family history were found to have absent or substantially abnormal electroretinograms, implying that there was an associated retinal dystrophy. This may suggest that the macular lesions are associated with a global failure of retinal development, with a regional preponderance rather than a purely localised cause such as an intrauterine infection. It is important to distinguish between congenital infections such as toxoplasmosis and developmental macular colobomata, which have a somewhat similar ophthalmoscopic appearance as a cause of bilateral macular abnormalities seen in young children, since they have different implications for genetic advice and future ophthalmic care.
Neurophysiological studies (EEG, ERG, VEP and BAEP) have been carried out on a total of fifty-four patients (fourty-five GM2 and nine GM1 gangliosidosis) at various stages of the disease process. In infantile GM2 gangliosidosis, the EEG was midly abnormal from an early age but by the age of one year there was a rapid and progressive deterioration. EEG changes in late onset GM2 gangliosidosis were very variable and unrelated to age or enzyme defect. In both Type 1 and Type 2 GM1 gangliosidosis there was a progressive deterioration of the EEG. Paroxysmal features were not prominent in any of the gangliosidoses, despite the occurrence of seizures. The ERG remained normal in both GM2 and GM1 patients. In the infantile GM2 patients there was progressive loss of the VEP between nine and fifteen months of age but the timing of VEP changes were more variable in all the other groups. Evidence of brainstem dysfunction was found in one of the two TSD patients tested. The combined neurophysiological features appear to be characteristic for each group of gangliosidosis and differ from other neurometabolic disorders of childhood.
In the initial phase of HSE the clinical symptomatology is more variable and insidious in babies and young children than in older children and adults. Combined clinical, neurophysiological and neuroradiological studies have been carried out in 12 children with proven HSE. Ten patients had the first EEGs taken during the acute phase of the illness and all showed large amplitude irregular slow activity, sharp waves and often spikes with variable distribution; in 7 cases periodic phenomena were recognisable. At a later stage localised low amplitude EEG activities were found in children with focal neurological symptoms. Areas of low attenuation were seen in the CT scans of the 7 children who had this investigation done at an early stage of their illness. Such low density regions persisted at follow-up and eventually cerebral atrophy with irregular features became obvious. Prompt EEG investigations combined with CT scans provide an early diagnostic clue for treatment. Follow-up EEG studies (including VEP) and CT scans may help assess the severity of residual cerebral damage in the survivors.
Neurophysiological studies (EEG, ERG, VEP) have been carried out on 8 children with proven GM1 gangliosidosis (3 of Type I and 5 of Type II). All the EEGs were abnormal showing an increasing amount of irregular slow activity as the disease progressed. Around 2 to 3 years of age, Type II patients often showed a fluctuating 4-5 c/s rhythmic activity especially prominent in the temporal regions. Paroxysmal activity was not a conspicuous feature in any of the patients. The ERG was normal in all cases but the VEP was variably altered. The EEG/ERG/VEP findings in GM1 gangliosidosis differ from those seen in most other neurometabolic disorders of childhood.
Neurophysiological investigations (EEG, ERG, VEP) were carried out in 13 patients with proven "mitochondrial myopathy". There were nine girls and four boys. Varied abnormalities were seen in the EEGs of all cases, and in one patient unusual repetitive bursts of irregular slow waves and spikes were observed. The ERG was abnormal in five of the 12 cases tested, while the VEP (flash) was definitely abnormal in six out of these 12 cases. These neurophysiological findings suggest some involvement of both the brain and the visual system. It seem therefore appropriate that this condition be considered a "mitochondrial disease" affecting many systems rather than only muscles.
Neurophysiological investigations (EEG, ERG, VEP) were carried out in 14 boys with adrenoleucodystrophy, and in two siblings with adrenocortical deficiency, but without neurological symptoms. Irregular large amplitude (200-800 microvolts) slow activity was found in the EEG of all adrenoleucodystrophy patients, usually more prominent over the posterior regions of the brain. No short duration spikes or complex wave were seen in any of the EEGs, even in those patients who had had seizures. Clinical deterioration was not always accompanied by an increase in EEG abnormalities. The ERG was of usual amplitude and wave form, while the VEP (flash) was altered in four cases. The two clinically unaffected siblings had normal ERG/VEP, and only a modest excess of slow waves in the EEG. The neurophysiological findings in adrenoleucodystrophy are not seen in other diseases with similar clinical symptoms in the same age group.
Repeated neurophysiological investigations over a six year period are reported in two children with histologically proven Alexander's leucodystrophy. The EEG alterations were already detectable at an early stage of the disease with subsequent progressive deterioration in both cases. There was no definite abnormality in the ERG-VEP studies which were only carried out in the younger patient. The EEG features in the course of the illness are different from those seen in most of the identified genetically determined neurometabolic diseases as well as in the group of so-called leucodystrophies of similar age groups. However, the EEG-ERG-VEP features are not sufficiently characteristic to be diagnostic.
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