Central sensitization is a neurophysiological concept originally associated with pain, and physiological tests such as quantitative sensory testing (QST) are appropriate for its evaluation. The Central Sensitization Inventory (CSI) is a questionnaire used to assess central sensitization. This questionnaire correlates with physiological tests such as QST and brain-derived neurotrophic factor (BDNF), and contributes to the efficient assessment of central sensitization. In our study, the Somatic Symptom Scale-8 (SSS-8) was also a useful questionnaire for screening central sensitization. For patients with conditions that cannot be adequately explained medically through organic testing, questionnaires can be used to explain the condition and offer hope. However, questionnaires are subjective and thus have drawbacks, such as the influence of bias and difficulty in distinguishing between the condition of the patient and other related conditions. Although care for conditions associated with central sensitization is still under development, it is important to use questionnaires effectively, considering their potential and limitations.

In recent years, in its classification of pain, the International Association for the Study of Pain (IASP) has termed pain that occurs without apparent tissue or nerve damage as “nociplastic pain”. Central sensitization has been hypothesized as a possible underlying mechanism. Central sensitization is a phenomenon in which the excitability of nociceptive neurons in the central nervous system (CNS) in response to ascending stimuli is enhanced, and pain sensitivity is increased. However, it has also been suggested that nociplastic pain has a different mechanism than central sensitization. For example, it may be derived from social pain, somatization, inappropriate cognitive-behavioral responses to pain, and psychiatric disorders. Clinically, each condition differs in terms of patient characteristics, disease course, and responsiveness to treatment. Therefore, it would be useful to distinguish between them to understand their pathophysiology and determine the appropriate treatment strategy. In this review, we discuss the mechanisms underlying nociplastic pain from a literature review and a clinical perspective.

Central sensitization presumably involves in chronic pain disorders. Among them, irritable bowel syndrome (IBS) is a representative disorder with chronic visceral pain. Centrally mediated abdominal pain syndrome (CAPS) is an allied condition of IBS with continuous abdominal pain induced by abnormal neurotransmission inside the central nervous system. IBS is known to have co-morbidity with painful diseases. Concerning disorders with visceral pain, functional dyspepsia (epigastric pain syndrome) or dysmenorrhea is often co-morbid with IBS. Concerning disorders with somatic pain, migraine, tension-type headache, temporomandibular joint disorder, cervicobrachial syndrome, low back pain, chronic pelvic pain, or fibromyalgia is often co-morbid with IBS. In IBS patients, visceral afferent signal activates sensorimotor network and salience network which switches default mode network to central executive network. Then emotional arousal network and central autonomic network are activated. Thus excitation of the autonomic nervous system and the endocrine secretion cause changes in function of the gut and the other organs. Abdominal pain as the results of central sensitization is presumably generated during the intracerebral processing. Further clarification of mechanism of central sensitization in IBS is warranted.

Myalgic encephalomyelitis (ME) has previously been referred to as chronic fatigue syndrome (CFS) ; however, it is currently often referred to as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The primary symptoms are severe physical and mental fatigue, leading to significant disruption of daily life. These symptoms may also be accompanied by fever. The exact cause and disease mechanisms remain elusive and no definitive treatment has been established. Central sensitization (CS) is defined as the amplification of nerve signals in the central nervous system, leading to hyperalgesia. CS heightens responsiveness to stimuli and impairs central pain control mechanisms, resulting in hyperalgesia, allodynia, depression, and sleep disturbances. This review addresses ME/CFS and CS and discusses their relationship.

Sleep deprivation and a nocturnal lifestyle are societal issues in Japan that affect individuals across various age groups. Adolescents and young adults often adopt a nocturnal lifestyle, finding it challenging to awaken early due to a shift in their biological clocks. Delayed sleep-wake phase disorder is characterized by habitual delayed sleep-wake timing. The disorder is prevalent among adolescents and young adults and is frequently associated with neurodevelopmental disorders, which have been linked to a higher prevalence of orthostatic dysregulation. Restless legs syndrome, a movement disorder characterized by abnormal sensations in the lower extremities, is increased in individuals with postural orthostatic tachycardia syndrome. Moreover, idiopathic hypersomnia, a central hypersomnia prevalent among adolescents and young adults, may present with accompanying symptoms of orthostatic dysregulation.

In the treatment of orthostatic dysregulation, providing instruction on sleep hygiene is important. It is crucial to assess sleep deprivation, evaluate bedtime/wake time rhythms, address leg discomfort experienced on falling asleep, and inquire about daytime sleepiness and lapses in alertness.

Introduction : Cerebrospinal fluid (CSF) leakage is often considered a problem in adults but also affects younger patients. In this study, we analyzed the clinical features of pediatric CSF leakage.

Material & Methods : A total of 212 patients (107 boys and 105 girls) who experienced the onset of CSF leakage before the age of 15 were investigated for causes, outcomes, and clinical features.

Results : Among the 212 patients, 61 (28.8％) were capable of limited self-care, and 55 (25.9％) were completely disabled. A total of 116 patients (54.7％) did not attend school before the epidural blood patch (EBP). After EBP, 190 (89.7％) patients recovered sufficiently to attend school. Complete recovery was achieved in 79 patients (37.3％).

Conclusions : CSF leakage is not well-recognized, particularly in children and adolescents. Some children were diagnosed with autonomic nervous system dysfunction, orthostatic dysregulation, Barré-Liéou syndrome, postural tachycardia syndrome, or depression. Despite administration of definitive therapies such as counseling, analgesics, tranquilizers, or antiepileptic drugs, these symptoms persisted chronically or progressed daily. In cases where patients experience related symptoms such as intractable headaches, CSF leakage should be considered in the differential diagnosis.

Orthostatic dysregulation (OD), a disease prevalent during adolescence, is caused by the failure of compensatory autonomic regulatory mechanisms; it encompasses a broad spectrum of processes associated with biological dysfunction and psychosocial involvement. Therefore, treating blood pressure abnormalities alone is not beneficial for patients. Recent research has expanded our understanding of the underlying diseases and comorbidities associated with OD. To provide beneficial care, the author outlines a comprehensive approach based on a bio-psychosocial model, including perspectives on drug-induced OD, OD resulting from school absenteeism, sleep disorders, and hereditary connective tissue disorders as comorbidities.

Chronic fatigue syndrome (CFS) often presents with autonomic dysfunctions, such as orthostatic dysregulation (OD), in addition to fibromyalgia, memory, and sleep disorders ; particularly, patients presenting with severe OD are often considered to have CFS. The diagnosis of this disease could provide a framework for the comprehensive treatment of CFS and support for various CFS-associated physical comorbidities.

This study examined the effects of perfectionist tendencies and non-functional beliefs regarding sleep on subjective sleep ratings and physiological sleep status. The participants included 130 patients (86 men and 44 women) who were suspected to suffer from sleep disorders and underwent polysomnography (PSG). The participants were surveyed using the new perfectionism scale, non-functional beliefs and attitudes toward sleep questionnaire, and Athens insomnia scale. The responses were analyzed along with the PSG results. The results demonstrated that perfectionist tendencies and non-functional beliefs regarding sleep influenced subjective sleep evaluation and physiological sleep status, respectively. These findings suggest that psychological approaches can help improve subjective sleep evaluation and physiological sleep status. Furthermore, mitigating perfectionist tendencies and non-functional beliefs regarding sleep may require support.