While we all experience pain at some point in our lives, in most cases it is short-lived and manageable.

But an estimated 1.5 billion people worldwide suffer from chronic pain, a constant pain that lasts for three months or more and which can leave people in agony, exhausted and unable to carry on with day-to-day activities.

At the New York-Presbyterian Hospital/Columbia University Medical Center, doctors are using electrical currents from implanted electrodes to numb the pain.

Reporter Dr Javid Abdelmoneim meets medics carrying out the technique, known as neuromodulation.

He also meets former New York firefighter Christopher Francis, a veteran of the September 11 attacks, as he undergoes the procedure to overcome a debilitating pain in his leg.

Source:Al Jazeera