Tolosa-Hunt syndrome (THS) is a rare autoimmune related disorder characterized by severe and unilateral headaches with extraocular palsies, usually involving the third, fourth, fifth, and sixth cranial nerves, and pain around the sides and back of the eye, along with weakness and paralysis (ophthalmoplegia) of certain eye muscles. The exact cause of THS is not known, but the disorder is thought to be, and often assumed to be, associated with inflammation of the areas behind the eyes. Symptoms are usually limited to one side of the head, and in most cases the individual affected will experience intense, sharp pain and paralysis of muscles around the eye. Symptoms may subside without medical intervention, yet recur without a noticeable pattern. The prognosis of THS is usually considered good. Patients usually respond to corticosteroids, and spontaneous remission can occur, although movement of ocular muscles may remain damaged. Roughly 30–40% of patients who are treated for THS experience a relapse.