Linkage studies in progressive myoclonus epilepsy: Unverricht-Lundborg and Lafora's diseases.

The progressive myoclonus epilepsies (PME) are a heterogeneous group of rare genetic disorders. Unverricht-Lundborg disease and Lafora's disease are two major classic forms of PME. We recently assigned the gene for Unverricht-Lundborg disease (EPM1) to human chromosome 21 band q22.3. We have now refined the localization of EPM1 by linkage analysis between the disease phenotype and nine DNA markers in 13 Finnish families. Loci MX1 and CD18 flank the EPM1 interval, which spans a distance of about 3.5 megabases. In this 20-centimorgan interval, no recombinations were detected between EPM1 and marker loci BCEI, D21S19, D21S42, D21S113, D21S154, and PFKL. Within this interval a maximum multipoint lod score of 11.04 was reached at loci D21S154-PFKL. In two Swedish families with Unverricht-Lundborg disease no recombinations were detected. In three Italian families with Lafora's disease the linkage results suggested that EPM1 is not the locus for Lafora's disease.

Pharmacokinetics of free and total sodium valproate in adolescents and young adults during maintenance therapy.

The pharmacokinetics of total and free valproic acid (VPA) in plasma and whole blood was investigated in seven adolescents and young adults (mean age 17.3 years) during a dosage interval at steady state. The concentration curves of VPA in whole blood after an oral morning dose (mean 8.2 mg/kg body wt.) closely followed those in plasma but at a reduced level. The apparent volume of distribution (Vd) of total VPA was 0.150-0.197 l/kg body wt. and of free VPA 0.911-1.58 l/kg body wt., which indicates considerable distribution of unbound VPA as well as drug binding to extravascular proteins. The terminal half-life of free VPA (6.4-6.7 h) was significantly shorter (P less than 0.05) than the half-life of total VPA (10.4-11.9 h). The binding of VPA in plasma was concentration dependent and fluctuated considerably within the individual dosage intervals. Concentrations of unbound VPA in plasma water of whole blood varied to a corresponding degree, since distribution to blood cells was low (mean 2.2%). It is concluded that there are substantial differences in the pharmacokinetics of free and total VPA. This may contribute to the well-known poor correlation between dose, plasma concentrations and effect of VPA.

Pharmacokinetics of total and free valproic acid during monotherapy in infants.

The pharmacokinetics of free and total valproic acid (VPA) in plasma and whole blood after oral administration during steady state was investigated in seven infants (mean age 10.7 months) receiving monotherapy. The VPA concentrations in whole blood closely followed those in plasma but at a reduced level. A positive correlation was found between dose and mean plasma concentration (r = 0.71). Mean terminal half-lives were similar in plasma and whole blood (12.5 and 15.5 h, respectively), but were considerably longer than for free VPA (6.4 and 6.5 h, respectively; P less than 0.01). There was a significant decrease in half-lives with increasing age (P less than 0.05). Plasma and whole blood clearance for total VPA was higher than reported in older infants and adults (17.8 and 28.9 ml/kg per hour) and was considerably higher for free VPA (127.6 and 188.8 ml/kg per hour, respectively). The increase in clearance compared with that in older subjects is well in concordance with a lower protein binding of VPA (mean 85.3%). Of special importance is that the percentage of unbound VPA increased with increasing concentrations of total VPA. The fraction of unbound VPA in plasma increased even more in subjects with low albumin concentrations (P less than 0.01).

Plasma concentrations of valproate during maintenance therapy in epileptic children.

A total of 20 children with various types of epilepsy were treated with valproate, 11 with monotherapy and 9 with valproate in combination with phenobarbitone, phenytoin, or carbamazepine. Valproate was given either every 8 or 12 h. At least two different dose levels were tried in each patient. The pharmacokinetics of valproate during the interval between doses was determined using a gas chromatographic technique. The clinical effect of the treatment was assessed by interviewing the parents. The plasma concentrations showed considerable fluctuation during the intervals between doses. The mean increase from pre-administration to peak level was 82% when the dose interval was 12 h, and 62% when it was 8 h. The mean plasma half-life of valproate, using a one-compartment model, was 10.9 +/- 1.3 h (mean +/- SD). The plasma half-life of valproate was decreased when the drug was combined with the other anti-epileptics. The calculated area under the concentration versus time curve was linearly related to dose, both in a single patient on four dose levels and when different patients were compared. The clinical effect of valproate monotherapy was best in patients with absences, usually good in myoclonus and less favourable in other types of epilepsy. For children with absences, the optimal dose range of valproate was between 20 and 40 mg/kg/24 h. In comparison, the myoclonic types of epilepsy needed a slightly higher dose level, between 30 and 60 mg/kg/24 h. In the latter group a "therapeutic window" seems to exist, since patients below and above the suggested dose levels were not well-controlled. Therapeutic monitoring of valproate does not appear meaningful when the drug is used as monotherapy. However, in combination therapy, determination of the plasma levels of all anti-convulsants used may be helpful. The large fluctuations of valproate during a dose interval must be taken into consideration when the clinical effects are analysed.

Monitoring of phenytoin in epileptic children: value of the single morning sample.

The intra-individual variation in plasma concentration of phenytoin was studied in ten clinically well controlled children on monotherapy. The drug concentration was determined in routine pre-dose samples taken on three to five different mornings. On two of these occasions, plasma phenytoin was also determined at 0.5, 1, 2, 3, 5 and 7 h after the dose. The difference between the highest and lowest morning concentrations in a patient varied between 7.5 and 40 mumol/l (mean 20.1 mumol/l). Half of all morning concentration values were lower than 40 mumol/l. This often-recommended lower limit for good seizure control should therefore be reconsidered. The two concentration versus time curves in each patient during 7 h after administration differed considerably in shape, and the first curve could not be used for prediction of the second curve. The ratio between unbound and total drug was very stable and amounted to 9.4, SD 0.94% (n = 168). It is concluded that the conventional single morning sample is satisfactory for routine monitoring in well-controlled children on monotherapy with phenytoin. In problem patients, and during combination therapy, however, more extensive investigation will be necessary, including repeated morning samples as well as determination of dose-interval curves and protein binding.

A comparison between microcrystalline and conventional phenytoin preparations: relative bioavailability and steady-state plasma concentrations.

Plasma concentrations of two phenytoin products (a conventional phenytoin acid preparation and a microcrystalline form of phenytoin acid) were studied after single dose administration and during steady-state conditions in four healthy male volunteers. Relative bioavailability for the conventional tablet in comparison with the microcrystallin was in the range of 48-80% during single dose administration and in the range 54-95% at steady-rate. The microcrystalline preparation gave, as expected, a higher rate of absorption. During steady-state conditions, however, this higher rate of absorption was associated with considerable fluctuations in plamsa concentration during the dosage interval. The mean maximum plasma concentration was about 50% high than the value at the beginning of the dose interval (2-dose concentration value) when the microcrystalline product was administered. The corresponding figure was only about 25% for the conventional tablet. Since upward fluctuations in plasma concentrations may be associated with side effects, the more even level obtained with the conventional product may be an advantage from the clinical point of view. An incresed rate of bioavailability is not a clinical improvement if it occurs at the expense of greater fluctuations in plasma concentration during the dose interval.

Variability of epileptiform activity in long-term EEGs with short and long intervals in children with epilepsy.

OBJECTIVE: To evaluate the impact of the time factor on the amount of epileptiform activity in long-term EEG recordings in children with epilepsy. METHODS: Ten children with epilepsy of different types underwent three 24 h EEG examinations during two consecutive days and with a month's interval. The number of epileptiform discharges during selected corresponding periods of time was counted. RESULTS: The number of epileptiform discharges on three repeated examination days showed no significant difference (ANOVA P = 0.88) as intraindividual increases and decreases on different days counterbalanced each other within the group. However the standard deviations of the relative changes were larger between recordings with a month's interval compared to those for consecutive days (86% and 33%). The mean magnitude of change was 55% between days separated by a month compared to 24% on consecutive days. The difference was non-significant but showed a trend towards larger changes with a longer interval (P = 0.07). CONCLUSIONS: The variability of epileptiform activity was larger when the interval between recordings was 1 month compared to consecutive days. The magnitude of the relative changes between intervals of 1 and 30 days showed a trend towards a difference although not statistically significant. When evaluating repeated long-term EEGs in relation to therapy in children, these variations should be considered.

Treatment of spasticity in children with low dose benzodiazepine.

In an attempt to investigate whether benzodiazepines at low dosage have a significant effect in reducing spasticity among children with cerebral palsy, we carried out a double-blind, placebo-controlled, cross-over study. Twelve children with either spastic diplegia or hemiplegia participated in this study. The mean age was 14 years. The restraint of passive knee movements was determined with a dynamic dynamometer and spastic stretch reflexes were measured as EMG activity in muscles stretched. Clonazepam was given at low dosage (0.02 mg/kg body weight). In each child measurements of passive restraint were made on 2 different days immediately before and 3 h after an i.m. injection of either clonazepam or placebo in randomized order. Clonazepam significantly reduced spastic restraint (P < 0.001) compared to non-significant reduction with placebo. The mean plasma concentration of clonazepam at time of spasticity evaluation was 21 mmol/l which is in the low dose range, far below conventional doses. The study thus shows a positive effect of low dose clonazepam in reducing spasticity in children when given as a single dose.

Flunarizine of limited value in children with intractable epilepsy.

Fourteen ambulatory children and adolescents with intractable epilepsy were studied in an open phase II study to investigate the pharmacokinetics and pharmacodynamics of flunarizine as an add-on treatment. Flunarizine was given in increasing doses starting with 0.1-0.3 mg/kg/day until effect was observed or a steady-state plasma concentration of 50-60 ng/ml was reached. Treatment was continued for 3 months at steady state. Pharmacokinetics were determined during the immediate posttreatment period. Positive antiepileptic effect (> or = 50% reduction in seizure frequency) was observed in 4 of 14 patients (29%; 95% CI: 52-5). Independently of antiepileptic effect, 10 of 14 parents (71.4%; 95% CI: 95-48) observed positive cognitive effects. In all patients treatment was withdrawn due to either lack of effect or weight gain. Flunarizine was rapidly absorbed; mean time of peak concentration (Tmax) was 2.7 hours (range: 1-8). The mean terminal half-life was 23.2 days (range: 7-48), the total plasma clearance of flunarizine per fraction of the dose absorbed (CLp/F) was 0.28 ml/min/kg (range: 0.07-042), and the volume of distribution of flunarizine per fraction of the dose absorbed (Vd/F) was 187 L/kg (range: 99-348). We conclude that flunarizine (0.1-0.3 mg/kg/day) seems to be of limited antiepileptic value in children with intractable epilepsy. The pharmacokinetic profile of flunarizine complicates its clinical use.

Perceived heart rhythm in relation to ECG findings after direct current cardioversion of atrial fibrillation.

OBJECTIVE: To investigate the agreement between perceived heart rhythm and the ECG-registered heart rhythm, as well as between symptoms and the ECG after direct current (DC) cardioversion of atrial fibrillation (AF). METHODS: Consecutive patients with symptomatic AF subjected to DC cardioversion were interviewed about perceived heart rhythm and symptoms one week after restoration of sinus rhythm (SR). An ECG was obtained after the interview. A chance-corrected measure of agreement was calculated by using Cohen's kappa test. RESULTS: 356 patients were enrolled. One week after successful cardioversion 160 patients considered their rhythm to be regular and 222 ECGs showed SR. 130 patients considered their heart rhythm to be regular in agreement with ECG in SR (kappa = 0.34, 95% confidence interval (CI) 0.24 to 0.44), indicating a fair agreement. At the same time 59 patients perceived AF and 134 ECGs showed AF. Thirty eight patients perceived AF, in agreement with AF found on their ECG (kappa = 0.13, 95% CI 0.02 to 0.25), a poor agreement. 141 of 356 patients reported improvement of symptoms in agreement with SR on their ECG (kappa = 0.26, 95% CI 0.15 to 0.36), indicating fair agreement. Perceived SR and improvement of symptoms were strongly associated (n = 129; p < 0.001). CONCLUSION: Agreement between perceived heart rhythm and ECG, as well as between improvement of symptoms and SR recorded on the ECG, is no more than poor to fair after successful cardioversion of patients with persistent AF. The association between perceived SR and improvement of symptoms is strong. These findings support the need for objective criteria to select patients who would benefit most from rhythm control. They also support the need for further studies on quality of life of patients with AF, with due attention paid to patients' perception of their cardiac rhythm.

Neuromuscular transmission in the corpus-fundus of the urinary bladder. An in vitro study in the cat.

In muscle strips from the corpus-fundus of the cat bladder the intramural nervous system was activated by field stimulation. The resulting muscle contraction could not be inhibited by atropine, phentolamine or quinidine. These drugs enhanced the response. Tetrodotoxin, methysergide, cyproheptadine and indomethacin blocked the field-stimulation response in a dose dependent manner. The interpretation of these results with references to transmission at the neuromuscular junction of the bladder is discussed.

Characterization of the beta-adrenergic receptors in the lower urinary tract of the cat.

The corpus-fundus and the outlet region of the urinary bladder of the cat was studied in vitro to characterize the beta-adrenergic receptors. In the corpus-fundus only beta1-receptors were found in contrast to the outlet region where the beta-receptors had both beta1-and beta2-characteristics.

Influence of adrenergic agonists and antagonists on urethral pressure, bladder pressure and detrusor hyperactivity in children with myelodysplasia.

In children with myelodysplasia and a low lumbar or sacral level of spinal cord lesions detrusor hyperactivity with pressure fluctuations is an almost constant phenomenon contributing to incontinence. In thirteen children with this type of dysfunction the effect of adrenergic agonists and antagonists on bladder and urethral pressures were studied by means of intravesical and urethral pressure recordings during the normal bladder-filling phase. Intravenous infusion of noradrenaline during the bladder-filling phase slightly reduced detrusor hyperactivity and the urethral pressure was increased. Following i.m. injection of the alpha-adrenergic antagonist phentolamine both the intravesical and proximal urethral pressures were reduced to about the same extent and the detrusor hyperactivity decreased. It is concluded that noradrenaline mainly changed urethral pressure while alpha-adrenergic blockade caused decreased tone in both the detrusor and the urethra as well as decreased detrusor hyperactivity.

Autonomic receptor functions of the human ureter: an in vitro study.

The autonomic receptor functions of ureteral smooth muscle were studied in vitro on strips of human ureter obtained at surgery. A dose-dependent, reproducible, contraction response to 5-hydroxytryptamine (Serotonin, 5-HT) was demonstrated. This response could be blocked by methysergide. Responses to acetylcholine and to drugs stimulating adrenergic receptor functions were also found, but they were weak and inconsistent. This suggests that contraction of ureteral smooth muscle is mediated through receptors which are sensitive to 5-hydroxytryptamine.

Neurotransmission in activation of the contractile response in the human urinary bladder.

The endogenous contracting transmitter at the neuromuscular junction in strips from human urinary bladder has been investigated using field stimulation and selective antagonists. Atropine in low concentrations was found to inhibit bladder contractions whereas higher concentrations of the drug sometimes had the opposite effects. Indomethacin inhibited, phentolamine enhanced and methysergide had no dose-dependent effect on the field stimulation response. It is proposed that acetylcholine is one of the transmitter substances responsible for the contraction of the human detrusor. Species differences which could be responsible for the alleged atropine-resistance of the bladder are discussed. It is concluded that anticholinergic drugs should be of therapeutic value for treatment of muscular hyperactivity in the human urinary bladder.

Observations on the internal sphincter mechanism during the filling phase in children with hyperactive neurogenic bladder.

The internal sphincter mechanism in the urinary bladder was investigated in three groups of children. Two groups had neurogenic bladder, one of them with and one without detrusor hyperactivity. The third group had no myelodysplasia and normal detrusor activity in the filling phase. In this group the sphincter contractions were sustained at high pressure level, with superimposed waves of substantial amplitude. Myelodysplasia of segments below L3 was associated with hyperactivity of the detrusor. The general sphincter pattern in this condition was the same as in the normal group, but the behavior of the sphincter was not synchronized with the pressure fluctuations in the bladder. In the children with low thoracic or high lumbar level of lesion ther was no detrusor hyperactivity. Their sphincter mechanism could be characterized as passive, with low mean pressure and low amplitude of superimposed waves. When detrusor hyperactivity is present, it seems to be the main factor in leakage from neurogenic bladder. In the absence of detrusor hyperactivity in neurogenic bladder, passivity of the internal urethral sphincter due to dissociation from the spinal centers is proposed as the explanation of incontinence.

Diagnosis of detrusor hyperactivity in children with neurogenic bladder.

Detrusor hyperactivity and its reproducibility was investigated in 22 patients with myelodysplasia and neurogenic bladder. The examinations were performed with microtransducers in the bladder, proximal urethra and rectum. Hyperactivity was found in 15 children all belonging to low lumbar and sacral neurological lesion groups. Patients without hyperactivity mostly had their levels of lesion higher in the spinal cord. In 6 children without neurologic disease no hyperactivity was found.