Nearly 40 million people in the U.S. suffer from migraines, making the painful disorder one of the most common that neurologists treat. It’s also among the most confusing. Because of the many ways it can show up, it can take more than a decade to receive an accurate diagnosis. “The general concept about migraine in the common population is that it’s a headache syndrome,” says Dr. Hamid S. Hamdi, a neurologist who leads the Headache Clinic at UTHealth Houston Neurosciences in Sugar Land, Texas.