With vegetative patients the brain injury causes sufficient damage to leave them with nothing but core reflexes and no higher cognitive function.

BBC: Finding a voice for the brain injured

Dr Freeland said he had seen patients with similar brain injuries recover from comas with very little lasting damage.

BBC: Slow, difficult period to come

"We cannot emphasise enough that measles is an illness that can kill, or leave patients with permanent complications including severe brain damage, and the only protection is two doses of the MMR vaccination, " she added.

BBC: Boy with measles

Without getting into a ton of details, it turns out that in some very specific cases, patients specifically with lateral prefrontal damage performed better than people without brain damage.

FORBES: When Brain Damage Leads to Better Thinking

The MRIs can tell how much brain tissue can be saved, and those patients with irreversible damage don't get the drug.

FORBES: Brain Repair

Biogen Idec and partner Elan had to pull their multiple sclerosis drug Tysabri after patients in clinical trials came down with a rare viral disorder that can lead to brain damage or death.

FORBES: Genentech's Next Act