[Magnesium, an electrolyte worth noticing].
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Animals↗
Biomedical subjects
E Mervaala
Publications and source records attributed to E Mervaala.
Long-term cognitive and EEG effects of tiagabine in drug-resistant partial epilepsy.
A new anti-epileptic drug, tiagabine, is a potent inhibitor of GABA uptake into neurons and glia. Tiagabine has shown promising efficacy and safety profiles as add-on treatment for partial seizures. We evaluated the long-term effects of tiagabine on cognition and EEG in 37 patients with partial epilepsy. The study protocol consisted of a randomized, double-blind, placebo-controlled, parallel-group add-on study and an open-label extension study. During the 3 month double-blind phase at low doses (30 mg/day) tiagabine treatment did not cause any cognitive or EEG changes as compared with placebo. Tiagabine treatment did not cause deterioration in cognitive performance or produce any rhythmic slow-wave activity or other constant, new abnormalities on EEG during longer follow-up with successful treatment on higher doses after 6-12 months (mean 65.7 mg/day, range 30-80 mg/day) and after 18-24 months (mean dose 67.6 mg/day, range 24-80 mg/day). The daily dosages in the long-term follow-up of the present study are higher than in the previous reports.
Adolescent↗
Interrelationships between salt and fish oil in stroke-prone spontaneously hypertensive rat.
The cardiovascular effects of a partially purified extract of fish oil, enriched in the n-3 series fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were studied in stroke-prone spontaneously hypertensive rats (SHR-SP) fed with high- and low-sodium diets during 5 weeks. Addition of salt to the low-salt control diet at a level commonly found in human food items (6% NaCl of the dry weight of the diet) produced a remarkable rise in blood pressure, an increase in left ventricular weight-to-body weight ratio (LVH-index) and an increase in kidney weight-to-body weight ratio (RH-index). Fish oil (20% of the dry weight of the diet) did not significantly influence the blood pressure or LVH-index or RH-index during the low-salt control diet. However, fish oil completely prevented the remarkable rise in blood pressure and clearly antagonized the rise of both LVH- and RH-indices, induced by the high-salt diet. The fish oil supplementation increased the levels of the polyunsaturated fatty acids of the n-3 series and decreased those of the n-6 series in plasma and kidney, irrespective of the salt content of the diet. Fish oil lowered serum thromboxane B2 concentration by approximately 75%. During the high-salt diet, fish oil markedly decreased water intake and urine volume, and increased urinary sodium concentration by about 60%. Our findings show that, in addition to an antihypertensive effect, fish oil also decreases LVH and RH. These effects appear to be due to an improved ability to excrete sodium and could be explained by the observed changes in the fatty acid composition and metabolism.
Animals↗
Adherence to and population impact of non-pharmacological and pharmacological antihypertensive therapy.
Efforts in Finland to implement the recommended non-pharmacological and pharmacological principles for the control of hypertension, stroke and ischaemic heart disease have been accompanied by an approximately 10 mm Hg fall in the population average of diastolic blood pressure, and about 60% decrease in deaths from both stroke and ischaemic heart disease among 30-59-year-old men and women from 1972 to 1992. Adherence to antihypertensive drug therapy has been quite good. However, the drug treatment does not seem to account for more than 5-6% of the observed fall of blood pressure, and 10-15% of the decrease in deaths from strokes and ischaemic heart disease. There has been no overall adherence to several non-pharmacological recommendations, and marked increases in the intake of alcohol, obesity among men, and smoking among women have been observed. However, the population adherence to recommendations to decrease the intakes of sodium and saturated fats, and to reduce the sodium-to-potassium ratio and the saturated-to-unsaturated fat ratio, has been good. These dietary changes appear to account for a major part of the fall of blood pressure and the decrease in the cardiovascular diseases. Currently a rapid further population-wide decrease in the dietary sodium-to-potassium ratio is taking place, due to a decrease in the use of salt and replacement of common salt by a novel sodium-reduced, potassium-, magnesium-, and l-lysine HCI-enriched salt, both in home kitchens and in the food industry.
Adult↗
Natural history of peripheral neuropathy in patients with non-insulin-dependent diabetes mellitus.
BACKGROUND: There is little information on the incidence and natural history of neuropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). METHODS: We studied patients with newly diagnosed NIDDM and control subjects both at base line and 5 and 10 years later. Polyneuropathy was diagnosed on the basis of clinical criteria (pain and paresthesias) and electrodiagnostic studies (nerve conduction velocity and response-amplitude values). We investigated the relation between metabolic variables (results of oral glucose-tolerance tests, serum lipid and insulin concentrations, and glycosylated hemoglobin values) and the development of polyneuropathy. RESULTS: In 10 years, 36 patients with NIDDM and 8 control subjects died; 86 patients and 121 control subjects completed the study. When the study ended, 18 percent of the patients were being treated only with diet, 59 percent with oral hypoglycemic drugs alone, 12 percent with insulin alone, and 11 percent with both insulin and oral hypoglycemic agents. At base line the prevalence of definite or probable polyneuropathy among the patients with NIDDM was 8.3 percent, as compared with 2.1 percent among the control subjects. These values 10 years later were 41.9 percent and 5.8 percent, respectively. The number of patients with NIDDM who had nerve-conduction abnormalities in the legs and feet increased from 8.3 percent at base line to 16.7 percent after 5 years and to 41.9 percent after 10 years. The decrease in sensory and motor amplitudes, indicating axonal destruction, was more pronounced than the slowing of the nerve conduction velocities, which indicates demyelination. Among the patients with NIDDM, those with polyneuropathy had poorer glycemic control than those without. Low serum insulin concentrations before and after the oral administration of glucose were associated with the development of polyneuropathy, regardless of the degree of glycemia. CONCLUSIONS: The prevalence of polyneuropathy among patients with NIDDM increases with time, and the increase may be greater in patients with hypoinsulinemia.
Blood Glucose↗
Vigabatrin vs carbamazepine monotherapy in patients with newly diagnosed epilepsy. A randomized, controlled study.
OBJECTIVE: To evaluate the efficacy, safety, and cognitive effects of initial vigabatrin monotherapy compared with initial carbamazepine monotherapy in patients with newly diagnosed epilepsy. DESIGN: Open, randomized, controlled design. Follow-up period of 12 months. SETTING: University hospital with an epilepsy center. PATIENTS: A total of 100 patients, aged 15 to 64 years, classified as suffering from partial seizures and/or generalized tonic-clonic seizures were randomized to either vigabatrin or carbamazepine monotherapy. Fifty-nine patients with a single epileptic seizure and no antiepileptic drug treatment served as a control population for objective safety measures. OUTCOME MEASURES: To evaluate the comparative efficacy and toxicity of vigabatrin and carbamazepine, the drug success rate (ie, the proportion of patients continuing successful treatment with the randomly assigned drug) after 12 months of steady-state treatment was used. To evaluate the safety of the drugs in addition to reported side effects, visual evoked potential recordings and neuropsychological evaluation were performed during follow-up. RESULTS: During the 12-month follow-up period, 60% of patients receiving vigabatrin and carbamazepine were treated successfully. Vigabatrin caused fewer side effects that required discontinuation of therapy. However, vigabatrin had to be discontinuated more often owing to lack of efficacy, and fewer of the successfully treated patients receiving vigabatrin achieved total freedom from seizures. Vigabatrin had no detrimental effects on cognitive functions. Retrieval from both episodic and semantic memory and flexibility of mental processing improved significantly in patients successfully treated with vigabatrin. CONCLUSION: Vigabatrin seems to be an effective and safe antiepileptic drug as primary monotherapy for epilepsy with fewer cognitive side effects than carbamazepine.
Adult↗
Lateralization of event-related potentials during discontinuation of antiepileptic medication.
The effect of short-term withdrawal of antiepileptic drugs (AEDs) on auditory event-related potentials (ERPs) was studied in 16 patients undergoing preoperative evaluation for epilepsy surgery. ERPs were performed for all patients during treatment with full medication and after a 1-week period during ongoing tapering of AEDs. To clarify whether AED discontinuation would provide evidence of lateralizing for ERPs, we also studied the subgroup of 9 patients who had already undergone temporal lobectomies (TLE group). In the TLE group, if habitual seizures occurred < 30 h before the ERP recording session, auditory N1 and P3 amplitudes across sphenoidal electrodes were markedly decreased on the side ipsilateral to the epileptic focus. If seizures did not occur, asymmetries in amplitudes were equivocal and not of lateralizing value. In the whole group, midline N1 latencies for standard responses decreased significantly during AED discontinuation. At baseline, long-term habituation of the N1 component for standard responses was attenuated as compared with that of controls. During AED discontinuation, however, enhanced habituation of N1 was observed in TLE patients who did not exhibit seizures before ERP recording.
Adolescent↗
Spectral EEG during short-term discontinuation of antiepileptic medication in partial epilepsy.
The effect of short-term discontinuation of antiepileptic drugs (AEDs) on spectral analysis of EEG background activity (spectral EEG) was studied in patients undergoing preoperative evaluation for epilepsy surgery. We also wished to clarify whether AED discontinuation would provide lateralizing evidence in spectral EEGs of patients with temporal lobe epilepsy (TLE). Spectral EEGs were performed in 15 patients receiving their regular medication regimen and again after a 1-week period during AED withdrawal. A subgroup of 9 patients who had previously undergone temporal lobectomies (TLE group) was studied separately. In this group, we evaluated the effect of preceding seizures on spectral EEG derived from temporal neocortical areas. In all patients, spectral EEG changes were detected even after a short-term AED withdrawal. The total amount of absolute delta activity was reduced and occipital peak frequency and relative alpha activity were increased as compared with baseline values. In TLE patients with habitual seizures occurring < 20 h before the spectral EEG recording, lateralization was correctly identified by the greater amount of absolute delta activity ipsilateral to the epileptogenic focus. Epileptic seizures are accompanied by subtle focal slowing in spectral EEG for a much longer period than has been assumed. In addition, postictal spectral EEG over the temporal lobes may have lateralizing value. Further studies in larger numbers of patients are needed to evaluate the role of spectral EEG in the preoperative evaluation of patients for temporal lobe surgery.
Adolescent↗
Preoperative EEG predicts memory and selective cognitive functions after temporal lobe surgery.
Preoperative and postoperative cognitive and memory functions, psychiatric outcome, and EEGs were evaluated in 32 epileptic patients who underwent temporal lobe surgery. The presence and location of preoperative slow wave focus in routine EEG predicted memory functions of the non-resected side after surgery. Neuropsychological tests of the function of the frontal lobes also showed improvement. Moreover, psychiatric ratings showed that seizure free patients had significantly less affective symptoms postoperatively than those who were still exhibiting seizures. After temporal lobectomies, successful outcome in postoperative memory functions can be achieved in patients with unilateral slow wave activity in preoperative EEGs. This study suggests a new role for routine EEG in preoperative evaluation of patients with temporal lobe epilepsy.
Adolescent↗
Dietary salt and blood pressure.
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Data Interpretation, Statistical↗
Does technetium-99m bicisate image local brain metabolism in late ictal temporal lobe epilepsy?
Ictal increase in regional cerebral blood flow as judged by single-photon emission tomography (SPET) is a common phenomenon during focal epileptic seizures. Up to 2 min postictally, regional hyperperfusion is a consistent finding with technetium-99m hexamethylpropylene amine oxime (HMPAO) in temporal lobe epilepsy. A new 99mTc-labelled lipophilic cerebral blood flow imaging agent, bicisate, has considerably longer radiochemical stability and yields better image quality than 99mTc-HMPAO. In this report, we present the case of a 21-year-old female patient with temporal lobe complex partial seizures. Magnetic resonance imaging revealed right hippocampal sclerosis. A dose of 550 MBq of 99mTc-bicisate was injected 35 s after the onset of a seizure during intracranial EEG-videotelemetry. At the moment of injection, subdural EEG demonstrated the beginning of late ictal discharges and postictal suppression in the right temporomesial areas. Late ictal SPET images showed marked right fronto-temporo-parietal hypoactivity. The interictal SPET study clearly showed right frontotemporal hypoactivity. These preliminary data suggest that 99mTc-bicisate shows late ictal/early postictal hypoactivity which might represent the primary change in neuronal metabolism rather than the secondary change in cerebral blood flow.
Adult↗
Cortical reactivity in progressive myoclonus epilepsy.
We studied 4 patients with progressive myoclonus epilepsy (Unverricht-Lundborg disease; ULD). Somatosensory evoked fields (SEFs), auditory evoked fields (AEFs), and spontaneous activity over the somatomotor cortex were recorded with a 24-channel SQUID gradiometer. All patients had "giant" 20-45 msec median nerve SEFs at the first somatomotor cortex, with 2-6 times larger amplitudes than the healthy control subjects. Later deflections were not similarly enhanced. The dependence of SEF amplitudes on interstimulus interval (0.2-4 sec) and on successive ulnar-median nerve stimulation (stimulus interval 40 msec) was comparable to that in controls. Cortical AEFs were attenuated and delayed. In 3 patients, the spontaneous activity consisted of 6-8 Hz mu rhythm, which originated within 2 cm from the sources of SEFs and was abolished by clenching of the contralateral fist. Control subjects had major spectral peaks around 10 and 20 Hz. The SEF amplitudes and the strength of the 6-10 Hz mu correlated strongly, suggesting that some components of evoked and spontaneous activity obtain contributions from overlapping neuronal populations. The results imply that ULD is associated with thalamo-cortical hyperreactivity in the sensorimotor but not in the auditory system.
Acoustic Stimulation↗
Electrophysiological and neuropsychological effects of a central alpha 2-antagonist atipamezole in healthy volunteers.
We studied the electrophysiological and neuropsychological effects of acute modulation of central noradrenergic (NA) transmission using a specific alpha 2-antagonist atipamezole (ATI) in sic healthy volunteers. ATI had effects on resting EEG, auditory event-related potentials and neuropsychological tests. Quantitative EEG revealed increased total power in frontal, parietal and temporo-occipital areas without significant changes in the mean or peak frequencies. Event-related potentials showed no effects on the active attention-related processing negativity or the passive mismatch negativity, but frontally recorded mean amplitude of target-P300 was decreased. Neuropsychological tests after ATI revealed improvement in Digit Span, more errors in Word Recognition task, and no effects on Moss spatial recognition task. In healthy subjects with intact NA systems and without any attention deficit, ATI produced evident NA overactivity. ATI decreased the spontaneous thalamocortical oscillation of EEG and improved focused attention (Digit Span). It impaired, however, more divided attention (decreased mean P300 amplitude, increased errors in Word Recognition).
Adrenergic alpha-Antagonists↗
Long-term antiepileptic efficacy of vigabatrin in drug-refractory epilepsy in mentally retarded patients. A 5-year follow-up study.
The long-term clinical, neurophysiologic, and psychological effects of add-on vigabatrin treatment were evaluated in a group of 36 mentally handicapped patients with drug-refractory epilepsy. After an initial 3-month follow-up period, 15 (42%) of 36 patients had at least a 50% decrease in seizure frequency compared with baseline. After a 2-year follow-up period, nine (25%) of 36 patients retained the initially observed antiepileptic effects of vigabatrin, and after 5 years, eight (22%) of 36 patients did so. Five (33%) of the 15 patients who initially exhibited a favorable antiepileptic response to vigabatrin lost that response during a 5-year follow-up. Partial-onset seizures represented the seizure type best controlled by vigabatrin. Side effects were mostly mild, and plasma levels of other antiepileptic medication remained unchanged. No impairment of psychological performance was observed during vigabatrin treatment compared with baseline. Also, no clear change was observed in the background or epileptiform activity in the electroencephalogram during the study. Our findings suggest that vigabatrin as an add-on therapeutic effectively controls seizures in a subpopulation of patients with severe epilepsy. In addition, the antiepileptic response, if achieved, is long lasting in about half of the patients.
Adult↗
The importance of neurophysiological evaluation of plexus brachialis injury caused by open heart surgery.
The risk of brachial plexus injury as a complication of coronary bypass operation should be emphasized since the number of coronary operations is rapidly increasing. We describe six patients who developed symptoms consistent with brachial plexus injury after coronary bypass surgery. Four out of six patients had definitive electroneuromyography (ENMG) abnormalities consistent with an acute injury in the brachial plexus. Abnormal somatosensory evoked potential (SEP) was seen in two patients studied. Two of our patients suffered from diabetic polyneuropathy, which even seems a predisposing factor for plexus brachialis injury and to prolong the duration of disability. Based on literature and our own experience we strongly recommend the use of ENMG and SEP to all patients who have any postoperative neurogenic symptoms in the upper extremities. These methods confirm the site of the nerve damage, e.g., differentiate brachial plexus injury from peripheral ulnar nerve lesion, and help to predict the outcome.
Adult↗
Slowing of the dominant occipital rhythm in electroencephalogram is associated with low concentration of noradrenaline in the thalamus in patients with Alzheimer's disease.
The thalamus is involved in the regulation of the neocortical rhythmicity reflected in EEG as the alpha rhythm. Recent evidence suggests that the thalamus is affected in Alzheimer's disease (AD). We studied the relationship between the dominant occipital rhythm of the lifetime EEG and the choline acetyltransferase activity (ChAT) and monoamine concentrations in the postmortem thalamus of 20 histologically verified AD patients. The AD patients were divided into 3 groups (5-6 Hz, 7 Hz and 8-9 Hz) according to the frequency of the dominant occipital rhythm (FOC). Noradrenaline (NA) concentrations were significantly lower for the 5-6 Hz and 7 Hz subgroups as compared to the 8-9 Hz subgroup. The NA content of the thalamus correlated significantly with the FOC (r = 0.46, P = 0.04). The ChAT activity or concentrations of dopamine or serotonin did not correlate with the FOC or differ across the AD subgroups. The results suggests that the noradrenergic deficit of the thalamus may contribute to slowing of the dominant occipital rhythm in AD.
Aged↗
Memory and attention in newly diagnosed epileptic seizure disorder.
Interictal disturbances of memory and attention were evaluated in 74 adults with newly-diagnosed untreated epileptic seizures and no other known brain pathology. In approximately 30% of the patients with cryptogenic seizures, the average memory and attention scores indicated subtle dysfunction compared with normal control group. The patients had difficulties in tasks requiring memory, sustained attention and flexible mental processing, whereas they had normal attention span, simple speed of tracking and simple psychomotor speed. The memory difficulties may be related to attentional dysfunction leading to impaired or slowed initial encoding of memory trace, and also to a deficit in storing process and hippocampal dysfunction. These findings could have important implications for establishing criteria for identifying patients who develop chronic epilepsy and who thereby would benefit from early therapeutic intervention.
Adolescent↗
Clinical benefits of scalp EEG studies in intractable seizure disorders.
Intractable seizure disorder is a clinical as well as a diagnostic problem. We evaluated the clinical role of extensive EEGs among patients (n = 64) considered to suffer from intractable paroxysmal neurologic symptoms. By reducing antiepileptic medication, ictal events were recorded in 89% of the cases. From the clinical point of view, intensive EEG-videomonitoring (IVM) was superior to all the other EEG studies. Combined interictal routine EEG (rEEG) and ictal ambulatory EEG (aEEG) findings proved to be surprisingly successful, in some clinical settings equal to IVM. Comprehensive EEG investigations and subsequent treatment in a neurologic ward resulted in proper medication and markedly improved seizure control, confirmed by a prospective clinical follow-up of two years.
Adolescent↗