Variant restless legs syndrome masquerading as refractory shoulder pain: a case report and literature review

Restless Legs Syndrome (RLS) is a common neurological disorder characterized by an irresistible urge to move the legs, often accompanied by uncomfortable sensations. These symptoms typically worsen during periods of rest or in the evening and are partially or temporarily relieved by movement. Variant RLS is diagnosed when these core symptoms extend to extra-leg regions-such as the arms, abdomen, or bladder-while still fulfilling the diagnostic criteria established by the International Restless Legs Syndrome Study Group. We report a case of an adult female patient with refractory right shoulder pain, ultimately diagnosed as variant RLS. Initially misdiagnosed as frozen shoulder, the correct diagnosis was confirmed through polysomnography, which revealed an elevated Periodic Limb Movement during Sleep index, and a supportive International RLS Rating Scale score. Following targeted treatment involving iron supplements for iron deficiency anemia and pramipexole for symptomatic relief, the patient's shoulder pain and other associated symptoms improved markedly. This case expands the known clinical spectrum of variant RLS by illustrating a pain-dominant upper limb phenotype. Furthermore, we provide a summary analysis of previously reported cases of restless arms syndrome, highlighting the importance of including variant RLS in the differential diagnosis for patients presenting with unexplained shoulder or arm discomfort.