Further testing for anti–glutamic acid decarboxylase (GAD) antibodies ultimately confirmed a diagnosis of Stiff Person Syndrome (SPS), a rare neuromuscular disorder characterized by progressive muscle rigidity and spasms due to autoimmune pathology. The patient also disclosed a family history of similar symptoms in two maternal aunts, highlighting a potential genetic component of SPS. Following diagnosis, the patient completed three months of IVIG treatment, resulting in modest improvement in gait, though other symptoms persisted.

This case highlights the diagnostic challenges associated with SPS, particularly when symptoms overlap with those of other neuromuscular disorders. Early symptoms, such as persistent chest pain due to intercostal muscle stiffness, may be misattributed to anxiety or other conditions, resulting in delayed diagnosis and treatment. Recognizing these atypical presentations is crucial for improving patient outcomes. A thorough clinical evaluation, including a detailed family history, is essential in patients with progressive neuromuscular symptoms. Increased awareness of SPS and its varied presentations can facilitate timely diagnosis, prevent unnecessary treatments, and improve quality of life for affected individuals.