Although pain is not a matter of life and death, it is a common cause of poor quality of life for people [1,2]. It is also the primary reason why patients visit hospitals. Therefore, clinicians should pay particular attention to the presence of a patient's pain and effectively control it.

Pain occurs primarily because of degeneration or damage to musculoskeletal structures. A herniated disc, spinal stenosis, rotator cuff disease, adhesive capsulitis, myofascial pain syndrome on the cervical or lumbar areas, knee and hip osteoarthritis, and musculoskeletal or nervous system injuries are common causes of pain, and clinicians are familiar with diagnosing and treating these diseases. However, clinicians are often unaware of pain in patients suffering from diseases of relatively low incidence. In this special issue, Kwak [3] reviews the pain patterns and pain management in patients with amyotrophic lateral sclerosis (motor neuron disease). In addition, Park and Chang [4] describe the methodology of ultrasound-guided intervention to treat thoracic spine and chest wall pain. Motor neuron disease is uncommon; furthermore, pain in patients with motor neuron disease is often overlooked because clinicians focus on and treat the patient's main symptoms, including muscle weakness. In addition, the incidence of thoracic spine and chest wall pain is relatively low compared to that of the abovementioned common diseases causing musculoskeletal pain, and thoracic spine and chest wall pain are often not actively treated by clinicians because of the risk of developing lung puncture during pain control interventions. This special issue allows clinicians to improve their understanding of pain in patients with motor neuron disease and implement interventions safely and confidently in patients with thoracic spine and chest wall pain.

In clinical practice, corticosteroid injections are mainly used to control musculoskeletal pain [5]. Although corticosteroid injections can effectively control various musculoskeletal disease-associated pain, several side effects, such as allergic reaction, flushing, hyperglycemia, immunosuppression, menstrual changes, and adrenal suppression may occur [6]. Thus, several methods have been assessed as corticosteroid injection replacements. Among these methods, PRF stimulation and PRP injections are known to have some pain control effects that are equivalent to those of corticosteroid injections [6,7]. Moreover, this special issue deals with pain treatment using pulsed radiofrequency (PRF) stimulation and platelet-rich plasma (PRP) injection. Park and Chang [8] review studies on mechanisms of PRP stimulation for controlling pain, and Thu [9] reviews studies related to PRP injection in the management of musculoskeletal pain. With the help of these review papers, we hope that clinicians can effectively use PRF stimulation and PRP injections to control pain in patients, thereby enhancing the therapeutic effectiveness of pain control.

We also expect that this special issue will serve as a bridge to advanced research on neglected pain-causing diseases, PRF stimulation, and PRP injections.