The definition of Pain, “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” (International Association for the Study of Pain : IASP, 1994), which is often used to explain its subjectivity. It is necessary to evaluate the pain objectively for diagnosis and effectiveness of therapy.
As an evaluation method of chronic pain, Visual Analog Scale (VAS) and Numerical Rating Scale (NRS) are used. Recent years, face visual analog scale and Current Perception Threshold (CPT) testing are also used commonly. Drug challenge test draws attention as it combines an evaluation method and an effective therapy. Meanwhile as a therapy of chronic pain, the reports of epiduroscopy and phototherapy are increasing. The epiduroscopy is an endoscopic operation for patients with the chronic low back pain. In Japan the therapy is performed increasingly for patients with the low back pain of spinal canal stenosis, failed back syndrome and lumbar disc herniation. Regarding the phototherapy, the reports which show the effectiveness of linear polarized infrared raytherapy and xenon phototherapy are mainly observed. Though the nerve block is still the dominant therapy in pain clinics, acupuncture therapy and phototherapy are prospected to increase their demands in future.