Anti-glutamic acid decarboxylase 65: Related stiff person syndrome – A report of two cases and literature review

Stiff person syndrome is a rare neurological disorder characterized by muscular rigidity, painful spasms, and gait abnormalities. The diagnosis is primarily clinical and often requires a high index of suspicion. While the pathophysiology is not fully understood, stiff person syndrome is frequently associated with anti-glutamic acid decarboxylase 65 antibodies, and in some cases, paraneoplastic syndromes. We present two cases of anti-glutamic acid decarboxylase 65positive stiff person syndrome in the Philippines: a 53-year-old diabetic woman presenting with a classical stiff person syndrome case that responded well to symptomatic treatment, and a 62-year-old woman with a history of thyroiditis presenting with paraneoplastic stiff person syndrome that showed significant improvement on follow up after plasmapheresis and tumor excision. These cases are particularly valuable due to their rare local presentation, contributing to the limited data on stiff person syndrome in our region. This article also includes a review of the existing literature on stiff person syndrome, highlighting key diagnostic and therapeutic approaches. The findings emphasize the importance of early diagnosis and intervention, as well as expanding clinical awareness of this condition in regions where it is not widely recognized.