Complex Regional Pain Syndrome (CRPS) is defined as a syndrome characterized by severe, persistent pain that is disproportionate to the extent of injury, accompanied by abnormalities in the autonomic, sensory, and motor systems [1]. Type 1 refers to cases without nerve damage, while Type 2 occurs following severe nerve injury, with Type 1 accounting for 90 % of cases. Both types present similar clinical symptoms, including burning pain accompanied by changes in skin temperature and color, increased sensitivity, abnormalities in hair and nail growth, joint swelling in the affected area, and impaired motor function [2]. The most common cause of CRPS is fractures (45 %), followed by sprains and surgeries. Less common causes include inflammatory diseases, heart attacks, smoking, genetic factors, and strokes, with less than 10 % of patients developing CRPS without an identifiable cause [3].

Post-stroke CRPS typically presents with clinical features distinct from other types of CRPS. The precipitating event for post-stroke CRPS is often unclear and generally involves pain in the shoulder and wrist joints while sparing the elbow [2], [4]. These clinical characteristics are the basis for referring to post-stroke CRPS as "shoulder-hand syndrome"[5]. Post-stroke CRPS can cause severe pain and swelling, which not only significantly diminish the quality of life but also hinder effective rehabilitation. Without appropriate treatment, it may lead to joint contractures.

Post-stroke CRPS is a significant complication among stroke survivors; however, the precise pathophysiological mechanisms and predictive factors that underlie post-stroke CRPS remain unknown [6]. While numerous studies have identified risk factors for CRPS due to other causes, research specifically focused on identifying the risk factors for post-stroke CRPS is lacking [7], [8]. Some previous studies have indicated that shoulder girdle weakness can lead to instability, subluxation, and immobilization, and that instability-induced shoulder damage may result in abnormal sympathetic nervous activity [9].

In stroke patients, identifying clinical symptoms and signs of CRPS can be challenging due to issues such as altered consciousness, cognitive decline, and aphasia, which may result in overlooked or delayed diagnoses compared to individuals without stroke. Thus, detailed information on risk factors for post-stroke CRPS enables healthcare providers to more effectively identify at-risk patients early. This facilitates the implementation of proactive preventive measures, such as shoulder girdle protection, which can contribute to improving patient outcomes.

Moreover, there is a lack of studies utilizing objective diagnostic tools, such as the Three Phase Bone Scan (TPBS), for CRPS diagnosis.

In this study, we investigated various clinical factors related to demographics, etiology, comorbidities, and stroke severity in order to identify the risk factors for CRPS in subacute first-ever stroke survivors. Additionally, we examined the nutritional status of the patients and certain blood test results related to thrombotic disorders.