PubMed Health⌕ Search

Biomedical subjects

P B Fenwick

Publications and source records attributed to P B Fenwick.

At least 37 records · Page 2Linked to original sources
PubMed1989

Evoked and psychogenic epileptic seizures: II. Inhibition.

The inhibition of seizure activity by behavioural methods is becoming more popular. Lockhart's monkey model of focal epilepsy suggests a theoretical approach to behavioural seizure inhibition. Behaviour, by changing the pattern of excitation and inhibition surrounding a focus, is thus able to inhibit seizure activity. This article describes single case studies in which the behavioural methods of cued arousal, covert desensitization and relaxation have brought about a decrease in seizure frequency.

Adult↗
PubMed1988

Effects of nitrous oxide on auditory cortical evoked potentials and subjective thresholds.

This study has examined the effects of inhaled nitrous oxide on the N1 and P2 components of the cortical auditory evoked potentials (AEP) in the latency interval 80-300 ms after the stimulus. The amplitudes, latencies and thresholds of the AEP were measured at a range of end-tidal nitrous oxide concentrations (0%, 10%, 20%, 40%) in 10 subjects with normal hearing. Systematic decreases in amplitude and latency were observed with an increase in threshold. A study of the effect of stimulus intensity on AEP amplitude showed that the amplitude change with nitrous oxide was accounted for largely by systematic increase in evoked potential threshold. Subjective pure tone thresholds were not affected by the concentrations of nitrous oxide used, indicating that the AEP changes were independent of subjective hearing level.

Adolescent↗
PubMed1988

The aetiology of aggression in temporal-lobe epilepsy.

A retrospective case-note survey was carried out on 31 subjects admitted with temporal-lobe epilepsy to the Maudsley hospital from 1974-1983 inclusive. Fourteen aggressive subjects were compared with the non-aggressive patients on 95 organic, developmental, and social variables. Aggressive behaviour was associated with male sex, early onset of seizures, and a history of long-standing behavioural problems. Aggressive subjects had lower mean IQ scores and poorer occupational records than controls. No relationship was found between aggression and the presence of specific EEG or CAT scan findings, or a history of psychosis. The results demonstrate the complex interplay between organic and socially mediated factors underlying aggressive behaviour in temporal-lobe epilepsy.

Adolescent↗
PubMed1987

Effect of oestrogen and testosterone implants on psychological disorders in the climacteric.

In a double-blind trial oestradiol, oestradiol/testosterone, or placebo implants were assessed for their effects on psychological symptoms in women attending a menopause clinic. After two months, women receiving active treatment scored better than the placebo group on a self-rating scale of distress, on anxiety, and on depression (p less than 0.05). Postmenopausal but not perimenopausal women improved after placebo, and at 4 months the scores in the three groups no longer differed significantly.

Adult↗
PubMed1986

Nocturnal penile tumescence and serum testosterone levels.

Ten patients with chronic epilepsy were selected; five had high and five had low total serum testosterone levels. Each patient slept for two nights in the sleep laboratory. EEG monitoring and measurements of nocturnal penile tumescence were carried out during sleep. A clear relationship between both total and free serum testosterone levels were found with nocturnal penile tumescence. FSH, LH, SHBG, and prolactin showed no relationship. The five patients with low serum testosterone levels all showed reduced sexual activity.

Adolescent↗
PubMed1986

Epilepsy and handicap from birth to age 36.

Fifty-five subjects with epilepsy were identified in the first 36 years of the 1946 birth cohort study. In 37 cases there was neither evident cause for the epilepsy nor associated brain-damage and these are referred to as 'uncomplicated', the rest as 'complicated'. Subjects with epilepsy came from poorer social backgrounds than the rest of the cohort. Mortality for both the complicated and uncomplicated groups was high. The educational and occupational achievements, marriage and parenthood, self-esteem and psychiatric morbidity of those surviving to adult life were compared with individually matched controls drawn from the same population. For the uncomplicated group there was no evidence of handicap at age 26, but 10 years later handicap was evident in this group in the economic sphere and in self-esteem.

Adult↗
PubMed1985

Sexual behaviour in a centre for epilepsy.

The sexual behaviour and hormonal profiles in 97 patients with chronic epilepsy from an epilepsy centre were studied. Sexual behaviour relating to numbers of sexual contacts, orgasms, spontaneous erections, and early morning erections, whether there was difficulty in obtaining or maintaining an erection, or in ejaculation, was assessed at interview. Hormonal profiles consisted of LH, FSH, prolactin, total testosterone, free testosterone, and SHBG. Information was obtained relating to type of seizure, seizure frequency, age of onset, likely pathology, IQ, and medication. The study showed that this patient group was profoundly hyposexual and had a high level of sexual dysfunction. Serum free testosterone levels were low, and it is suggested that the high level of sexual dysfunction and lack of sexual interest may well have a hormonal basis. The reasons for this are discussed.

Adolescent↗
PubMed1984

Changes in the pattern reversal visual evoked potential as a function of inspired nitrous oxide concentration.

The VEP to pattern displacement was measured at different levels of inspired N2O concentrations in air in 10 normal subjects. The inspired concentrations were 10, 20, 30 and 40% N2O. Expired CO2 concentrations were also measured. Ten normal controls went through the same procedure but breathed air on each trial rather than N2O. The results showed a significant decrease at 10%, almost at 20% and again significant at 30% and 40% for the amplitude of the N65-P95 wave. The P95-N125 wave was more resistant--10% was not significant, 20% was again nearly significant and 30% and 40% were significant. There were no latency changes. Because of the wider variance between group comparisons there was a significant reduction at 40% only for the N65-P95 wave and no significant difference for the P95-N125 wave. There was some evidence that the amplitude of the early components was still significantly reduced after the end of the experiment.

Adult↗
PubMed1984

Stigma in patients with early epilepsy: a national longitudinal study.

Forty six cases of epilepsy were identified from the National Survey of Health and Development. An index of social visibility at school was constructed from teachers' reports of survey members' behaviour at 15 years of age. For the sample as a whole this index was significantly associated with poorer educational outcomes, after adjusting for social background and measured attainment, but was not associated with poor occupational achievement. However the index did not differentiate between epileptic and non-epileptic children. Although cases with epilepsy were shown to be more at risk of psychiatric disturbance, it is concluded that their lives were less disrupted than might have been expected, and that there is no evidence from this study that stigma affects the lives of those whose epilepsy was not complicated by other pathologies.

Adolescent↗
PubMed1984

The contingent negative variation, personality and antisocial behaviour.

Using a classical click/flash paradigm the contingent negative variation (CNV) was recorded from 60 consecutive male admissions to Broadmoor Hospital. Clinical and psychometric Minnesota Multiphasic Personality Inventory (MMPI) assessments were made independently of the electroencephalography (EEG) data. A trend for higher amplitude CNV's to be recorded from patients with a clinical diagnosis of antisocial (psychopathic) personality was observed. Patients with a Mental Health Act diagnosis of psychopathic disorder had significantly higher voltage CNV's than those in the mental illness category. These CNV differences were only found in the primary (non-anxious, sociable) psychopaths. Secondary (neurotic, unsociable) psychopaths did not differ from staff controls. A positive association between CNV voltage and the personality factor of sociability(sociable-shy dimension) was observed. A weak, negative correlation between CNV amplitude and impulsivity (impulsive-controlled dimension) was also apparent. All subjects showed an habituation effect across trials. No difference in response variability between successive series of trials was apparent in any of the patient groups.

Antisocial Personality Disorder↗
PubMed1983

Acne and anticonvulsants.

The severity of acne and rate of excretion of sebum were assessed in 243 patients with epilepsy taking various anticonvulsants who were in hospital long term and in matched controls derived from a normal population of 2176 people. Neither the prevalence of acne nor the sebum excretion rate significantly increased in the patients compared with the controls or in patients taking phenytoin compared with those not. It is concluded that anticonvulsant treatment does not cause acne.

Acne Vulgaris↗
PubMed1983

Changes in the visual evoked potential to pattern reversal with lithium medication.

Previous reports in the literature have suggested that lithium medication does not affect the VEP to flash stimulation. It was predicted that this would not be true for pattern reversal stimulation. Seven patients had their pattern evoked potential measured using a 42' check to fractional pattern displacement of 1/4, 1/2, 3/4 and full square. The VEP was measured before, 1 week after and 5 weeks after the commencement of lithium medication. The results show that there is a significant increase in both the N65-P95 and P95-N125 amplitudes when the 'before lithium' sessions are compared to 'after lithium.' Seven normal subjects matched for the age and sex of the patient group were tested twice, once as a 'control' and a further 5 weeks after this. No significant differences were found in the 'control' sessions between patient and normal groups although a significant difference in both the N65-P95 and P95-N125 amplitude after the treatment of the patient group with lithium was found.

Adult↗
PubMed1981

The visual evoked response to pattern reversal in 'normal' 6-11-year-old children.

The visual evoked response to a 7 mm (40') check using a pattern reversal stimulus was measured in 73 normal children, aged 6-11. Full pattern displacement for the right and left eye and 1/4 and 1/2 pattern displacement for the right eye were studied. The amplitudes of the N65-P95 and P95-N125 wave, together with the P95 latency, were measured. Analysis of the data showed that there was no clear relationship between the mean amplitude or latency of the evoked response and age. However, significant changes were found between linear displacement and linear age for the N65-P95 wave and there was a complex interaction for the same wave between age, sex and eye. There was a significant difference in latencies between right and left eye between the boys and the girls, with the boys having longer latencies. There are thus both age- and sex-related differences in the amplitude and latency of the N65-P95 wave in 6-11 year-old children.

Brain↗
PubMed1980

Sex hormone changes in male epileptics.

Mean plasma levels of LH, FSH, PRL, and sex-hormone binding globulin (SHBG) were raised in twenty-seven epileptics on anticonvulsants compared with age matched controls. Sexual activity appeared to be reduced. Anticonvulsant therapy results in raised SHBG levels which may be associated with a lowered free testosterone level as indicated by raised LH levels and lowered sexual activity.

Adult↗
PubMed1980

EEG spectral analysis in schizophrenia.

Four channels of EEG (T4-T6, P4-02, T3-T5, P3-01) were recorded from several groups of control subjects and schizophrenia patients on analogue tape. They were later digitized and analysed by computer; power spectra were computed for 30 second epochs of EEG per channel; eyes closed, eyes open. No difference between normal controls and neurotic in-patients was apparent. An acute schizophrenic group had less alpha power, this change being confined largely to the temporal areas. A chronic outpatient sample showed less alpha and beta power, while chronic long-stay schizophrenic patients had an excess of delta power. The changes in both chronic patient groups were diffuse rather than local.

Acute Disease↗
PubMed1978

The contingent negative variation in antisocial behaviour: a pilot study of Broadmoor patients.

Using a classical click/flash paradigm, the CNV was recorded from the following three groups of subjects at Broadmoor Hospital: (1) 14 'psychopathic' patients selected by use of the 4/9 MMPI profile and confirmed by independent clinical diagnosis; (2) 15 'non psychopathic' patients, all psychotic and mainly schizophrenic; (3) 14 healthy staff control subjects. All three groups were matched for age and sex; the two patients groups were also matched for length of stay. Two series of 32 paired stimuli were used, separated by an interval of 30 minutes. The mean CNV voltage was significantly lower in the 'non-psychopathic' patients. The amplitude of the 'psychopath's' CNV response did not differ significantly from that of the staff controls, but the response variability between the first and second series of trials was much greater in the 'psychopathic' patients than in the other two subject groups. The 'psychopathic' subjects tended to show more rapid initial development of the CNV.

Adult↗