Central Sensitization (CS) has been proposed as a common pathophysiological mechanism to explain related syndromes for which no specific organic cause can be found. The term Central Sensitivity Syndrome (CSS) has been proposed to describe these poorly understood disorders related to CS. The goal of this investigation was to develop the Central Sensitization Inventory (CSI), which identifies key symptoms associated with CSSs, and quantifies the degree of these symptoms. The utility of the CSI, to differentiate among different types of chronic pain patients that presumably have different levels of CS impairment, was then evaluated. Study 1 demonstrated strong psychometric properties (test-retest reliability = 0.817; Cronbach's alpha = 0.879) of the CSI in a cohort of normative subjects. A factor analysis (including both normative and chronic pain subjects) yielded 4 major factors (all related to somatic and emotional symptoms), accounting for 53.4% of the variance in the dataset. In Study 2, the CSI was administered to four groups: fibromyalgia (FM); chronic widespread pain (CWP) without FM; work-related regional chronic low back pain (CLBP); and normative control group. Analyses revealed that the FM patients reported the highest CSI scores, and the normative population the lowest (p<.05). Analyses also demonstrated that the prevalence of previously diagnosed CSSs and related disorders was highest in the FM group and lowest in the normative group (p<.001). Taken together, these two studies demonstrate the psychometric strength, clinical utility, and the initial construct validity of the CSI in evaluating CS-related clinical symptoms in chronic pain populations.

Central Sensitization (CS) is a proposed physiological phenomenon in which central nervous system neurons become hyper-excitable, resulting in hypersensitivity to both noxious and non-noxious stimuli. The term Central Sensitivity Syndrome (CSS) describes a group of medically-indistinct (or nonspecific) disorders, such as fibromyalgia, chronic fatigue, and irritable bowel, for which CS may be a common etiology. In a previous study, the Central Sensitization Inventory (CSI) was introduced as a screening instrument for clinicians to help identify patients with a CSS. It was found to have high reliability and validity (test-retest reliability = 0.82; Cronbach’s alpha = 0.88). The present study investigated a cohort of 121 patients who were referred to a multidisciplinary pain center, which specialized in the assessment and treatment of complex pain and psychophysiological disorders, including CSSs. A large percentage of patients (n = 89, 74%) met clinical criteria for one or more CSSs, and CSI scores were positively correlated with the number of diagnosed CSSs. A Receiver Operating Characteristic (ROC) analysis determined that a CSI score of 40 out of 100 best distinguished between the CSS patient group and a non-patient comparison sample (n = 129) (AUC= 0.86, Sensitivity = 81%, Specicifity = 75%). PERSPECTIVE The Central Sensitization Inventory (CSI) is a new self-report screening instrument to help identify patients with Central Sensitivity Syndromes, including fibromyalgia. The present study investigated CSI scores in a heterogeneous pain population, with a large percentage of CSSs, and a normative non-clinical sample, to determine a clinically-relevant cutoff value.

This study provides support for these CSI severity levels as a guideline for healthcare providers and researchers in interpreting CSI scores and evaluating treatment responsiveness.

The CSI is a useful and valid instrument for screening patients for the possibility of a CSS, although the chances of false positives are relatively high when evaluating patients with complex pain and psychophysiological disorders.