Barbara Cullen, 52, suffered from 'cluster headaches' for three years. The pain was so unbearable she considered taking her own life. But a remarkable new treatment has left her virtually pain-free. Here, Barbara, a lecturer who lives in Grimsby with husband Fred, 57, a financial adviser, talks to Natasha Coutenay-Smith about her experiences, and her surgeon, Mr Lawrence Watkins, describes the operation: THE PATIENT The first time that I experienced a cluster headache I felt as though I was being attacked with a pneumatic drill. Despite the fact it was Boxing Day, I knew my headache wasn't anything to do...