" You're quite right, " said Dumbledore serenely, shaking back his sleeve to reveal the tips of those burned and blackened ringers; the sight of them made the back of Harry's neck prickle unpleasantly.
" Yes, " said Harry, as his scar gave another painful prickle, " and I'm sure Sirius is still alive, but I can't see how we're going to get there to help him."
In the peripheral nervous system, they can cause peripheral neuropathy and paresthesia which is numbness and prickling sensations, particularly in the legs and feet.