[Medicinal cannabis for diseases of the nervous system: no convincing evidence of effectiveness].

--In 1996, the Netherlands Health Council issued a negative recommendation regarding the use of medication on the basis of cannabis (marihuana). However, interest in medicinal cannabis has certainly not waned since. --The neurological diseases for which cannabis could presently be used therapeutically are: multiple sclerosis, chronic (neuropathic) pain and the syndrome of Gilles de la Tourette. --Since September 2003, the Dutch Ministry of Health, Welfare and Sport delivers medicinal cannabis to Dutch pharmacies, so that now for the first time, medicinal cannabis can be given to patients on a prescription basis within the framework of the Opium Law. The result of this is that doctors and patients now assume that this is a medication for which the efficacy and safety have been established. --The question arises whether new scientific data have become available since 1996 that provide scientific support for the current Governmental policy. --In a recent clinical trial that has aroused much discussion, patients with multiple sclerosis and problematic spasticity were treated with oral cannabis or a placebo. There was no significant effect of treatment on the primary outcome measure, i.e. objectively determined spasticity. Nevertheless, it was concluded that the mobility was improved and that the pain was subjectively decreased. --Until now, convincing scientific evidence that cannabinoids are effective in neurological conditions is still lacking. --However, it is also not possible to conclude definitely that cannabinoids are ineffective; still, this is no basis for official stimulation of their use.