Is randomized case controled experiment always the best way to evaluate a treatment?

I recently read a report saying that an extract of a specific cultivar of the Cannabis plant was effective in treatment of Dravet Syndrome, a rare, severe form of intractable epilepsy. It is reported that children affected by this syndrome, suffering hundreds of seizures per month and responding to no other medication, become seizure free after taking the extract. I don't know if the media report is true, or if this is something which occurred in a number of cases or is an isolated event that might be explained by some other change in the child or the child's situation.

However, it suggests that perhaps something other than a standard randomized case, controlled, double blinded study would be appropriate for approval of the use of such an extract. A radical reduction of symptoms in a case for which there was no alternative effective treatment, especially for a totally debilitating or fatal disease, would seem to call for trials in other children, and as long as the treatment proved uniformly beneficial, why would one give a placebo to other afflicted children. I am assuming that in the case of Dravet Syndrome, the diagnosis is confirmed by detecting the genetic defect that causes the seizures, and that there is sufficient historical evidence from untreated clinical cases that the seizures continue.