Atraumatic Shoulder-Hand Syndrome Presenting as Complex Regional Pain Syndrome Type 1 in an 81-Year-Old Patient With Diabetes Mellitus

Complex regional pain syndrome type 1 (CRPS-1), formerly called reflex sympathetic dystrophy, is defined by the absence of a confirmed nerve lesion and accounts for many CRPS cases."Shoulder-hand syndrome" describes a related but distinct clinical pattern of ipsilateral shoulder and hand involvement that can occur in either CRPS-1 or CRPS-2, the latter defined by a confirmed nerve lesion.CRPS-1 most commonly follows a noxious inciting event, such as fracture, sprain, surgery, or a period of immobilization, that does not involve direct nerve damage.Fully atraumatic presentations are uncommon and represent a diagnostic challenge, particularly in elderly patients with diabetes mellitus, whose overlapping musculoskeletal and neuropathic comorbidities can obscure the underlying pathophysiology.We report a case of an 81-year-old man with a history of long-standing diabetes mellitus who presented to our clinic two months after the onset of his symptoms with progressive pain, swelling, stiffness, and vasomotor and trophic changes of the right shoulder and hand, in the absence of any known inciting event.Examination revealed allodynia, hyperalgesia, decreased skin temperature, erythema, edema, dryness, hair loss, and severe restriction in motion.Plain radiographs and MRI of the hand and shoulder were unremarkable.The inflammatory markers available at the time, including erythrocyte sedimentation rate and C-reactive protein, were normal.The last HbA1c was moderately elevated.Adhesive capsulitis and diabetic cheiroarthropathy were considered given the patient's diabetic status but were excluded on clinical and imaging grounds.The patient fulfilled the Budapest clinical criteria for CRPS-1, with symptoms and signs including the sensory, vasomotor, sudomotor/edema, and motor/trophic domains.After several weeks of physical therapy to no avail, he responded favorably to a high dose of gabapentin.This case underscores the importance of maintaining a high index of suspicion for atraumatic CRPS-1 in older diabetic patients.It illustrates the diagnostic workup required to differentiate it from more common diabetes-associated shoulder-hand pathology.