Pseudo-Exacerbation in Primary Progressive Multiple Sclerosis: A Case Report

Primary progressive multiple sclerosis (PPMS) is characterised by gradual neurological deterioration from disease onset without distinct relapses. Acute neurological worsening in patients with PPMS can present a diagnostic challenge, particularly when occurring in the context of systemic infection, where pseudo-relapse may mimic disease progression or a true inflammatory relapse. We report the case of a 65-year-old woman with established PPMS who presented with fever, sore throat, and acute bilateral lower-limb weakness. Assessment included a detailed history, neurological examination, and laboratory investigations demonstrating increased inflammatory markers. Neurology review was undertaken to distinguish pseudo-relapse from true relapse. In the absence of new focal neurological deficits and with a probable infective trigger, the episode was considered a pseudo-relapse secondary to presumed pharyngitis. The patient was treated with empirical antibiotics and supportive rehabilitation without corticosteroids. Significant clinical improvement was observed, with return to baseline mobility and functional status. As no contemporaneous MRI was performed, the diagnosis and treatment were based on clinical grounds. At the two-month follow-up, she remained clinically stable with no new neurological deficits. This case highlights the importance of distinguishing pseudo-relapse from true relapse in patients with PPMS presenting with acute neurological deterioration. Careful clinical assessment and recognition of reversible systemic triggers can help avoid unnecessary corticosteroid exposure while ensuring appropriate management of the underlying cause.