Recent developments in the drug treatment of motor neurone disease

ISIS Survey: an international study on the diagnostic process and its implications in amyotrophic lateral sclerosis

In a number of ALS patients, a long delay between onset of symptoms and diagnosis is reported. In this international study (ISIS Survey) we have identified the pathway followed by ALS patients from first symptoms to diagnosis confirmation. Diagnostic data from a total of 201 patients with definite ALS from 6 countries (Argentina, Brazil, Germany, Italy, Spain and the USA) were analyzed. The median time needed to confirm diagnosis was found to be 14 months; time to first consultation took 2 months, time to consultation with a neurologist took 8 months, and time for observation and diagnostic assessment by the neurologist took 4 months. This time delay was shorter when presentation was at bulbar level and when fasciculations were present. The major causes of diagnostic delay were unfamiliarity of the physician with the disease, unusual clinical presentation, coexistence of other diseases to which clinical symptomatology was attributed, misleading findings or misinterpretation of neuro-radiological or neurophysiological findings. The diagnostic delay has several implications for patients and their families, including mismanagement, delay in establishing appropriate and individualized pharmacological and symptomatic therapies, and difficulty in planning personal and familiar future.

Riluzole. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic potential in amyotrophic lateral sclerosis

Riluzole, a benzothiazole, affects neurons by 3 mechanisms: by inhibiting excitatory amino acid release, inhibiting events following stimulation of excitatory amino acid receptors and stabilising the inactivated state of voltage-dependent sodium channels. It has demonstrated neuroprotective activity in vivo and in vitro. Results from 2 randomised double-blind placebo-controlled trials in patients with amyotrophic lateral sclerosis (ALS; motor neuron disease) have demonstrated that riluzole can extend survival and/or time to tracheostomy. After 18 months, the relative risk of death or tracheostomy with riluzole 100 mg/day was reduced by 21%. Although riluzole slowed the rate of deterioration in muscle strength in the first trial, this was not confirmed in the second, larger trial. Riluzole had no effect on any other functional or secondary variable. Gastrointestinal effects, anorexia, asthenia, circumoral paraesthesia and dizziness were reported more frequently with riluzole than placebo. Elevated alanine aminotransferase levels were observed in 10.6 versus 3.8% of patients treated with riluzole 100 mg/day versus placebo, leading to treatment withdrawal in 3.8 versus 2.1% of patients. In conclusion, riluzole is the first drug that has been shown to have an effect on survival in patients with ALS. Although the effect of riluzole was modest, it has allowed some insight into the pathogenesis of ALS from which future gains may be made.

Investigation of a null mutation of the CNTF gene in familial amyotrophic lateral sclerosis

Neurotrophic factors, such as ciliary neurotrophic factor (CNTF), have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), a human neurodegenerative disease primarily of upper and lower motor neurones. A null mutation of the CNTF gene has recently been described. The mutation is an intronic point mutation (G to A) which generates a new splice acceptor site and a 4 bp insertion within the CNTF coding region, and prevents the expression of the normal protein. We investigated this as a candidate gene in 49 families with ALS, where the genetic component may be expected to be strongest. 65% were normal homozygotes, and 35% were heterozygotes for the mutation. No mutant homozygotes were detected. The absence of CNTF protein expression associated with the homozygote mutation does not appear to be of major significance in the development of ALS.