Carbamazepine therapy in restless legs. Discrimination between responders and non-responders

Is it possible to characterize recurrent urinary stone formers who benefit from thiazide prophylaxis? Application of discrimination analysis

Twenty-three patients with recurrent urinary stones have been treated for 12-54 months with hydrochlorthiazide and 25 with placebo. Discrimination analysis was performed in order to distinguish patients with new stone formation (non-responders) from those without stone recurrence (responders) during the treatment. The discriminant function classified 16 out of 18 responders as such and 5 non-responders as such by using a combination of the three initial variables urinary pH, 24-h urine volume and serum phosphate. Eighteen other analysed variables and patient factors did not contribute to this discrimination. By using "leaving-one-out-technique", the probability for erroneously classifying a patient increased from 9 to 17%. Applying the discriminant function on the group receiving placebo, 92% of these patients were classified as responders to thiazide. It is concluded that discrimination analysis may give valuable information in characterizing patients who will benefit from a special therapy.

[Restless legs syndrome, periodic limb movements, and psychopharmacology]

Restless legs syndrome (RLS) and the often associated periodic limb movement disorder in sleep (PLMD) frequently occur in the general population as a primary disorder. In addition to organic disease, secondary forms are caused by psychotropic medication. Several antidepressants, antipsychotics, lithium, and opioid withdrawal have been shown to induce or exacerbate RLS and PLMD, while several antiepileptics used as mood stabilizers and some benzodiazepines demonstrate therapeutic potential for treating RLS/PLMD. Systematic or controlled studies for evaluating these side effects still do not exist. Among the antidepressants at higher risk of inducing this disorder are selective serotonin reuptake inhibitors, venlafaxine, and some tetracyclic antidepressants. Under medication with some tricyclic substances, periodic limb movements were observed more often. For some antidepressants with differing transmitter profiles such as bupropion RLS/PLMD ameliorating effects or at least neutral effects (Trazodon, Nortriptylin) have been described in small studies. In case of continued of or newly occurring insomnia a thorough history should be taken to identify a possible RLS/PLMD as an intolerable side effect of treatment. A change in medications should be considered if clinically feasible. In case of RLS/PLMD occurring in psychotic patients switching the antipsychotic and additionally using a second line medication such as antiepileptics or a benzodiazepine should be considered.

Restless legs syndrome: pathophysiology, diagnosis and treatment

Restless legs syndrome (RLS) is clinically defined by the presence of (i) an urge to move the legs with or without an actual paraesthesia; (ii) a worsening of symptoms with inactivity; (iii) improvement with activity; and (iv) a worsening of symptoms in the evening and at night. Patients may use a variety of semantic phrases to describe their symptoms but all must have an urge to move. Most people with RLS also have periodic limb movements during sleep, although this is not part of the clinical diagnostic criteria. RLS is very common. About 10% of all Caucasian populations have RLS, although it may be mild in the majority of cases. Women generally outnumber men by about 2:1. As a general rule, RLS severity worsens through the first seven to eight decades of life, but may actually lessen in old age. The aetiology of RLS is only partly understood. There is a strong genetic component, and several genetic linkages and three causative genes have been identified worldwide. Several medical conditions, including renal failure, systemic iron deficiency and pregnancy, and possibly neuropathy, essential tremor and some genetic ataxias, are also associated with high rates of RLS. In all cases to date, the actual CNS pathology of RLS demonstrates reduced iron stores, in a pattern that suggests that the homeostatic control of iron is altered, not just that there is not enough iron entering the brain. The relationship between reduced CNS iron levels and the clinical phenotype or treatment response to dopaminergics is not known but generates promising speculation. Treatment of RLS is usually rewarding. Most patients respond robustly to dopamine receptor agonists. Over time, response may lessen, or the patients may develop 'augmentation', whereby they have a worsening of symptoms, usually in the form of an earlier onset. Other treatment options include gabapentin, or similar antiepileptic drugs, and opioids. High-dose intravenous iron is a promising but still experimental approach.

EFNS guidelines on management of restless legs syndrome and periodic limb movement disorder in sleep

In 2003, the EFNS Task Force was set up for putting forth guidelines for the management of the Restless Legs Syndrome (RLS) and the Periodic Limb Movement Disorder (PLMD). After determining the objectives for management and the search strategy for primary and secondary RLS and for PLMD, a review of the scientific literature up to 2004 was performed for the drug classes and interventions employed in treatment (drugs acting on the adrenoreceptor, antiepileptic drugs, benzodiazepines/hypnotics, dopaminergic agents, opioids, other treatments). Previous guidelines were consulted. All trials were analysed according to class of evidence, and recommendations formed according to the 2004 EFNS criteria for rating. Dopaminergic agents came out as having the best evidence for efficacy in primary RLS. Reported adverse events were usually mild and reversible; augmentation was a feature with dopaminergic agents. No controlled trials were available for RLS in children and for RLS during pregnancy. The following level A recommendations can be offered: for primary RLS, cabergoline, gabapentin, pergolide, ropinirole, levodopa and rotigotine by transdermal delivery (the latter two for short-term use) are effective in relieving the symptoms. Transdermal oestradiol is ineffective for PLMD.

Dopamine and iron in the pathophysiology of restless legs syndrome (RLS)

BACKGROUND AND PURPOSE

The evaluation of the pathophysiology of restless legs syndrome (RLS) stems largely from recognition of the information provided by both pharmacological treatment of the disorder and the secondary forms of the disorder. This article examines the pathophysiological implications of each of these clinical aspects of RLS.

PATIENTS AND METHODS

The article reviews the existing literature in relation to possible pathology suggested by the clinical data. It will then explore other data supporting each of the possible pathologies and examine the relationships between these pathologies.

RESULTS

The pharmacological treatment data strongly support a dopaminergic abnormality for RLS. Other pharmacological data and some imaging data also support this, although the data are not entirely consistent. The secondary forms of RLS strongly support an iron deficiency abnormality for RLS, further documented by several other studies. Some animal studies have shown a relation between iron deficiency and dopaminergic abnormalities that have some similarity to those seen in the RLS patient.

CONCLUSIONS

It is concluded that there may be an iron-dopamine connection central to the pathophysiology of RLS for at least some if not most patients with this disorder.

Restless legs and periodic leg movements in sleep syndromes

Restless legs syndrome (RLS) is a common sensorimotor disorder with an estimated prevalence of between 1% and 5%. The symptomatology is characterized by unpleasant sensations experienced predominantly in the legs and rarely in the arms. The symptoms occur only at rest and become more pronounced in the evening or at night. In addition, the patients suffer from a strong urge to move the limbs, typically manifest as walking around, which leads to complete but only temporary relief of the symptoms. Most of the patients with RLS have periodic leg movements (PLMS) during sleep and relaxed wakefulness that are characterized by repetitive flexions of the extremities. PLMS can occur as an isolated phenomenon, but often they occur together with other sleep disorders including RLS, narcolepsy, sleep apnoea syndrome or REM sleep behaviour disorder. In all these disorders, PLMS, contribute considerably to disturbed sleep, as the movements may lead to brief arousals or repeated full awakenings. The aetiology of RLS and PLMS is unknown. It is hypothesized that periodic leg movements result from a suprasegmental disinhibition of descending inhibitory pathways. Based on the efficacy of the drugs listed below, the dopaminergic, adrenergic and opiate systems are thought to play a major role in the pathogenesis of RLS/PLMS. Since the cause is unclear, therapy of RLS and PLMS remains symptomatic except for some secondary forms. Studies on the pharmacological treatment of RLS have shown the efficacy of levodopa, dopamine agonists, benzodiazepines, opioids, clonidine and carbamazepine. With regard to the drug treatment of PLMS in other sleep disorders including their isolated occurrence, indications and efficacy have been poorly defined until now.

Biometric evaluation of gastric urease activity in man

The 14C-urea breath test is claimed to be the best test for detection of Helicobacter pylori infection. We present a procedure for estimating its cutoff value on the basis of biometric evaluation only, without involving other diagnostic methods. Cumulative gastric urease activity (CA) was determined during the first 30 min after oral administration of 14C-urea (92.5 kBq) in 56 random volunteers and 49 consecutive patients with peptic ulcer disease. The distribution of CA in random volunteers was positively skewed. Logarithmic transformation yielded two separate populations, each normally distributed. Their normal probability density functions intercepted at log cutoff value. A bimodal distribution of log CA was confirmed in patients with peptic ulcer disease before and after treatment aimed at H. pylori eradication. Cutoff values were determined for both random volunteers and patients with peptic ulcer disease. By application of the present procedure for determination of cutoff value, the 14C-urea breath test distinguishes between individuals who have an increased gastric urease activity and individuals who do not, with the smallest possible arbitrariness.

The multi-crossover model for classifying patients as responders to a given treatment

The strength and the validity of the multi-crossover model (MCO model) were investigated to optimalize the procedure for correctly classifying individual responders to a given therapy. One hundred and fifteen patients with non-ulcer dyspepsia from seven Norwegian hospitals were included in a 6-week double-blind MCO-designed trial with alternating weekly treatments with ranitidine and placebo. An individual effect score (X score) was calculated on the basis of the number of times the active drug was associated with less symptoms than the preceding or following placebo period. Patients categorized as responders (X score greater than or equal to 4) or unclassifiables (X scores = 2 or 3) after the MCO period continued single-blind active treatment for 4 weeks and were then reclassified by means of cross-tabulation of efficacy and adverse effects. Eighty-five per cent of the MCO responders and 62% of the 42 MCO unclassifiables were reclassified as responders. The reclassified responders were then included in a single-blind follow-up placebo period until relapse or for a maximum of 8 weeks. The relapse rate was significantly greater (p less than 0.01) and the time to relapse significantly shorter (p less than 0.01) in the group of MCO responders than in the MCO unclassifiables. The large response and relapse rates in the group of MCO responders verify that the MCO model is a reliable method for correctly classifying responders to treatment. Our results indicate that by including patients with an X score of 3 in the definition of 'responder', the MCO model could be modified to optimalize the procedure for correct classification.

Acute bronchiolitis: predisposing factors and characterization of infants at risk

Fifty-one infants hospitalized because of acute bronchiolitis and 24 control children were prospectively followed until 2 years of age. Respiratory syncytial virus was detected initially in 31 index children, parainfluenza virus in two, and rhinovirus in one. More index children were born during the months April through September, and six index children had neonatal respiratory complications. The index children were breast-fed for shorter periods, lived in more crowded homes, and had more siblings. No significant differences were found for atopic background and atopic illness at 2 years of age. The index children had more respiratory infections and episodes of bronchopulmonary obstruction during the follow-up period (60% with three or more episodes). To characterize the hospitalized children, a discriminant analysis was performed. A discriminant function classified 47 of 51 index children as belonging to the index group and 21 of 24 control children to the control group.