The Unstoppable Spasm: A Rare Case of Stiff Person Syndrome

Background: Stiff-person spectrum disorders (SPSD) are rare autoimmune neurological conditions characterized by progressive muscle stiffness, painful spasms, and exaggerated startle responses, often leading to severe functional impairment. Diagnosis is frequently delayed due to clinical overlap with other neuromuscular disorders. Case presentation: We report a 45-year-old male with an acute history of progressive axial stiffness, lower-limb rigidity, and episodic painful spasms causing gait disturbance and recurrent falls. Neurological examination revealed marked paraspinal and proximal limb rigidity with preserved sensation and reflexes. Routine laboratory investigations were unremarkable. Serum anti–glutamic acid decarboxylase (GAD65) antibodies were strongly positive. Needle electromyography demonstrated continuous motor unit activity at rest, confirming SPSD. Brain and spinal imaging excluded structural pathology. Management and outcome: The patient was initiated on benzodiazepines and baclofen, which provided partial symptomatic relief. Given the autoimmune profile and progressive disability, a short course of steroids (dexamethasone) was administered, resulting in a significant reduction in spasm frequency and improved gait at 3-month follow-up. Conclusion: This case highlights the importance of considering SPSD in adults presenting with progressive axial rigidity and spasms. Early recognition, supported by Electromyography (EMG) and GAD65 antibody testing, facilitates timely initiation of symptomatic and immunomodulatory therapies, which can markedly improve mobility and quality of life.