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Biomedical subjects

Roderick Duncan

Publications and source records attributed to Roderick Duncan.

8 recordsLinked to original sources
PubMed2006

Late onset psychogenic nonepileptic attacks.

OBJECTIVE: To investigate differences between groups of patients with early vs late onset psychogenic nonepileptic attacks (PNEA). METHODS: The authors compared patients with onset of PNEA after age 55 years (n = 26) to patients whose onset of PNEA was before age 55 years (n = 241). The authors examined sociodemographic variables, factors potentially predisposing to PNEA, clinical semiology, and medical and psychiatric background. RESULTS: Patients with late onset PNEA were more likely to be male (p = 0.029) (p values are quoted uncorrected for multiple comparisons). They were less likely to report antecedent sexual abuse (p = 0.008), and more likely to have severe physical health problems (p < 0.001) and to report health-related traumatic experiences (p < 0.0001). There were no clear differences in PNEA clinical semiology. There was a trend to better baseline mental health in the late onset group. CONCLUSIONS: The data suggest a distinct subgroup of patients with late onset psychogenic nonepileptic attacks, in whom psychological trauma related to poor physical health plays a prominent role.

Age Distribution↗
PubMed2006

The withdrawal of antiepileptic drugs in patients with non-epileptic seizures: safety considerations.

The majority of patients with psychogenic non-epileptic seizures (PNES) do not have epilepsy. There are a number of compelling reasons to take these patients off antiepileptic drugs (AEDs), including drug toxicity and teratogenicity, as well as possibly poorer outcome of PNES and increased risk of iatrogenic harm when patients present to emergency rooms on AEDs as emergencies. However, many patients with PNES who do not have epilepsy remain on AEDs postdiagnosis. Some studies do report patients taken off medication as an outcome measure, but with no assessment of the safety of withdrawal, or specification of the criteria for 'excluding' epilepsy. One study has assessed the safety of taking patients satisfying some simple criteria for the absence of an underlying epilepsy off AEDs, and has found the procedure to be safe, given appropriate postwithdrawal follow-up. Patients with PNES who do not have evidence of epilepsy should be referred to a centre with appropriate expertise in epilepsy diagnosis so that AEDs can be withdrawn in safe conditions.

Adult↗
PubMed2005

Recollection of vivid memories after perirhinal region stimulations: synchronization in the theta range of spatially distributed brain areas.

Electrical stimulation of the temporal cortex in patients with epilepsy sometimes elicits experiential phenomena such as recollection of vivid memories. The neurophysiological substrate of such phenomena is poorly understood. Furthermore, the relation between the site of stimulation and the type of memory elicited has only recently started to be investigated. We investigated these issues in patient FGA who had intracerebral electrodes stereotaxically implanted in the right temporal lobe for investigation of drug-resistant epilepsy. We report the results of electrical stimulations of the perirhinal region. Two stimulations elicited experiential phenomena consisting of visual memories that belonged to FGA's past, but which were not related to any particular episode. These visual memories consisted of objects or of details of objects. These two stimulations were contrasted with other stimulations in the same subhippocampal region. Cross-correlation analysis of the depth-EEG signals filtered in frequency sub-bands revealed that experiential phenomena occurred only when the various brain structures involved in the after-discharge were synchronized in the theta range. These structures included the perirhinal region, the hippocampus, other limbic structures as well as a primary visual area. Our results suggest that recollection of vivid memory after electric stimulation of the cortex may rely on wide networks of brain areas that transiently synchronize. These results also highlight the role of the perirhinal region in human memory. Experiential phenomena are rarely obtained after brain stimulation. Replication of these results is thus required due to the small number of observations reported.

Adult↗
PubMed2005

Dose-dependent safety and efficacy of zonisamide: a randomized, double-blind, placebo-controlled study in patients with refractory partial seizures.

PURPOSE: To evaluate the safety and efficacy of zonisamide (ZNS) as adjunctive treatment in patients with refractory localization-related epilepsy. METHODS: This was a double-blind, placebo-controlled study of adjunctive ZNS in 351 patients with refractory partial seizures receiving a stable regimen of one to three antiepileptic drugs (AEDs). Patients were randomized to placebo or ZNS, 100 mg, 300 mg, or 500 mg/day (2:1:1:2) after a 12-week baseline. Dose titration was undertaken over a 6-week titration phase, which was followed by an 18-week fixed-dose assessment phase. Primary efficacy parameters were the differences between ZNS, 500 mg/day, and placebo in the change from baseline in frequency of complex partial (CP) seizures during the fixed-dose assessment phase and in the proportion of CP responders (> or =50% decrease from baseline in seizure frequency). Safety and tolerability also were assessed. RESULTS: Compared with placebo, the highest dose of ZNS (500 mg/day) resulted in a significantly greater decrease in CP seizure frequency from baseline (51.2% vs. 16.3%; p < 0.0001) and a significantly higher proportion of CP responders (52.3% vs. 21.3%; p < 0.001). Both ZNS, 500 mg/day, and 300 mg/day were statistically superior to placebo in reducing the frequency of "all seizures" and simple partial (SP) + CP seizures. For all seizures, a significant dose-response relation was observed (p < 0.0001). The most common adverse events were somnolence, headache, dizziness, and nausea during the titration phase and headache and pharyngitis during the fixed-dose assessment phase. CONCLUSIONS: ZNS provides dose-dependent, effective, and generally well-tolerated adjunctive therapy in patients with partial seizures.

Adolescent↗
PubMed2003

Perspectives on epilepsy in people with intellectual disabilities: comparison of family carer, staff carer and clinician score profiles on the Glasgow Epilepsy Outcome Scale (GEOS).

PURPOSE: Clinical practice with people with intellectual disability relies heavily upon caregiver report. Crucially, the carer's perspective may depend upon his or her relationship to the patient. We investigated similarities and differences within and between family and paid carers in their reports on the Glasgow Epilepsy Outcome Scale (GEOS), an instrument that quantifies concerns about epilepsy in this population [Epilepsia 42 (2001) 1043]. METHODS: GEOS forms were available on 186 patients (108 males; mean age 39 years) across 384 primary respondents (141 staff, 83 family, 160 clinicians) and independently completed secondary respondents (67 staff, 36 family). Data were analysed to consider levels of concern as rated bv staff carers, family members and clinicians, and also to consider inter-rater agreement on the concerns raised. RESULTS: There were significant differences in the magnitude of concern on each sub-scale [concerns about seizures, treatment, caring and social impact; range of F(2,171)=9.5-64.7; all P<0.0001]. Post hoc testing revealed that family members scored all sub-scales more highly than staff carers or clinicians, and that staff carers scored more highly than clinicians on all but one sub-scale. Inter-rater agreement between family members was considerably higher (range of r=0.69-0.91) than between staff carers (r=0.30-0.47) across the GEOS sub-scales. Association between staff and family ratings was also modest (r< or = 0.39). CONCLUSIONS: It is preferable for the same staff member to complete each administration of the GEOS because of inter-staff variability in reporting of concerns. Families provide a consistent, but more extreme, picture and clinicians generally underestimate the concerns of direct caregivers. However, content of concerns varies relatively little across respondents.

Adult↗
PubMed2002

Investigation into the mechanisms of vagus nerve stimulation for the treatment of intractable epilepsy, using 99mTc-HMPAO SPET brain images.

Vagus nerve stimulation (VNS) has gained recognition as a treatment for refractory epilepsies where surgical treatment is not possible. While it appears that this treatment is effective in some patients, the mechanism of action is not clearly understood. The purpose of this study was to clarify findings of other positron emission tomography and single-photon emission tomography (SPET) investigations by measuring the acute effect of VNS on patients who have normal cerebral anatomy on magnetic resonance imaging and who have not previously been exposed to VNS. We investigated six subjects (two males and four females, mean age 29.5 years, range 21-39 years) with intractable epilepsy. One patient had primary generalised epilepsy causing generalised tonic-clonic seizures; the remaining five patients had localisation-related epilepsy causing complex partial seizures. SPET imaging was performed using 250 MBq of (99m)Tc-HMPAO and a four-scan paradigm - two with and two without stimulation. The stimulation began at VNS current levels of 0.25 mA and was increased according to the limit of patients' tolerance, usually defined by coughing or discomfort. The stimulating waveform was of continuous square wave pulses of 500 micro s duration at 30 Hz. Image analysis was by SPM99. Reduced perfusion during stimulation was observed in the ipsilateral brain stem, cingulate, amygdala and hippocampus and contralateral thalamus and cingulate. The study provides further evidence of the involvement of the limbic system in the action of vagal nerve stimulation.

Adult↗